Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet（UV） radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. H...Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet（UV） radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. Here, we conducted a field-based experiment in 2011 in the southeastern Horqin Sandy Land, Northeast China, to investigate the effects of UV radiation, litter layer thickness, and their interaction on the mass loss and chemical properties of decomposing litter from Xiaozhuan poplar（Populus × xiaozhuanica） and Mongolian pine（Pinus sylvestris var. mongolica） plantation trees. We found that UV radiation accelerated the decomposition rates of both the Xiaozhuan poplar litter and Mongolian pine litter. For both species, the thick-layered litter had a lower mass loss than the thin-layered litter. The interaction between UV radiation and litter layer thickness significantly affected the litter mass loss of both tree species. However, the effects of UV radiation on the chemical properties of decomposing litter differed between the two species, which may be attributed to the contrasting initial leaf litter chemical properties and morphology. UV radiation mostly had positive effects on the lignin concentration and lignin/N ratio of Xiaozhuan poplar litter, while it had negative effects on the N concentration of Mongolian pine litter. Moreover, litter layer thickness and its interaction with UV radiation showed mostly positive effects on the N concentration and lignin/N ratio of Xiaozhuan poplar litter and the ratios of C/N and lignin/N of Mongolian pine litter, and mostly negative effects on the C/N ratio of Xiaozhuan poplar litter and the N concentration of Mongolian pine litter. Together, these results reveal the important roles played by UV radiation and litter layer thickness in the process of litter decomposition in this semi-arid region, and highlight how changes in the litter layer thickness can exert strong influences on the photodegradation of litter in tree plantations.展开更多
In this paper, we adopted simulation method to discuss influences of litter layer on plants habitat in grassland. Results indicated that ground surface evaporation, soil moisture, surface temperature, soil pH, soil bu...In this paper, we adopted simulation method to discuss influences of litter layer on plants habitat in grassland. Results indicated that ground surface evaporation, soil moisture, surface temperature, soil pH, soil bulk density and soil porosity were all strongly related to the litter quantity. Potassium （K） and organic materials in the soil covered by litter layer were higher than those in the soil uncovered by litter layer. With 100 g.ln-z increase of litter, the percentage of organic materials increased by 17.9%, nitrogen （N） increased by 7.6%, phosphor （P） increased by 26.4%, and K increased by 3.8%. With the litter accumulation amounting up to 600 g-m-2, the percentage of organic materials increased by 1.8 times, N increased by 81.5%, P increased by 1.8 times and K increased by 26.4%. According to the expected coefficient method of optimization, a mathematical model was established about the optimal accumulation quantity of litter.展开更多
基金supported by the National Natural Science Foundation of China (31270668,41373038)the National Basic Research Program of China (2012CB416902)the China Postdoctoral Science Foundation (2016M601342)
文摘Forests and grasslands in arid and semi-arid regions receive high-intensity ultraviolet（UV） radiation year-round. However, how the UV radiation affects the litter decomposition on the forest floor remains unclear. Here, we conducted a field-based experiment in 2011 in the southeastern Horqin Sandy Land, Northeast China, to investigate the effects of UV radiation, litter layer thickness, and their interaction on the mass loss and chemical properties of decomposing litter from Xiaozhuan poplar（Populus × xiaozhuanica） and Mongolian pine（Pinus sylvestris var. mongolica） plantation trees. We found that UV radiation accelerated the decomposition rates of both the Xiaozhuan poplar litter and Mongolian pine litter. For both species, the thick-layered litter had a lower mass loss than the thin-layered litter. The interaction between UV radiation and litter layer thickness significantly affected the litter mass loss of both tree species. However, the effects of UV radiation on the chemical properties of decomposing litter differed between the two species, which may be attributed to the contrasting initial leaf litter chemical properties and morphology. UV radiation mostly had positive effects on the lignin concentration and lignin/N ratio of Xiaozhuan poplar litter, while it had negative effects on the N concentration of Mongolian pine litter. Moreover, litter layer thickness and its interaction with UV radiation showed mostly positive effects on the N concentration and lignin/N ratio of Xiaozhuan poplar litter and the ratios of C/N and lignin/N of Mongolian pine litter, and mostly negative effects on the C/N ratio of Xiaozhuan poplar litter and the N concentration of Mongolian pine litter. Together, these results reveal the important roles played by UV radiation and litter layer thickness in the process of litter decomposition in this semi-arid region, and highlight how changes in the litter layer thickness can exert strong influences on the photodegradation of litter in tree plantations.
基金Acknowledgements： This research work was supported by the National Natural Science Foundation of China （No. 30590382 and No. 30570273） and Science Foundation for Young Teachers of Northeast Normal University （No. 20070502）.
文摘In this paper, we adopted simulation method to discuss influences of litter layer on plants habitat in grassland. Results indicated that ground surface evaporation, soil moisture, surface temperature, soil pH, soil bulk density and soil porosity were all strongly related to the litter quantity. Potassium （K） and organic materials in the soil covered by litter layer were higher than those in the soil uncovered by litter layer. With 100 g.ln-z increase of litter, the percentage of organic materials increased by 17.9%, nitrogen （N） increased by 7.6%, phosphor （P） increased by 26.4%, and K increased by 3.8%. With the litter accumulation amounting up to 600 g-m-2, the percentage of organic materials increased by 1.8 times, N increased by 81.5%, P increased by 1.8 times and K increased by 26.4%. According to the expected coefficient method of optimization, a mathematical model was established about the optimal accumulation quantity of litter.
