ترجمه مقاله سهم تعامل ساز و کارهای زیستی با تثبیت خاکدانه ها در چمنزارهای بازسازی شده

SummaryÐA better understanding of the soil aggregation process is needed to address a variety of concerns, including soil quality and erosion, agricultural sustainability, soil C sequestration, the mobility of hazardous chemicals and remediation of contaminated sites. We used data from a chronosequence of tallgrass prairie restorations and a path analysis approach to evaluate how the lengths of two dia size classes of ®brous roots, the length of external mycorrhizal hyphae, microbial biomass C, hot-water soluble carbohydrate C and soil organic C interact to promote the stabilization of soil aggregates. The measured binding agents accounted for 88% of the variation in macroaggregates >212 mm diameter and goodness-of-®t indexes indicated a good practical ®t of the path model to the data. The restoration of macroaggregate structure in this system was apparently driven by the direct and indirect e€ects of roots and external hyphae, with lesser relative contributions by the three measured C pools. Although the two root size classes had similar direct e€ects on the percentage of macroaggregates, their indirect contributions di€ered substantially. Fine roots (0.2±1 mm diameter) exerted considerable indirect e€ects via their strong in¯uences on external hyphae and microbial biomass C. Very ®ne roots (<0.2 mm dia) made a stronger contribution to soil organic C than ®ne roots, but their overall indirect contribution to aggregation was minimal. In addition, the relative importance of each binding agent varied for di€erent size fractions of macroaggregates and generally supported the hypothesis that the e€ectiveness of various binding mechanisms depends on the physical dimensions of the binding agents relative to the spatial scales of the aggregate planes of weakness being bridged.