细根是植物根系中直径<2 mm的部分,对植物群落功能的发挥和土壤碳库及全球碳循环具有重要意义。人工林是森林的重要组成部分,在全球碳循环中扮演着重要的角色,但目前对人工林的研究相对较少。沙枣人工林是西部荒漠地区重要的人工林类型,目前对于其固碳能力的研究尚属空白。利用土柱法和分解袋法,于2010年5~10月整个生长季节内,对三工河流域人工沙枣群落的细根生物量、分解与周转规律进行了研究。结果表明:沙枣群落的细根生物量表现出明显的季节和垂直变化,即在5~8月逐渐增加,8月达到最大值,9~10月逐渐下降。平均月细根生物量为146.24 g/m~2,活细根和死细根分别占总细根生物量的73%和27%。在垂直变化上,随土壤深度增加细根生物量逐渐降低,其中,0~10 cm 土层细根生物量比例最大,占总生物量的44.63%。沙枣群落的细根年分解率为58.5%。达到半分解和95%分解时,分别需要277 d和1 093 d。沙枣群落的细根净生产力分别为151.99 g·m~(-2)·a~(-1),细根年周转率分别为1.43次。实验证明,沙枣人工群落地下根系具有较高的生产力,具有良好的固碳能力,是适合在荒漠地区大力推广的人工林树种。
英文摘要:
Facing the global climate change,fine root biomass,growth and turnover,longevity,seasonal dynamics and influence on the biogeochemical cycling in terrestrial ecosystems has gradually become a hot topic. Fine root is the plant root with diameter less than 2 mm and is an important part of the plant roots,as well as the most active part of the plant root system,which determine the growth and development of plants. Its productivity,dynamic and cycle play an important role in terrestrial ecosystem carbon cycle and in nutrient cycling. According to the previous studies, the amount of carbon entering the soil through fine root turnover accounted for about 30% to 50% of the whole ecosystem amount,and plant roots consume about 30% of the global net primary productivity. Therefore,it is of great significance to conduct research of effect of root biomass and turnover on soil carbon pool and the global carbon cycle. Plantation is an important part of the forest and plays an important role in carbon sequestration. Elaeagnus angustifolia L. plantations are common in the western desert region in China. However,there are no researches on the ability of E. angustifolia plantations at present. Previous studies mainly focused on natural forest communities, and in this research,plantations are focused. The continuous soil drilling method and fine root bag method was used to investigate the fine root dynamic and fine root turnover of E. angustifolia communities from May to October in 2010(the whole growing season)at the Sangong River Basin,Changji Prefecture,Xinjiang,China. Fine root biomass of the E. angustifolia shows the significant seasonal change and vertical distribution,the value of fine root biomass increased gradually from May to August,and reached maximum in August,then declined gradually from September to October. Monthly average fine root biomass was 146.24 g/m~2,and live fine root biomass and dead fine root biomass were 73% and 27% of total fine root biomass,respectively. Fine root biomass reduced gradually as soil depth increased,and fine root biomass in 0-10 cm soil layer was the largest part,with 44.63% of total fine root biomass. Annual fine root decomposition rate was 58.5%,277 days and 1093 days were needed to reach half decomposition and 95% decomposition,respectively. Fine root net productivity was 151.99 g·m~(- 2)·a~(- 1),and fine root annual turnover rate was 1.43 times/a. The study proves that the roots of E. angustifolia plantations have higher ability of carbon sequestration than that of the some natural communities,for example,Haloxylon ammodendron community. E. angustifolia plantations could be used widely in west desert region in China.