Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We inv...Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.展开更多
Aims The redistribution of forest gaps based on solar radiation and precipitation(mainly rainfall and snowfall)can create heterogenous microenvironments inside and outside the gaps.Here,we investigated the effects of ...Aims The redistribution of forest gaps based on solar radiation and precipitation(mainly rainfall and snowfall)can create heterogenous microenvironments inside and outside the gaps.Here,we investigated the effects of forest gaps on carbon(C),nitrogen(N)and phosphorus(P)stoichiometry in decaying logs by altering the microenvironments.Methods Minjiang fir(Abies faxoniana)logs of decay classes I–V were incubated in situ on the floor under the gap center(GC),gap edge(GE)and closed canopy(CC)in a subalpine forest in the eastern Qinghai-Tibet Plateau.The C,N and P concentrations in decaying bark,sapwood and heartwood were measured in August from 2013 to 2016.Important Findings Our results showed that the N concentration in bark decreased from the CC to the GC,while the opposite trend was found in sapwood and heartwood.Additionally,the C/N ratio in sapwood and heartwood of decay classes IV and V decreased from the CC to the GC,and the N/P ratio in heartwood of decay class V increased from the CC to the GC,implying that forest gaps have strong effects on C/N/P stoichiometry in highly decayed logs.Briefly,highly decayed logs are more susceptible to the microenvironment,and the proportion of highly decayed logs under the CC or the GC should be appropriately adjusted if necessary.展开更多
基金This research was sponsored by National Natural Science Foundation of China (Grant No. 39630240 and 3000132).
文摘Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), a fast-growing, ever-green conifer tree with high yield and excellent quality, is the most important tree species of timber plantations in subtropical China. We investigated the characteristics of biomass, litterfall and nutrient fluxes in the 8, 14 and 24 year-old stands, representing the young, middle-aged and mature stands. The results showed that Chinese fir plantations in central Fujian province had high productivity, and the proportion of stem mass in total biomass was between 50%-70%. Chinese fir was low nutrient-return tree species with litterfall. Nutrient withdrawal from senescing needles was a strong age-dependence for nitrogen, phosphorous and potassium in Chinese fir. With a management system of such short-rotation and continuously pure-crop planting, harvesting timber can lead to great nutrient loss, which may be one of the causes for site degradation.
基金This work was supported by the National Natural Science Foundation of China(31870602,31901295 and 32071745)the National Key R&D Program of China(2017YFC0503906)the Program of Sichuan Excellent Youth Sci-Tech Foundation(2020JDJQ0052).
文摘Aims The redistribution of forest gaps based on solar radiation and precipitation(mainly rainfall and snowfall)can create heterogenous microenvironments inside and outside the gaps.Here,we investigated the effects of forest gaps on carbon(C),nitrogen(N)and phosphorus(P)stoichiometry in decaying logs by altering the microenvironments.Methods Minjiang fir(Abies faxoniana)logs of decay classes I–V were incubated in situ on the floor under the gap center(GC),gap edge(GE)and closed canopy(CC)in a subalpine forest in the eastern Qinghai-Tibet Plateau.The C,N and P concentrations in decaying bark,sapwood and heartwood were measured in August from 2013 to 2016.Important Findings Our results showed that the N concentration in bark decreased from the CC to the GC,while the opposite trend was found in sapwood and heartwood.Additionally,the C/N ratio in sapwood and heartwood of decay classes IV and V decreased from the CC to the GC,and the N/P ratio in heartwood of decay class V increased from the CC to the GC,implying that forest gaps have strong effects on C/N/P stoichiometry in highly decayed logs.Briefly,highly decayed logs are more susceptible to the microenvironment,and the proportion of highly decayed logs under the CC or the GC should be appropriately adjusted if necessary.
