Abstract
Exploring carbon allocation pattern and its influencing factors is of great significance for estimating the carbon sequestration rate and potential of forest ecosystems. Here, we investigate all carbon pool components (including above and belowground biomass of tree, shrub and herb layers, and dead biomass and soil carbon pools) in four successional stages of broad-leaved and Korean pine (Pinus koraiensis Siebold & Zucc.) mixed forests in Northeast China. We explore the change of allocation among carbon pools with succession and examine the relative importance of succession, stand age, and stand factors on carbon allocation pattern. Our results illustrate that above- and belowground vegetation carbon increase as maximum tree height increases. Below- to aboveground vegetation carbon ratio (R/S ratio) decreases significantly with succession and increases significantly as mean diameter at breast height (DBH) increases, but does not significantly correlate with stand age. With succession and increasing stand age, understory (shrub, herb) to tree carbon ratio (understory/tree ratio) and soil to vegetation carbon ratio (soil/vegetation ratio) decrease significantly. The joint effect of succession, stand age, and stand factors have the largest contribution on above- and belowground vegetation carbon and understory/tree ratio (26.83%, 27.93%, and 49.48% of variations explained, respectively). As for the pure effects, stand factors explain the largest proportion of variations in vegetation aboveground carbon (11.25%) and soil carbon (20.18%). Meanwhile, succession is the variable with the largest contribution to vegetation belowground carbon (12.64%), R/S ratio (21.83%), understory/tree ratio (25.84%), and soil/vegetation ratio (6.68%). Overall, these results suggest that species composition change during forest succession, instead of stand factors and stand age, is the main driver of forest vegetation carbon allocation. In contrast, stand factors play a major role in soil carbon allocation. Our findings suggest more studies to better understand the role of species composition (in addition to stand factors and age) on biomass allocation, and the influence of stand factors and litterfalls on soil carbon sequestration, which are critical to improve forest management strategies (e.g., adjustment of species composition and forest structure) to increase the future ability of forest carbon sequestration.
Highlights
IntroductionThere is a need for accurate information concerning carbon storage and allocation pattern in forest ecosystems to improve our understanding in processes and mechanisms of the global carbon cycle [5]
The current carbon stock in the world’s forests is estimated to be 861 Pg C (1 Pg = 1015 g), and grows at a rate of 2.4 Pg C per year, which plays an important role in alleviating the increase of atmospheric CO2 concentration [1]
This study reveals the relative importance of successional stages, stand age and stand structure on carbon storages and allocation pattern in a temperate forest ecosystem
Summary
There is a need for accurate information concerning carbon storage and allocation pattern in forest ecosystems to improve our understanding in processes and mechanisms of the global carbon cycle [5]. Many studies have explored variation in forest carbon storage and allocation with successional stages, including studies from local, reginal to global scales [8,9,10]. Few studies have explored all carbon pool components (vegetation, dead biomass, soil) and their allocation patterns in forest ecosystems. Wei et al [11] explored the variation of carbon stocks (vegetation, litterfall, soil) with succession for five forest types in Northeast China. Chen et al [12] examined the aboveand belowground carbon allocation (vegetation, litterfall) change with species and forest age in four tropical plantations and naturally restored shrub lands
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