Western Sichuan sub-alpine is an extension of Qinghai-Tibet Plateau to southeastern China and is covered with forests in the valleys, mainly dark coniferous ones. As a result of long-term over-logging on a large scale...Western Sichuan sub-alpine is an extension of Qinghai-Tibet Plateau to southeastern China and is covered with forests in the valleys, mainly dark coniferous ones. As a result of long-term over-logging on a large scale, they have been greatly reduced and degraded. In this paper, in order to analyse the influences of forest management and topography factors on sub-alpine forest restoration in west Sichuan, Miyaluo was selected as a case study area. The cutting volume, artificial regeneration area and tending area from 1953 to 2000 were collected, forest survey and plot investigation were taken in 7 watersheds. The results showed that sub-alpine forest restoration in west Sichuan was influenced by both forest management and natural regeneration. Taking Miyaluo as an example, forest management could be divided into two stages, cutting period (1953—1978) and restoration period (1978—now), and cutting period also could be divided into period Ⅰ (1953—1965) and period Ⅱ (1966—1978). In cutting period with logging on a large scale and fast regeneration, artificial regeneration could not catch up with cutting, tending could not catch up with regeneration, the young growth tending was worse and survival rate was low, especially in period Ⅰ. That resulted in the mosaic patch of plantations, natural secondary forests and ones from both artificial and natural regeneration in cutting area. The pattern was influenced by aspect. Spruce from artificial regeneration was dominant on half-sunny and sunny slope; birch and firs from natural regeneration were on half-shady and shady slopes. In restoration period, cutting was little and stopped at last, artificial regeneration was little; survival rate was high from well tending to young growth. Spruce regenerated artificially in 1980s and at the beginning of 1990s had closed to young forests after successive tending with many years. In sub-alpine forest regions, the regeneration methods and species should be selected according to the habitat types that changed with altitud展开更多
随着全球大气氮沉降的明显增加,将有可能显著影响我国西部地区受氮限制的亚高山森林生态系统。土壤微生物是生态系统的重要组成部分,是土壤物质循环和能量流动的重要参与者。由于生态系统类型、土壤养分、氮沉降背景值等的差异,土壤呼...随着全球大气氮沉降的明显增加,将有可能显著影响我国西部地区受氮限制的亚高山森林生态系统。土壤微生物是生态系统的重要组成部分,是土壤物质循环和能量流动的重要参与者。由于生态系统类型、土壤养分、氮沉降背景值等的差异,土壤呼吸和土壤生物量碳氮对施氮的响应存在许多不确定性。而施氮会不会促进亚高山森林生态系统中土壤呼吸和微生物对土壤碳氮的固定?基于此假设,选择了川西60年生的四川红杉(Larix mastersiana)亚高山针叶林为研究对象,通过4个水平的土壤施氮控制试验(CK:0 g m^-2 a^-1、N1:2 g m^-2 a^-1、N2:5 g m^-2 a-1、N3:10 g m^-2 a^-1),监测了土壤呼吸及土壤微生物生物量碳氮在一个生长季的动态情况。结果表明:施氮对土壤呼吸各指标和土壤微生物碳氮都有极显著的影响,施氮能促进土壤全呼吸、自养呼吸、异养呼吸通量和土壤微生物生物量碳氮的增长,施氮使土壤呼吸通量提高了11%—15%,土壤微生物量碳提高了5%—9%,土壤微生物量氮提高了23%—34%。在中氮水平下(5 g m^-2 a^-1)对土壤呼吸的促进最显著。相关分析发现,土壤呼吸与微生物生物量碳氮和微生物代谢商极呈显著正相关,微生物量碳氮与土壤温度呈极显著的正相关,与土壤湿度呈极显著负相关。通过一般线性回归拟合土壤呼吸速率与土壤10 cm温湿度的关系,发现土壤呼吸速率与土壤温度呈极显著的正相关,与土壤湿度极显著负相关(P<0.001),中氮水平下土壤温度敏感性系数Q10值(7.10)明显高于对照(4.26)。展开更多
文摘Western Sichuan sub-alpine is an extension of Qinghai-Tibet Plateau to southeastern China and is covered with forests in the valleys, mainly dark coniferous ones. As a result of long-term over-logging on a large scale, they have been greatly reduced and degraded. In this paper, in order to analyse the influences of forest management and topography factors on sub-alpine forest restoration in west Sichuan, Miyaluo was selected as a case study area. The cutting volume, artificial regeneration area and tending area from 1953 to 2000 were collected, forest survey and plot investigation were taken in 7 watersheds. The results showed that sub-alpine forest restoration in west Sichuan was influenced by both forest management and natural regeneration. Taking Miyaluo as an example, forest management could be divided into two stages, cutting period (1953—1978) and restoration period (1978—now), and cutting period also could be divided into period Ⅰ (1953—1965) and period Ⅱ (1966—1978). In cutting period with logging on a large scale and fast regeneration, artificial regeneration could not catch up with cutting, tending could not catch up with regeneration, the young growth tending was worse and survival rate was low, especially in period Ⅰ. That resulted in the mosaic patch of plantations, natural secondary forests and ones from both artificial and natural regeneration in cutting area. The pattern was influenced by aspect. Spruce from artificial regeneration was dominant on half-sunny and sunny slope; birch and firs from natural regeneration were on half-shady and shady slopes. In restoration period, cutting was little and stopped at last, artificial regeneration was little; survival rate was high from well tending to young growth. Spruce regenerated artificially in 1980s and at the beginning of 1990s had closed to young forests after successive tending with many years. In sub-alpine forest regions, the regeneration methods and species should be selected according to the habitat types that changed with altitud
文摘随着全球大气氮沉降的明显增加,将有可能显著影响我国西部地区受氮限制的亚高山森林生态系统。土壤微生物是生态系统的重要组成部分,是土壤物质循环和能量流动的重要参与者。由于生态系统类型、土壤养分、氮沉降背景值等的差异,土壤呼吸和土壤生物量碳氮对施氮的响应存在许多不确定性。而施氮会不会促进亚高山森林生态系统中土壤呼吸和微生物对土壤碳氮的固定?基于此假设,选择了川西60年生的四川红杉(Larix mastersiana)亚高山针叶林为研究对象,通过4个水平的土壤施氮控制试验(CK:0 g m^-2 a^-1、N1:2 g m^-2 a^-1、N2:5 g m^-2 a-1、N3:10 g m^-2 a^-1),监测了土壤呼吸及土壤微生物生物量碳氮在一个生长季的动态情况。结果表明:施氮对土壤呼吸各指标和土壤微生物碳氮都有极显著的影响,施氮能促进土壤全呼吸、自养呼吸、异养呼吸通量和土壤微生物生物量碳氮的增长,施氮使土壤呼吸通量提高了11%—15%,土壤微生物量碳提高了5%—9%,土壤微生物量氮提高了23%—34%。在中氮水平下(5 g m^-2 a^-1)对土壤呼吸的促进最显著。相关分析发现,土壤呼吸与微生物生物量碳氮和微生物代谢商极呈显著正相关,微生物量碳氮与土壤温度呈极显著的正相关,与土壤湿度呈极显著负相关。通过一般线性回归拟合土壤呼吸速率与土壤10 cm温湿度的关系,发现土壤呼吸速率与土壤温度呈极显著的正相关,与土壤湿度极显著负相关(P<0.001),中氮水平下土壤温度敏感性系数Q10值(7.10)明显高于对照(4.26)。
