In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris v...In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris var. mongolica trees from two provenances （natural forests and plantations）. The results indicated that natural tree needles had lower N, P and C concentrations, and higher K concentrations than those of plantation tree needles. For plantation tree needles, ratios of N： P, P. K and N： K increased with tree age before 45 years old; but they were not clear for the natural tree needles. Compared with the conclusions reported on Pinus spp., we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles. This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var. mongolica on sandy land. However, foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp. （〉4.80 g kg-1）.The N： P ratio of natural needles was in the adequate ranges, but N： P ratio of plantation needles was out of the adequate ranges. These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations. If only considering the foliar nutrient concentrations of P sylvestris var. mongolica from different provenances, it might be concluded that the degradation phenomenon of P. sylvestris var. mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P, but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients. The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.展开更多
The thickness of snow accumulated near different kinds of protection forest, i.e. shelterbelt ( Pinus sylvestris var. mongolica ) with ventilation structure, grouped protection forest ( P. sylvestris var. mongolica ) ...The thickness of snow accumulated near different kinds of protection forest, i.e. shelterbelt ( Pinus sylvestris var. mongolica ) with ventilation structure, grouped protection forest ( P. sylvestris var. mongolica ) with closed structure, and the protection forest ( Lespedeza bicolor ) with loose structure, at Baiyinhua Sand in Fuxin of Liaoning Province were measured. The shape of snow drift on the windward side and leeward side near shelterbelt was long and thin, and distributed evenly. The farther the snow drift away from the shelterbelt, the more even it distributed. The grouped protection forest had the thickest snow accumulated (30.5 cm) on the forest edge on the windward side, but distributed unevenly. The snow accumulated on the edge of leeward side of protection forest with loose structure was 15.8 cm in thickness, and the snow in the forest was thicker than the average. Grouped protection had the greatest influence on the thickness of snow accumulated, followed by the forest with loose structure, and the shelterbelt the least. The effective distance of snow accumulation on lee side was longer (84 m at its maximum) than on windward side (42 m at its maximum). Mathematical equations were established by regression analysis to forecast the thickness of snow at different distances away from the forests.展开更多
基金The research was supported by Innovation Research Project of Chinese Academy of Sciences (KZCX3-SW-418), and the 100 Young Researcher Project of Chinese Academy of Sciences.
文摘In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris var. mongolica trees from two provenances （natural forests and plantations）. The results indicated that natural tree needles had lower N, P and C concentrations, and higher K concentrations than those of plantation tree needles. For plantation tree needles, ratios of N： P, P. K and N： K increased with tree age before 45 years old; but they were not clear for the natural tree needles. Compared with the conclusions reported on Pinus spp., we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles. This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var. mongolica on sandy land. However, foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp. （〉4.80 g kg-1）.The N： P ratio of natural needles was in the adequate ranges, but N： P ratio of plantation needles was out of the adequate ranges. These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations. If only considering the foliar nutrient concentrations of P sylvestris var. mongolica from different provenances, it might be concluded that the degradation phenomenon of P. sylvestris var. mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P, but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients. The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.
基金The research was supported by innovation research project of Chinese Academy of Sciences （KZCX3-SW-418）, the 100-Young-Researcher-Project of Chinese Academy of Sciences, and by Nature Science Foundation of Liaoning Province （20021006）. Acknowledgements We thank Professor Hexin Wang （Dalian University, China）, Dr. Professor Zeng Dehui, and the graduate students in research group of Ecology and Management of Secondary Forest （Institute of Applied Ecology, Chinese Academy of Sciences） for their valuable discussion. We are grateful to Mr. Tao Yang （Institute of Applied Ecology, Chinese Academy of Sciences） for his field work. We also thank Dr. Professor Qingcheng Wang （Northeast Forestry University, China）, Mr. Menqi Tu and Mr. Yuxiang Ge （Honghuaerji Forestry Bureau, Inner Mongolia, Hulunbeier, China） for providing the convenience during the field investigation.
文摘The thickness of snow accumulated near different kinds of protection forest, i.e. shelterbelt ( Pinus sylvestris var. mongolica ) with ventilation structure, grouped protection forest ( P. sylvestris var. mongolica ) with closed structure, and the protection forest ( Lespedeza bicolor ) with loose structure, at Baiyinhua Sand in Fuxin of Liaoning Province were measured. The shape of snow drift on the windward side and leeward side near shelterbelt was long and thin, and distributed evenly. The farther the snow drift away from the shelterbelt, the more even it distributed. The grouped protection forest had the thickest snow accumulated (30.5 cm) on the forest edge on the windward side, but distributed unevenly. The snow accumulated on the edge of leeward side of protection forest with loose structure was 15.8 cm in thickness, and the snow in the forest was thicker than the average. Grouped protection had the greatest influence on the thickness of snow accumulated, followed by the forest with loose structure, and the shelterbelt the least. The effective distance of snow accumulation on lee side was longer (84 m at its maximum) than on windward side (42 m at its maximum). Mathematical equations were established by regression analysis to forecast the thickness of snow at different distances away from the forests.
