Effects of light intensity variation on nitrogen and phosphorus contents, allocation and limitation in five shade-enduring plants
Aims To enhance the understanding on nitrogen (N) and phosphorus (P) physiological responses to different light environments in shade-enduring plants and provide references to improve the stand structure and ecosystem functions of plantation forests.Methods We selected seedlings of five shade-enduring species with high ecological and economic value in subtropical area of China to study the effects of light intensity on leaf N and P contents,allocation and nutrient limitation in shade-enduring plants.A light intensity gradient of five different levels was set to simulate the varying understory light environment.Importantfindings With decreasing light intensity,the total biomass and total N and P accumulation of five shade-enduring plants all showed a decreasing trend,but N,P contents in different organs increased.Among them,Gardeniajasminoides (GJ) had the highest while Illicium henryi (IH) had the lowest N content;The P contents of Quercus phillyraeoides (QP) and GJ were significantly higher than Elaeocarpus sylvestris (ES),Ardisia crenata (AC) and IH.QP and GJ had the highest N,P contents under extremely low light intensity (6％ natural light intensity) condition (LIC),while AC and IH had the highest N and P contents in low (15％ natural light intensity) and moderate (33％ and 52％ natural light intensity) LIC.ES demanded differently for LIC on N and P,which were 52％ and 6％ natural light intensity,respectively.N and P allocation of ES,AC and IH followed leaf ＞ root ＞stem,but for QP and GJ were root ＞ leaf ＞ stem.Decreasing LIC significantly affected N and P allocation.N content variations shown good consistency among different organs under higher LIC (100％ natural light intensity)while distinct variability under lower LIC (15％ and 6％ natural light intensity) in all five species.Phosphorus contents exhibited good consistency in IH,QP and GJ but varied in ES and AC.Decreasing LIC significantly affected organ N/P ratios of shade-enduring plants,but the fundamental growth restriction patterns remained.Light intensity variation and tree species co-regulated N,P utilization and allocation in shade-enduring plants,and then affected the total biomass and total N,P accumulation,which might result from the change of N and P utilization strategy.Therefore,light intensity preference and N,P nutrient balances in shade-enduring plants should be taken into account when constructing multiple layer and uneven-aged forests.
NETL
NSTL
万方数据
维普
