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Invasion of an exotic annual forb affects grass-feeding termites in a semi-arid woodland
Austral Ecology ( IF 1.5 ) Pub Date : 2022-05-16 , DOI: 10.1111/aec.13184
James Val 1 , David J. Eldridge 2, 3
Affiliation  

Invasive plants are known to have dramatic and generally negative effects on ecosystems. The rapid spread and naturalization of Carrichtera annua (wards weed) across large areas of southern Australia has been widely reported, but its effects on biodiversity and ecosystem functions are poorly known. We examined the effects of Carrichtera on grass-feeding termites Drepanotermes spp. and hypothesized that increasing cover of Carrichtera would reduce termite abundance, which we assessed using the density of their above-ground pavements as a proxy for density. Our study was conducted at two spatial scales to explore (i) potential effects of Carrichtera invasion under variable intensities of grazing and (ii) differences between invaded and uninvaded sites at a long-ungrazed conservation reserve. Increasing cover of Carrichtera was associated with a greater density of pavements, both under grazed conditions and within the conservation reserve. However, increasing grazing intensity tended to be associated with reduced pavement density and size, through indirect reductions in plant biomass. Greater cover of Carrichtera was associated with declines in the cover of native plants and biocrusts, but not native plant richness. Pavement size tended to decline with increasing pavement density. Under conservation, Carrichtera sites supported more pavements, but densities declined markedly in drought years. The lower resilience to droughts and the fact that pavements in Carrichtera-invaded sites tended to be less cemented and contain more ants, suggest that invasion by Carrichtera may have long-term functional implications for processes mediated by termites. Increasingly, drier climates in southern Australia may exacerbate reductions in ecosystem functions given the pivotal role played by termites in dryland food webs and ecosystem functions.

中文翻译:

一种异国情调的一年生草本植物的入侵影响了半干旱林地中的食草白蚁

众所周知,入侵植物会对生态系统产生巨大且普遍的负面影响。Carrichtera annua (病房杂草)在澳大利亚南部大片地区的迅速传播和归化已被广泛报道,但其对生物多样性和生态系统功能的影响却鲜为人知。我们检查了Carrichtera对草食白蚁Drepanotermes spp 的影响。并假设增加Carrichtera的覆盖率会降低白蚁的丰度,我们使用它们地上路面的密度作为密度的代表来评估。我们的研究是在两个空间尺度上进行的,以探索 (i) Carrichtera的潜在影响不同放牧强度下的入侵和(ii)长期未放牧保护区内入侵和未入侵地点之间的差异。在放牧条件下和保护区内,增加Carrichtera的覆盖率与更高密度的人行道有关。然而,通过植物生物量的间接减少,放牧强度的增加往往与路面密度和尺寸的降低有关。Carrichtera的更大覆盖与原生植物和生物结皮覆盖率的下降有关,但与原生植物丰富度无关。随着路面密度的增加,路面尺寸趋于减小。在保护下,Carrichtera场地支持更多的人行道,但在干旱年份密度显着下降。对干旱的抵抗力较低以及Carrichtera入侵地点的路面往往胶结较少且包含更多蚂蚁,这表明Carrichtera的入侵可能对白蚁介导的过程具有长期的功能影响。鉴于白蚁在旱地食物网和生态系统功能中发挥的关键作用,澳大利亚南部越来越干燥的气候可能会加剧生态系统功能的下降。
更新日期:2022-05-16
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