人工固沙植被恢复对地表节肢动物群落组成及多样性的影响

人工绿洲是干旱区主要的自然景观之一,为了维护绿洲稳定而营建的防护林强烈改变地表生态水文过程,进而影响着地上和地下生物多样性。然而,以往的研究对地上植被关注较多,而对土壤动物研究较少。以张掖绿洲外围人工固沙植被群落和天然固沙植被群落为研究对象,探讨人工固沙植被恢复对荒漠地表节肢动物群落组成及多样性的影响及不同动物类群对植被变化的响应模式。研究表明,天然固沙植被群落转变为人工固沙植被群落显著降低了地表节肢动物数量,但提高了地表节肢动物类群丰富度和多样性,这在5月份表现尤为明显。植被类型对地表节肢动物群落的影响不同,8月人工柽柳林群落地表节肢动物活动密度、类群丰富度和多样性均显著高于人工梭梭林群落。人工固沙植被恢复显著降低了适应荒漠环境的拟步甲科甲虫,而蚁科和部分蜘蛛的数量显著增加,它们对人工固沙植被恢复的响应模式不同决定了群落结构及多样性的变化规律。此外,研究还发现一些地表节肢动物类群对不同生境具有强烈的指示作用,如拟步甲科等可指示荒漠生境,潮虫科等可指示梭梭林生境,而蠼螋科和狼蛛科等可指示柽柳林生境。综上所述,人工栽植固沙灌木形成的固沙植被群落导致了一些适应荒漠环境的地表节肢动物类群的数量降低,但也为更多的地表节肢动物类群提供了适应栖居环境和充足的食物资源等,从而提高了地表节肢动物的多样性。

Effects of introduced sand-fixing vegetation on community structure and diversity in ground-dwelling arthropods

Sand-fixing vegetation introduced at the edges of oases strongly affects eco-hydrological processes in arid areas, structuring both above-and belowground biodiversity. However, most of research in this area focuses on the response of vegetation to afforestation in arid ecosystems, and little research has been conducted on soil fauna communities. We studied desert habitat in which Haloxylon ammodendron (HAP) and Tamarix ramosissima (TRP) had been planted in the desert-oasis ecotone and nearby natural desert (ND) at a location near the Zhangye Oasis, and we assessed the composition and diversity of ground-dwelling arthropod communities using pitfall trapping in early May and mid-August. The primary findings of our study are as follows. We found that when sand-fixing vegetation was introduced to the natural desert area, ground-dwelling arthropod abundance decreased, whereas taxa richness and Shannon diversity index increased, particularly in May. Furthermore, the abundance, taxa richness, and Shannon diversity index were significantly higher in communities to which HAP was introduced than in communities to which TRP was introduced. Introduced sand-fixing vegetation caused the activity density of tenebrionid beetles to decrease substantially, whereas the activity density of ants, carabid beetles, and some spiders increased significantly, all of which determine ground-dwelling arthropod assemblages in this ecosystem. We also identified indicator taxa among ground-dwelling arthropods for each type of desert habitat. Tenebrionid beetles function as indicator taxa in ND habitats; members of Trachelipidae function as indicator taxa in HAP habitats; and members of Labiduridae and Lycosidae function as indicator taxa in TRP habitats. In summary, sand-fixing vegetation introduced to sandy desert ecosystems promoted the diversity of ground-dwelling arthropods by providing food sources and habitats, but caused the abundance of certain native taxa to decrease, sometimes to zero.