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生物结皮是土壤表面具有光合活性的致密复合层,是土-气界面CO2通量的影响因子之一.本文采用改进的Li-8100土壤碳通量测量系统,研究了黄土丘陵区退耕地上不同演替阶段生物结皮对土壤CO2通量的影响.结果表明:光照条件下,生物结皮土壤CO2通量较除去生物结皮显著下降,其中藻结皮和藓结皮分别下降了92%和305%;生物结皮对土壤CO2通量的降低程度与其生物组成和生物量有关,深色藻结皮和藓结皮土壤CO2通量较裸地分别降低了141%和484%.生物结皮土壤CO2通量的日变化呈降低-升高-降低的趋势,而裸地CO2通量日变化趋势为单峰曲线,藻结皮、藓结皮的碳吸收峰值分别出现在8:00和9:00前后,其CO2通量分别为0.13和-1.02μmolCO2·m-2·s-1;藻结皮24hCO2通量排放总量较裸地增加7.7%,而藓结皮减少了29.6%.生物结皮对土壤CO2通量的影响显著,在评价退耕地土壤碳循环时,应考虑生物结皮的影响.
Bio-crust is a compact composite layer with photosynthetic activity on soil surface and is one of the influencing factors of CO2 flux at soil-atmosphere interface. In this paper, an improved Li-8100 soil carbon flux measurement system The effects of biological crusts on soil CO2 flux in the succession stage were studied.The results showed that the CO2 fluxes of the bio-crust soil decreased significantly compared with the removal of biological crusts under light irradiation, in which the algal crusts and moss crusts decreased by 92% 305%. The reduction of soil CO2 flux was related to its biological composition and biomass, while the CO2 flux in dark-skin algal crusts and moss crusts was reduced by 141% and 484%, respectively. The diurnal variation of soil CO2 flux showed a trend of decrease-increase-decrease, while that of bare soil CO2 flux was unimodal curve. The peak of carbon absorption of algal crust and moss crust appeared at 8:00 and 9 respectively : CO2 flux was 0.13 and -1.02μmolCO2 · m-2 · s-1 respectively before and after 00. The flux of 24hCO2 in algal crust increased by 7.7% compared with bare soil, while the moss crust decreased by 29.6% The impact of crusting on soil CO2 flux is significant. When evaluating the soil carbon cycling, the effects of biological crust .