【作者】 卢华正；

【导师】 沙丽清；

【作者基本信息】 中国科学院研究生院（西双版纳热带植物园） ， 生态学， 2009， 硕士

【摘要】 本实验从2008年1月到2009年2月采用挖壕沟法+红外气体分析法(IRGA)对比研究西双版纳热带季节雨林(Tropical rainforest, RF)和人工橡胶(Hevea brasiliensis)林(Rubber plantation, RP)的根系呼吸(Root respiration, RR)、异养呼吸(Heterotrophic respiration, HR)对土壤呼吸(Soil respiration, SR)的贡献率以及相应的环境因子。与此同时,用分解袋法研究了这两种林型的四种不同径级根的分解情况；用定期扫描法研究细根生长动态变化。结果表明：(1)季节雨林内根系呼吸对土壤呼吸的贡献率小于橡胶林：季节雨林为29%、橡胶林为42%,p<0.01；而异养呼吸正好相反,分别为71%、58%,p<0.01。根系呼吸对土壤呼吸贡献率变化范围为：季节雨林内根系呼吸占土壤呼吸6-51%,橡胶林根系呼吸占21～77%。(2)根系呼吸对土壤呼吸的贡献率的影响因子很多,既有环境因子又有生物因子。根据简单的线性相关分析,贡献率与土壤温湿度、空气温度都具有显著相关性,这种关系在季节雨林内尤其明显。(3)季节雨林内土壤呼吸、根系呼吸和异养呼吸平均速率分别为2.66、0.71、1.95μm-2·s-1,橡胶林内分别是2.06、0.84、1.22μmolCO2m-2·s-1;除了根系呼吸差异不显著外,季节雨林内土壤呼吸和异养呼吸均显著大于橡胶林。两种林型内土壤呼吸和异养呼吸均呈现雨季>干热季>雾凉季的规律。但根系呼吸不同,季节雨林内呈现雨季>雾凉季>干热季,橡胶林内呈现雾凉季>雨季>干热季。(4)土壤温湿度是土壤呼吸及其组分的关键影响因子,用5cm土温拟合,季节雨林内上壤呼吸、异养呼吸、根系呼吸的Q10分别为2.948、3.900、1.455,橡胶林分别为1.493、2.328、～(根系呼吸不显著)。(5)热带季节雨林与橡胶林的根系分解速率有显著差异,前者分解慢而后者分解快；四种不同径级的根分解速率差异显著,细根、小根分解速度比中根、粗根快。(6)热带季节雨林的细、小、中、粗根失重率分别为：30%、56%、25%、30%；橡胶林的分别为：63%、52%、41%、51%。季节雨林的细、小、中、粗根日分解系数分别为：0.0010、0.0025、0.0007、0.0007,橡胶林的分别为：0.0030、0.0019、0.0013、0.0017。(7)根系分解速率与根系呼吸对土壤呼吸的贡献率有强相关性。(8)细根生长动态变化：季节雨林内单位面积细根长大于橡胶林；两林型内,雨季单位面积细根长大于干季。更多还原

【Abstract】 A trenching method and an open-flow gas exchange system with an infrared gas analyzer (IRGA) were used to investigate the differences between tropical seasonal rain forest (RF for short below) and rubber plantation (RP for short below) in the contribution of root respiration (RR for short below) and heterotrophic respiration (HR for short below) to soil respiration (SR for short below), and the factors influencing soil respiration and its components as well, in Xishuangbanna, Yunnan, SW China from January 2008 to February 2009. In addition, a one-year litterbag experiment was designed to research the decomposition of different-size roots in these two forests simultaneously. And the fine root growth was studied by scanning regularly in both forests.The main results were as follows.a) The contribution of RR to SR in RF was much less than that in RP with 29% in RF and 42% in RP (p<0.01), but the contribution of HR to SR was on the contrary,71% in RF and 58% in RP (p< 0.01). The contribution of RR to SR in both forests showed strong seasonal variation. Over the sampling period, the contribution of RR to SR in RF ranged from 6% to 51%, in RP from 21% to 77%.b) Environmental and biological factors significantly affected the contribution of RR to SR in both forests. Linear regression analyzing demonstrated strong correlation between the contribution of RR to SR and soil temperature, soil moisture or air temperature.c) On an annual average, SR, RR and HR rates in RF were 2.66,0.71,1.95μmolCO2m 2·s-1, respectively, and 2.06,0.84,1.22μmolCO2m-2·s-1 in RP, respectively. And SR and HR rates in RF were significantly higher than those in RP except for RR rate. SR and HR rates in both forests fluctuated seasonally, with a rank of rainy season> dry-hot season> foggy season, while RR rate in RF with a rank of rainy season> foggy season> dry-hot season, and RR rate in RP with foggy season> rainy season> dry-hot season.d) Soil temperature and moisture were the main key factors of SR, RR and HR. In the model of soil temperature at 5cm depth (T5), Q10 of SR, HR and RR was 2.948,3.900 and 1.455 in RF, respectively, and 1.493,2.328,～in RP, respectively, except that the correlation between T5 and RR in RF was not significant.e) The root decomposition rate in RF was significantly lower than that in RP. And in each forest, the decomposition rates of fine and small roots were significantly higher than those of medium and coarse roots.f) After one-year’s decomposition, the mass-loss rates of fine, small, medium and coarse roots in RF were 30%,56%,25%,30%, respectively, and 63%, 52%,41%,51% in RP, respectively. And the daily decomposition coefficients of fine, small, medium and coarse roots in RF were 0.0010, 0.0025,0.0007,0.0007, respectively, and 0.0030,0.0019,0.0013,0.0017 in RP, respectively.g) There was strong correlation between root decomposition rate and contribution of RR to SR.h) The fine root growth rate was much higher in RF than that in RP. Furthermore, the fine root growth rate in both forests varied seasonally, and the rate in dry season was much lower than that in rainy season.更多还原