亚热带不同植被恢复阶段林地凋落物层现存量和养分特征

为揭示亚热带森林植被自然恢复过程中,凋落物层现存量及其养分元素储存能力的演变,采用空间代替时间的方法,在位于亚热带丘陵区的长沙县选取地域相邻、生境条件基本一致的檵木+南烛+杜鹃灌草丛(Loropetalum chinense+Vaccinium bracteatum+Rhododendron simsii scrub-grass-land,LVR)、檵木+杉木+白栎灌木林(L.chinense+Cunninghamia lanceolata+Quercus fabri shrubbery,LCQ)、马尾松+柯+檵木针阔混交林(Pinus massoniana+Lithocarpus glaber+L.chinense coniferous-broad leaved mixed forest,PLL)、柯+红淡比+青冈常绿阔叶林(L.glaber+Cleyera japonica+Cyclobalanopsis glauca evergreen broad-leaved forest,LAG)作为一个恢复序列,设置固定样地,采集未分解层(U层)、半分解层(S层)、已分解层(D层)凋落物样...

Stock and nutrient characteristics of litter layer at different vegetation restoration stages in subtropical region, China

This paper aims to investigate the evolution of litter stocks and its nutrient storage capacity along the natural restoration of subtropical forest vegetation. We used the space-for-time substitution method by selecting four adjacent vegetation communities with almost same habitat conditions in Changsha County, Hunan Province, China. The four communities are comprised of Loropetalum chinense + Vaccinium bracteatum + Rhododendron simsii scrub-grass-land (LVR), L. chinense + Cunninghamia lanceolata + Quercus fabri shrubbery (LCQ), Pinus massoniana + Lithocarpus glaber + L. chinense coniferous-broad leaved mixed forest (PLL), and L. glaber + Cleyera japonica + Cyclobalanopsis glauca evergreen broad-leaved forest (LAG) to represent the secondary forest successional sequence in this region. Permanent plots were established in each vegetation community. Litter samples were collected up into un-decomposed layer litter (U), semi-decomposed layer litter (S) and decomposed layers (D). The standing crop of litter, the main nutrient elements content, reserves and release rates were measured. The correlation between plant diversity and litters stock, contents of main nutrients was analyzed. The results showed that:1) the stocks of litter layers and its different decomposed layers increased with the vegetation restoration. The stocks in the D layer were the highest, accounted for 41.59%-51.02% of stocks of litter layer at the same restoration stage. The difference between different decomposition layers increased with the vegetation restoration. The decomposition rates of litters were from 0.44 to 0.61 at different restoration stages, and the cycle time were 1.65 to 2.28 a. 2) The contents of main nutrients in litters layer and its different decomposed layers were in the order of N > Ca > Mg > K > P, and presented different variations with vegetation restoration. With vegetation restoration, content of N and P increased on the whole, but K content was the highest in LAG (except U layer) and the lowest in PLL. Ca content was the highest in LCQ and the lowest in PLL, as well as Mg content was the highest in LAG (except U layer) and the lowest in LAG. Contents of N, P (except PLL and LAG), K, Ca and Mg decreased with the decomposition of litters at the same restoration stage. 3) The storage of nutrient elements in litter layer followed the order of N > Ca > Mg > K > P at different restoration stages. The total amount of nutrient elements and various nutrient elements in litter layer and its different decomposed layers all increased with the restoration vegetation. At the same restoration stage, both N and P storage increased with the decomposition of litters, however neither K, Ca nor Mg storage changed. With the restoration vegetation, both the nutrient element storage capacity and the transformed-returned capacity of litters were improved, especially N. The release rate of nutrient elements decreased with restoration vegetation, indicating that it was beneficial to the fixation of nutrients. 4) Effects of plant diversity index in arbor layer, shrub layer and herb layer on the stocks and nutrient element contents of litter were different, among which the effect of arbor layer was the most.