Abstract

Invasive alien trees transform landscapes and subsequent ecosystem function. For grassland ecosystems, fragmentation following invasion by alien woody species is of concern. In this study, we examined how an invasive alien tree, Robinia pseudoacacia L. (Fabaceae) impacts grassland microclimates and the subsequent assemblages of endemic arthropods. The phenological trajectory of R. pseudoacacia, temperature and light intensity, as well as arthropod abundances in both invaded and uninvaded habitats, were monitored. Results showed that R. pseudoacacia significantly lowers average understory temperatures and light penetration in grassland ecosystems. Average temperatures were at least 2 °C lower in understory habitats than open grasslands while light intensity was lower by more than 1200 lumens/ft². In addition, arthropod communities differed between invaded and uninvaded habitats. The most affected taxa were Acridids from the order Orthoptera as they were excluded from understory habitats while Coleopterans were more abundant under R. pseudoacacia. Apart from absence of main host plants, invasion mediated differences in microenvironments appeared to be the main driver of this shift in affected arthropod taxa.

Implications for insect conservation

These results highlight the need to sustainably manage R. pseudoacacia invasions especially in grassland ecosystems. In addition to their conservation value due to their role in nutrient cycling, grassland arthropods also serve as important indicators of ecosystem health. Hence, they can be used to monitor ecosystem recovery post invasive alien tree management.

中文翻译：

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入侵外来树，刺槐林冠性状及其对草地小气候和后续节肢动物组合的影响的评估

摘要

外来入侵树木改变了景观，进而改变了生态系统的功能。对于草原生态系统而言，外来木本植物入侵后的破碎是令人关注的问题。在这项研究中，我们检查了入侵的外来树刺槐（Fabaceae）如何影响草地的小气候和随后的特有节肢动物的组合。的物候轨迹刺槐，温度和光的强度，以及在这两个侵入和未侵入生境节肢动物丰度，进行了监测。结果表明，拟金合欢大大降低了草地生态系统的平均地下温度和光穿透力。下层生境的平均温度比草原开阔的平均温度低至少2°C，而光强则降低超过1200流明/ ft ²。此外，节肢动物群落在被入侵和未被入侵的栖息地之间也有所不同。受影响最大的类群是Acridids从订单直翅目，因为他们被排除在林下生境而鞘翅目是在更丰富的刺槐。除了缺乏主要寄主植物外，入侵介导的微环境差异似乎是影响节肢动物类群转变的主要驱动力。

对昆虫保护的意义

这些结果突出了需要可持续地管理拟金丝猴入侵，特别是在草地生态系统中。除了由于其在养分循环中的作用而具有保护价值外，节肢动物还可以作为生态系统健康的重要指标。因此，它们可用于监视入侵的外来树管理后的生态系统恢复。