Aims Litterfall is a key parameter in forest biogeochemical cycle and fire risk prediction.However,considerable uncertainty remains regarding the litterfall variations with forest ages.Quantifying the interannual vari...Aims Litterfall is a key parameter in forest biogeochemical cycle and fire risk prediction.However,considerable uncertainty remains regarding the litterfall variations with forest ages.Quantifying the interannual variation of forest litterfall is crucial for reducing uncertainties in large-scale litterfall prediction.Methods Based on the available dataset(N=318)with continuous multi-year(≥2 years)measurements of litterfall in Chinese planted and secondary forests,coefficient of variation(CV),variation percent(V_(P)),and the ratio of next-year litterfall to current-year litterfall were used as the indexes to quantify the interannual variability in litterfall.Important Findings The interannual variations of litterfall showed a declining trend with increasing age from 1 to 90 years.The litterfall variations were the largest in 1-10 years(mean CV=23.51%and mean V_(P)=−28.59%to 20.89%),which were mainly from tree growth(mean ratio of next-year to current-year=1.20).In 11-40 years,the interannual variations of litterfall gradually decreased but still varied widely,mean CV was~18%and mean V_(P) ranged from−17.69%to 21.19%.In 41-90 years,the interannual variations minimized to 8.98%in mean CV and~8%in mean V_(P).As a result,forest litterfall remained relatively low and constant when stand age was larger than 40 years.This result was different from the previous assumptions that forest litterfall reached relatively stable when stand age was larger than 30,20 or even 15 years.Our findings can improve the knowledge about forest litter ecology and provide the groundwork for carbon budget and biogeochemical cycle models at a large scale.展开更多
Large areas of forest plantations have been developed in China. It is important to evaluate the soil fauna in plantations and the conditions needed for their recovery in view of the large areas of plantations in China...Large areas of forest plantations have been developed in China. It is important to evaluate the soil fauna in plantations and the conditions needed for their recovery in view of the large areas of plantations in China. Three Pinus tabulaeformis forests, a 26-year-old plantation （P26） and a 45-year-old plantation （P45）, exposed to clear-cutting before plantation, and an 80 260-year-old natural forest （N260）, were chosen to study the effects of different forest ages/types on Collembola community in the lifter and soil layers during 2008 and 2009. Soil conditions in P26 and P45 were significantly deteriorated when compared to N260. A higher value of soil bulk density and lower values of soil organic matter, soil N, litter depth, soil pH, and soil water content were observed in P26 and P45. Totally, the same genera of Collembola tended to occur in the forests of all ages studied; however, the Collembola community structure was significantly impacted by the differences in forest age. Both in the litter and soil layers, the density and generic richness of the Collembola were the highest in N260 and the lowest in P26. Some collembolan groups were sensitive to soil conditions in particular forest ages. N260 was associated with relatively high abundance of Plutomus collembolans and P45 with relatively high abundance of Pseudofolsomia collembolans. The canonical correspondence analysis showed that the community structure of Collembola was mainly affected by forest age in both litter and soil layer. The ordination analysis of non-metric multidimensional scaling also found that the Collembola community did not recover to the level of natural forests in 26-year regeneration after clear-cutting. Even in 45-year regeneration after clear-cutting, the Collembola community only showed a slight recovery to the level of natural forests. Our results clearly showed that both Collembola community and soil conditions did not recover in 26- and 45-year regeneration after clear-cutting in P. tabulaeforrnis plantations; however, they might have the potential to recover in the future because the same genera of Collembola were distributed in the plantations and natural forests.展开更多
基金supported by the National Key Research and Development Program of China(2017YFC0503906)the China Special Fund for Meteorological Research in the Public Interest(GYHY201406034).
文摘Aims Litterfall is a key parameter in forest biogeochemical cycle and fire risk prediction.However,considerable uncertainty remains regarding the litterfall variations with forest ages.Quantifying the interannual variation of forest litterfall is crucial for reducing uncertainties in large-scale litterfall prediction.Methods Based on the available dataset(N=318)with continuous multi-year(≥2 years)measurements of litterfall in Chinese planted and secondary forests,coefficient of variation(CV),variation percent(V_(P)),and the ratio of next-year litterfall to current-year litterfall were used as the indexes to quantify the interannual variability in litterfall.Important Findings The interannual variations of litterfall showed a declining trend with increasing age from 1 to 90 years.The litterfall variations were the largest in 1-10 years(mean CV=23.51%and mean V_(P)=−28.59%to 20.89%),which were mainly from tree growth(mean ratio of next-year to current-year=1.20).In 11-40 years,the interannual variations of litterfall gradually decreased but still varied widely,mean CV was~18%and mean V_(P) ranged from−17.69%to 21.19%.In 41-90 years,the interannual variations minimized to 8.98%in mean CV and~8%in mean V_(P).As a result,forest litterfall remained relatively low and constant when stand age was larger than 40 years.This result was different from the previous assumptions that forest litterfall reached relatively stable when stand age was larger than 30,20 or even 15 years.Our findings can improve the knowledge about forest litter ecology and provide the groundwork for carbon budget and biogeochemical cycle models at a large scale.
基金supported by the Innovation Pro-gram of Chinese Academy of Science(No.KSCX2EW-Z-6)the Special Program of the Ministry of Science and Technology,China(Nos.2009ZX08012-005B and 2012ZX08011002)the National Natural Sciences Foundation of China(No.31200331)
文摘Large areas of forest plantations have been developed in China. It is important to evaluate the soil fauna in plantations and the conditions needed for their recovery in view of the large areas of plantations in China. Three Pinus tabulaeformis forests, a 26-year-old plantation （P26） and a 45-year-old plantation （P45）, exposed to clear-cutting before plantation, and an 80 260-year-old natural forest （N260）, were chosen to study the effects of different forest ages/types on Collembola community in the lifter and soil layers during 2008 and 2009. Soil conditions in P26 and P45 were significantly deteriorated when compared to N260. A higher value of soil bulk density and lower values of soil organic matter, soil N, litter depth, soil pH, and soil water content were observed in P26 and P45. Totally, the same genera of Collembola tended to occur in the forests of all ages studied; however, the Collembola community structure was significantly impacted by the differences in forest age. Both in the litter and soil layers, the density and generic richness of the Collembola were the highest in N260 and the lowest in P26. Some collembolan groups were sensitive to soil conditions in particular forest ages. N260 was associated with relatively high abundance of Plutomus collembolans and P45 with relatively high abundance of Pseudofolsomia collembolans. The canonical correspondence analysis showed that the community structure of Collembola was mainly affected by forest age in both litter and soil layer. The ordination analysis of non-metric multidimensional scaling also found that the Collembola community did not recover to the level of natural forests in 26-year regeneration after clear-cutting. Even in 45-year regeneration after clear-cutting, the Collembola community only showed a slight recovery to the level of natural forests. Our results clearly showed that both Collembola community and soil conditions did not recover in 26- and 45-year regeneration after clear-cutting in P. tabulaeforrnis plantations; however, they might have the potential to recover in the future because the same genera of Collembola were distributed in the plantations and natural forests.
