Effects of wood constituents and content, and glass
森林生态学碳固定关键科学问题
森林生态学碳固定关键科学问题英文回答：Key scientific questions in forest ecology carbon sequestration:1. How does forest structure and composition influence carbon sequestration? Forests are composed of various tree species with different growth rates and carbon storage capacities. Understanding how these factors interact and influence carbon sequestration is crucial. For example, a mixed-species forest with a diverse range of tree sizes and ages may have higher carbon sequestration rates compared to a monoculture forest.2. What are the effects of disturbance events on carbon sequestration in forests? Forests are subject to various disturbances such as wildfires, insect outbreaks, and logging activities. These disturbances can release large amounts of carbon stored in vegetation and soils. Studyingthe recovery process and the long-term effects of disturbances on carbon sequestration can provide insights into forest management strategies. For instance, a study on the impact of wildfire on carbon sequestration in a pine forest may reveal the importance of post-fire reforestation efforts.3. How do climate change and atmospheric CO2 concentrations affect forest carbon sequestration? Rising atmospheric CO2 levels and changing climatic conditions can influence forest productivity and carbon sequestration. Increased CO2 concentrations may enhance photosynthesis and promote tree growth, leading to higher carbon sequestration rates. However, the effects of climate change on forest carbon dynamics can be complex and vary across different forest types and regions. For example, a study on the response of a tropical rainforest to changing precipitation patterns and CO2 levels may reveal the potential impacts on carbon sequestration in these ecosystems.4. What is the role of soil carbon in forest carbon sequestration? Soils play a crucial role in carbonsequestration, as they can store large amounts of organic carbon. Understanding the processes that control soil carbon storage and turnover in forests is essential. For instance, a study on the effects of land management practices, such as forest thinning or organic matter additions, on soil carbon sequestration can provideinsights into sustainable forest management strategies.5. How do forest disturbances and management practices interact with carbon sequestration? Forest management practices, such as timber harvesting or afforestation, can influence carbon sequestration rates. Additionally, disturbances like fire or insect outbreaks can affect the success of management interventions. Understanding the interactions between forest disturbances and management practices is crucial for optimizing carbon sequestration efforts. For example, a study on the combined effects of timber harvesting and wildfire on carbon sequestration in a managed forest can inform sustainable forest management strategies.中文回答：森林生态学碳固定的关键科学问题：1. 森林结构和组成如何影响碳固定？森林由不同生长速度和碳储存能力的树种组成。
树在生态系统中的作用的英语作文
树在生态系统中的作用的英语作文Title: The Role of Trees in EcosystemsTrees are an integral part of ecosystems across the globe, playing a foundational role in maintaining the balance and health of these complex systems. Their significance transcends their mere physical presence, as they perform numerous functions that sustain life in various forms. This essay explores the multifaceted roles of trees in ecosystems, highlighting their impact on environmental stability, biodiversity, and human well-being.One of the primary functions of trees is their contribution to carbon sequestration and oxygen production through photosynthesis. Trees absorb carbon dioxide from the atmosphere, using it as a source of carbon for their growth, and in turn, release oxygen. This process is crucial in regulating the concentration of greenhouse gases in the atmosphere, mitigating the effects of global climate change. By acting as natural 'carbon sinks', trees help in reducing the carbon footprint of ecosystems and the planet at large.Trees are also instrumental in conserving soil integrity and preventing erosion. Their extensive root systems anchor the soil, reducing its vulnerability to water and wind erosion. Thisstabilization ensures that fertile topsoil remains in place, enabling the growth of other vegetation and maintaining the productivity of ecosystems. Furthermore, trees play a vital role in the cycling of nutrients, breaking down dead plant and animal matter into compost, which enriches the soil and supports the growth of various organisms.In addition to their ecological contributions, trees provide habitats for a myriad of species, thereby supporting biodiversity. Different layers of a forest, from the canopy to the understory, create diverse environments that cater to the specific needs of various creatures. These habitats offer food, shelter, and breeding grounds for insects, birds, mammals, and reptiles, among others. Thus, trees serve as keystone structures in ecosystems, around which the diversity of life revolves.Trees also have significant impacts on the hydrological cycle. They contribute to the regulation of water cycles by intercepting rainwater with their leaves, reducing runoff and increasing water infiltration into the soil. This process helps recharge groundwater supplies and maintains the availability of water resources for both ecosystems and human uses. Additionally, the shade provided by trees can moderate soiltemperatures and reduce evaporation rates, further preserving water content in the soil.Lastly, trees are of immense value to human society. They provide materials for construction, fuel, and medicinal purposes, and also offer aesthetic and recreational benefits. Forests and woodlands rich in tree diversity are often sites for ecotourism, allowing people to experience and appreciate the beauty and serenity of nature, which in turn fosters a conservation ethic.In conclusion, the role of trees in ecosystems is both profound and multifaceted. From influencing climate patterns and soil stability to promoting biodiversity and supporting human livelihoods, trees are truly the backbone of life on Earth. Their presence and health are indicators of the overallwell-being of ecosystems, making them invaluable assets that demand our utmost care and protection.。
2016年新托福写作范文素材：种树与保护环境
新托福写作范⽂素材：种树与保护环境 1 While you probably think about planting trees for Arbor Day, you may not know justhow much of an impact tree planting can have on your lawn and energy consumption as well as the environment. Trees can provide shade for your home and lawn as well as a barrier against cold winter winds. They also filter water and air to reduce soil erosion and greenhouse gases. And did you know that trees have also been shown to reduce stress? Manyurban residents find themselves calmer and happier when they are around trees. 2 Energy-saving benefits of planting trees According to the U.S. Department of Agriculture, a young, healthy tree can provide a net cooling effect equivalent to ten room-sized air conditioners operating for 20 hours a day! While it will take a few years for a newly planted sapling to reach the point where it can cast shade on your home, it’s a relatively low-cost investment, and you’ll find it’s worth the wait. Dr. E. Greg McPherson of the Center for Urban Forest Research says that a new tree planted on the western side of your home will reduce your energy bill by about three percent in five years and by close to 12 percent in 15 years. Plus, shade isn’t the only way planting trees can reduce your family’s energy consumption. Trees located on the north and northwest sides of your home can block frigid winter winds and lower your heating bill. 3 Benefit of trees on the environment While planting trees can certainly have a positive impact on your energy bill, sustainable gardening can also positively impact the environment. Trees absorb greenhouse gases like nitrogen dioxide, sulfur dioxide, ozone, carbon dioxide and carbon monoxide. They also convert carbon dioxide to oxygen through photosynthesis.Wondering how that relates to you? Just one tree can clean about 330 pounds of carbon dioxide from the air each year, according to the U.S. Forest Service, which provides enough oxygen for a family of four! One of the reasons planting new trees is seen as sustainable gardening is because they act as air and water filters. In a study conducted by the USDA, it was found that trees were able to remove more than 1,800 metric tons of air pollution from New York City. The roots filter groundwater and control run off and erosion by holding soil in place. They also cool down the air, and not just with shade. The transpiration process they go through releases moisture into the air, producing a cooling effect. 4 Maintaining your trees and lawn Trees are beneficial to the aesthetics of your lawn, your home’s energy bill, and your family’s overall health. For all these reasons, it’s important to properly maintain your trees and the soil they grow in. You don’t want to over-shape new trees or prune too much when you first plant them, but you will have a much healthier tree if you trim back dead branches over the years. There are several options when it comes tooutdoor power equipment to maintain the trees you’ve planted. Chainsaws and pole saws are great choices for cutting down large limbs. They also work well for pruning, whether you need to allow for new growth or prevent branches from hitting obstacles like houses or power lines. There are even battery-operated, cordless saws available to reduce your carbon footprint even further. The shade from the trees you’ve planted will help improve water conservation, so you’ll maintain a lush and green lawn with very little maintenance. However, you should still mow high and often, to avoid roots and promote new grass growth, being especially careful around the base of your trees. You may even want to spread mulch and compost to the drip line and maintain the edge with a string trimmer. 新托福写作范⽂素材摘抄： how much of an impact tree planting can have on your lawn and energy consumption： 植树多⼤程度上影响你的草坪和能源消耗 provide shade for ：提供阴凉 a barrier against cold winter winds：对寒冷的冬天风来说就是个屏障 also filter water and air to reduce soil erosion and greenhouse gases：同时过滤⽔和空⽓减少⼟壤侵蚀和温室⽓体 urban residents find themselves calmer and happier when they are around trees. 城市居民发现⾃⼰平静快乐的时候周围的树⽊。
Deforestation Causes and Effects
Deforestation Causes and Effects Deforestation is a critical issue that has far-reaching causes and effects on the environment, wildlife, and human populations. It is the process of clearing forests for agricultural, commercial, or residential purposes, and it has become a significant concern due to its adverse impact on the planet. The causes of deforestation are multifaceted, including agricultural expansion, logging, infrastructure development, and urbanization. These activities not only lead tothe loss of valuable forest ecosystems but also contribute to climate change, soil erosion, and the extinction of plant and animal species. Furthermore,deforestation has detrimental effects on indigenous communities and local economies, making it a complex and pressing problem that requires immediate attention. One of the primary causes of deforestation is agricultural expansion. As the global population continues to grow, the demand for food and agricultural products has increased exponentially. This has led to the clearing of vast tracts of forested land to make way for large-scale farming operations. In many cases, forests are cleared through slash-and-burn techniques, where trees and vegetation are cut down and set on fire to create fertile land for crops. While this practice may provide short-term benefits for farmers, it has devastating long-term consequences for the environment, including soil degradation, loss of biodiversity, and increased greenhouse gas emissions. Another significant cause ofdeforestation is logging, which involves the extraction of timber for commercial purposes. The logging industry is driven by the demand for wood products,including furniture, paper, and building materials. As a result, forests are systematically harvested, leading to the destruction of valuable ecosystems andthe displacement of wildlife. Moreover, illegal logging practices further exacerbate the problem, as they often involve the destruction of protected areas and the exploitation of vulnerable communities. This not only contributes to deforestation but also fuels corruption and organized crime in many regions around the world. In addition to agricultural expansion and logging, infrastructure development and urbanization are also major contributors to deforestation. Ascities expand and populations grow, there is an increasing need for land to build roads, highways, and residential areas. This has led to the clearing of forests ona massive scale, resulting in the fragmentation and destruction of natural habitats. Furthermore, the construction of dams, mines, and other industrial facilities often requires the clearance of large areas of forested land, leadingto irreversible environmental damage and the displacement of indigenous communities. The effects of deforestation are wide-ranging and have significant implications for the planet and its inhabitants. One of the most immediate consequences of deforestation is the loss of biodiversity. Forests are home to a vast array of plant and animal species, many of which are unique and irreplaceable. When forests are cleared, these species lose their habitats and are often drivento extinction. This loss of biodiversity has profound ecological implications, asit disrupts the delicate balance of ecosystems and can lead to the collapse of entire food chains. Moreover, deforestation has a direct impact on climate change, as forests play a crucial role in regulating the Earth's climate. Trees absorb carbon dioxide from the atmosphere and store it in their biomass, helping to mitigate the effects of greenhouse gas emissions. When forests are cleared, this carbon is released back into the atmosphere, contributing to global warming and climate instability. Furthermore, deforestation reduces the Earth's capacity to absorb carbon dioxide, exacerbating the effects of climate change and leading to more frequent and severe natural disasters. In addition to its environmental consequences, deforestation also has profound effects on indigenous communitiesand local economies. Many indigenous peoples rely on forests for their livelihoods, as they provide food, medicine, and resources for traditional crafts. When forests are cleared, these communities lose their way of life and are often forced to relocate to unfamiliar and inhospitable environments. Furthermore, deforestation can lead to the degradation of soil and water resources, making it difficult for local farmers to sustain their agricultural practices. This, in turn, can lead to food insecurity and economic hardship for communities that are already vulnerable. In conclusion, deforestation is a complex and multifaceted problem that has far-reaching causes and effects. It is driven by a combination of factors, including agricultural expansion, logging, infrastructure development, and urbanization. The consequences of deforestation are dire, including the loss of biodiversity,climate change, and the displacement of indigenous communities. Addressing thisissue requires a concerted effort from governments, businesses, and individuals to promote sustainable land use practices and protect the world's remaining forests. By raising awareness about the causes and effects of deforestation and advocating for conservation and reforestation efforts, we can work towards preserving our planet's invaluable natural resources for future generations.。
托福综合写作之木材的生态认证
托福综合写作之木材的生态认证托福综合写作有很多常考的题材，当然，按照ETS的出题风格，有一些题目还是会再次出现在以后的考试中的。
所以，考过的题目有很好的参考价值。
前程百利小编今天就为大家带来了托福综合写作经常考的一类题目，托福综合写作中的木材生态认证问题。
备考托福的小伙伴，赶紧看过来了!阅读文本部分：In an effort to encourage ecologically sustainable forestry practices, an international organization started issuing certifications to wood companies that meet high ecological standards by conserving resources and recycling materials. Companies that receive this certification can attract customers by advertising their products as ecocertified. Around the world, many wood companies have adopted new, ecologically friendly practices in order to receive ecocertification. However, it is unlikely that wood companies in the United States will do the same, for several reasons.First, American consumers are exposed to so much advertising that they would not value or even pay attention to the ecocertification label. Because so many mediocre products are labeled 'new" or improved,'' American consumers do not place much trust in advertising claims in general.Second, ecocertified wood will be more expensive than uncertified wood because in order to earn ecocertification, a wood company must pay to have its business examined by a certification agency. This additional cost gets passed on to consumers-American consumers tend to be strongly motivated by price, and therefore they are likely to choose cheaper uncertified wood products. Accordingly, American wood companies will prefer to keep their prices low rather than obtain ecocertification.Third, although some people claim that it always makes good business sense for American companies to keep up with the developments in the rest of the world, this argument is not convincing. Pursuing certification would make sense for American wood companies only if they marketed most of their products abroad. But that is not the case—American wood businesses sell most of their products in the United States, catering to a very large customer base that is satisfied with the merchandise.根据阅读文本的内容，看一下文中的词汇和疑难句。
阐述森林保护的多重重要性：一份详尽的英语论述
阐述森林保护的多重重要性：一份详尽的英语论述Forests, often referred to as the "lungs of the earth," play a vital role in maintaining the ecological balance and supporting life on our planet. Their conservation is not just a matter of environmental concern but a comprehensive issue that encompasses economic, social, and cultural aspects. This essay will delve into the multifaceted importance of forest protection, highlighting its significance in each domain.1. Biodiversity and Ecosystem ServicesForests are home to an incredible array of flora and fauna, many of which are still undiscovered or endangered. They serve as habitats for countless species, providing them with food, shelter, and breeding grounds. The intricate web of life in forests supports essential ecosystem services, such as carbon sequestration, water purification, soil fertility, and pollination. These services are crucial for climate regulation, agriculture, and human well-being.2. Climate Change MitigationForests act as carbon sinks, absorbing and storing large amounts of atmospheric carbon dioxide. By protecting and restoring forests,we can mitigate climate change by reducing greenhouse gas emissions. Deforestation, conversely, contributes significantly to global warming, as trees absorb less carbon when they are cut down or burned. Therefore, forest conservation is a critical strategy in the fight against climate change.3. Economic ValueForests are a significant source of income for many communities worldwide. They support industries like timber, non-timber forest products (NTFPs), and ecotourism. NTFPs, such as medicinal plants, mushrooms, and honey, provide livelihoods for millions of people, particularly in developing countries. Sustainable forest management ensures these resources are conserved while benefiting local economies.4. Cultural and Indigenous KnowledgeForests hold immense cultural value for indigenous communities, who have lived in harmony with nature for generations. They possess deep knowledge about the forest's ecosystems and the resources it provides. Preserving forests, therefore, respects their cultural heritage and promotes traditional ecological practices. Moreover, these communities' stewardship can contribute to more sustainableforest management.5. Soil Conservation and Flood PreventionForests act as natural barriers, preventing soil erosion and maintaining water cycles. The roots of trees help stabilize soil, preventing landslides and maintaining riverbanks. During heavy rainfall, forests slow down water flow, reducing the risk of flash floods and preserving downstream habitats.6. Aesthetics and RecreationForests offer recreational opportunities, enhancing mental health and promoting physical well-being. They provide spaces for hiking, camping, birdwatching, and other outdoor activities, contributing to the quality of life for urban dwellers and rural communities alike.In conclusion, forest conservation is a vital necessity for the long-term survival of our planet. It safeguards biodiversity, mitigates climate change, supports economies, preserves cultural heritage, and offers recreational benefits. Recognizing and implementing effective conservation measures is crucial for the well-being of both present and future generations. As we face theongoing challenges of climate change and habitat loss, the importance of protecting forests cannot be overstated.中文翻译：标题：森林保护的多元重要性：一份详尽的论述森林，常被称为“地球之肺”，在维持生态平衡和支持地球生命方面起着至关重要的作用。
3-Wood Structures and Wood as a Structural Material
Wood Structures and Wood as a Structural material
木结构及木材作为结构材料
Softwood and Hardwood
针叶材 与 阔叶材
Frank Lam
林中法
University of British Columbia Vancouver, BC Canada
全球暖效应潜势 (1/2）
GWP is referenced by greenhouse gas emissions measured in the form of CO2 or equivalent amount of CO2 for other greenhouse gases. This measurement includes the emission of CO2 during the production process, such as steel making or cement production 全球变暖潜势是参考温室气体排放量，通过测量CO2 或相 当于CO2 的其它温室气体。这个测量包括 CO2 在加工过 程的排放量，如在钢铁的制造或水泥生产过程中所排放的
Toxity Index cont’d
毒性指数 (续1)
The air toxicity index for the wood house is 74% less than sheet metal and 115% less than concrete 木质房屋空气毒性指数比金属板房屋低74%， 比 混凝土房屋低115%
0.02 -0.41 0.00 0.17 1.18 0.0 0.04 -0.24
50.4 64.3 26.5 24.7 17.5 65.9 72.0 29.4
树木和植物的功能英语作文
树木和植物的功能英语作文英文回答：Trees and plants play a vital role in the Earth's ecosystem, providing numerous functions that support both humans and the environment. Their significance cannot be overstated, as they contribute to the balance and stability of our planet.Foremost, trees and plants act as the primary producers in the food chain. Through photosynthesis, they convert sunlight, carbon dioxide, and water into glucose, which serves as the foundation of the food web. This process generates oxygen, a vital gas for all aerobic organisms. Moreover, trees and plants provide food and shelter for countless animal species, fostering biodiversity and maintaining the ecological equilibrium.Beyond their role in the food chain, trees and plants offer a multitude of environmental benefits. They regulatethe Earth's climate by absorbing carbon dioxide and releasing oxygen, mitigating greenhouse gas emissions and combatting global warming. Their extensive root systems help anchor soil and prevent erosion, protecting against landslides and floods. Additionally, trees and plants contribute to the hydrological cycle by interceptingrainfall and releasing it gradually, reducing runoff and ensuring a steady supply of water resources.Furthermore, trees and plants provide numerous economic and social benefits. They are a source of raw materials for industries such as construction, paper manufacturing, and pharmaceuticals. Their timber is used to build homes, furniture, and countless other products. Additionally, trees and plants play a crucial role in tourism and recreation, offering scenic landscapes, hiking trails, and other recreational opportunities. Their aesthetic value enhances the beauty of our surroundings and contributes to our overall well-being.In urban environments, trees and plants provide shade, reduce air pollution, and mitigate noise levels. Theycreate green spaces that offer respite from the hustle and bustle of city life and promote physical and mental health. Studies have shown that exposure to nature can reduce stress, improve mood, and enhance cognitive function.However, despite their immense value, trees and plants are facing significant threats due to deforestation, pollution, climate change, and invasive species. It is imperative that we take collective action to protect and conserve these precious resources. By planting trees, reducing our carbon footprint, and supporting sustainable forestry practices, we can ensure the continued benefits of trees and plants for generations to come.中文回答：树木和植物的功能。
树木的作用很大英语作文
As a high school student with a keen interest in environmental conservation, I have always been fascinated by the myriad roles trees play in our lives. From the moment I first learned about the importance of trees in elementary school, I have been captivated by their multifaceted contributions to our planet. Here, I wish to share my perspective on the significant role trees hold in our ecosystem and society.Growing up in a suburban neighborhood, I was surrounded by lush greenery, with trees lining the streets and parks. I remember the serene feeling of walking under a canopy of leaves, the cool shade providing a respite from the summer heat. Trees are natures air conditioners, their leaves and branches creating a microclimate that moderates the temperature. This natural cooling effect is not only beneficial for the environment but also for the people who live nearby, reducing the need for artificial cooling systems and thus saving energy.One of the most critical roles trees play is in the process of photosynthesis. They absorb carbon dioxide, a greenhouse gas that contributes to global warming, and release oxygen, which is essential for life on Earth. This process is a natural and efficient way to combat climate change, as trees can store carbon in their wood, leaves, and roots for decades or even centuries.Moreover, trees are the backbone of biodiversity. They provide habitats for countless species of birds, insects, and mammals. The intricate network of branches and leaves forms a complex ecosystem where different species coexist and interact. For instance, I once observed a family of squirrelsplaying and foraging in the branches of an old oak tree in our local park. It was a heartwarming sight that underscored the importance of trees as a sanctuary for wildlife.Trees also play a vital role in water conservation. Their roots help to absorb and retain water, reducing the risk of floods and soil erosion. Additionally, trees can slow down the runoff of rainwater, allowing it to percolate into the ground and recharge aquifers. This is particularly important in urban areas where the prevalence of concrete and asphalt can exacerbate flooding.In terms of aesthetics, trees enhance the beauty of our surroundings. They add color and texture to the landscape, with their changing leaves reflecting the seasons. The sight of a tree in full bloom or a vibrant autumn display can lift spirits and provide a sense of connection to nature that is often missing in our increasingly urbanized world.Economically, trees contribute to the value of properties and the attractiveness of public spaces. They can increase property values by providing shade, privacy, and a pleasant view. Furthermore, trees in urban areas can reduce noise pollution, improve air quality, and even extend the life of buildings by providing shade and protection from the elements.However, the importance of trees is not just confined to their ecological and economic benefits. They also hold cultural and historical significance. Many communities have ancient trees that are revered for their age and the stories they embody. These trees serve as living monuments,connecting us to our past and reminding us of the continuity of life.In conclusion, trees are integral to our existence, providing us with oxygen, cooling our environment, supporting biodiversity, conserving water, enhancing aesthetics, and contributing to our economy and culture. It is our responsibility to protect and nurture these silent sentinels of the natural world. As a high school student, I am committed to raising awareness about the importance of trees and advocating for their conservation. By doing so, we can ensure a greener, healthier, and more sustainable future for generations to come.。
树木对环保的重要性英语作文
树木对环保的重要性英语作文Trees, the silent guardians of our planet, play a pivotal role in environmental protection. They are not just passive components of the natural world; they are active agents in maintaining the health and balance of our ecosystems. The importance of trees to environmental conservation cannot be overstated, as they provide a range of vital services that directly impact the quality of life for all living beings.Firstly, trees are the lungs of our planet. They absorb carbon dioxide, a greenhouse gas that contributes to climate change, and release oxygen, essential for all aerobic life. This process, known as photosynthesis, not only sustains life but also helps mitigate the effects of global warming by reducing the concentration of carbon dioxide in the atmosphere.Moreover, trees act as natural sponges, regulating the water cycle and preventing soil erosion. Their roots bind the soil, preventing it from being washed away by rain or wind. The leaves intercept rainwater, allowing it to percolate slowly into the ground, thus recharginggroundwater reserves and maintaining soil moisture. This process is crucial for water conservation and the sustainability of agricultural practices.Trees also provide habitats for a diverse array of wildlife, from insects and birds to mammals and even microorganisms. These ecosystems are rich in biodiversity and are critical for maintaining the health of our planet. The loss of tree cover often leads to a decline in biodiversity, as many species depend on trees for food, shelter, and breeding grounds.In addition to their ecological value, trees also contribute significantly to our economic and social well-being. They provide timber for construction and other uses, fruits and nuts for nourishment, and medicinal herbs for healing. Trees also offer recreational spaces for people to relax, exercise, and connect with nature. The psychological and emotional benefits of spending time in tree-lined areas are well-documented, with studies showing that contact with nature can reduce stress, improve mood, and enhance overall well-being.Unfortunately, deforestation and forest degradation are major threats to the survival of trees and the ecological services they provide. Human activities such as logging, agricultural expansion, and urbanization have led to the loss of millions of hectares of forest cover worldwide. This loss not only affects the environment but also hasfar-reaching consequences for human society, including climate change, soil degradation, loss of biodiversity, and reduced economic opportunities.To address these challenges, it is crucial toprioritize the conservation and restoration of tree cover. Policies and laws that protect forests from unsustainable activities are essential. At the same time, community-based forest management and education programs can empower local communities to take ownership of their forests and ensure their sustainable use. Individual actions such as planting trees, reducing paper waste, and supporting sustainable forestry practices can also make a significant difference. In conclusion, trees are indispensable to environmental protection. They perform vital functions that support life on our planet, from regulating the climate to providinghabitats for wildlife. The loss of trees is not just an environmental crisis; it is a threat to our economic, social, and cultural well-being. It is time for us to recognize the value of trees and take action to conserve and restore them for the sake of our planet and future generations.**树木：环保的支柱**树木，作为我们星球上无声的守护者，在环保中发挥着至关重要的作用。
植树带来的效应英语作文
Trees are an integral part of our environment,providing a multitude of benefits that contribute to the overall health and wellbeing of our planet.The effects of planting trees are farreaching and multifaceted,encompassing ecological,economic,and social aspects.Ecological Benefits1.Carbon Sequestration:Trees absorb carbon dioxide from the atmosphere,helping to mitigate the effects of climate change.This process,known as photosynthesis,converts carbon dioxide into oxygen,which is essential for life on Earth.2.Biodiversity:Planting trees creates habitats for a variety of species,increasing biodiversity.Different types of trees support different ecosystems,providing food and shelter for numerous forms of wildlife.3.Soil Conservation:Tree roots help to hold soil together,preventing erosion and the loss of fertile topsoil.This is particularly important in areas prone to landslides or where soil degradation is a concern.4.Water Cycle Regulation:Trees play a crucial role in the water cycle by absorbing and releasing water.They help to regulate the amount of water in the atmosphere,reducing the risk of droughts and floods.Economic Benefits1.Timber and NonTimber Products:Trees are a source of timber for construction and furniture,as well as nontimber products like fruits,nuts,and medicinal ingredients.This contributes to local economies and provides income for communities.2.Tourism:Forests and green spaces attract tourists,boosting the local economy through increased spending on accommodations,food,and other services.3.Recreation and Health:Urban green spaces,including parks and treelined streets, provide recreational areas for people to relax and exercise.This can lead to improved mental and physical health,reducing healthcare costs.Social Benefits1.Aesthetic Value:Trees enhance the beauty of urban and rural landscapes,improving the quality of life for residents and visitors alike.munity Engagement:Tree planting initiatives often involve community participation,fostering a sense of ownership and pride in local environments.cational Opportunities:Trees provide a handson way to teach about ecology, environmental stewardship,and the importance of biodiversity.Challenges and ConsiderationsWhile the benefits of tree planting are numerous,there are also challenges to consider:1.Species Selection:Its important to choose native species that are adapted to local conditions,as nonnative species can sometimes become invasive and disrupt local ecosystems.2.Maintenance:Trees require care and maintenance to ensure they grow healthily and do not cause problems,such as root damage to infrastructure.3.Urban Planning:In urban areas,finding space for trees can be a challenge.Planners must consider how to integrate trees into the urban landscape without compromising other necessary services and infrastructure.In conclusion,the effects of planting trees are profound and contribute significantly to the health of our planet.By understanding and addressing the challenges,we can maximize the benefits of tree planting for future generations.。
为什么树重要英语作文
为什么树重要英语作文Title: The Significance of Trees: An English Essay。
Trees are vital components of our ecosystem, playing multifaceted roles that extend far beyond their aesthetic appeal. Their significance encompasses environmental, social, and economic dimensions, making them indispensableto the well-being of both nature and humanity.Firstly, trees are champions of environmental sustainability. Through the process of photosynthesis, they absorb carbon dioxide from the atmosphere, mitigating the effects of climate change by reducing greenhouse gas levels. Furthermore, trees release oxygen, which is essential for the survival of all living organisms, thus maintaining the delicate balance of the Earth's atmosphere. Their extensive root systems also help prevent soil erosion, stabilizing landscapes and preserving fertile land for agriculture.In addition to their environmental benefits, treescontribute significantly to the social fabric of communities worldwide. They provide shade and shelter, creating pleasant outdoor spaces for recreation and relaxation. Parks and forests, adorned with towering trees, serve as gathering places for people to connect with nature and each other. Moreover, urban areas with abundant greenery experience lower levels of stress and improved mental well-being among residents, highlighting the therapeutic value of trees in modern society.Economically, trees are invaluable resources with diverse applications across various industries. The timber industry relies on trees for the production of lumber, paper, and countless other wood products essential for construction, manufacturing, and packaging. Additionally, trees yield fruits, nuts, and other agricultural products that contribute to global food security and provide livelihoods for millions of people worldwide. Furthermore, the tourism sector benefits from attractions such as national parks and botanical gardens, drawing visitors eager to explore the beauty of natural landscapes teeming with diverse flora.Furthermore, trees serve as habitats for a myriad of plant and animal species, fostering biodiversity and ecological resilience. Forests, in particular, areintricate ecosystems teeming with life, where countless species coexist in a delicate balance. The loss of treesand deforestation jeopardize this intricate web of life, leading to the extinction of species and disrupting vital ecological processes essential for the health of the planet.In conclusion, trees are indispensable allies in the fight against environmental degradation and climate change. Their significance extends beyond mere aesthetics, encompassing environmental, social, and economic dimensions crucial for the well-being of both nature and humanity. As stewards of the Earth, it is our collective responsibilityto recognize and safeguard the invaluable contributions of trees to the sustenance of life on our planet. Bypreserving and nurturing these majestic beings, we ensure a greener, healthier, and more sustainable future for generations to come.。
树的重要性用途保护的英语作文
树的重要性用途保护的英语作文The Importance, Uses, and Conservation of Trees.Trees, the towering guardians of our planet, play a pivotal role in maintaining the ecological balance of our environment. Their significance extends far beyond their visible presence, encompassing a range of vital functions that support life on Earth. From providing oxygen and absorbing carbon dioxide to sheltering wildlife andoffering resources for human sustenance, trees are the unsung heroes of our ecosystem.Oxygen Production and Carbon Dioxide Absorption.Trees are nature's efficient machines for converting carbon dioxide into oxygen. Through the process of photosynthesis, they consume carbon dioxide, water, and sunlight to produce glucose and oxygen. This oxygen is then released into the atmosphere, supplying the oxygen we breathe. Without trees, the Earth's oxygen supply woulddwindle, and life as we know it would cease to exist.Habitat and Shelter for Wildlife.Trees provide essential habitat and shelter for a diverse array of wildlife. Their branches, trunks, and crowns offer nesting sites, refuge, and food sources for birds, insects, mammals, and other organisms. Trees also act as corridors for wildlife movement, facilitating the connectivity of ecosystems and the genetic flow of species.Soil Stabilization and Water Conservation.The roots of trees help stabilize soil, preventing erosion and landslides. They bind the soil particles together, creating a strong foundation that holds the ground in place during rainfall and windy conditions. Additionally, trees transpire water, releasing it back into the atmosphere through their leaves. This process helps to maintain humidity levels and regulate the local climate, ensuring that water resources are conserved and recycled effectively.Provision of Resources.Trees are a renewable source of numerous valuable resources, including wood, fruits, nuts, and resins. Woodis used in construction, furniture making, and paper production, among other applications. Fruits and nuts provide nourishment for humans and animals alike, while resins are used in various industries such as perfumes, adhesives, and varnishes.Aesthetic and Cultural Value.Trees add beauty and serenity to our landscapes, providing a sense of tranquility and well-being. They are a symbol of life, growth, and resilience, often used in art, literature, and religion to evoke emotional and spiritual connections. Trees have been integral to human civilization since ancient times, serving as meeting places, monuments, and symbols of community and heritage.The Need for Tree Conservation.Despite their immense value, trees are facing numerous threats today. Deforestation, climate change, urbanization, and soil degradation are among the primary causes of tree loss. The rapid pace of human development has led to the loss of millions of hectares of forested areas, causing a significant imbalance in the Earth's ecosystem.The conservation of trees is crucial for sustainable development and the well-being of future generations. Here are some key measures that can be taken to conserve trees and promote their sustainable use:Afforestation and Reforestation: Planting new trees and regenerating degraded land is essential to restoring and enhancing forest cover. Afforestation refers to the deliberate planting of trees on barren or degraded land, while reforestation involves regenerating natural forests on land that has been cleared or degraded.Sustainable Logging Practices: Ensuring that timber extraction is conducted in a sustainable manner is crucialfor maintaining healthy forests. This involves harvesting trees in a controlled and selective manner, ensuring that the rate of harvesting does not exceed the rate of natural regeneration.Education and Awareness: Educating the public aboutthe importance of trees and the need for their conservation is essential.Raising awareness among individuals and communities about the ecological, economic, and cultural values of trees can foster a culture of respect and carefor them.Urban Greening Initiatives: Incorporating trees and green spaces into urban planning can help mitigate the effects of urbanization on tree cover. Green belts, parks, and street trees can provide valuable habitats for wildlife, improve air quality, and enhance the aesthetic value of urban landscapes.International Cooperation: Combating deforestation and promoting tree conservation requires global cooperation and collaboration. International agreements and treaties suchas the United Nations Framework Convention on Climate Change (UNFCCC) and the Convention on Biological Diversity (CBD) provide platforms for countries to work together towards achieving sustainable forest management and conservation goals.In conclusion, trees are invaluable assets that support our environment, economy, and culture. Their importance extends far beyond their visible presence, encompassing a range of functions that are critical for life on Earth. It is our responsibility to conserve and protect these precious resources, ensuring that they continue to provide us with the benefits they have for generations. By taking concerted action and fostering a culture of respect and care for trees, we can ensure a sustainable future for ourselves and the planet we share.。
树木是否应该砍伐雅思作文
树木是否应该砍伐雅思作文## The Complex Debate of Deforestation: A Multifaceted View The question of whether trees should be felled has sparked heated debates and passionate arguments, dividing opinions across a spectrum of perspectives. It's a complex issue, interwoven with environmental concerns, economic necessities, and social implications. To truly understand the debate, we must delve into the various viewpoints, each with its own merit and motivation. From an environmental standpoint, the argument against deforestation is undeniably strong. Trees are the lungs of our planet, playing a crucial role in maintaining the delicate balance of our ecosystem. They act as natural air purifiers, absorbing carbon dioxide and releasing life-sustaining oxygen. Their extensive root systems prevent soil erosion, while their leaves provide shelter and sustenance for countless species, fostering biodiversity. Deforestation disrupts this intricate balance, leading toa cascade of detrimental consequences. The loss of trees contributes to climate change, intensifies the greenhouse effect, and disrupts rainfall patterns, potentially leading to droughts and floods. The destruction of natural habitats pushes countless species towards extinction, eroding the rich tapestry of life on Earth. However, the economic realities of many developing nations cannot be ignored. For communities reliant on agriculture and logging, forests represent a source of livelihood and economic growth. Timber harvesting provides jobs, generates revenue, and fuels local economies. Agricultural expansion, often achieved through deforestation, allows for increased food production, meeting the needs of growing populations. In regions struggling with poverty and limited resources, the immediate economic benefits of deforestation can outweigh the long-term environmental consequences. This creates a difficult dilemma, forcing achoice between ecological sustainability and economic survival. The social and cultural dimensions of deforestation further complicate the issue. Many indigenous communities have deep-rooted connections to forests, relying on them for food, medicine, shelter, and spiritual practices. Deforestation not only disrupts their way of life but also threatens their cultural identity and ancestral heritage. The displacement of these communities due to deforestation can lead to social unrest, cultural erosion, and the loss of invaluable traditional knowledge aboutsustainable forest management practices. Technological advancements and sustainable forestry practices offer a glimmer of hope in this complex situation. Innovations in agriculture, such as vertical farming and precision agriculture, can help increase food production while minimizing land use. Sustainable logging practices, including selective logging and reforestation efforts, can ensure the long-term viability of forests as valuable resources. Moreover, promoting ecotourism and investing in non-timber forest products can create alternative income sources for communities, reducing their dependence on deforestation. The debate surrounding deforestation is far from simple. It's a multifaceted issue with valid arguments on both sides. While the environmental consequences of deforestation are undeniable, the economic realities and social complexities cannot be ignored. Moving forward, a holistic approach that balances environmental protection with economic development and social equity is crucial. Embracing sustainable practices, investing in technological advancements, and respecting the rights and wisdom of indigenous communities are key steps towards a future where humans and forests can co-exist in harmony.。
大树对环境的作用英语作文
大树对环境的作用英语作文Trees are the silent guardians of our environment, providing a multitude of benefits that are essential for a healthy ecosystem. They absorb carbon dioxide, a major greenhouse gas, and release oxygen, which is vital for the survival of all living beings.In urban landscapes, trees play a crucial role in reducing noise pollution and improving air quality. Their leaves and bark filter out dust and pollutants from the air, creating a cleaner and more pleasant environment for city dwellers.Moreover, trees contribute to the conservation of water resources. They help in the absorption and filtration of rainwater, reducing runoff and preventing soil erosion. This natural water cycle is vital for maintaining the balance of water in our environment.The presence of trees also supports biodiversity by providing habitats for various species of birds, insects, and mammals. They form the backbone of many ecosystems, ensuring the survival of countless forms of life.Furthermore, trees enhance the aesthetic appeal of an area, offering a sense of tranquility and beauty. They can also provide shade and cooling effects, which areparticularly important in warmer climates.In addition to these environmental benefits, trees also have economic value. They can be a source of timber, fruits, and other products that contribute to local economies.Lastly, trees are a testament to the passage of time and the resilience of nature. They stand as living monuments tothe history of the land, inspiring a sense of awe and respect for the natural world.In conclusion, trees are indispensable to the environment. They offer a wide range of ecological, social, and economic benefits that are too valuable to overlook. It is our responsibility to protect and nurture these natural wondersfor the well-being of our planet and future generations.。
The Significance of Protecting Natural Habitats
The Significance of Protecting NaturalHabitatsThe significance of protecting natural habitats cannot be overstated. Natural habitats are not only home to a wide variety of plant and animal species, but they also provide numerous ecosystem services that are essential for human well-being. From providing clean air and water to regulating climate and supporting pollination, natural habitats play a crucial role in maintaining the balance of our planet. In this essay, I will explore the various perspectives on why protecting natural habitats is of utmost importance. From an ecological perspective, natural habitats are the building blocks of biodiversity. They support a vast array of species, each playing a unique role in the ecosystem. When these habitats are destroyed or degraded, it can lead to the loss of species, disrupting the delicate balance of the ecosystem. For example, the destruction of coral reefs can result in the decline of fish populations, which in turn affects the livelihoods of coastal communities that depend on fishing. By protecting natural habitats, we ensure the survival of these species and maintain theintricate web of life on Earth. Beyond biodiversity, natural habitats also provide essential ecosystem services. Forests, for instance, act as carbon sinks, absorbing carbon dioxide from the atmosphere and mitigating climate change. Wetlands help in water purification by filtering pollutants and preventing floods. Mangroves serve as a natural barrier against storm surges, protecting coastal communities from the devastating impacts of hurricanes. These are just a few examples of the invaluable services that natural habitats offer. By safeguarding these habitats, we can mitigate the effects of climate change, ensure clean water sources, and enhance the resilience of communities. Protecting natural habitats is not only crucial for ecological and environmental reasons but also for economic and social well-being. Many communities around the world rely on natural habitats for their livelihoods. Indigenous peoples, for instance, have strong cultural and economic ties to their ancestral lands, which are often rich in biodiversity. By protecting these habitats, we respect their rights and preserve their traditional knowledge, ensuring the continuation of their way of life. Moreover, naturalhabitats also offer opportunities for ecotourism, providing economic benefits to local communities and contributing to sustainable development. Furthermore, protecting natural habitats can have significant health benefits for humans.Studies have shown that spending time in nature can reduce stress, improve mental health, and enhance overall well-being. Natural habitats offer a respite from the fast-paced urban life, allowing people to reconnect with nature and experience its calming effects. By preserving these habitats, we create spaces for recreation and relaxation, promoting a healthier society. While the significance of protecting natural habitats is clear, there are challenges and obstacles that need to be addressed. One major challenge is the encroachment of human activities on these habitats. Deforestation, urbanization, and industrialization are some of the major drivers of habitat destruction. Balancing the needs of human development with the conservation of natural habitats is a complex task that requires careful planning and sustainable practices. It requires collaboration between governments, businesses, and communities to find innovative solutions that minimize thenegative impacts on habitats while still meeting the needs of a growing population. Another challenge is the lack of awareness and understanding about the importanceof natural habitats. Many people are disconnected from nature and fail torecognize the value it provides. Education and awareness campaigns are crucial in fostering a sense of responsibility and encouraging individuals to take action in protecting natural habitats. By raising awareness about the significance of these habitats, we can inspire people to make sustainable choices in their daily livesand support conservation efforts. In conclusion, protecting natural habitats isof utmost importance due to their ecological, environmental, economic, and social significance. They are essential for maintaining biodiversity, providing ecosystem services, supporting livelihoods, promoting human health, and fostering a sense of connection with nature. However, achieving effective habitat protection requires overcoming challenges such as habitat destruction and lack of awareness. Byworking together and taking collective action, we can ensure the preservation of these invaluable habitats for future generations.。
The Formation of Petrified Wood
The Formation of Petrified WoodPetrified wood is a fascinating natural phenomenon that has captured the curiosity of scientists and nature enthusiasts for centuries. The formation of petrified wood is a complex process that involves a combination of geological, chemical, and biological factors. In this response, we will delve into the various perspectives on the formation of petrified wood, exploring the scientific, historical, and cultural significance of this unique natural material.From a scientific perspective, the formation of petrified wood begins with the burial of wood in sedimentary layers. Over time, the wood becomes saturated with groundwater that is rich in minerals such as silica, calcium, and iron. These minerals gradually replace the organic material in the wood, resulting in the formation of a fossilized replica of the original wood. The process of petrification can take millions of years, during which the wood undergoes a series of chemical and structural changes. The end result is a piece of petrified wood that retains the external appearance and cellular structure of the original wood, but is now composed of minerals instead of organic matter.The formation of petrified wood also holds historical significance, as it provides valuable insights into ancient ecosystems and climate conditions. Petrified wood is often found in regions that were once covered by dense forests, indicating that the climate and environmental conditions in these areas were vastly different in the past. By studying the growth rings and cellular structure of petrified wood, scientists can reconstruct the growth patterns of ancient trees and gain a better understanding of past climate fluctuations. This information is crucial for developing accurate models of climate change and understanding the long-term effects of environmental shifts on plant life.In addition to its scientific and historical importance, petrified wood also holds cultural significance for many indigenous communities around the world. In some cultures, petrified wood is revered as a sacred material with spiritual properties. It is often used in traditional healing practices and religious ceremonies, symbolizing strength, endurance, and the interconnectedness of all living beings. For these communities, the formation of petrified wood is not just a geological process, but a reflection of the enduring relationship between humans and the natural world.From an emotional standpoint, the formation of petrified wood evokes a sense of wonder and awe at the immense timescales and transformative power of nature. The idea that a piece of wood can slowly turn into stone over millions of years is a testament to the resilience and adaptability of the natural world. Petrified wood serves as a tangible reminder of the deep history and interconnectedness of all life on Earth, inspiring a sense of humility and reverence for the forces that have shaped our planet over billions of years.In conclusion, the formation of petrified wood is a multifaceted process that encompasses scientific, historical, and cultural dimensions. From its origins as a living tree to its eventual transformation into stone, petrified wood offers valuable insights into the Earth's ancient past and the enduring relationship between humans and the natural world. Whether viewed through a scientific lens, a historical context, or a cultural perspective, the formation of petrified wood continues to captivate and inspire curiosity, reverence, and a deep appreciation for the wonders of nature.。
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Effects of wood constituents and content,and glass fiber reinforcement on wear behavior of wood/PVC composites qSupreeda Jeamtrakull a ,Apisit Kositchaiyong a ,Teerasak Markpin a ,Vichai Rosarpitak b ,Narongrit Sombatsompop a ,⇑aPolymer Processing and Flow (P-PROF)Group,School of Energy,Environment and Materials,King Mongkut’s University of Technology Thonburi (KMUTT),Thongkru,Bangmod,Bangkok 10140,Thailand bV.P.Wood Co.,Ltd.,25/5Moo 4,Soi Suksawad 66,Thongkru,Bangmod,Bangkok 10140,Thailanda r t i c l e i n f o Article history:Received 26April 2011Received in revised form 18August 2011Accepted 23August 2011Available online 3May 2012Keywords:A.Glass fibersB.Mechanical properties A.Natural fiber composites B.Weara b s t r a c tIn flooring applications,experimental data and insight from scientific investigations on wear properties of wood/polymer composites (WPCs)are important for engineers to understand how to design and for-mulate WPC materials with high resistance to wear.In this work,three different types of wood flour –namely Xylia kerrii Craib &Hutch.,Hevea brasiliensis Linn.,and Mangifera indica Linn.–were utilized and incorporated into poly(vinyl chloride)(PVC)with a fixed content (10phr)of E-chopped strand glass fiber.The physical,mechanical and wear properties,in terms of specific wear rate,were then assessed as a function of wood content and sliding distance.The experimental results suggested that the addition of wood flour increased the flexural modulus and strength up to 40phr;beyond this concentration,the flex-ural properties decreased.Hardness was not affected by the addition of wood flour.The mechanical and wear properties of WPVC composites were found to improve with the addition of the E-glass fiber.Xylia kerrii Craib &Hutch.wood exhibited the lowest specific wear rate for non-reinforced WPVC composites,whereas Hevea brasiliensis Linn.wood showed the lowest specific wear rate for the glass fiber reinforced WPVC composites.The longer the sliding distance,the greater the specific wear rate in all cases.Ó2012Elsevier Ltd.All rights reserved.1.IntroductionWood flour was initially used for purposes of cost reduction,and for reducing large amounts of natural fiber wastes in both structural and non-structural applications.Recently,wood flours have been used for reinforcement in polymeric materials,offering wood/polymer composite (WPC)products with low density and better dimension stability.Wood/polymer composites (WPCs)have been developed so that they can now be utilized for building and construction,and in automotive,gardening and outdoor prod-ucts as well as in marine applications [1],although their mechan-ical strengths are still lower than those of natural woods.A large number of research works on WPC have been published;most of these have investigated the mechanical,thermal and morphologi-cal properties of WPC,and how they are affected by the addition of synthetic fibers and nanoparticles [2–6],processing techniques and conditions [7,8],the cross-sectional design of shaping dies [9–11],chemical and physical treatments of wood surfaces [12,13],and the type of thermoplastics used [11].These publishedworks [2–13]have aimed to improve the mechanical properties of WPC in structural applications,in order to compete with the natu-ral woods.The two-body abrasion process that is traditionally applied in woods includes a sanding process for surface finishing;and the use of loose particles in three-body abrasion becomes a major problem in the wear resistance of flooring and construction mate-rials [14,15].The wear behavior of WPC materials is a relatively new area of study,and could be considered to incorporate three separate components:wood,polymer,and WPC.The wear behav-iors of woods [16,17]and polymers [18–20]have been extensively studied,whereas few reports have been published on the wear behavior of WPC materials [1,21].Works by Ohtani and Kamasaki [16]and Ohtani et al.[17]suggested that different types of timber woods resulted in different wear rates obtained,and that this was dependent on the direction of the applied pressure on the wood samples.None of the existing literature has investigated the wear behavior of composite wood flour and thermoplastic materials in light of the effect of wood species.A few recent works [1,21]have attempted to study the wear properties of WPC.Kim et al.[1]revealed that the wear resistance of wood impregnated with poly-ethylene glycol (PEG)was higher than that impregnated with lubricant oil,release agent,and epoxy.This was attributed to the low friction coefficient of PEG.Aurrekoetxea et al.[21]studied1359-8368/$-see front matter Ó2012Elsevier Ltd.All rights reserved./10.1016/positesb.2012.04.031qPart of this manuscript was presented at the 7th Asian-Australasian Conference on Composite Materials (ACCM#7)15–18November 2010,Taipei,Taiwan.⇑Corresponding author.Tel.:+6624708645;fax:+6624708647.E-mail address:narongrit.som@kmutt.ac.th (N.Sombatsompop).wear resistances of pine wood,polypropylene,and wood-rein-forced polypropylene(PP)using a‘‘block-on-ring’’tribometer. The results suggested that the wear rate of pine wood/PP compos-buckling,microfissuring and delamination inherent in the cellular structure of the woodfibers.As stated earlier,published works on the wear behavior ofFig.1.FTIR spectrum for wood particles.Fig.2.Physical morphologies of wood particles:(a)XK,(b)HB,(c)MI. 2722S.Jeamtrakull et al./Composites:Part B43(2012)2721–27292.Experimental 2.1.Raw materials2.1.1.Poly(vinyl chloride)or PVCSuspension PVC was supplied by V.P.Wood Co.,Ltd.(Bangkok Thailand)in the form of powder (trade name,SIAMVIC 258RB)hav-ing a K value of 58.The PVC powder was dry-blended with various necessary additives whose compound formulations were the same as used in our previous work [22].2.1.2.Wood floursThree different types of wood flour particles –namely Xylia kerrii Craib &Hutch.(XK ),Hevea brasiliensis Linn.(HB ),and Mangif-era indica Linn.(MI )–were used.Their chemical structures were characterized by Fourier transform infrared spectroscopy (ATR-FTIR),using a Nexus 470(Thermo-Nicolet Ltd.,USA).All woods were supplied by Pongsiri Co.,Ltd.(Ratchaburi,Thailand).The wood content in all PVC compounds varied from 0to 60parts per hundred (phr)by weight of PVC powder.Wood particles were chemically surface-treated with 1.0wt.%N-2(aminoethyl)-(3-ami-nopropyl)trimethoxysilane (M w =222.4);details regarding the experimental procedure can be found in our previous work [22].2.1.3.Glass fiber reinforcementE-chopped strand (ECS)glass fibers (3mm long and 13l m in diameter)were used to improve the mechanical and wear proper-ties of wood/PVC composites.The E-glass fibers used were supplied by Pongpana Co.,Ltd.(Bangkok Thailand).A silane coupling agent,3-methacryloxypropyl-trimethoxysilane (KBM503)having an average molecular weight of 248.4,was coated on the glass fiber surface.A fixed content of ECS glass fibers (10phr of PVC com-pound)was introduced in the wood/PVC (WPVC)composites.Our previous findings [2,8]suggested that 10phr E-glass fibers could give a relatively good and consistent mixture with WPVC composite for mechanical property improvement in the compres-sion molding process.2.2.Constituents,initial hardness and morphology of wood particles All woods were characterized in terms of constituents and ini-tial hardness properties.Analysis of the constituents of the woods was performed using solvent extraction method,whose experi-mental procedures can be found elsewhere [23].Hardness proper-ties of all woods were measured using wood strip samples,the sample preparation and test procedures following ASTM 2240-05(Shore D hardness).2.3.Preparation of wood/PVC composite specimensSilane-treated wood flour was dried at 80°C for 24h in a hot oven for elimination of residual humidity.WPVC composite speci-mens were directly prepared by blending PVC and treated wood flour at wood concentrations of 0,20,40and 60phr,using a high speed mixer.The dry-blended wood/PVC compound was then filled in a steel mold having a cavity size of 180Â180Â3mm 3,and was plate-shaped by a compression molding machine (LP-S-20laboratory press,Labtech Engineering,Bangkok,Thailand)at a preheating temperature of 180°C and 18MPa compression pres-sure for 7min,before being cooled down to room temperature for 5min.For all glass fiber reinforced WPVC composites,10phr glass fibers were used,and their blending procedures were the same as used for preparation of WPVC composite specimens.T a b l e 1C o n s t i t u e n t s o f w o o d p a r t i c l e s ,i n i t i a l h a r d n e s s a n d p h y s i c a l m o r p h o l o g i e s f o r d i f f e r e n t t i m b e r w o o d s .C o n s t i t u e n tE x t r a c t i o n c o n d i t i o n sC o m p o s i t i o n c o n t e n t (%)X K w o o dH B w o o dM I w o o dE x t r a c t i v e s E t h a n o l :t o l u e n e (2:1),100°C ,5h 563L i g n i n 72%S u l f u r i c a c i d ,w a t e r b a t h 100°C ,2hH o l o c e l l u l o s e 96%A c e t i c a c i d a n d s o d i u m c h l o r i t e ,w a t e r b C e l l u l o s e 17.5%S o d i u m h y d r o x i d e ,r o o m t e m p e r a t u r e ,H e m i c e l l u l o s eW h e m i c e l l u l o s e (w t .%)=W h o l o c e l l u l o s e (w t .%)ÀW c e l l u l H a r d n e s sS E M o f w o o d t i m b e r sS.Jeamtrakull et al./Composites:Part B 43(2012)2721–272927232.4.Characterizations2.4.1.Mechanical propertiesThe mechanical properties of WPVC composites and glassfiber reinforced WPVC composites were investigated throughflexural properties and Shore D hardness(ASTM D2240,2005).Theflexural properties were determined according to ASTM D790(2003):spec-imen dimensions of15Â120mm2,support span of86mm,and a crosshead speed of 1.7mm/min.It should be noted that the mechanical property results reported in this work were averaged from10independent determinations.posite roughnessSurface roughness(Ra)of WPVC composites and glassfiber reinforced WPVC composites were measured using a SV-3000pro-filometer(Mitutoyo,Kawasaki,Japan).A conical stylus with aTable2Effects of type and content of woodflour on mechanical and physical properties of WPVC composites.Wood Mechanical properties Physical propertyType Content Hardness(Shore D)SD Flexuralmodulus(MPa)Flexuralstrength(MPa)SD Roughness(l m)SDXK078 1.7121917 4.1 3.20.4 2078 1.1176533 2.8 3.80.24081 1.8208134 3.1 4.10.46081 1.0210332 5.8 4.30.5HB078 1.7121917 4.1 3.20.4 2078 1.6175533 1.4 4.00.84079 1.6193632 2.4 4.40.36080 1.3157625 5.2 4.50.9MI078 1.7121917 4.1 3.20.4 2081 1.0177830 2.9 4.10.24082 1.5225138 3.3 4.20.36082 1.1213033 5.6 4.20.3(a)Sliding distance of 0.5 km (c)Sliding distance of 1.5 km (b)Sliding distance of 1.0 km (d)Sliding distance of 2.0 kmcontent of woodflour on specific wear rate of WPVC composites at various sliding distances:(a)0.5km,(b)1.0 2724S.Jeamtrakull et al./Composites:Part B43(2012)2721–2729spherical tip of2l m radius and60°cone angle was used;the sty-lus speed was0.5mm/s.The roughness results reported in this work were averaged fromfive independent determinations.2.4.3.Specific wear ratesWear tests were performed using a Taber5130Abraser(Taber Industries,North Tonawanda,NY)with abrasive wheels(CS-17) which were attached to a load of250g,following ASTM D4060 (2007)for determinations of specific wear rates of neat PVC,WPVC, and glassfiber reinforced WPVC composites.The specimen dimen-sions used were120Â120Â3mm3.The sliding distance varied from0.5to2.0km.The specific wear rate(K)was measured by determination of weight loss of the test specimen,which can be calculated using the following equation[24]:K¼D MLF qð1Þwhere D m is the weight loss(mg),L is the sliding distance(m),F is the applied load(N)and q is specimen density(g/cm3).2.4.4.Scanning electron microscope(SEM)investigationMorphologies of wood particles and worn WPVC composite sur-faces,with and without E-glassfiber in WPVC composites,were investigated using a JSM-6301F scanning electron microscope (JEOL,Tokyo,Japan)at15kV accelerating voltage.Details of the experimental procedure and sample preparation can be found ina previous work[25].3.Results and discussion3.1.Chemical,morphological and physical characterizations of wood flours usedThe chemical structures of XK,HB and MI by FTIR technique are shown in Fig.1.It can be seen that all woodflours used had similar chemical functional groups,suggesting that the differences in the mechanical properties of wood/PVC(WPVC)composites obtained were not caused by the differences in the chemical functional groups among these three woodflours.Fig.2shows the initial morphologies for XK,HB and MI wood particles by SEM technique. All types of woods had an average particle size of100–250l m.The aspect ratios for XK,HB and MI woodflour were measured to be 4.78,1.63and4.96,respectively.The constituents and initial hardness results of woodflours used are shown in Table1.It can be observed that all woods had different proportions of cellulose and hemicellulose,and their hardness results obtained from the original wood timbers.It has been established that the cellulose portion enhances the rigidity of the wood:the greater the cellulose content,the higher the hard-ness[14,17].The opposite effect is found for hemicellulose content. XK wood appeared to have the lowest hemicellulose content(66%), the highest cellulose content(45%),and the highest hardness value (71Shore D);thus XK is regarded as a hard wood.MI had the high-est content of hemicellulose(69%)and the lowest initial hardness (49Shore D),and was regarded as a soft wood in this work.The SEM texture surfaces for all woods were also different:i.e.HB and MI woods were relatively less compact(high porosity)com-pared with XK wood.It should be noted that the differences in as-pect ratios,constituents and initial hardness values,as well as the textures of these three woods,will be taken into account when analyzing the differences in the mechanical and wear properties of WPVC.3.2.Physical and mechanical properties of WPVC compositesTable2shows the physical roughness and mechanical proper-ties of WPVC composites containing three different types of wood particles and various wood contents.The results showed that the hardness values for WPVC composites with three different wood types were very similar,the differences being within an acceptable experimental error range(+/À2.0%),although the initial hardness values for these three woods(Table1)were different.The worn surfaces of WPVC composites for different wood types at60phr wood content at a sliding distance ofdifferences in the hardness results were because the hardness of the WPVC composites was measured on the surface of composites,whereas the wood particles were embedded underneath and with-in the PVC matrix.However,it was also found that increasing wood content tended to result in higher hardness.Similar behavior was also observed for roughness result and flexural modulus.The flex-ural strength increased with increasing wood content up to 40phr,and then slightly decreased at a wood content of 60phr (except for HB wood).The increases in the flexural properties indicated PVC reinforcement by the wood particles,whereas the decreases in the flexural properties probably resulted from difficulty in dispers-ing the wood particles around the PVC matrix due to high wood content [2,26–28].Regarding the effect of wood type,it was found (Fig.2)that for any given wood contents,the flexural properties decreased in the order of:MI,XK and HB wood.Since the chemical functional groups on the surfaces of these three wood types were the same,the dif-ferences in flexural properties found in this work were not caused by the differences in chemical functional groups on the wood sur-faces.Therefore,the results should be explained in terms of differ-ences in physical forms and constituents of these three woods.The higher flexural properties of WPVC with MI and XK woods were caused by the higher aspect ratios of the MI and XK woods (see Fig.2).The higher flexural properties for MI as compared with XK wood was associated with the high porosity of MI wood,which al-lowed the PVC to penetrate into the fiber body during processing;this would probably form a physical interlocking,and result in greater flexural properties of the WPVC composite.3.3.Specific wear rate of WPVC compositesFig.3a–d shows the specific wear rates for WPVC composites with XK,HB and MI woods at different wood contents (0–60phr),and for sliding distances of 0.5,1.0,1.5and 2.0km.In general,as the sliding distance increased the specific wear rate appeared to in-crease (as one would expect).For 0.5–1.0km sliding distances,the specific wear rates of WPVC composites for all wood contents were not different,taking the experimental error bars into account.However,the effects of wood type and content became more pro-nounced as the sliding distances were increased to 1.5and 2.0km.The addition of wood particles into the PVC matrix enhanced the wear resistance of the WPVC composite,indicating the wood rein-forcement in the PVC matrix.This view was in line with the results of hardness,roughness and flexural properties as given in Table 2.The increased wear resistance of the WPVC composites by the addition of wood was because the wood particles were more rigid than PVC and had the ability to resist the force exerted on the WPVC sample.At high sliding distances (1.5–2.0km),it was found that the specific wear rates for WPVC composites with XK and MI woods appeared to decrease up to 40and 20phr,respectively,and then started to increase at higher wood contents.The reduc-tions of the specific wear rates were caused by the wood reinforce-ment,as mentioned earlier.The optimal wood content of XK wood to obtain the highest wear resistance (lowest specific wear rate)of WPVC composites was higher than that of MI ,due to the greater stiffness of XK wood compared to MI wood (see Table 1).Above the optimal wood contents (40–60phr for MI and 60phr for XK ),the specific wear rates increased.This was probably caused by the three-body abrasion effect [29],where wood particles escape from the WPVC surface during abrasion testing.The abrasive ac-tion of hard wood debris is exhibited on the surface of the WPVC sample,as seen in SEM micrographs in Fig.4showing the scratch lines on the worn surface of an XK -filled PVC composite sample.The differences in the magnitude of increase in the specific wear rates between XK and MI were related to the differences in the ini-tial hardness of these two woods,as indicated in Table 1.T a b l e 3E f f e c t s o f t y p e a n d c o n t e n t o f w o o d flo u r o n m e c h a n i c a l a n d p h y s i c a l p r o p e r t i e s o f W P V C c o m p o s i t e s w i t h o u t a n d w i t h g l a s s fib e r .W o o d t y p eM e c h a n i c a l p r o p e r t i e sP h y s i c a l p r o p e r t yT y p eC o n t e n tH a r d n e s s (S h o r e D )F l e x u r a l m o d u l u s (M P a )F l e x u r a l s t r e n g t h (M P a )R o u g h n e s s (l m )W i t h o u t G FS DW i t h 10%G FS D%C h a n g eW i t h o u t G FS DW i t h 10%G FS D%C h a n g eW i t h o u t G FS DW i t h 10%G FS D%C h a n g eW i t h o u t G FS DW i t h 10%G FS D%C h a n g eX K0781.7800.9+312194.124073.3+97174.1393.3+1223.20.43.51.0+920781.1811.0+417652.832533.5+84332.8493.5+503.80.23.80.3+140811.8821.1+120813.133441.3+61343.1491.3+474.10.43.70.2À960811.0831.4+221035.834254.1+63325.8514.1+614.30.54.00.5À9H B0781.7800.9+312194.124073.3+97174.1393.3+1223.20.43.51.0+920781.6800.8+317551.428962.6+65331.4512.6+574.00.83.50.4À1440791.6821.0+419362.431753.5+64322.4513.5+614.40.33.70.2À1660801.3821.1+315765.236043.1+129255.2483.1+934.50.93.90.6À14M I0781.7800.9+312194.124073.3+97174.1393.3+1223.20.43.51.0+920811.0801.6À117782.927983.0+57302.9413.0+364.10.24.20.2+140821.5831.6+122513.334165.5+52383.3465.5+214.20.34.00.3À660821.1831.1+121305.635454.2+66335.6454.2+344.20.34.20.5À22726S.Jeamtrakull et al./Composites:Part B 43(2012)2721–2729In the case of the specific wear rate result for WPVC composite with HB woodflour in Fig.3,it was noticeable that the specific wear rate gradually decreased with increasing wood content,and showed no optimal wood content for specific wear rate under the experimental conditions used in this work.Again,the effect was more evident for higher sliding distances(1.5–2.0km).The wear behavior for WPVC composites with HB were different from those with XK and MI woods,because the HB wood had a much lower aspect ratio and tended to give relatively low reinforcement [30–33]as opposed to XK and MI woods.It should be stressed again that the differences in the properties of WPVC composites found in this work were not caused by the differences in chemical func-tional groups on the wood surfaces.3.4.Effect of glassfiber reinforcementTable3shows the physical and mechanical properties of WPVC composites without and with10phr glassfiber reinforcement for three different types of wood particles and various wood contents. The results clearly indicate that the addition of10phr glassfiber into WPVC composites greatly improved theflexural modulus and strength–by52–129%and21–93%,respectively,depending on the type and content of woodflour added.However,the hard-ness and roughness of the WPVC composites hardly changed with the addition of10phr glassfiber,due to the embedding action of wood particles within the PVC matrix.Fig.5a and b shows a comparison of specific wear rates for WPVC composites at a sliding distance of0.5km,without and with 10phr glassfiber reinforcement;and Fig.5c and d illustrates the specific wear rate results for a sliding distance of2.0km for WPVC composites without and with10phr glassfiber reinforcement.The results clearly indicate that the addition of glassfiber resulted in an improvement of the wear resistance(reduced specific wear rate)of WPVC composites,the effect being more pronounced for a sliding distance of2.0km.Among the three wood types used,HB appeared to give the lowest specific wear rate for the glassfiber reinforced WPVC composites.This result was different from that for the WPVC samples without glassfiber given in Fig.3,which indicated that XK gave the lowest specific wear rate.The decreased specific wear rate of the glassfiber reinforced WPVC specimen at2.0km in Fig.5d is supported by SEM micrographs showing the appear-ances of the glassfiber on the worn WPVC surface with the addi-tion of40phr XK wood to resist the abrasive forces exerted(see Fig.6).This seems to confirm that the addition of glassfiber can en-hance the mechanical properties and wear resistance of wood/PVC composites.4.ConclusionsThe experimental results suggested that the differences in the mechanical properties and wear behavior of WPVC composites found in this work were associated with the aspect ratio and constituents of the wood particles,and the initial wood hardness(c) without glass fiber at 2.0 km(d) with glass fiber at 2.0 km(a) without glass fiber at 0.5 km(b) with glass fiber at 0.5 kmcontent of woodflour on specific wear rate of WPVC composites at two different sliding distances:(a)without glassfiber glassfiber at2.0km,(d)with glassfiber at2.0km.S.Jeamtrakull et al./Composites:Part B43(2012)2721–27292727values of the three woods used.The hardness of WPVC composites did not change with increasing wood content,whereas theflexural properties of WPVC composites tended to increase with wood con-tent up to40phr.Mangifera indica Linn.gave the WPVC with high-estflexural properties.The wood particles with high aspect ratio (Xylia kerrii Craib&Hutch.,and Mangifera indica Linn.)acted as reinforcement by reducing the specific wear rate of PVC.The opti-mum content of wood particles for highest wear resistance was dependent on the constituents of wood,aspect ratio and sliding distance.Xylia kerrii Craib&Hutch.at40phr gave the lowest spe-cific wear rate for WPVC composites at a sliding distance of2.0km, whereas Hevea brasiliensis Linn.gave the lowest specific wear rate for the glassfiber reinforced WPVC composites.The addition of glassfiber increased theflexural modulus and strength by52–129%and21–93%,respectively,as well as the wear resistance. 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