Aims The functions of global forests are threatened by the increasing frequency of severe drought.Due to drought inducing reductions in soil nutrient availability,efficiencies of nutrient use and resorption of trees b...Aims The functions of global forests are threatened by the increasing frequency of severe drought.Due to drought inducing reductions in soil nutrient availability,efficiencies of nutrient use and resorption of trees become crucial for forest functions and biogeochemical cycles.However,understanding the dynamics of responses of foliar nutrient use and resorption efficiencies to drought,especially in tropical or subtropical forests,is still limited.Our goal was to detect whether and how the importance of leaf nutrient use and resorption changes across different species in the hot and wet forests when suffering drought stress in different months.Methods Based on a 70%throughfall exclusion experiment in a subtropical forest,we collected green and senesced leaves of Schima superba and Lithocarpus glaber in different months from October 2016 to May 2019,to estimate the effects of drought on leaf nitrogen(N)and phosphorus(P)use and resorption efficiencies(i.e.NUE and PUE,NRE and PRE).Important Findings The effects of drought on nutrient use and resorption efficiencies varied between species and months.Based on a 2-year observation,drought had no effect on S.superba,but significantly decreased NUE,NRE and PRE of L.glaber by 3.4%,20.2%and 7.1%,respectively.Furthermore,the negative drought effects were aggravated by the natural summer drying in 2017.As a result,NUE and PUE of L.glaber were significantly depressed by 17.2%and 58.1%,while NRE and PRE were significantly reduced by 56.5%and 53.8%in August 2017.Moreover,the responses of NRE,PRE and NUE to drought were related with soil moisture(SM)for L.glaber,and when SM decreased to a threshold near 9 v/v%,drought effects were shifted from unresponsive to negative.Our results highlight a species-specific threshold response of nutrient use under drought in a subtropical forest.展开更多
Forest productivity and carbon(C) sequestration largely depend on soil N and P availability.To date,however,the temporal variation of nutrient limitation along forest succession is still under debate.Leaf stoichiometr...Forest productivity and carbon(C) sequestration largely depend on soil N and P availability.To date,however,the temporal variation of nutrient limitation along forest succession is still under debate.Leaf stoichiometry and nutrient resorption are important indicators for predicting nutrient limitation of plant growth.Here,we measured nitrogen(N)and phosphorus(P)concentrations in green leaves and leaf liter for all woody species at four stages of temperate forest succession,and analyzed how abiotic and biotic factors affect leaf stoichiometry and nutrient resorption along forest succession.At the individual scale,leaf N and P concentrations had a significant increase at the end of the succession,while no change in leaf N:P ratio was detected.Nitrogen resorption efficiency(NRE)increased significantly with succession,but P resorption efficiency(PRE)first increased and then decreased.Significant increases in NRE:PRE ratios only occurred at the end of the succession.Moreover,plant N cycling was less responsive to soil nutrient than P cycling.At the community scale,we found that leaf N and P concentrations first decreased and then increased along forest succession,which were mainly affected by Shannon-Wiener index and species richness.Leaf N:P ratio significantly varied with succession and was mainly determined by community-weighted mean diameter at breast height(DBH).NRE increased and was significantly influenced by species richness and DBH,while PRE was relatively stable along forest succession.Thus,the NRE:PRE ratios significantly increased,indicating that N limitation is exacerbated with the temperate forest succession.These results might reflect the intense interspecific competition for limiting resource in a higher biodiversity community.In conclusion,our findings highlight the importance of biotic factors in driving forest ecosystem nutrient cycling and provide valuable information for sustainable fertilizer management practices in China's temperate and boreal forests.展开更多
基金supported by the National Natural Science Foundation of China(31800400 and 31722009)and the Natural Science Foundation of Shanghai(18ZR1412100).
文摘Aims The functions of global forests are threatened by the increasing frequency of severe drought.Due to drought inducing reductions in soil nutrient availability,efficiencies of nutrient use and resorption of trees become crucial for forest functions and biogeochemical cycles.However,understanding the dynamics of responses of foliar nutrient use and resorption efficiencies to drought,especially in tropical or subtropical forests,is still limited.Our goal was to detect whether and how the importance of leaf nutrient use and resorption changes across different species in the hot and wet forests when suffering drought stress in different months.Methods Based on a 70%throughfall exclusion experiment in a subtropical forest,we collected green and senesced leaves of Schima superba and Lithocarpus glaber in different months from October 2016 to May 2019,to estimate the effects of drought on leaf nitrogen(N)and phosphorus(P)use and resorption efficiencies(i.e.NUE and PUE,NRE and PRE).Important Findings The effects of drought on nutrient use and resorption efficiencies varied between species and months.Based on a 2-year observation,drought had no effect on S.superba,but significantly decreased NUE,NRE and PRE of L.glaber by 3.4%,20.2%and 7.1%,respectively.Furthermore,the negative drought effects were aggravated by the natural summer drying in 2017.As a result,NUE and PUE of L.glaber were significantly depressed by 17.2%and 58.1%,while NRE and PRE were significantly reduced by 56.5%and 53.8%in August 2017.Moreover,the responses of NRE,PRE and NUE to drought were related with soil moisture(SM)for L.glaber,and when SM decreased to a threshold near 9 v/v%,drought effects were shifted from unresponsive to negative.Our results highlight a species-specific threshold response of nutrient use under drought in a subtropical forest.
基金the National Natural Science Foundation of China(31870399,32071533)the Strategic Priority Research Program ofthe(Chinese Academy of Sciences(XDB31030000).
文摘Forest productivity and carbon(C) sequestration largely depend on soil N and P availability.To date,however,the temporal variation of nutrient limitation along forest succession is still under debate.Leaf stoichiometry and nutrient resorption are important indicators for predicting nutrient limitation of plant growth.Here,we measured nitrogen(N)and phosphorus(P)concentrations in green leaves and leaf liter for all woody species at four stages of temperate forest succession,and analyzed how abiotic and biotic factors affect leaf stoichiometry and nutrient resorption along forest succession.At the individual scale,leaf N and P concentrations had a significant increase at the end of the succession,while no change in leaf N:P ratio was detected.Nitrogen resorption efficiency(NRE)increased significantly with succession,but P resorption efficiency(PRE)first increased and then decreased.Significant increases in NRE:PRE ratios only occurred at the end of the succession.Moreover,plant N cycling was less responsive to soil nutrient than P cycling.At the community scale,we found that leaf N and P concentrations first decreased and then increased along forest succession,which were mainly affected by Shannon-Wiener index and species richness.Leaf N:P ratio significantly varied with succession and was mainly determined by community-weighted mean diameter at breast height(DBH).NRE increased and was significantly influenced by species richness and DBH,while PRE was relatively stable along forest succession.Thus,the NRE:PRE ratios significantly increased,indicating that N limitation is exacerbated with the temperate forest succession.These results might reflect the intense interspecific competition for limiting resource in a higher biodiversity community.In conclusion,our findings highlight the importance of biotic factors in driving forest ecosystem nutrient cycling and provide valuable information for sustainable fertilizer management practices in China's temperate and boreal forests.