气象因子与地表植被生长相关性分析_徐兴奎

第23卷第2期2003年2月生 态 学 报ACT A ECOLOGICA SINICA V o l.23,N o.2Feb.,2003气象因子与地表植被生长相关性分析徐兴奎,林朝晖,薛　峰,曾庆存(中国科学院大气物理研究所国际气候和环境科学中心,北京　100029)基金项目:国家重点基础发展规划研究资助项目(G 1998040900);国家自然科学基金资助项目(40105011,49905004)收稿日期:2001-08-23;修订日期:2002-04-20作者简介:徐兴奎(1966～),男,黑龙江人,博士。

主要从事遥感反演和陆面过程模式研究。

E-mail:xk xu@ Foundation item :T he National Key Fundamen tal S tu dy Project (Grant No.G1998040900)and the National Natural Sci-ence Foundation of C hina (Grant Nos .40105011,49905004)Received date :2001-08-23;Accepted date :2002-04-20Biography :Xu Xing-Kui,Doctor.M ainly engaged in the rem ote sensin g applications and land su rface models.E-mail:xkxu @Acknowledgements :Th e au th ors w is h to thank the Distributed Active Arch ive C enter (Code 902.2)at the Goddard Space Flight Center,Gr eenbelt,M D,20771,for pr odu cing the data in th eir present form and dis tr ibuting them.T he original data products were produ ced u nder the NOAA /NAS A Pathfinder program ,by a proces sing team head ed by M s .M ary James of th e Goddard Glob al Change Data Center;and the s cience algorithms w ere establis hed by the AVHRR L and Sci-ence Work ing Grou p,chair ed by Dr.Joh n T ow nsh end of the University of M aryland.Goddard's contrib ution s to these activities w ere sponsored by NAS A's M iss ion to Plan et E arth program摘要:降水和气温是影响地表植被覆盖状况的两个重要的气象要素,地表植被的生长对它们的响应又存在一定的滞后效应。

利用我国334个气象台站和1982～1994年N O AA -AV HRR 卫星数据,通过相关分析研究了我国4～7月份各气候区域降水和活动积温对地表植被的影响。

结果显示,不同的气候区域和月份,降水和积温对地表植被的作用程度明显不同;前期降水和活动积温对植被作用的有效时间尺度也分布不均,并与土壤质地类型分布有关,因此,通过某一固定时间尺度的降水或活动积温不能准确的预测大区域地表植被的生长状况。

关键词:归一化的植被指数;降水;活动积温;土壤质地Correlation analysis between meteorological factors and the ratio of vegetation coverXU Xing -Kui ,LIN Zhao -Hui ,XUE -Feng ,ZENG Qing -Cun (ICCE S ,Institute of A tmosp hericP hysics ,CA S ,B eij ing 100029,China ).Acta Ecologica Sinica ,2003,23(2):221～230.Abstract :R ainfall and temperatur e ar e two impor tant fa ct or s that influence v eget atio n cov erag e o ver the land surface.T he up-gr ow th of veg etation lag s behind r ainfall and temperat ur e in g ener al.Due t o their in-homo geneous distr ibutio n ,t he effect of rainfall and temper ature on land surfa ce veg etation co ver differ s distinctly.Some resear ch result s sho w that t he time lag is 14day s,and sugg ested that the ND VI (N o r-malized Differ ence V eg etation Index )could be used as an index fo r t he reco nstr uct ion o f r ainfall in so me reg io ns.T her e are different climatic r egions in China such as t emper ate zone,subt ro pica l zone and tr opical zone .T he inter actio ns between meteo ro lo gical factor s and v eget atio n in each climatic r egion are sig nifi-ca nt ly different.M any facto rs such as t he inho mog eneous dist ribution of rainfall and temper ature,differ-ence of v egeta tio n types and soil text ur es pla y impo r tant r oles in interactions .T o dev elo p advanced landsur face feature m odels ,t hese facto rs must be consider ed .Ba sed o n the daily mean r ainfall and to tal activ e temperat ur e fr om 334w eather st atio ns and N O AA -A VHR R data fr om N ASA during t he per io d fro m 1982to 1994,the influence of rainfall and tot al activ e temperat ur e o n v eget atio n in China is analy zed fro m Apr il to July thro ug h co rr elatio n analy sis .T he A tmo-spher ic co r rectio n scheme o f channel o ne a nd channel tw o fo llo ws the alg or it hm o f Go rdon .N DV I is com-po sited by taking the max imum N DV I value fro m the daily data w ithin 10days,w it h spatial r esolut ion o f 8km ×8km.T he max imum N DV I w it hin a 10day per io d is assumed to equal t he N DV I of the tenth da y .T his a s-sumption also co rr espo nds to t he character o f v eget atio n gr ow th .F ir st ,rainfall o r temperatur e is added ret ro spectiv ely day by day ,and then the cor relatio n co efficients ar e calculated.T he final o utputs are max i-mum cor r elation co efficients and accumulative number o f days while max imum co rr ela tio n coefficient o c-cur s .T he r esult show s reg io nal character s in each month.Veg etation does not g r ow in the nor th o f China in A pr il because o f lo wer tempera tur e.Co rr elatio n co efficient is low betw een N DV I and r ainfall.Because w inter w heat is g ro w ing then and r ainfall is relativ ely lo wer.T he reg io ns w ith higher co rr ela tio n ar e locat-ed basically in humid par ts of the So uth T emper ate Zone .In contr ast ,there is no evidence o f hig her cor re-lat ion in the subt ro pics and tr o pics due to ex cessiv e r ainfall a nd soil humidity a ltho ug h it is also being in the v egetat ion per iod.As t emper ature increases,t he dist ributio n of maximum cor relation coefficient s ex-pends in M ay in nor thern China ex cept for so me r egions with sno w co ver ,wher e melting sno w made so il much mor e humid ;co rr ela tio n in all other r egio ns increases .A t this time ,the ripe wint er w heat ca used the co rr elatio n to decrease in t he South T emper ate Z one.V egeta tio n also does not depend on ra infall so uth of the Yang tze Riv er beca use of ov erm uch rainfa ll.In June a nd July,v egeta tio n demands much mor e rain-fall in the middle par t of the mo ist tempera te zo ne,ow ing to up-g ro wth.Cultiv ation of late autumn cr ops made veg etatio n mo re r eliant o n r ainfall .In the m iddle and low er r eaches of the Yang tze River ,the adv ent of M eiyu r esults in no cor r elat ion betw een N DV I and rainfall.T he tempor al plot show s t hat N DV I lags behind rainfall with quite appar ent differ ences in climatic re-gions w here cor relatio n coefficients ar e higher than 0.3.In dro ught reg io ns ,since a litt le rainfall co uld chang e v egetat ion co ver sig nificantly ,the time lags ar e less than that in ot her r eg ions .In r ainy reg io ns ,precipita tio n supplies continuously w ater for veg etatio n gr ow th and r esults in r elat ively lo ng time lag s.In A pr il in the souther n humid tempera te zone w it h hig her co rr ela tio n,to tal r ainfall dur ing 45～65days is best relative to ND VI .T hat means v egetat ion w ill be furt her affect ed if the t otal pr ecipitation ov er 45～65da ys cha ng es .In M ay ,in t he mid -var iable zo nes and semi -dr o ug ht reg io ns ,v eget atio n is v ery sensitive to ra infall.As a consequence ,r ainfall w ithin 15～45days is mo st impo rtant for veg etatio n.In June and July,soil mo isture in no rther n China t ends to be stable.So t he day s o f ra infall ar e basically limit ed to 25～45.T he r elat ion betw een N DV I and temper ature is opposit e t o ra infall due to inv erse -co rr elatio n betw een temperat ur e and rainfall .In rainy seasons ,r ainfall beco mes a main reaso n ag ainst t he g ro wt h o f pla nt s ,so cor relation betw een ND VI and temper atur e is higher in g eneral.M eanw hile,v egetat ion also dema nds much mo r e accumulat ed temper ature.In dr y seasons,t his kind o f co rr elatio n is no t evident.T he differ ent so il tex tures and veg etatio n t ypes cause uneven distr ibutio n of cor r elations betw een N D-V I and r ainfall or temper ature .F or r ainfall ,t her e a re higher cor r elat ions betw een N DV I and ra infall in sandy tex tur e r egions,and lo wer co rr elatio ns in the clayey t ext ur e reg ions.F or t emper atur e,there ar e low er co rr elat ions in sandy tex ture r egions and low er co rr elat ions in cla yey t ext ur e r egio ns.T he abov e co rr elatio n analysis sug g est s that it is no t appr opriate to apply only rainfall or temper atur e 222　生　态　学　报23卷to pr edict the dist ribution of N DV I .R ather ,a N DV I -predicting model w ith bo th temperatur e and the up-per or low er limit of r ainfall inco rpo rated is mo re accept able and mor e phy sically meaning ful.Key words :N or malized Differ ence Veg etation Index ;rainfall;to tal activ e temper atur e;soil t extur e 文章编号:1000-0933(2003)02-0221-10　中图分类号:Q142,Q948.1　文献标识码:A 地表植被类型的空间分布是长期气候适应的结果,同时植被对气候又有一定的反馈作用。