亚高山森林土壤生物化学特征对冻融交替及其格局变化的响应

亚高山土壤 土壤活性有机碳 轻组分有机碳 土壤酶 土壤冻融交替
孙辉 2009-01 项目
【英文摘要】Responses of soil temperature dynamics, freeze-thaw cycles, soil labile organic carbon fractions, and soil enzyme activities to snow and litterfall cover have been monitored and determined in subalpine forest soil in the western China during cold season through homogenized soil incubation in situ from 2008 to 2011. The results show that: (1) soil freezing period is shortened, and freeze-thaw cycles and freezing depth are also reduced for litter-covered soil, while they are not impacted significantly by snowcover. The minimum temperature of soil profile is often high than -5℃, and the most of freeze-thaw cycles are 24 hours or less. (2) Concentrations of soil labile organic carbon fractions (LFOC) are impacted significantly by snow, litter, and sampling time except easily oxidized organic carbon (EOC) and particulate organic carbon (POC), hence soil LFOC concentrations is more suitable as an early indicator for environmental change during the cold season. (3) Soil enzyme activities are sensitive to snow and litter cover except for soil invertase and cellulase to snowcover. Activities of polyphenol oxidase, invertase, and cellulose are one of suitable early indicators for subalpine soil biochemical responses to environmental changes. (4) Soil POC concentrations increase with the increase of length and number of freeze-thaw cycles, while LFOC decreases with the increase of length and number of freeze-thaw cycles. Microbial biomass carbon (MBC) decreases with the increase of number of freeze-thaw cycle. (5) Percentage of soil POC and LFOC increases along elevation gradients. The ratio of POC is 96.07% and LFOC is 87.62% of total organic carbon in soil of humus layer, which indicates that the dynamics of POC and LFOC influence the size and stability of soil carbon pool significantly in the subalpine soil.
【中文摘要】本项目通过均质化土壤原位培养研究低温季节西南亚高山土壤温度动态与冻融特征、活性有机碳与酶活性及变化格局、活性组分沿海拔变化规律,揭示环境变化下土壤冻融格局、土壤碳与酶等响应特征。(1)凋落物缩短土壤冻结时间和减少冻融交替次数、降低冻融深度;雪被对冻融时间长度、冻融交替次数、冻结深度影响不明显;土壤温度多高于-5℃,以日冻融循环为主。(2)除EOC与POC受积雪影响不显著、POC受凋落物效应不显著外,各组分含量均受积雪与凋落物显著影响;活性有机碳组分受时间影响显著;LFOC对覆盖处理、深度、时间及交互作用响应均显著,最适作为环境变化土壤有机碳短期效应指标。(3)除纤维素酶、转化酶对积雪效应不显著外,其余酶对积雪和凋落物覆盖的效应显著;纤维素酶、转化酶和多酚氧化酶较适作亚高山短期土壤生化效应指标。(4)随冻融周期和次数增加,POC逐渐增加到一个稳定水平而LFOC随之降低;MBC随冻融次数增加而降低;冻结最低温影响POC、DOC和EOC含量;土壤含水量影响POC、MBC和LFOC。(5)POC和LFOC比例随海拔上升;腐殖质层POC(96.07%)和LFOC(87.62%)动态影响土壤碳。