作 者 ：刘彦春,张远东*,刘世荣,张笑鹤
期 刊 ：生态学报 2010年 30卷 21期 页码：5810~5820
Keywords:aboveground biomass, altitudinal gradient, subalpine, secondary forest, natural restoration,
摘 要 ：川西亚高山针阔混交林是该地区云冷杉暗针叶林大规模采伐后自然恢复形成的主要次生林类型之一，是由采伐迹地向顶极暗针叶林演替过程中的重要阶段。采用样地调查与异速生长模型相结合的方法，研究了川西亚高山林区4个海拔梯度（A：2900—3050 m；B：3150—3300 m；C：3300—3450 m；D：3450—3550 m）40 a生针阔混交林的生物量与生产力变化。结果表明，林分乔木层生物量、生产力随海拔上升而不断下降，分别由A梯度的157.07t/hm2、3.43 t ? hm-2 ? a-1下降到D梯度的 5465t/hm2、136 t? hm-2 ? a-1，气温的海拔间差异以及林分密度的递减是影响林分生物量、生产力变化的主要原因；阔叶类树种单株平均生物量、生产力随海拔升高而显著下降，由A梯度的200.55 kg、4.96 kg/a下降到D梯度的47.86 kg、1.19 kg/a；而针叶类树种单株平均生物量、生产力则逐渐上升，由A梯度的51.57 kg、1.28 kg/a上升到D梯度的73.88 kg、1.84 kg/a，但未达显著水平，阔、针叶类树种生物量、生产力变化分异是物种的生物学特性和林分环境共同作用的结果。相关分析显示，该地区阔叶类树种对海拔梯度的响应比针叶树种更为敏感和显著。
Abstract:Subalpine forest region of Western Sichuan was located in the outer fringe of southeastern Qinghai-Tibet Plateau with high mountains and deep valleys, and was covered with subalpine forests, mainly dark coniferous ones. The forest had been greatly reduced and degraded, as a long-term over-logging on a large scale. Natural secondary coniferous-broadleaved forest was one of the main secondary forest types in subalpine region of Western Sichuan, which was originated from the clear-cutting lands between 1950s-1980s due to the overexploitation of coniferous forests. Additionally, it was an important transitional stage in the secondary succession from cutting-blank to climax community. Our objectives were to quantify the aboveground biomass and aboveground net primary productivity (ANPP) of coniferous-broadleaved forests at different altitude, and to explore whether different response of coniferous species and broadleaf ones to changing altitude was existed or not. Based on the history data of forest management and field survey, we investigated eighteen sample plots of coniferous-broadleaved forests with 40 years old, distributed along four (A: 2900-3050 m; B: 3150-3300 m; C: 3300-3450 m; D: 3450-3550 m) altitudes from 2900 m to 3550 m, all of which were located on the same slope of Jiabi Mountain in Miyaluo forest region. We sampled 4 or 5 plots with similar site conditions and stand factors in each gradient. All tree layer plants (DBH ≥ 5 cm) were surveyed and sorted into two groups: broadleaf species and coniferous species, based on the leaf characters. Aboveground biomass was calculated using allometric relationships of this region summarized by other experts. The ANPP was estimated by the mean annual increment method. The biomass and ANPP of tree layer decreased from 157.07 t/hm2, 3.43 t ?hm-2 ?a-1 to 54.65 t?hm-2, 1.36 t?hm-2 ?a-1 respectively, with increasing elevation. The temperature difference and reducing stand density among altitudes were possibly the main factors affecting the stand biomass and ANPP. Individual biomass and ANPP of broadleaf species decreased from 200.55 kg, 4.96 kg/a at A to 47.86 kg, 1.19 kg/a at D with increasing altitude. However, opposite conclusion was found in coniferous species. The corresponding values of coniferous species increased from 51.57 kg、1.28 kg/a at A to 73.88 kg、1.84 kg/a at D. But there were no significant difference at 0.05 level. This heterogeneity seems to be in part responsible for differences in biological characteristics of species and forest habitat. Correlation analysis revealed that broad-leaf species were more significant and sensitive in response to altitude than coniferous species in this region. The difference of biomass and ANPP between different altitudes may be narrowed down with the global warming.
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