干旱荒漠区不同演替阶段白刺灌丛沙堆土壤呼吸特征及其影响因素分析

Characteristics of Soil Respiration of Nitraria tangutorum at Different Succession Stages in Desert Areas & the Influencing Factors

为了研究干旱荒漠区不同演替阶段白刺土壤呼吸特征,探讨土壤呼吸对环境因子变化的响应,采用自动土壤二氧化碳通量监测系统,测定了不同演替阶段(雏形、稳定、发育、衰退)白刺灌丛沙堆的土壤呼吸速率,同步测定了土壤温度、水分等指标,分析了环境因子与土壤呼吸之间的关系。结果表明:1)不同演替阶段白刺灌丛沙堆土壤呼吸变化呈"单峰曲线"。土壤呼吸速率均值按大小顺序排列为稳定阶段>雏形阶段>发育阶段>衰退阶段;2)4种演替阶段土壤呼吸速率与10cm处土壤温度之间有一定的相关关系,对白刺灌丛沙堆土壤温度可以解释雏形70.16%、发育82.67%、稳定87.81%、衰退88.73%的土壤呼吸变化;3)随着水分的增加,土壤呼吸速率也相应的增大,当土壤水分达到最高时,水分的限制作用减小,水分增加对土壤呼吸的促进作用减弱;4)各发育阶段不同坡位土壤呼吸日变化动态存在差异,但平均值都表现为迎风坡中部>迎风坡底部>迎风坡顶部>背风坡中部>背风坡底部。对不同演替阶段白刺灌丛沙堆土壤呼吸及其影响因素的研究有助于认识区域生态过程和全球气候变化。

In order to study the soil respiration of Nitraria tangutorum at different succession stages （the initial, stable, developmental and degradation stages） as well as the response of soil respiration to environ- mental factors,the automatic soil CO2 flux monitoring system （Li-8100, LI-COR Inc. , Lincoln, NE, USA） was used to determine the soil respiration rate. Soil temperature and soil water were measured simultane- ously. The correlations between environment factors and soil respiration rate were analyzed. The result showed that ：1） the variation of soil respiration presented a single-peak curve. The soil respiration rate was ranked from high to low as： stable stage〉initial stage〉developmental stage〉degradation stage; 2） The soil respiration rate at different stages was correlated with soil temperature at the depth of 10 cm. The soil respiration rates in initial, stable, developmental and degradation stages were 70.16%, 87.81%, 82.67%, and 88.73%,respectively^3） With the increase of soil water,soil respiration increased. When soil water reached the maximum value, the limitation function of soil water reduced, the impact of soil water increase on soil respiration reduced;4） The daily variation of soil respiration at different slope positions were diffeent. The mean values was in the order of the middle of windward slope 〉 base of windward slope 〉 top of windward slope 〉 middle of leeward slope〉the base of leeward slope.