Biological invasions are a leading cause of global change, yet their long-term effects remain hard to predict. Invasive species can remain abundant for long periods of time, or exhibit population crashes that allow native communities to recover. The abundance and impact of non-native species may also be closely tied to temporally variable habitat characteristics. We investigated the long-term effects of habitat fragmentation and invasion by the Argentine ant (Linepithema humile) by resurveying ants in 40 scrub habitat fragments in coastal southern California that were originally sampled 21 years ago. At a landscape scale, fragment area, but not fragment age or Argentine ant mean abundance, continued to explain variation in native ant species richness; the species-area relationship between the two sample years did not differ in terms of slope or intercept. At local scales, over the last 21 years we detected increases in the overall area invaded (+36.7 %, estimated as the proportion of occupied traps) and the relative abundance of the Argentine ant (+121.95 %, estimated as mean number of workers in pitfall traps). Argentine ant mean abundance also increased inwards from urban edges in 2017 compared to 1996. The greater level of penetration into fragments likely reduced native ant richness by eliminating refugia for native ants in fragments that did not contain sufficient interior area. At one fragment where we sampled eight times over the last 21 years, Argentine ant mean abundance increased over time while the diversity of native ground-foraging ants declined from 14 to 4 species. Notably, native species predicted to be particularly sensitive to the combined effect of invasion and habitat loss were not detected at any sites in our recent sampling, including the army ant genus Neivamyrmex. Conversely, two introduced ant species (Brachymyrmex patagonicus and Pheidole flavens) that were undetected in 1996 are now common and widespread at our sites. Our results indicate that behaviorally and numerically dominant invasive species can maintain high densities and suppress native diversity for extended periods.

中文翻译：

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蚂蚁入侵和破碎对原生蚂蚁组合的普遍和持久影响

生物入侵是全球变化的主要原因，但其长期影响仍难以预测。入侵物种可以在很长一段时间内保持丰富，或者表现出使本地社区恢复的种群崩溃。非本地物种的丰度和影响也可能与随时间变化的栖息地特征密切相关。我们通过重新调查 21 年前最初采样的南加州沿海 40 个灌木栖息地碎片中的蚂蚁，调查了阿根廷蚂蚁 (Linepithema humile) 栖息地破碎和入侵的长期影响。在景观尺度上，碎片面积，但不是碎片年龄或阿根廷蚂蚁平均丰度，继续解释本地蚂蚁物种丰富度的变化；两个样本年份之间的物种-面积关系在斜率或截距方面没有差异。在局部范围内，在过去 21 年中，我们发现入侵的总面积增加（+36.7%，估计为占用陷阱的比例）和阿根廷蚂蚁的相对丰度（+121.95%，估计为陷阱陷阱）。与 1996 年相比，2017 年阿根廷蚂蚁的平均丰度也从城市边缘向内增加。更大程度地渗透到碎片中可能会通过消除内部区域不足的碎片中的本地蚂蚁的避难所而降低本地蚂蚁的丰富度。在过去 21 年中我们进行了八次采样的一个片段中，阿根廷蚂蚁的平均丰度随着时间的推移而增加，而本地地面觅食蚂蚁的多样性从 14 种下降到 4 种。尤其，在我们最近的采样中，包括军蚁属 Neivamyrmex 在内的任何地点都没有检测到预计对入侵和栖息地丧失的综合影响特别敏感的本地物种。相反，在 1996 年未被发现的两种引入的蚂蚁物种（Brachymyrmex patagonicus 和 Pheidole flavens）现在在我们的站点很常见并且很普遍。我们的研究结果表明，行为和数量上占优势的入侵物种可以长时间保持高密度并抑制原生多样性。1996 年未被发现的两种引入的蚂蚁物种（Brachymyrmex patagonicus 和 Pheidole flavens）现在在我们的站点很常见且广泛存在。我们的研究结果表明，行为和数量上占优势的入侵物种可以长时间保持高密度并抑制原生多样性。1996 年未被发现的两种引入的蚂蚁物种（Brachymyrmex patagonicus 和 Pheidole flavens）现在在我们的站点很常见且广泛存在。我们的研究结果表明，行为和数量上占优势的入侵物种可以长时间保持高密度并抑制原生多样性。