Sap flow for beech(Fagus sylvatica L.)in a natural and a managed forest—effect of spatial heterogeneity

作     者：Lise Dalsgaard Teis Nørgaard Mikkelsen Annemarie Bastrup-Birk 

作者机构：Forest and LandscapeFaculty of Life SciencesUniversity of CopenhagenRolighedsvej 231958 Frederiksberg CDenmark RisøNational Laboratory for Sustainable EnergyTechnical University of DenmarkFrederiksborgvej 399P.O.Box 494000 RoskildeDenmark 

出 版 物：《Journal of Plant Ecology》 (植物生态学报（英文版）)

年 卷 期：2011年第4卷第1期

页      面：23-35页

核心收录：

学科分类：08[工学] 0812[工学-计算机科学与技术（可授工学、理学学位）] 

基　　金：Danish Research Council Forest and Landscape Denmark, The Faculty of Life Sciences, University of Copenhagen 

主　　题：canopy gap canopy structure tree size tree water use 

摘      要：Aims Beech(Fagus sylvatica L.)is an important species in natural and managed forests in *** drought-sensitive species dominates even-aged stands as well more natural stands composed of a mixture of tree species,age and size *** study evaluates the extent that heterogeneity in spacing and tree diameter affect the seasonal availability and use of *** Two stands were evaluated:(i)a heterogeneous forest remnant(NAT)with trees up to;300 years old,a mean top height of 28.4 m and a total of 733 stems ha
1with stem diameters averaging 18 cm and(ii)an even-aged 80-year old stand(MAN),with a height of 25 m,and a total of 283 stems ha
1 with diameters averaging 38 *** sap flow,Js(g m
2 s
1),was continuously measured in 12(MAN)and 13(NAT)trees using 20-mm long heat dissipation *** tree measures of sap flow were correlated using non-linear statistical methods with air vapour pressure deficit(D,hPa)and global radiation(Rg,J m
2 day
1),along with constraints imposed by reductions in soil water content(SWC).SWC was measured as volumetric%using time domain *** Findings The daily integrated Js(Js-sum)for trees growing in the evenly spaced MAN stand and trees in canopy and closed forest positions in NAT stand decreased as the availability of soil moisture was *** the heterogeneous NAT stand,SWC in a recently formed canopy gap remained high throughout the vegetation *** on regression models,the predicted relative decrease in Js-sum for dry relative to moist soil water conditions in the closed forest(at mean daily D=10 hPa)was 7–11%for trees near the gap and 39–42%for trees in the closed *** MAN,the reduction in Js-sum was 29%in dry relative to moist ***-sum in the outer 20 mm of the xylem in NAT was lower than that in MAN and the rate of decline in Js with xylem depth was less in NAT than in *** MAN,Js-sum in deep and outer xylem was negatively affected at low soil moisture availability