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Knowledge of macroinvertebrate distributions and associated environmental drivers in subtropical Asian rivers is relatively scarce. To fill this knowledge gap, we examined the spatial variation of macroinvertebrate community structure and associated environmental conditions in a subtropical river system, the Dongjiang River Basin, in southeastern China. A total of 70 families and 9 classes of macroinvertebrates were identified from 74 sites sampled in January 2013. Our study has the following findings: (1) a distinct spatial differentiation of macroinvertebrate communities was present in the Dongjiang River Basin indicated by non-metric multidimensional scaling (NMDS), which corresponded to the northern region (NR), middle region (MR), and southern region (SR) gradient; (2) ANOVAs showed that diversity indices (total taxa, Margalef index and the Shannon diversity index), biotic indices (richness of EPT, percentage of EPT, and family biotic index) and most of the studied environmental conditions (elevation, slope, steam order, water temperature, electrical conductivity, dissolved oxygen, pH, substrates, ammoniacal nitrogen, total phosphorus, percentage of urban land, percentage of rural land, and percentage of forest land) differed significantly among the three regions and a degradation gradient was observed in the NR–MR–SR direction; (3) Canonical correspondence analysis (CCA) revealed that NR sites were characterized by steep slope and coarse substrate, MR sites were characterized by high water temperatures and shallow slopes, and SR sites were primarily characterized by high total phosphorus and ammoniacal nitrogen concentrations; and (4) the Indicator Species Analysis, in conjunction with CCA analysis indicated that the most representative indicator taxon is Tipulidae for NR, Semisulcospira sp. for MR, and Branchiura sp. for SR.

[Display omitted] • We analysed 3596 soil loss events at 307 plots in citrus orchards globally. • We quantified the efficiency of soil and water conservation measures (SWCMs). • SWCMs are efficient in soils cultivated with citrus at risk of erosion. • Combined measures were more effective than single measures. • The SWCMs efficacy was significantly related to slope gradient and slope length. The rapid expansion of citrus orchards and their increased cultivation intensity have accelerated soil erosion, which has impeded the achievement of Sustainable Development Goals. In citrus orchards, the benefits of soil and water conservation measures for alleviating soil erosion have been widely tested at the plot scale. These studies provide crucial information, but they inevitably involve considerable uncertainty and cannot fully characterize the efficacy of soil and water conservation measures. Given the seriousness of soil erosion in citrus orchards and the uncertain factors in the efficiency of soil and water conservation measures, data published in the literature were collected. A meta-analysis of 346 plots (representing 4443 events) for runoff and 307 plots (representing 3596 events) for soil loss was conducted to evaluate the effectiveness of soil and water conservation measures in citrus orchards. This study aims to (i) summarize the level of soil erosion in citrus orchards worldwide, (ii) explore the influence of soil and water conservation measures on soil erosion control in citrus orchards and (iii) identify the trade-offs between runoff reduction and soil loss reduction. The results showed that the citrus orchards without soil and water conservation measures had a probability of approximately 80% of exceeding tolerable levels of soil loss. The effectiveness of soil and water conservation measures in reducing soil erosion decreased in the order biological measures + engineering measures > engineering measures > biological measures. The trade-off between runoff reduction and soil loss reduction showed that soil and water conservation measures provide better soil loss control than runoff control. Overall, besides considering the ecological benefits of soil and water conservation measures, decision maker should also consider the economic benefits to obtain an optimal citrus orchard management for farmers. [ABSTRACT FROM AUTHOR]