Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, SE901 83, Umeå, Sweden.
Ecology. 2011 Mar;92(3):645-56. doi: 10.1890/10-1223.1.
Despite their ubiquity, the role of ants in driving ecosystem processes both aboveground and belowground has been seldom explored, except within the nest. During 1995 we established 16 ant exclusion plots of approximately 1.1 x 1.1 m, together with paired control plots, in the understory layer of a boreal forest ecosystem in northern Sweden that supports high densities of the mound-forming ant Formica aquilonia, a red wood ant species of the Formica rufa group. Aboveground and belowground measurements were then made on destructively sampled subplots in 2001 and 2008, i.e., 6 and 13 years after set-up. While ant exclusion had no effect on total understory plant biomass, it did greatly increase the relative contribution of herbaceous species, most likely through preventing ants from removing their seeds. This in turn led to higher quality resources entering the belowground subsystem, which in turn stimulated soil microbial biomass and activity and the rates of loss of mass and carbon (C) and nitrogen (N) from litter in litterbags placed in the plots. This was accompanied by losses of approximately 15% of N and C stored in the humus on a per area basis. Ant exclusion also had some effects on foliar stable isotope ratios for both C and N, most probably as a consequence of greater soil fertility. Further, exclusion of ants had multitrophic effects on a microbe-nematode soil food web with three consumer trophic levels and after six years promoted the bacterial-based relative to the fungal-based energy channel in this food web. Our results point to a major role of red wood ants in determining forest floor vegetation and thereby exerting wide-ranging effects on belowground properties and processes. Given that the boreal forest occupies 11% of the Earth's terrestrial surface and stores more C than any other forest biome, our results suggest that this role of ants could potentially be of widespread significance for biogeochemical nutrient cycling, soil nutrient capital, and sequestration of belowground carbon.
尽管蚂蚁无处不在，但它们在地上和地下驱动生态系统过程的作用除了在巢内之外，很少被探索过。1995 年，我们在瑞典北部的一个北方森林生态系统的林下层建立了 16 个大约 1.1 x 1.1 平方米的蚂蚁排除区，以及配对的对照区，这些区域支持着筑巢蚂蚁 Formica aquilonia 的高密度，这是 Formica rufa 组的一种红林蚁物种。然后，在 2001 年和 2008 年对破坏性采样的子区进行了地上和地下测量，即设置后 6 年和 13 年。虽然蚂蚁排除对林下总植物生物量没有影响，但它确实大大增加了草本物种的相对贡献，这很可能是通过防止蚂蚁去除它们的种子。这反过来又导致了更高质量的资源进入地下子系统，从而刺激了土壤微生物生物量和活性，以及从放置在地块中的袋中损失的质量和碳 (C) 和氮 (N) 的速度。这伴随着每单位面积上大约 15%的储存于腐殖质中的 N 和 C 的损失。蚂蚁排除对叶片稳定同位素比 C 和 N 也有一些影响，这很可能是由于土壤肥力的增加。此外，排除蚂蚁对一个具有三个消费者营养级的微生物-线虫土壤食物网产生了多营养级效应，并且在六年后促进了这个食物网中基于细菌的能量通道相对于基于真菌的能量通道。我们的结果表明，红林蚁在确定森林地面植被方面起着重要作用，从而对地下特性和过程产生广泛影响。鉴于北方森林占据了地球陆地表面的 11%，并储存了比任何其他森林生物群落都多的碳，我们的结果表明，蚂蚁的这种作用可能对生物地球化学养分循环、土壤养分资本和地下碳封存具有广泛的意义。
