| Under the leadership of the "dual-carbon" strategy,the forest carbon sink function has become the core of research on terrestrial ecosystem carbon sink functions worldwide.Accurately assessing and monitoring the distribution of forest carbon storage and exploring its influencing factors and driving mechanisms can provide important basis for the accurate evaluation and prediction of forest carbon sink function,as well as targeted protection and enhancement of its carbon sequestration capacity.Currently,most studies on aboveground carbon storage in forests focus on all species within a region,neglecting the differences between dominant and non-dominant species and failing to investigate the contribution of different characteristic species to aboveground carbon storage accumulation.In addition,comprehensive studies on the spatial distribution of small-scale forest aboveground carbon storage considering various influencing factors are lacking,and it is necessary to comprehensively investigate its driving mechanisms by combining biological and nonbiological factors.Moreover,most studies only qualitatively examine the effects of factors influencing aboveground carbon storage,without exploring the spatial scale effects of carbon storage distribution and quantifying the effects of influencing factors at different scales.Based on this,this study mainly conducted the following three aspects of research using species survey data and terrain and soil monitoring data of a typical forest community in the South Asian tropical region-the monsoon evergreen broad-leaved forest:(1)The accumulation,spatial distribution characteristics,and differences of aboveground carbon storage of dominant species,non-dominant species,and the entire community were investigated in detail,and the scale effect of the spatial distribution of forest aboveground carbon storage was analyzed.The results showed that the accumulation of aboveground carbon storage in the community mainly relied on large-diameter species(67.68%)rather than a large number of species(7.03%).The aboveground carbon storage of both dominant and non-dominant species was positively influenced by the number of individual species,and dominant species played a leading role in maintaining the forest ecosystem carbon sink function.The aboveground carbon storage of dominant species in the Dinghushan South Asian tropical monsoon evergreen broad-leaved forest was mainly distributed in the northeast and southeast regions of the sample plots,while the aboveground carbon storage of non-dominant species was mainly distributed in the southwest region of the sample plots,with spatial distribution differences.The spatial distribution of total aboveground carbon storage had a significant scale effect,showing heterogeneity with different scales,and the heterogeneity of spatial distribution was stronger at smaller scales,gradually weakening with the increase of scale.(2)Further research and exploration were conducted on the coupling relationship between the spatial distribution of aboveground carbon storage,species diversity,and structural diversity in the South Asian tropical monsoon evergreen broad-leaved forest.The analysis found that species diversity had a significant negative impact on the spatial distribution of aboveground carbon storage of dominant species,while it had a significant positive impact on non-dominant species.As dominant species play a leading role in the community,their impact on the overall spatial distribution of aboveground carbon storage is similar to that of dominant species and also has a significant negative impact.Structural diversity had a significant positive impact on the aboveground carbon storage of dominant species,non-dominant species,and the total,but the degree of its positive impact on dominant and non-dominant species differed,with a higher impact on non-dominant species.(3)The influence of terrain and soil factors on the spatial distribution of aboveground carbon storage was studied in depth.By constructing a composite structural equation model,the pathways,effect sizes,scale effects,and driving mechanisms of various influencing factors on the overall spatial distribution of aboveground carbon storage were explored.The study found that both terrain and soil factors had a positive impact on the spatial distribution of aboveground carbon storage,but their impact on dominant and non-dominant species differed.In addition to terrain factors,other influencing factors had both direct and indirect pathways to aboveground carbon storage,and different influencing factors had different direct and indirect effects on aboveground carbon storage at different scales.The spatial distribution of aboveground carbon storage in the South Asian tropical monsoon evergreen broad-leaved forest was mainly affected by structural diversity(0.64),followed by terrain factors(0.47)and then soil factors(0.46).The impact of species diversity was the smallest(0.23),and there was an obvious scale effect in the degree of influence of various influencing factors on aboveground carbon storage.Habitat heterogeneity and dispersal limitation had a joint effect on aboveground carbon storage in the South Asian tropical forest,and as the research scale increased,the relative importance of dispersal limitation decreased,and the relative importance of habitat heterogeneity increased.Habitat heterogeneity was the most important driving mechanism affecting the spatial distribution of aboveground carbon storage in the South Asian tropical forest. |
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