Influence of Planting Spacing on Mechanical Properties of Eucalyptus grandis × E. urophylla Pla
tpo32三篇托福阅读TOEFL原文译文题目答案译文背景知识
tpo32三篇托福阅读TOEFL原文译文题目答案译文背景知识阅读-1 (2)原文 (2)译文 (5)题目 (7)答案 (16)背景知识 (16)阅读-2 (25)原文 (25)译文 (28)题目 (31)答案 (40)背景知识 (41)阅读-3 (49)原文 (49)译文 (53)题目 (55)答案 (63)背景知识 (64)阅读-1原文Plant Colonization①Colonization is one way in which plants can change the ecology of a site.Colonization is a process with two components:invasion and survival.The rate at which a site is colonized by plants depends on both the rate at which individual organisms(seeds,spores,immature or mature individuals)arrive at the site and their success at becoming established and surviving.Success in colonization depends to a great extent on there being a site available for colonization–a safe site where disturbance by fire or by cutting down of trees has either removed competing species or reduced levels of competition and other negative interactions to a level at which the invading species can become established.For a given rate of invasion,colonization of a moist,fertile site is likely to be much more rapid than that of a dry, infertile site because of poor survival on the latter.A fertile,plowed field is rapidly invaded by a large variety of weeds,whereas a neighboring construction site from which the soil has been compacted or removed to expose a coarse,infertile parent material may remain virtually free of vegetation for many months or even years despite receiving the same input of seeds as the plowed field.②Both the rate of invasion and the rate of extinction vary greatly among different plant species.Pioneer species-those that occur only in the earliest stages of colonization-tend to have high rates of invasion because they produce very large numbers of reproductive propagules(seeds,spores,and so on)and because they have an efficient means of dispersal(normally,wind).③If colonizers produce short-lived reproductive propagules,they must produce very large numbers unless they have an efficient means of dispersal to suitable new habitats.Many plants depend on wind for dispersal and produce abundant quantities of small,relatively short-lived seeds to compensate for the fact that wind is not always a reliable means If reaching the appropriate type of habitat.Alternative strategies have evolved in some plants,such as those that produce fewer but larger seeds that are dispersed to suitable sites by birds or small mammals or those that produce long-lived seeds.Many forest plants seem to exhibit the latter adaptation,and viable seeds of pioneer species can be found in large numbers on some forest floors. For example,as many as1,125viable seeds per square meter were found in a100-year-old Douglas fir/western hemlock forest in coastal British Columbia.Nearly all the seeds that had germinated from this seed bank were from pioneer species.The rapid colonization of such sites after disturbance is undoubtedly in part a reflection of the largeseed band on the forest floor.④An adaptation that is well developed in colonizing species is a high degree of variation in germination(the beginning of a seed’s growth). Seeds of a given species exhibit a wide range of germination dates, increasing the probability that at least some of the seeds will germinate during a period of favorable environmental conditions.This is particularly important for species that colonize an environment where there is no existing vegetation to ameliorate climatic extremes and in which there may be great climatic diversity.⑤Species succession in plant communities,i.e.,the temporal sequence of appearance and disappearance of species is dependent on events occurring at different stages in the life history of a species. Variation in rates of invasion and growth plays an important role in determining patterns of succession,especially secondary succession. The species that are first to colonize a site are those that produce abundant seed that is distributed successfully to new sites.Such species generally grow rapidly and quickly dominate new sites, excluding other species with lower invasion and growth rates.The first community that occupies a disturbed area therefore may be composed of specie with the highest rate of invasion,whereas the community of the subsequent stage may consist of plants with similar survival ratesbut lower invasion rates.译文植物定居①定居是植物改变一个地点生态环境的一种方式。
植物对我们的影响英语作文
植物对我们的影响英语作文The Profound Impact of Plants on Our Lives.Plants, the silent yet powerful inhabitants of our world, have a profound impact on our lives. They are notjust static components of our environment; they are dynamic, vital, and essential to our survival and well-being. From the air we breathe to the food we eat, plants touch every aspect of our existence.Oxygen Production.At the fundamental level, plants are responsible for oxygen production. Through the process of photosynthesis, plants convert sunlight, water, and carbon dioxide into oxygen and glucose. This oxygen is then released into the atmosphere, providing the essential gas for animal respiration, including our own. Without plants, the oxygen levels in the air would deplete, and life as we know it would cease to exist.Food Production.Plants are also the primary source of food for most of the world's population. From grains and vegetables tofruits and nuts, plants provide us with a diverse array of nutrients. They are rich in vitamins, minerals, and fiber, essential for maintaining good health. Agriculture, the practice of cultivating plants for food production, hasbeen a cornerstone of human civilization, shaping ourhistory and culture.Medicinal Uses.Plants have also played a crucial role in medicine. For centuries, people have relied on plants for their healing properties. Herbal medicine, a form of alternative medicine, uses plants to treat various ailments. From common colds to serious diseases, plants like ginseng, turmeric, and cannabis have been used to alleviate symptoms and promote health.Ecological Balance.Plants are essential for maintaining ecological balance. As the primary producers in most ecosystems, they provide energy and nutrients to other organisms through the food chain. They also play a crucial role in soil stabilization, preventing erosion and desertification. Additionally,plants provide habitats for wildlife, fosteringbiodiversity and ecological diversity.Aesthetic Value.Plants add beauty and tranquility to our lives. Gardens, parks, and forests are spaces where we can escape thehustle and bustle of daily life and connect with nature.The colors, shapes, and textures of plants provide visual interest and joy, enhancing our environment andcontributing to our mental well-being.Economic Importance.Plants are also economically significant. Theagriculture industry, which relies heavily on plant production, is a major contributor to global economies. The demand for plant-based products, such as food, fuel, and fibers, drives economic growth and employment opportunities. Additionally, the horticulture industry, which specializesin cultivating ornamental plants, generates significant revenue and employment.Cultural Significance.Plants hold a special place in many cultures. They are often symbols of life, fertility, and renewal. Various cultures have incorporated plants into their religions, traditions, and artforms. The use of plants in festivals, ceremonies, and rituals adds depth and meaning to cultural practices.In conclusion, plants have a profound impact on our lives. They provide us with oxygen, food, medicine, and so much more. They maintain ecological balance, add beauty to our world, and have significant economic and cultural value. As we move forward in our technological and industrializedworld, it is important to remember the role plants play in our existence and to cherish and protect them.。
保护植物的英语作文
Protecting plants is an essential aspect of preserving our environment and ensuring the sustainability of our ecosystems.Here are some key points to consider when writing an essay on this topic:1.Introduction:Begin by highlighting the importance of plants in our lives.Mention how they provide oxygen,food,and habitats for various species.2.Importance of Plants:Elaborate on the various roles plants play in the ecosystem. Discuss their contribution to the food chain,their role in the water cycle,and their ability to prevent soil erosion.3.Threats to Plant Life:Discuss the various threats that plants face today,such as deforestation,pollution,climate change,and invasive species.4.Consequences of Not Protecting Plants:Explain the negative impacts of not protecting plants,including loss of biodiversity,disruption of ecosystems,and the potential for increased greenhouse gas emissions.5.Individual Actions:Suggest ways in which individuals can contribute to plant conservation.This could include planting trees,reducing paper waste,and supporting local nurseries that sell native plants.munity and Government Initiatives:Describe largerscale efforts that can be undertaken by communities and governments to protect plant life.This might involve creating protected areas,implementing reforestation programs,and enforcing laws against illegal logging.7.Technological Solutions:Mention how technology can aid in plant conservation,such as using drones for monitoring deforestation or employing apps that help identify and report illegal logging activities.cation and Awareness:Stress the importance of educating the public about the need to protect plants.Awareness campaigns can help change attitudes and behaviors towards the environment.9.International Cooperation:Discuss the role of international agreements and cooperation in plant conservation,such as the Convention on Biological Diversity and the efforts of organizations like the World Wildlife Fund WWF.10.Conclusion:Summarize the main points of your essay and reiterate the importance ofprotecting plants.Encourage readers to take action and contribute to the preservation of plant life.Remember to use clear and concise language,provide evidence to support your arguments,and maintain a logical flow throughout your essay.。
植树带来的效应英语作文
植树带来的效应英语作文Title: The Effects of Tree Planting。
Tree planting is a practice that holds immense significance in various aspects of our lives and the environment. The act of planting trees not only contributes to the beautification of our surroundings but also brings about a plethora of positive effects that extend far beyond aesthetic appeal. In this essay, we will explore the multifaceted effects of tree planting and its profound impact on the environment, economy, and society.First and foremost, tree planting plays a crucial role in mitigating the adverse effects of climate change. Trees act as natural carbon sinks, absorbing carbon dioxide from the atmosphere during photosynthesis and storing it intheir biomass. By reducing the concentration of greenhouse gases in the atmosphere, trees help alleviate global warming and its associated consequences, such as rising temperatures, erratic weather patterns, and sea-level rise.Therefore, widespread tree planting initiatives are essential in combating climate change and preserving the habitability of our planet for future generations.Moreover, trees play a vital role in maintaining ecological balance and biodiversity. Forests serve as habitats for numerous plant and animal species, providing them with food, shelter, and breeding grounds. The preservation of natural habitats through tree planting efforts is crucial for the conservation of endangered species and the overall health of ecosystems. Additionally, trees help prevent soil erosion by stabilizing the soil with their roots, thereby preserving fertile land for agriculture and reducing the risk of landslides in hilly terrain.Furthermore, tree planting has significant economic benefits for communities and nations. Forests contribute to the economy through the provision of timber, fuelwood, and non-timber forest products such as fruits, nuts, and medicinal plants. The forestry sector also generates employment opportunities in various activities such as treeplanting, forest management, and wood processing industries. Additionally, trees enhance property values and attract tourists, thereby stimulating local economies andsupporting livelihoods.In addition to its environmental and economic benefits, tree planting has positive social impacts as well. Green spaces and urban forests created through tree planting initiatives improve the quality of life in urban areas by providing recreational opportunities, promoting physicaland mental well-being, and reducing air and noise pollution. Trees also have aesthetic value, enhancing the visualappeal of neighborhoods, parks, and streetscapes. Moreover, tree planting projects often foster community engagementand social cohesion as people come together to participatein tree planting events and environmental conservation efforts.In conclusion, tree planting is a powerful tool for addressing a wide range of environmental, economic, and social challenges facing our planet. From mitigatingclimate change and preserving biodiversity to supportingsustainable development and enhancing quality of life, the benefits of tree planting are manifold and far-reaching. Therefore, it is imperative that we continue to prioritize and invest in tree planting initiatives as part of our collective efforts to build a greener, healthier, and more sustainable future for all.。
为什么说植物对我们很重要 英文 作文
为什么说植物对我们很重要英文作文如下：Title: The Importance of Plants to Our LivesPlants are an integral part of our world, providing a multitude of benefits that are essential for the survival and well-being of all living beings. Their importance cannot be overstated, as they play a crucial role in maintaining the balance of ecosystems, contributing to human health, and supporting various industries. Here are several reasons why plants are so vital to us:1. Oxygen Production: One of the most fundamental reasons plants are important is their ability to produce oxygen through the process of photosynthesis. Oxygen is vital for respiration in animals and humans, allowing us to convert food into energy. Without plants, the atmospheric oxygen levels would decrease, making it difficult for life as we know it to exist.2. Carbon Dioxide Reduction: Alongside producing oxygen, plants absorb carbon dioxide from the atmosphere during photosynthesis. This helps regulate the Earth's greenhouse gas levels and mitigate the impacts of climate change. As such, plants act as natural carbon sinks, helping to cool the planet and maintain a stable climate.3. Food Source: Plants provide a primary source of nutrition for humans and animals alike. Cereal crops like wheat, rice, and corn form the basis of many diets around the world, while fruits and vegetables supply essential vitamins, minerals, and fiber. Without plants, our food supply would be drastically reduced, leading to food scarcity and malnutrition.4. Medicinal Properties: Many plants have medicinal properties that can cure diseases or alleviate symptoms. From traditional remedies to modern pharmaceuticals, plant-based medicines save countless lives each year. Compounds derived from plants are used to treat illnesses ranging from cancer to anxiety, demonstrating the profound impact of plants on healthcare.5. Habitat and Ecosystem Support: Plants provide habitats for a wide array of species,from the tiniest insects to large mammals. They also form the base of many food chains, supporting biodiversity within ecosystems. The loss of plant life could lead to the collapse of these intricate webs, resulting in diminished biodiversity and ecological imbalance.6. Soil Conservation: Plants, especially those with extensive root systems, help prevent soil erosion by holding the soil together. This is particularly important in areas prone to flooding or high winds. By protecting the soil, plants ensure that it remains fertile for future generations and continue to support terrestrial life.7. Aesthetic and Recreational Value: The beauty and diversity of the plant kingdom contribute significantly to our quality of life. Parks and gardens filled with plants offer spaces for relaxation and recreation, improving mental health and overall well-being. Additionally, floriculture and horticulture are forms of art and science that engage and inspire people worldwide.8. Economic Importance: The agricultural industry, which relies heavily on plants, is a major contributor to global economies. Crops and plant-based products are traded internationally, creating jobs and income for millions. Furthermore, the plant-based goods sector includes not only food but also timber, paper, textiles, and more –all of which are integral to modern society.9. Climate Regulation: Plants help regulate local and global climates through processes like transpiration, where they release water vapor into the atmosphere. This can influence rainfall patterns and contribute to the cooling effect known as urban greening, which can make cities more livable by reducing heat island effects.10. Education and Research: Plants provide invaluable resources for scientific research and education. Studying plants enhances our understanding of biology, ecology, genetics, and more. Innovations in plant science have led to breakthroughs in agriculture, medicine, and environmental conservation.In conclusion, plants are vital to our existence in numerous ways, from sustaining the air we breathe and the food we eat to enriching our culture and economy. It isimperative that we recognize their importance and work to protect and preserve them for future generations. By doing so, we ensure the continued health and prosperity of our planet and all its inhabitants.。
写植树的英语作文
Planting trees is an important environmental activity that contributes significantly to the health of our planet.Here are some key points to consider when writing an essay on this topic:1.Introduction to the Topic:Begin by explaining the significance of trees in our ecosystem.Mention how trees provide oxygen,absorb carbon dioxide,and support biodiversity.2.Importance of Trees:Elaborate on the various roles trees play in the environment. Discuss their ability to prevent soil erosion,regulate climate,and provide habitats for wildlife.3.Environmental Benefits:Highlight the environmental benefits of tree planting.This could include reducing air pollution,lowering temperatures in urban areas,and increasing the overall green cover of the land.4.Economic Benefits:Discuss how trees can also have economic benefits,such as providing timber,fruits,and other resources,as well as contributing to tourism and recreation.5.Social Benefits:Mention the social benefits of tree planting,such as improving mental health by providing green spaces for relaxation and recreation,and fostering a sense of community involvement.6.Challenges in Tree Planting:Address the challenges that can be faced during tree planting initiatives.This may include issues like finding suitable land,ensuring the survival of saplings,and dealing with pests and diseases.7.Strategies for Successful Tree Planting:Suggest strategies for overcoming these challenges,such as selecting native species,using proper planting techniques,and providing ongoing care and maintenance.ernment and Community Involvement:Discuss the role of governments and communities in promoting tree planting.Mention policies,incentives,and public awareness campaigns that can encourage participation in tree planting activities.9.Personal Actions:Encourage readers to take personal action by planting trees in their own gardens or participating in community tree planting events.10.Conclusion:Summarize the importance of tree planting and reiterate the benefits itbrings to the environment,economy,and society.End with a call to action,urging everyone to contribute to this cause.Remember to use clear,descriptive language and provide examples or case studies to support your points.Writing an essay on tree planting is an opportunity to raise awareness about the importance of this activity and to inspire others to take part in environmental conservation efforts.。
种植植物的重要性英语作文
种植植物的重要性英语作文英文回答：Plants play a vital and multifaceted role in ourplanet's ecosystem and human well-being. Their significance extends beyond their aesthetic appeal, providing us with a myriad of benefits that are essential for sustaining lifeon Earth.Ecological Importance:Carbon Sequestration: Plants absorb carbon dioxidefrom the atmosphere, mitigating the effects of climate change.Oxygen Production: Plants release oxygen into the air, which is essential for all living organisms.Soil Conservation: Plant roots help to anchor the soil, preventing erosion and preserving soil fertility.Habitat Provision: Plants provide shelter and food for a wide range of wildlife, including insects, birds, and mammals.Biodiversity: Plants contribute to the Earth's biodiversity, supporting a vast array of plant and animal species.Economic Importance:Agriculture: Plants are the foundation of our food supply, providing us with fruits, vegetables, grains, and other essential nutrients.Timber Industry: Trees are used for construction, furniture, and paper products.Pharmaceuticals: Plants contain various compounds that have been used for centuries in traditional medicine and modern pharmaceuticals.Tourism: Natural landscapes dominated by plantsattract tourists, generating revenue for local economies.Climate Regulation: Plants help to regulate temperature and humidity levels in local environments.Health and Well-being:Air Purification: Plants remove pollutants and allergens from the air, improving air quality.Stress Reduction: Studies have shown that exposure to plants can reduce stress levels and promote relaxation.Herbal Medicine: Plants are used in herbal medicine to treat a wide range of illnesses, from minor ailments to chronic conditions.Improved Sleep: Plants such as lavender and chamomile have been found to promote sleep and reduce anxiety.Physical Activity: Gardening and other outdooractivities involving plants encourage physical activity and improve overall health.Conclusion:Plants are indispensable to our planet and our lives. Their ecological, economic, and health benefits highlight the profound importance of preserving and cultivating plant life. By protecting and nurturing our plant resources, we ensure a sustainable future for generations to come.中文回答：植物的重要性。
关于plant的英语八年级作文开头
The Beauty and Importance of Plants in OurLivesPlants, the silent yet powerful life forms that dot our world, are often overlooked in the hustle and bustle of daily life. However, their presence and role in our lives are far more significant than we might realize. From the fresh air we breathe to the delicious food we eat, plants are an integral part of our existence.The importance of plants in our environment cannot be overstated. They purify the air by absorbing carbon dioxide and releasing oxygen, creating a healthy atmosphere for us to breathe. Furthermore, plants act as natural filters, trapping harmful pollutants and toxins before they can harm us. Imagine walking into a room filled with lush green plants; the feeling of tranquility and freshness is instantly noticeable. This is because plants not only enhance the aesthetic value of our spaces but also contribute to our overall well-being.Plants also play a crucial role in maintaining the ecological balance of our planet. They provide food and shelter to a vast array of animals, from insects to birdsand mammals. The intricate web of life that plants supportis essential for the survival of many species. In addition, plants contribute to soil conservation and water cycle, ensuring that our planet remains fertile and hydrated.Moreover, plants have a profound impact on our mental health. Studies have shown that interacting with plants can reduce stress levels, improve concentration, and enhance overall mood. Gardens and green spaces have become increasingly important in urban settings, where theyprovide a sense of tranquility and connectivity with nature. In conclusion, plants are not just simple life forms; they are vital components of our environment, economy, and society. It is our responsibility to appreciate and carefor them, ensuring their survival and prosperity for generations to come. By understanding and recognizing the importance of plants in our lives, we can create a healthier, more beautiful, and sustainable world.**植物在我们生活中的美丽与重要性**植物，这些静谧而强大的生命体点缀着我们的世界，常常在日常生活的喧嚣中被忽视。
助剂_380_对杀菌剂在芒果叶片上展着能力的影响
热带作物学报2022, 43(8): 1646 1653Chinese Journal of Tropical Crops助剂380对杀菌剂在芒果叶片上展着能力的影响闫超1，辜柳霜1，刘志军2，叶火春1，朱发娣1，张静1，冯岗1*1. 中国热带农业科学院环境与植物保护研究所，海南海口 571101；2. 华南农业大学，广东广州 510632摘要：当今现有农药利用率低造成一系列社会问题，如非靶标生物和人畜安全受影响，以及环境污染等。
如何提高现有农药的利用率迫在眉睫。
为提高芒果生产中杀菌剂的有效利用率，结合芒果的特性，研究添加农药助剂对杀菌剂在芒果叶片上润湿展布性和农药持留量的影响，为农药的高效利用提供理论指导。
本研究以防治芒果细菌性角斑病的杀菌剂为研究对象，通过测定液体在芒果叶片的接触角及不同浓度液体的表面张力，根据表面张力及接触角结果，获取芒果叶片的临界表面张力以及助剂的临界胶束浓度（critical micelle concentration, CMC）。
通过添加助剂，分析其对药液在芒果叶片表面上展布和最大持留量（maximum retention, Rm）的影响。
本研究中，助剂380从实验室前期研究基础上筛选得到，结果表明，助剂380可以降低药液表面张力，增加药液在叶面的润湿展布，对常用细菌性角斑病防治药剂表面张力值的降低范围为23.54%~75.94%，最低可达(17.62±0.65)mN/m，低于芒果叶片的临界表面张力；且加入助剂的药液能很好地在芒果叶面上展布，在芒果叶上的持留量显著增加，最大增加率为203.53%。
因此，在芒果细菌性角斑病防治过程中，可以通过添加助剂380来提升药液在作物叶面的展布效果和持液量，从而提高农药的利用率。
关键词：助剂380；杀菌剂；接触角；表面张力；最大持留量中图分类号：S436.67；TQ450.1.2 文献标识码：AInfluence of Adjuvant 380 to the Adhesion Property of Fungicides on Mango LeavesYAN Chao1, GU Liushuang1, LIU Zhijun2, YE Huochun1, ZHU Fadi1, ZHANG Jing1, FENG Gang1*1. Institute of Environment and Plant Protection, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan 571101, Chi-na;2. Agricultural University of South of China, Guangzhou, Guangdong 510632, ChinaAbstract: Nowadays, the low effective utilization rate of existing pesticides has caused a series of social problems, such as the impact on the safety of non target organisms, human and livestock, and even environmental pollution. How to improve the utilization of existing pesticides is more urgent and necessary. Therefore, in order to improve the utilization of existing pesticides, the effects of pesticide additives playing an important role on the wetting distribution and pesti-cide retention of fungicides on mango leaves were studied in combination with crop characteristics, so as to provide theoretical guidance for improving the utilization rate of mango fungicides. Through measuring the contact angle of liquid in mango leaves and the surface tension of different concentrations of liquid, according to the results of surface tension and contact angle, the critical surface tension of mango leaves and the critical micelle concentration (CMC) of additives were obtained. The effects of additives on the distribution and maximum retention (Rm) of liquid medicine on the surface of mango leaves were analyzed. In this study, the fungicide for the control of mango bacterial angular spot was used as the research object. The effects of adjuvant 380 to different fungicides on the wetting property and retention on mango leaves were studied. According to the results of γ and contact angles tested by a contact angle/interfacial ten-sion meter, the critical surface tension value of mango leaves and the critical micelle concentration (CMC) of adjuvant 380 were determined. The selected concentration of adjuvant 380 was added to different fungicides to analyze the 收稿日期 2021-11-15；修回日期 2022-03-09基金项目 海南省高层次人才项目（No. 322RC752）；国家重点研发计划项目（No. 2017YFD0202100）；中国热带农业科学院托举人才项目（No. 1630042019011）。
植树作文模板六级英语高中
植树作文模板六级英语高中Title: The Importance of Planting Trees。
Introduction。
The act of planting trees has been a tradition in many cultures for centuries. Trees are not only essential for the environment but also for the well-being of all living beings on the planet. In this essay, we will explore the importance of planting trees and the impact it has on our planet.Body。
Firstly, planting trees helps in combating climate change. Trees absorb carbon dioxide and release oxygen through the process of photosynthesis. This helps in reducing the levels of greenhouse gases in the atmosphere, which in turn helps in mitigating the effects of global warming. By planting trees, we can contribute to the fight against climate change and its devastating effects on the planet.Secondly, trees play a crucial role in maintaining the ecological balance. They provide habitats for a wide variety of wildlife, including birds, insects, and mammals. Trees also help in preventing soil erosion and maintaining the fertility of the soil. In addition, they contribute to the water cycle by absorbing water from the ground and releasing it into the atmosphere through transpiration. Without trees, the delicate balance of the ecosystem would be disrupted, leading to a loss of biodiversity and ecological stability.Furthermore, planting trees has numerous benefits for human health and well-being. Trees provide shade and cool the air, which helps in reducing the urban heat island effect in cities. They also improve air quality by filtering out pollutants and particulate matter. Studies have shown that being in the presence of trees can have a calming and stress-reducing effect on people, leading to improved mental and physical health. By plantingtrees in urban areas, we can create healthier and more livable environments for people to thrive in.Moreover, planting trees can have a positive impact on the economy. Trees provide valuable resources such as timber, fruits, and nuts, which can be used for various purposes. They also contribute to the tourism industry by attracting visitors to natural landscapes and forests. Additionally, trees increase the value of properties and contribute to the aesthetic appeal of neighborhoods and communities. By investing in tree planting initiatives, we can create sustainable economic opportunities and improve the overall quality of life.Conclusion。
植树对地球的影响英语作文
Planting trees has a profound impact on our planet, and it is an essential activity for maintaining the health of the Earths ecosystems. Here is a brief essay on the positive effects of tree planting:Title: The Impact of Tree Planting on EarthIntroduction:The Earth is a vibrant and diverse ecosystem, and trees play a crucial role in sustaining its balance. Tree planting is not just an act of environmental stewardship it is a commitment to the future health and vitality of our planet.Body:1. Carbon Sequestration:Trees are natural carbon sinks, absorbing carbon dioxide from the atmosphere and storing it in their tissues. This process, known as carbon sequestration, helps to mitigate the effects of climate change by reducing the amount of greenhouse gases in the atmosphere.2. Biodiversity:By planting trees, we create habitats for a wide variety of species, from insects and birds to mammals. This increase in biodiversity is essential for the stability of ecosystems and contributes to the overall health of the environment.3. Soil Conservation:The roots of trees help to bind 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 significant issue.4. Water Cycle Regulation:Trees play a vital role in the water cycle by absorbing and releasing water through a process called transpiration. This helps to regulate local climates, reduce the risk of flooding, and maintain water quality in rivers and streams.5. Air Quality Improvement:In addition to carbon sequestration, trees also filter pollutants from the air, improving air quality and providing cleaner air for humans and wildlife to breathe.6. Economic Benefits:Forests and trees contribute to the economy through timber, nontimber forest products,and ecotourism. They also provide raw materials for industries such as paper and furniture manufacturing.7. Mental Health Benefits:Interacting with nature, including trees, has been shown to reduce stress and improve mental wellbeing. Urban green spaces, including parks and community gardens, are increasingly recognized for their role in promoting public health.Conclusion:The act of planting trees is a simple yet powerful way to contribute to the health of our planet. It is a collective effort that requires the participation of individuals, communities, and governments. By understanding and embracing the impact of tree planting, we can work towards a more sustainable and resilient future for all life on Earth.。
植物对人类环境动物的重要性英语作文
Plants are the silent heroes of our planet, playing a pivotal role in maintaining the health and balance of our environment. Their significance extends far beyond their aesthetic appeal, encompassing the vital functions they perform for both humans and animals. This essay aims to delve into the multifaceted importance of plants, analyzing their role from various perspectives and adhering to high-quality standards.Firstly, plants are crucial for the purification of air and water. Through the process of photosynthesis, plants convert carbon dioxide into oxygen, a vital gas for both humans and animals to breathe. Additionally, plants act as natural filters, absorbing pollutants and toxins from the air and water, helping to cleanse our environment. This purifying function is particularly important in urban areas, where air pollution can be a significant issue.Moreover, plants provide food and shelter for a wide range of animals. From fruits and vegetables to grains and nuts, plants are the primary source of nutrition for many species. They also offer shelter and nesting sites, providing safe havens for animals to rest and reproduce. This symbiotic relationship between plants and animals is integral to the health and diversity of our ecosystems.Furthermore, plants contribute to soil fertility and erosion control. Their roots stabilize the soil, preventing it from being eroded by wind and water. At the same time, plants release organic matter into the soil, enriching it with nutrients that are essential for plant growth. This cycle of fertility and erosion control is crucial for maintaining the fertility of our agricultural lands and preserving the integrity of our natural landscapes.From a cultural perspective, plants hold immense value. They have been used in traditional medicines, dyes, and other crafts for centuries. Many cultures revere plants for their spiritual significance, incorporating them into their rituals and ceremonies. Plants also play a vital role in the tourism industry, attracting visitors to gardens, parks, and natural landscapes.Additionally, plants contribute to climate regulation. Forests and othervegetative areas act as carbon sinks, absorbing and storing carbon dioxide from the atmosphere. This helps to mitigate the effects of climate change, reducing the concentration of greenhouse gases and potentially slowing down global warming.However, the importance of plants is often overlooked or underestimated. The unchecked deforestation, urbanization, and pollution are putting immense pressure on plant populations, leading to their decline and extinction. This, in turn, has a domino effect on the environment and animals, disrupting the delicate balance of our ecosystems.Therefore, it is crucial that we recognize and appreciate the significance of plants. We must take concerted efforts to protect and conserve them, ensuring that they continue to thrive and perform their vital functions. This includes adopting sustainable practices, promoting reforestation, and reducing pollution.In conclusion, plants are indispensable to our environment, animals, and humans. They purify our air and water, provide food and shelter for animals, contribute to soil fertility and erosion control, and hold immense cultural and spiritual value. Their role in climate regulation is also crucial, helping to mitigate the effects of climate change. our responsibility to safeguard these vital organisms, ensuring that they continue to enrich our lives and our planet. By doing so, we can ensure a healthier, more sustainable future for all.To further elaborate on the significance of plants, we must also consider their economic importance. The agricultural industry, which relies heavily on plants, is a major contributor to global economies. Crops such as wheat, rice, and corn are staples of human diets, while fruits, vegetables, and other plant-based products are essential for maintaining good health. The demand for these products drives economic growth and creates jobs in rural areas.Moreover, plants play a crucial role in the tourism industry. Natural landscapes, gardens, and botanical gardens attract millions of tourists every year, generating significant revenue for local economies. This, in turn,supports job creation and infrastructure development in these areas.Plants also have significant medicinal value. Many plants have been used for centuries in traditional medicine to treat various ailments. Today, scientific research is uncovering the healing properties of plants, leading to the development of new drugs and therapies. The pharmaceutical industry, which relies on plants as a source of medicine, is a multibillion-dollar industry that contributes significantly to global health and well-being.In addition to their economic and medicinal value, plants also contribute to our mental and emotional well-being. The presence of plants in our living spaces can reduce stress, improve mood, and enhance overall well-being. Green spaces and parks provide opportunities for recreation and relaxation, promoting physical and mental health.In conclusion, plants are invaluable to our environment, animals, and humans. They purify our air and water, provide food and shelter, contribute to soil fertility and erosion control, hold cultural and spiritual significance, and play a crucial role in climate regulation. Additionally, plants have significant economic, medicinal, and mental health benefits.。
植物生存的重要性英语作文
Plants are an integral part of the Earths ecosystem,playing a crucial role in sustaining life on our planet.Here are some key reasons why the survival of plants is of paramount importance:1.Oxygen Production:Plants are the primary producers of oxygen through the process of photosynthesis.They convert carbon dioxide and sunlight into oxygen and glucose, which is essential for the respiration of most living organisms,including humans.2.Carbon Sequestration:By absorbing carbon dioxide during photosynthesis,plants help to mitigate the effects of climate change.They act as natural carbon sinks,reducing the amount of greenhouse gases in the atmosphere.3.Food Source:Plants are the foundation of the food chain.They provide direct nourishment for herbivores and indirectly for carnivores and omnivores.Many staple foods,such as grains,fruits,and vegetables,are derived from plants.4.Soil Conservation:Plant roots help to hold the soil together,preventing erosion and maintaining soil fertility.They also contribute to the water cycle by absorbing and releasing water,which helps to regulate the climate.5.Habitat Provision:Plants provide habitats for a multitude of species.Forests, grasslands,and wetlands are home to countless animals and insects,supporting biodiversity.6.Medicine:Many plants have medicinal properties and have been used for centuries to treat various ailments.Modern medicine also relies on plantderived compounds for the development of new drugs.7.Economic Value:Plants are a source of raw materials for various industries,including textiles,paper,and construction.They also contribute to the economy through agriculture and tourism.8.Cultural Significance:Plants have been central to human culture,religion,and art. They symbolize growth,renewal,and the cycle of life.9.Aesthetic Value:Plants enhance the beauty of the natural and urban landscapes, providing a sense of tranquility and wellbeing.cational Value:The study of plants,known as botany,is a significant field of science that helps us understand the complexities of life and the environment.In conclusion,the importance of plant survival cannot be overstated.They are essential for the health of our planet and the wellbeing of all living beings.It is our responsibility to protect and preserve plant life for future generations.。
分层接种对猪粪厌氧干发酵产气性能及微生物群落结构的影响
第37卷第1期农业工程学报V ol.37 No.1 2021年1月Transactions of the Chinese Society of Agricultural Engineering Jan. 2021 251分层接种对猪粪厌氧干发酵产气性能及微生物群落结构的影响李丹妮1，高文萱1，张克强1，孔德望2，王思淇1，杜连柱1※（1. 农业农村部环境保护科研监测所，天津300191；2.杭州能源环境工程有限公司，杭州310020）摘要：为避免厌氧干发酵酸抑制，提高产气效率，以猪粪和玉米秸秆为发酵原料，采用中温批式试验，在总固体（Total Solid, TS）为20%、接种比为25%的条件下研究分层接种和混合接种对猪粪干发酵厌氧消化性能的影响。
结果表明：2种接种方式下的发酵体系内挥发性脂肪酸（V olatile Fatty Acids,VFAs）均发生明显积累，其中，分层接种在第15天的TVFAs 质量浓度达到33.0 mg/g，之后明显降低，至发酵结束时VFAs消耗殆尽。
混合接种从第15天至发酵结束，TVFAs质量浓度维持在29.2～38.5 mg/g高水平范围内。
分层接种的累积挥发性固体甲烷产率为211.5 mL/g。
高通量测序结果显示，氢营养型产甲烷途径在2种接种方式下均占主导，但分层接种增加了发酵体系中微生物的丰富度和多样性，且群落结构更加稳定。
进一步分析表明，乙酸和pH值是影响厌氧干发酵中微生态结构的主要环境因子。
该研究结果为解除畜禽养殖废弃物酸抑制、提高产气效率提供理论依据与有益借鉴。
关键词：发酵；粪；微生物群落；分层接种；混合接种doi：10.11975/j.issn.1002-6819.2021.01.030中图分类号：X705 文献标志码：A 文章编号：1002-6819(2021)-01-0251-08李丹妮，高文萱，张克强，等. 分层接种对猪粪厌氧干发酵产气性能及微生物群落结构的影响[J]. 农业工程学报，2021，37(1)：251-258. doi：10.11975/j.issn.1002-6819.2021.01.030 Li Danni, Gao Wenxuan, Zhang Keqiang, et al. Influences of layer inoculation on biogas production and microbial community in solid-state anaerobic fermentation of pig manure[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2021, 37(1): 251-258. (in Chinese with English abstract) doi：10.11975/j.issn.1002-6819.2021.01.030 0 引 言近年来，中国的沼气产业发展迅速，已经成为最大的生物质能源产业之一[1]，随着畜禽养殖向集约化、规模化发展方式转变，沼气发酵成为消纳养殖废弃物应用最广泛的有效措施之一[2]。
植物对地球的重要性英语作文
植物对地球的重要性英语作文The Crucial Role of Plants in Sustaining Our Planet.Plants play a pivotal role in maintaining the health and vitality of our planet. They are the primary producers of food and oxygen, contributing significantly to the ecological balance and overall well-being of life on Earth. This essay delves into the multifaceted importance of plants to our environment, economy, and society.Firstly, plants are the foundation of the food chain. As autotrophs, they convert sunlight, water, and carbon dioxide into glucose and oxygen through photosynthesis. This process not only sustains plant life but also provides energy and nutrients for other organisms. Animals,including humans, rely on plants as a source of food,either directly or indirectly. Without plants, the food chain would collapse, leading to a catastrophic decline in biodiversity and the collapse of ecosystems.Moreover, plants are crucial for maintaining the carbon cycle and mitigating climate change. Through photosynthesis, plants absorb carbon dioxide from the atmosphere, helpingto reduce greenhouse gas concentrations. They then store carbon in their tissues, roots, and soils. This carbon sequestration is vital for balancing the carbon cycle and mitigating the impacts of climate change. Additionally,plant-based solutions, such as afforestation and reforestation, are being increasingly recognized aseffective means of reducing carbon emissions and enhancing climate resilience.Plants also contribute significantly to soil health and erosion control. Their roots stabilize soil particles, preventing erosion and enhancing soil fertility. Plantlitter and dead roots decay, releasing nutrients thatenrich the soil, supporting the growth of futuregenerations of plants. This cycle ensures soil fertilityand productivity, vital for sustainable agriculture andfood security.Economically, plants are a critical resource forindustries ranging from agriculture to pharmaceuticals. The agricultural sector, which relies heavily on plants forfood and fiber production, is a significant contributor to global GDP. Plants also provide raw materials for biofuels, bioplastics, and other sustainable products, driving innovation and growth in renewable industries. In addition, plants have been a rich source of medicinal compounds, yielding cures for various diseases and conditions.Plants also play a therapeutic role in human life, offering stress relief and promoting well-being.Gardening, for instance, is a popular hobby that promotes relaxation and improves mental health. The presence of plants indoors has been shown to improve air quality, reduce stress levels, and enhance overall well-being.Moreover, plants are an integral part of cultural and spiritual practices worldwide. They have been used inrituals and ceremonies, symbolizing life, death, rebirth, and transformation. Plants have also been a source of inspiration for art, literature, and music, reflectingtheir profound connection to human experience andimagination.In conclusion, plants are invaluable to the health and sustainability of our planet. They are the lifeblood of ecosystems, providing food, oxygen, and habitat formillions of species. Their role in carbon sequestration,soil health, and erosion control is crucial for mitigating climate change and maintaining soil fertility. Economically, plants drive growth and innovation in various industries, from agriculture to pharmaceuticals. Furthermore, they play a significant role in human well-being, offering stress relief, therapeutic benefits, and cultural significance.As we move forward, it is crucial to recognize and appreciate the crucial role of plants in our lives. We must strive to protect and conserve plant diversity, promote sustainable agriculture, and integrate plants into ourdaily lives. By doing so, we can ensure a healthier, more sustainable future for ourselves and the planet we share.。
八年级上册英语植物的重要性作文
The Vital Importance of PlantsPlants play a pivotal role in our lives, serving as the foundation of our ecosystem and contributing significantly to our well-being. Their importance is multifaceted, extending from their role in maintaining environmental balance to their practical applications in various aspects of human life.Firstly, plants are essential for the production of oxygen. Through the process of photosynthesis, plants convert carbon dioxide and water into glucose and oxygen. This oxygen is then released into the atmosphere, vital for the respiration of all living organisms, including humans. Without plants, the oxygen levels in the atmosphere would deplete, leading to the extinction of most life forms.Moreover, plants regulate the climate and mitigate the effects of climate change. They absorb carbon dioxide, a greenhouse gas that contributes to global warming, and store it in their tissues. This process helps reduce the atmospheric concentration of carbon dioxide, thusmitigating the negative impacts of climate change. Additionally, plants provide shade and cool the surroundingair, creating a more comfortable environment for humans and other organisms.Plants also serve as a source of food and medicine for humans. Many plants provide fruits, vegetables, grains, and other edible parts that are essential for human nutrition. Furthermore, numerous plant species have medicinal properties and are used to treat various ailments and diseases. Herbal remedies derived from plants have been used for centuries in traditional medicine systems, and many modern drugs are also derived from plant-based compounds.Beyond their environmental and practical benefits, plants also enrich our lives culturally and spiritually. They beautify our surroundings, adding color and life to our landscapes. Gardens and parks filled with plants provide spaces for relaxation and recreation, enhancing our quality of life. Additionally, plants have been a source of inspiration for artists, poets, and philosophers throughout history, reflecting their deep connection with humanculture and spirit.In conclusion, plants are indispensable to life on Earth. Their role in maintaining environmental balance, providing food and medicine, and enriching our cultural and spiritual lives is immense. It is crucial that we recognize and appreciate the vital importance of plants and strive to protect and conserve them for future generations.**植物的重要性**植物在我们的生活中扮演着至关重要的角色，它们不仅是生态系统的基础，而且对我们的福祉有着重大贡献。
植物对人类重要性的作文英语
植物对人类重要性的作文英语Plants play a crucial role in our daily lives. They not only beautify our environment but also provide us with essential resources. For instance, many plants are a source of food for both humans and animals. Fruits, vegetables, grains, and nuts all come from plants, and they are packed with nutrients that our bodies need.In addition to nourishment, plants also have therapeutic benefits. Herbal remedies have been used for centuries to treat various ailments. The essential oils extracted from plants can soothe our minds and bodies, providing natural relief from stress and anxiety.Another important aspect of plants is their ability to purify the air. Through photosynthesis, plants absorb carbon dioxide and release oxygen, making our environment more breathable. Indoor plants can also improve air quality in our homes and offices, helping us breathe easier.Moreover, plants contribute significantly to biodiversity. They are habitats for countless species of animals, insects, and microorganisms, all of which play vital roles in maintaining the balance of our ecosystems. The loss of plant species can have devastating effects on the rest of the food chain.Lastly, plants bring joy and comfort to our lives. Whether it's the sight of blooming flowers in spring or the rustling of leaves in autumn, plants add beauty and tranquility to our surroundings. They provide a source of inspiration and a connection to nature that we all need in today's fast-paced world.。
植物对我们的影响英语作文
植物对我们的影响英语作文英文回答：Plants have a profound and intricate relationship with humans, influencing our physical, mental, and emotional well-being in countless ways. They provide us with sustenance, oxygen, and shelter, purify our air and water, and offer a sanctuary for relaxation and contemplation.Physical Health.Plants are the ultimate source of nutrition for humans, providing us with essential vitamins, minerals, carbohydrates, and proteins. Fruits, vegetables, and grains form the foundation of a healthy diet, helping to prevent chronic diseases such as heart disease, stroke, type 2 diabetes, and certain types of cancer. Plants also contain antioxidants, which protect our cells from damage by free radicals.Mental Health.Studies have shown that spending time in nature has a positive impact on mental health. Exposure to plants can reduce stress, anxiety, and depression. It can also improve mood, boost creativity, and enhance cognitive function. The act of gardening has been found to have therapeutic benefits, providing a sense of accomplishment and connection with the natural world.Environmental Health.Plants play a vital role in maintaining the health of our planet. They absorb carbon dioxide from the atmosphere, helping to mitigate climate change. They also release oxygen into the air, which is essential for life. Plants filter pollutants from the air and water, and they help to stabilize soil and prevent erosion.Spiritual Health.For many cultures around the world, plants havespiritual significance. They are often associated with deities, spirits, and ancestors. Plants are used in religious ceremonies, rituals, and healing practices. They can provide a sense of connection to the divine and to the natural world.Aesthetic Beauty.Plants add beauty and color to our surroundings, enhancing our quality of life. They can create a sense of peace and tranquility, and they can inspire creativity and joy. Plants are used in landscaping, gardening, andinterior design to create visually appealing and stimulating environments.Economic Value.Plants are an important economic resource. They are used to produce food, beverages, medicines, cosmetics, and building materials. The cultivation of plants, including agriculture and forestry, is a major industry that employs millions of people worldwide.Challenges.While plants provide us with numerous benefits, there are also some challenges associated with their abundance. Invasive plant species can disrupt ecosystems and threaten native plants. The excessive use of pesticides and herbicides can harm plants and pollinators. Deforestation and habitat loss pose threats to plant biodiversity.Conclusion.Plants are a precious gift to humankind. They sustain our physical, mental, emotional, and spiritual well-being. They protect our environment and provide us with economic benefits. It is essential that we cherish and protect plants, ensuring their continued existence for generations to come. By fostering a harmonious relationship with the plant kingdom, we can create a more sustainable and fulfilling world for ourselves and our descendants.中文回答：植物对我们的影响。
学会种植技能的重要性英文作文高中
学会种植技能的重要性英文作文高中The Importance of Learning Planting SkillsIn today's fast-paced world, many people have become disconnected from nature and the food they eat. As a result, there is a growing interest in learning how to grow one's own food through planting skills. Planting skills are not only important for those who want to become self-sufficient but also for those who want to contribute to sustainable agriculture and food security. In this essay, we will discuss the importance of learning planting skills in high school.First and foremost, learning planting skills in high school can help students develop a better understanding and appreciation of the natural world. By getting their hands dirty and seeing how plants grow and thrive, students can gain a deeper appreciation for the beauty and complexity of the natural world. This can foster a sense of stewardship and responsibility towards the environment, encouraging students to make more sustainable choices in their daily lives.Additionally, learning planting skills can help students develop important life skills such as patience, perseverance, and problem-solving. Planting and caring for plants require patienceand dedication as students must wait for their plants to grow and overcome challenges such as pests, diseases, and weather fluctuations. By learning to overcome these challenges, students can develop a sense of resilience and learn how to adapt to changing circumstances.Furthermore, planting skills can also provide students with valuable vocational skills that can be applied in a variety of industries. The agricultural sector is a key industry that relies on skilled workers to grow and harvest crops, and learning planting skills can provide students with a strong foundation for a career in agriculture. In addition, the skills learned through planting can also be applied in other fields such as environmental science, landscaping, and urban planning.Moreover, learning planting skills can have a positive impact on students' health and well-being. Planting and caring for plants has been shown to have therapeutic benefits such as reducing stress, improving mood, and increasing physical activity. By incorporating planting skills into the high school curriculum, students can have the opportunity to connect with nature and experience these benefits firsthand.In conclusion, learning planting skills in high school is important for a variety of reasons. Not only does it providestudents with a better understanding and appreciation of the natural world, but it also helps them develop valuable life skills, vocational skills, and improve their health and well-being. By incorporating planting skills into the high school curriculum, we can help prepare the next generation to be more environmentally conscious, resilient, and skilled individuals.。
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V ol 7N o 12008Influence of Planting Spacing on Mechanical Proper ties ofEucalyptus grandis ×E.urophylla Planted in China*LIU Bo 1LUO Bin 1,2YIN Y afang 1**JIANG Xiaomei 1LUO Xiuqin 1HENSON Michael 31.Resea rch Institute of W ood Industr y ,C hinese Academy of Forestr y ,Beijing 100091,P.R.China2.College of La ndsca pe a nd A r t,Jiangxi A gricultur al University,Nanchang 330045,P.R.China3.F or ests NSW ,P O Box J19,Coffs Ha rbour Jetty ,NSW ,2450,A ustra liaAbstr act s:The objective of this study was to understand inf luence of planting spacing on m echanical properties of Euca lyptus gr andis ×E.ur ophylla planted as a potential species for solid wood products in C hina.Four trees at age of 13were selected f rom each of 6groups of pla nting spacing and a total of 24sampling trees were selected from the Dongmen Forestry Center of Guangxi Province in China.Furthermore,a one-meter-long log from each tree was cut into small blocks for wood properties testing.MOE,MOR and compression str ength pa rallel to wood grain were determined in accordance with Chinese standards.I n addition,wood density and shrinkage properties were measured.Statistical analysis by SAS software indicated significant differences among the 6groups of planting spacings on the air-dried density,radial shrinkage and bending M OR properties at the 0.05level,and also on the compression strength at the 0.10level.However,it was observed that there is no significant differences among shrinkages in tangential and volume,and MOE.Key words:planting spacing,mechanical properties,density,shrinkage,Euca lyptus gr andis ×E.urophylla ,pla ntationIn China,with implementation of the Natural Forest Conservation Program since 1998,the main supply of wood has been shifting from natural fore sts to plantation forests.With the large-scale establishment of Euca lyptus plantation in the Southern part of China to supple ment diminishing supplie s from na tu ra l f o re sts re s our c e s,the r e se a r c h o n Euca lyptus wood quality is shifting to the possible improve ment of solid wood utilization from most uses of pulping and wood-based panel.Although a few studies ha ve been conducted on the strength properties of small clear specimens from Eucalyptus pla ntation,the e ff ec t of pla nting spac ing on*Fund ing :Ch ina-ACIRA (Au stralian Cen tre for Intern atio nal Agricu ltu ral Research)co operation project (FST /1999/095)and Chin ese “”j (N 53)**mec hanic al proper ties of Euca lyptus planta tion wood wa s not foc use d on (Ba o Fuc he ng et a l.1998;Sumiya e t al.1982;Yin et al.2004).The c olle c tion of me ch anica l prop er ties da ta is a necessary ste p in understanding and learning how to control the qua lity of pla ntation w ood.The objec tive of this research is to understand of impact of planting spa cing on mechanical properties of E.gr andis ×E.ur ophylla which we re planted as a pote ntia l species for solid wood products in China.The results should provide useful information for timber mana gers in optimizing silvicultural practices for quality wood produc tion.(57-63)948Pro ect o.200-4-7.Corresp onding author.C HINES E F ORE ST RY S CIENCEAN DT E CHNOL OG Y1MA TERIALS AND METHODSFour trees of E.gr andis ×E.urophylla at age of 13were selected from each of 6groups of planting treatments and a total of 24sampling trees we re se lec te d fr om the D ongmen Fore stry Center of Guangxi Province in China (Table 1).The 6groupsTa ble 1.Ba sic cha r acter istics of sam ple logsof planting spacing (m)were 3.0×1.5,3.0×2.0,4.0×2.0,4.0×3.0,5.0×3.0a nd 6.0×2.0.Furthermore,a one-meter-long log from each tree at height of 1.9m was tra nsporte d to the laboratory in the Rese a r ch I nstitute of Wo od Indu stry,Chinese A cademy of Fore str y a nd cut into small blocks for w ood prope rties testing.Characteristics Tree heightClean lengthDiameter at 1.9m heightMC of sapwoodMC of heartwood(m)(m)(cm)(%)(%)Mean 26.2322.5415.3818.9180.98SD 5.44 5.97 4.91 2.7818.47Max 32.6028.2527.1030.23112.76Min15.008.757.8516.0530.93From the 24logs,some small rough specimens of 30mm (R)×30mm (T)×450mm (L)for static modulus of elasticity (MOE)and modulus of rupture (MOR)tests,30mm (R)×30mm (T)×50mm (L)for compression stre ngth parallel to wood grain,30mm (R)×30mm (T)×30mm (L)for density and shrinka ge te sts we re sawn from all the halves of logs.After 4-month air-drying,the small specimens were planed a nd finished into 20mm (R)×20mm (T)×300mm (L)for MOE and MOR tests,20mm (R)×20mm (T )×30mm (L)f or the test of compression strength parallel to grain,20mm (R)×20mm (T)×20mm (L)for density and shrinkage tests,separately.A total of 418pieces of small clear spe cimens were prepared and conditioned into the equilibrium m oisture content (EMC)of approximately 12%by storing in a room maintained at tempearture of 20o C and relative humidity of 65%.Due to small log diameter,defects distribution and size of testing samples,the number of small clear f f 56T f y,properties,MOE,MOR and compression stre ngth parallel to grain were performed in accordance with the national sta nda rds The Testing Me thods for Physica l an d Me cha nica l Prope rties of Wood (GB1927-1943—1991).The analysis of variance (ANOV A)for mechanica l properties was carried out by SAS software.2RESULTS AND DISCUSSIONS2.1Effect of planting spacing on wood density The average D BH of the 24sampling trees ranges from 7.9to 27.1cm.For he artw ood of logs,the MC is 31%to 113%.But,for sapwood,the MC is 16%to 30%(Table 1).The results of air-dried density of the 24logs a re listed in Table 2and Figure 1.The average density of f 56363ff f %T yspecimens obtained rom each log varied rom 1to 2.he te sts o w ood den sit sh rinkag eair-dried wood changes rom 0.29to 0.88g/cm with a coe icient variationo 8.99.he largestdensitV ol 7N o 12008Ta ble 2.Air -dr ied densityGroup of planting Number of M ean SD CV Max M in spacing (m)specimens(g/cm 3)(g/cm 3)(%)(g/cm 3)(g/cm 3)3.0×1.5170.70970.0451 6.350.79940.61883.0×2.0180.70760.06258.830.81860.60844.0×2.0220.67740.070310.380.80050.52964.0×3.0240.66550.06489.740.82600.54345.0×3.0260.70320.05617.970.81430.59896.0×2.0160.72530.077910.740.83860.56010.7253g/c m 3is in the gr oup of 6.0×2.0,followe d by 0.7097g/cm 3in that of 3.0×1.5,0.7076g/cm 3in that of 3.0×2.0,0.7032g/c m 3in that of 5.0×3.0,and 0.6774g/c m 3in tha t of 4.0×2.0;while the smallest density 0.6655g/cm 3is in tha t of 4.0×3.0.ANOV A indicates significant differences among the 6groups of planting spacings on the air-dried density at the 0.05level (Table 3),espec ially between 2groups of 4.0×3.0a nd 5.0×3.0.Figure 1.Air -dr ied density of 6gr ou psThe result in this test is different from that of Wang et al.(1996)who described that the lar gest de nsity of Japanese cedar was in the 1.0m ×1.0m spaced stands,where as the smalle st wa s in the 5.0m ×5.0m sp ac ed sta nds.Zobe l et a l.(1989)a lso indicated that the pe rcentage of latew ood in Sitka spruce,Norw ay spruce and Scotch pine decrea sed with the inc rease of plantation spac ing,and theyexpla ined tha t the larger spac ed plantation trees had a large r width of e arlywood.But our re sultcannot follow in the definite rule above due to the small number of samples.Beside s,the re gr ession ana lysis suggests tha t the correla tion c oefficients betwe en the de nsity and the compression stre ngth,density and MOE,and de nsity and MOR of small clea r spec imens are highly signific ant a t the 0.001level,with R =0.76,0.73,a nd 0.56,re spec tive ly,wh ic h is close to the rela te d reports of conife r spe cies (Wang et al.1996).Ta ble 3.ANOVA for a ir -dr ied den sity by SAS softwar eSource S um of squaresDf Mean square F value P value Model 0.050050.0100 2.480.0359**Error 0.47151170.0040Corrected total0.5215122**f ff 5in dicates sig ni ican t d i erences at the 0.0levelC HINES E F ORE ST RY S CIENCEAN DT E CHNOL OG Y2.2Effect of planting spacing on shr inka ge pr oper tiesThe data of wood shrinkages in tangential (T),radial (R)directions and volume (V)cut from the 6groups of planting spacing are shown in Table 4and Figure 2.The average shrinkages in T,R and V are between 5.64%-6.06%,3.03%-3.39%and 8.54%-9.26%,Table 4.Shr ink age p roper tiesItemGroup of planting Number of MeanSDCV MaxM inspacing (m)specime ns(%)3.0×1.515 5.760.539.27 6.67 4.973.0×2.015 6.050.9115.179.05 4.38T4.0×2.0195.92 1.0217.189.05 4.384.0×3.023 5.97 1.2923.4610.60 4.465.0×3.025 5.640.9516.888.01 4.076.0×2.016 6.06 4.7778.827.44 4.77Shrinkage 3.0×1.515 3.390.5416.05 4.45 2.54(%)3.0×2.015 3.320.5215.924.34 2.15R4.0×2.019 3.270.5416.61 4.050.524.0×3.023 3.040.6920.77 3.86 1.335.0×3.025 3.030.4514.95 3.97 1.906.0×2.016 3.37 2.0661.00 3.87 2.063.0×1.5158.990.869.5810.747.913.0×2.0159.21 1.2013.0612.75 6.88V4.0×2.0199.02 1.3414.8312.75 1.004.0×3.0238.87 1.6218.7413.37 6.585×35535636×663333Figu r e 2.Shr inka ge pr oper ties of 6gr oupsrespectively.From these results,the largest shrinkages of T,R and V are in 3groups of 6.0×2.0,3.0×1.5and 6.0×2.0,respectively;while the smallest ones are in the other groups.It is observed that the largest averages are 6.9%,11.0%and 8.0%greater than the smalle st ones,respectively.ANOV A indicates significant differences among the 6groups of planting spacings on the shrinkage of R a t the 0.05level (Table 5).However,there is no significant differences in shrinkages of T and V between groups.2.3Effect of pla nting spacing on compr ession str ength pa r allel to gra inResults from compression strength testsparallelto wood grain are shown in Table 6and Figure 3,which indicate that the compression strength range s from 40.98to 74.52MPa with a coefficient variation of 10.81%.Fromthese results,the largest values of compression strength.0.028.4 1.171.711.14.8.0 2.019.27.78.410.887.7V ol 7N o 12008Ta ble 5.ANOV A for r adial sh rinka ge by SAS softwar eSource Sum of squaresDf Mean square F value P value Model 3.76350.7526 2.340.0467**Error 34.4541070.3220Corrected total38.22112**indicates sign ificant difference at the 0.05lev elTa ble p ression strength pa r allel t o gr a inGroup of planting spacing (m)Number of specim ensMea n (MP a)SD(MPa)CV (%)Max (MP a)Min (MPa)3.0×1.51762.64 5.358.5469.9251.983.0×2.01860.78 6.6410.9274.5246.624.0×2.02258.358.2014.0467.6440.984.0×3.02457.12 5.9410.4065.1444.375.0×3.02657.70 6.1710.6970.0445.036.0×2.01659.896.1510.2670.2346.48F igur e 3.M echan ica l pr oper ties of 6gr oupsappear in the group of 3.0×1.5,followed by in the groups of 3.0×2.0,6.0×2.0,4.0×2.0and 5.0×3.0,while the sma llest is in the group of 4.0×3.0.The lar ge st mea n va lue is 8.8%gr ea te r th an th e smallest one.ANOVA indica te s signific ant differ ences among the 6groups on the c ompre ssion str ength a t the 0.10level (Table 7).Ta ble 7.ANOV A for compr ession strength pa r a lle l to gr ain b y S AS softwa reSource Sum of squaresDf Mean squareF value P value Model 473.0594.59 2.2400.0550*Er ror 494511742.275*f ff The results from Table 6show that the compression strength of wood cut from the group with a narrower spacing is higher than that of the others,except for the group of 6.0×2.0,which is similar to that of Japanese cedar (Wang et al.1996).2.4Effect of planting spacing on MOR and MOEResults from the bending tests of small clear specimensare illustrated in Table 8and Figure 3,which indicate that MOR range s from 34.93to 156.06MPa with a coefficient variation of 10.81%and MOE ranges from 8.64to 19.13GPa with a 13.3%coefficient variation.From these results,the largest values of MORand MOE appear respectively in groups of 5.0×3.0and 3.0×1.5,followed by in the groups of 3.0×1.5,4.0×2.0,6.0×2.0,3.0×2.0,4.0×3.0and the groups of 3.0×2.0,4.0×2.0,5.0×3.0,4.0×3.0,respectively;while the smallestCorrected total418122in dicates si gni i cant d i eren ce at the 0.10lev el.C HINES E F ORE ST RY S CIENCEAN DT E CHNOL OG YTable 8.MOR and MOEItemGroup of planting spacing (m)Number of specimensM ean SD CV(%)Max M in 3.0×1.517115.1018.4115.99138.4388.363.0×2.018107.3420.3818.98138.2471.15MOR (MP a)4.0×2.022111.2818.8516.94140.7076.504.0×3.024103.1020.3219.71127.3246.665.0×3.026119.2819.6716.49156.0668.236.0×2.016108.4740.0936.96152.0234.933.0×1.51714.96 1.5310.2317.2812.563.0×2.01814.38 1.6911.7517.5811.87MOE (GPa)4.0×2.02214.26 2.0114.1117.749.554.0×3.02414.21 2.0014.1019.1310.145.0×3.02614.24 1.9913.9618.5410.856.0×2.01613.602.1515.8217.278.64ones are in the group of 4.0×3.0and the group of 6.0×2.0,respectively.The largest averages for MOR and MOE are 13.6%and 9.1%greater than the smallest ones,respectively.The data of MOE from the 6groups indicates that the ave ra ges decrease with the increase of plantation spacing,which is similar to that of the othe r reports (Kazuo et al.1982;Wang et al.1996;Zobel et al.1989).ANOVA indicates a significant difference among the 6groups on MOR at the 0.05level (Table 9),but no significant difference on MOE among the 6groups of planting spacings.The regression a nalysis suggests that a correlation coe fficie nt (R =0.63)be tween MOR and MOE of small clea r spec ime ns is highly signific ant at the 0.001level.Ta ble 9.ANOVA for M OR by SAS softwar eSource Sum of squaresDf Mean square F value P value Model 5066.051013.2 2.4100.0407**Error 49253117420.9653**f ff 53CONCLUSIONS1)ANOV A by SAS software indicates a significant difference among the 6groups of planting treatments in air-dried wood density,radial shrinkage,and MOR at the 0.05level and also in the compression strength at the 0.10level.However,there is no signif icant differe nc e in MOE and shr inka ge s of ta nge ntia l direction and volume.2)The results of the 6groups of planting spacings indicate that the average MOE decreases with the increase of plantation spacing.3)The results provide useful information for timber managers inoptimizing silvicultural practicesfor quality wood production.Corrected total419122indicates signi icant di erence at the 0.0level.V ol7N o12008 ACKNOWLEDGEMENTSThe authors appreciate ACIAR(the Australia Centrefor International Agricultural Research)project and theState Forestry Administration project for their greatfinancial supports,and thank the Guangxi DongmenForestry Centre for sample logs collection and Mrs.Xu Mingkun from the Chinese Academy of Forestryfor her laboratory testing.REFERENCESBao Fucheng,Jiang Zehui.1998.Wood properties of main treespe cies fr om plantation in China.B eijing:F orestryPublishing House:162-171.Sumiya K,Shimaji K,Itoh T,et al.1982.A consideration onsome physical properties of Japanese cedar(Cryptomer iaja ponica D.Don)and Japanese cypress(Chamaecypar isobtuse S.and Z.)planted at different densities.Journal ofthe Institute of Wood Science,28(4):255-259.W ang S L,Lin S H.1996.Effects of plantation spacings on thequality of visually graded lumber and mechanical propertiesof T aiwan-grown Japanese cedar.Journal of the Instituteof Wood Science,42(5):435-444.Yin Y F,Nakai T,Na gao H,et al.2004.Nondestructiveevaluation of C hinese fir plantation wood strength.In:The8th World Conference on Timber Engineering,Lahti,Finland,June14-17,2004:681-684.Zobel B J,Baijtence J P.1989.Wood var iation and its causesand control.Berlin:Spring-Verlag.anaging editor:A ishengM YU N Y。