Seasonal Dynamic And Spatial Distribution Of Fine Roots Along An Elevation Gradient Of Wuyi Mountains In Southeastern China

Forest is important natural resources.The processes of physiology and ecology in forest environment affect fine roots energy transfer and metabolic process between trees and environment,and play a crucial role in the forest ecosystem production.However,we understand poorly about it,especially in fine roots variety across an elevation gradient in the same area.We conducted the experiment in four different elevation of Wuyi Mountain located in subtropics.We measured the existing fine roots biomass,fine roots SRL(Special root length),fine roots Lv (Length per volume),fine roots Sv(Surface area per volume),fine roots Vv(Fine roots Volume per volume),analyzed their seasonal and temporal dynamic,also analyzed their correlation with soil moisture soil temperature and soil respiration. The results show that:(1)The total existing fine roots(including dead fine roots and living fine roots) biomass along elevation was:Alpine Meadow(12.08Kg/m~3)＞Coniferous Forest(9.74Kg/m~3)＞Dwarf Forest(4.41Kg/m~3)＞Evergreen Broadleaf Forest(4.01Kg/m~3).The fine roots SRL(Special root length),fine roots Lv(Length per volume),fine roots Sv(Surface area per volume),fine roots Vv(Fine roots Volume per volume)of both living fine roots and dead fine roots in Alpine meadow are higher than any other three forests at each layer.The fine roots SRL(Special root length),fine roots Lv(Length per volume),fine roots Sv(Surface area per volume), fine roots Vv(Fine roots Volume per volume)of living fine roots are all higher than dead fine roots at each forest.(2)The fine roots biomass,fine roots Lv(Length per volume),fine roots Sv (Surface area per volume),fine roots Vv(Fine roots Volume per volume)of both Living fine roots and dead fine roots at the depth of 0～10cm are all significantly higher than that of 10～25cm(P＜0.01)at each forest.The proportion of living fine roots biomass at 0～10cm to that of 0～25cm is Dwarf Forest(84.8%),Alpine meadow(83.0%),Evergreen Broadleaf Forest(80.8%),Coniferous Forest(77.8%). The proportion of dead fine roots biomass at 0～10cmto 0～25cm is Alpine meadow(69.1%),Dwarf Forest(68.7%),Evergreen Broadleaf Forest(64.9%), Coniferous Forest(60.1%).Living fine roots biomass and total fine roots biomass at the depth of 0～10cm are all significantly higher than that of 10～25cm(P＜0.01)at each forest. (3)At each forest,living fine roots and dead fine roots(0-2.0mm)do greatest contribution to total fine roots(0-5.0mm)length,total fine roots surface area,and total fine roots volume at each soil layer.Fine roots of 0-1.0mm take high proportion than fine roots of1.0-2.0mm.The lengths of fine roots(2.0-5.0mm)take only a very small part of total fine roots length.(4)At each forest,the maximum biomass of living fine roots at 0～10cm appeared in autumn,the peak value of each forest is Evergreen Broadleaf Forest(3.48Kg/m~3),Coniferous Forest(9.19Kg/m~3),Dwarf Forest(4.40Kg/m~3),Alpine meadow(14.86Kg/m~3).The fine roots biomass,fine roots SRL(Special root length), fine roots Lv(Length per volume),fine roots Sv(Surface area per volume),fine roots Vv(Fine roots Volume per volume)of each forest displayed seasonal dynamic at different degree.Some indexes had significant difference or very significant difference among different seasons at some forest;most of the indexes had no significant difference among different seasons.Fine roots index at different soil layer didn't display the same seasonal dynamic completely.(5)At each forest,soil respiration had no significant correlation with fine roots biomass,fine roots SRL(Special root length),fine roots Lv(Length per volume), fine roots Sv(Surface area per volume),fine roots Vv(Fine roots Volume per volume).