| Litterfall,an important part of the forest ecosystem carbon pool and nutrient pool,plays a significant role in the circulation of carbon,nitrogen and phosphorus in the ecosystem,and plays a unique ecological function in the biogeochemical cycle.As a special zonal vegetation,the subtropical evergreen broad-leaved forest distributed widely in China.Thus,it is vital to research the litterfall in ecology.Leaf-litter is of great significance to the nutrient cycling of forest ecosystems,so in subtropical evergreen broad-leaved forest,the study of litterfall is supposed to focus on leaf-litter,learn its basic conditions of nutrient content,explore the spatial and temporal distribution features.In this study,a 20-hectare dynamic monitoring plot of Zhejiang Tiantong was used as a platform to collect litter in one year?August 2015-July 2016?.Firstly,the contents of C,N,P in leaf-litter in three peaks were determined,and the use efficiency,return and stoichiometric ratio of three elements were analyzed.Then the temporal variation characteristics of leaf-litter nutrient in three peaks and the spatial distribution characteristics different elevation,convexity and habitats were explored;finally,the influencing factors are explored.The main results in this study are as follows:1.The annual average C content of leaf-litter in this region is 487.26±19.10 g·kg-1.On the temporal scale,except for the disturbed habitat,the peak 1?5,November,2015?is lower than the peak 2?15,April,2016?and below peak 3?1,June,2016?,the difference is significant;on the spatial scale,the C content coefficient of variation is the smallest?3.92%?,and the disturbed habitat and valley habitat are significantly lower than the slope habitat and ridge habitat;the Carbon Use Efficiency has the opposite results.2.The annual average value of leaf-litter N content is 11.64±2.13 g·kg-1.On the temporal scale,except for the disturbed habitat and ridge habitat,the peak1 is significantly higher than the peak 2 and peak 3.On a spatial scale,the coefficient of variation of N content is 18.3%,and the disturbed habitats and valley habitats?especially the low-altitude valley habitats?are significantly higher than other habitats;the Nitrogen Use Efficiency has the opposite results.3.The annual average value of leaf-litter P content is 0.42±0.15 g·kg-1.On the temporal scale,except for the disturbed habitat,low-altitude valley habitat and ridge habitat,the value of peak1 is significantly higher than the peak 2 and peak 3.On the spatial scale,the coefficient of variation of P content is the largest?35.55%?,the disturbed habitats and valley habitats are significantly higher than ridge habitats,and the low-altitude habitats at peak 3 are significantly higher than high-altitude habitats;the Philosophy Use Efficiency has the opposite results.4.The annual average values of leaf-litter Renturn of C,N,P in the three peaks of the region are 23.26±9.40 g·m-2,550.94±238.64 mg·m-2 and 15.52±10.00 mg·m-2,respectively.On the temporal scale,except for the disturbed habitats and the ridge habitats,the peak1 was significantly higher than the peaks 2 and peak 3.On the spatial scale,the coefficient of variation of the three is 40.41%,43.32%,and 64.43%,respectively,and P Return is still the biggest.The N,P Return in low-altitude habitats were significantly higher than the high-altitude habitats;the C,N Return in the ridge habitats was significantly lower than others at peak1 of the ridge,and the ridge habitats was significantly higher than the valley habitats at peak 3.5.The annual average values of the C:N,N:P,and C:P in leaf-litter are 43.27±8.07,30.15±6.45,and 1289.37±412.42,respectively.On the temporal scale,C:N and C:P were significantly lower than peaks2 and peak3 except for disturbed habitats,low-altitude valley habitats and ridge habitats;N:P had no significant difference among the three peaks;On the spatial scale,the three coefficients of variation were18.65%,21.39%,and 31.76%,respectively.N:P and C:P in disturbed habitats and valley habitats were significantly lower than ridge habitats,and the three stoichiometric in high-altitude habitats are significantly higher than the low-altitude habitats at peak 3.There are few topographical,soil and community factors that have significant effects on C content and CUE of litter in this area,and there was no obvious law;N content and NUE and C:N of leaf-litter of are mainly affected by soil C,P Content and species composition;leaf-litter P content,PUE,N:P and C:P are mainly affected by soil P content,density of large tree and species composition,and the elevation and soil pH may also affect these indexes;the influence factors of the three elements'Return are basically consistent with the influence factors of the leaf-litter,mainly affected by the elevation and the convexity,and is also affected by the C concent of soil at peak1besides.In summary,the leaf-litter nutrients in this area are mainly affected by the convexity,soil nutrient content and species composition.On the temporal scale,mainly shows the difference between the peak of deciduous species?peak 1?and the peak of evergreen species?peak 2,peak 3?.On the spatial scale,mainly shows the difference among the disturbed habitats,the valley habitats and the ridge habitats.Phosphorus,a limiting element in this area,tends to show more significant differences at different temporal and spatial scales. |
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