干旱与半干旱区灌丛微生境中红砂枯落物分解特征及中小型节肢动物的作用

在干旱区(内蒙古乌拉特后旗)和半干旱区(宁夏盐池)荒漠草原区，选择柠条灌丛内外微生境为研究样地，以红砂枯落物为研究对象，利用2种规格网孔分解袋(30目和250目网孔),探索中小型节肢动物在红砂枯落物分解过程中的作用规律，研究灌丛微生境中红砂枯落物质量损失变化特征及节肢动物群落的贡献。结果表明：(1)在干旱与半干旱区，红砂枯落物分解常数K均表现为灌丛内外微生境间无显著差异，且有无节肢动物参与对K的影响均较小。(2)分解至12个月时，无节肢动物参与的情况下，干旱与半干旱区红砂枯落物残留率均表现为裸地显著低于灌丛；但有节肢动物参与时，枯落物残留率则表现为灌丛内外微生境间无显著差异。分解至44个月时，无节肢动物参与的情况下，仅在干旱区枯落物残留率表现为裸地显著高于灌丛；而有节肢动物参与时，干旱与半干旱区枯落物残留率均表现为灌丛内外微生境间无显著差异。(3)节肢动物对红砂枯落物质量损失的贡献率呈现单峰值现象，且在分解至24个月时达到峰值。枯落物分解至12个月时，仅半干旱区节肢动物对红砂枯落物分解的贡献率表现为裸地显著低于灌丛；分解至44个月时，仅干旱区节肢动物对红砂枯落物分解的贡献率表现为裸地显...

The decomposition process of Reaumuria soongorica litter and the role of microarthropods in shrub microhabitats in arid and semi-arid regions

In desertified grasslands of the arid Urad Rear Banner of the Inner Mongolia and the semi-arid Yanchi of Ningxia, the Caragana korshinskii shrub microhabitats beneath shrub canopies and in the open spaces were setup as study sites. The litter of Reaumuria soongorica was used as the research object. Two sizes of mesh (30-mesh, and 250-mesh) for litter bags were used to explore the role of soil microarthropods on litter decomposition of Reaumuria soongorica. The objective of present study was to probe into the mass loss of the litter and the contribution of soil microarthropod community in the shrub microhabitats. The results showed that:(1) there was no significant difference in decomposition constant K of litter between shrub canopy and open spaces; the presence or absence of microarthropods had little effect on K. (2) At decomposition stage of 12 months, there was significantly lower mass remaining rate of the litter in open spaces than beneath shrub canopy without the presence of microarthropods, but there was no significant difference between shrub canopy and open spaces in the case of microarthropods presence. At decomposition stage of 44 months, the mass remaining rate of litter was significantly higher in open spaces than beneath shrub canopy only in arid regions without the participation of microarthropods; however, there was no significant difference between both shrub microhabitats with microarthropod presence in both arid and semi-arid regions. (3) The contribution rate of microarthropods to the mass loss of litter showed a unimodal type during decomposition process, with a single peak at 24 months. At decomposition stage of 12 months, there was significantly lower contribution rate of microarthropods to the decomposition of litter in open spaces than beneath shrub canopy only in semi-arid region. At decomposition stage of 44 months, the contribution rate of microarthropods to the decomposition of litter was significantly higher in open spaces than beneath shrub canopy only in arid region. (4) In the semi-arid region, the contribution rate of microarthropods to litter mass loss was closely correlated to the group richness of microarthropod, soil sand content, soil total carbon, and water content. In the arid region, however, the contribution rate of microarthropods to the mass loss of litter was closely correlated to soil pH, soil sand, soil C/N, and clay and silt content. In conclusion, the overall litter decomposition in shrub microhabitats in arid and semi-arid regions was little affected by the role of microarthropods. However, at certain decomposition stages, the difference in mass loss of the litter between shrub microhabitats was affected remarkably by the role of microarthropods. There was a law of weak (12 months)-strong (24 months)-weak (44 months) role of microarthropods on litter decomposition that was regulated by the climatic factors.