اثرات لاشه آبزیان مهاجم در شیمی خاک و جوامع میکروب زمینی Effects of invasive aquatic carrion on soil chemistry and terrestrial microbial communities

Introduction Decomposition of detritus plays a crucial role in the recycling of nutrients and organic matter (Swift et al. 1979; Moore et al. 2004). Defined as any resource of nonliving organic matter, detritus is considered the basal trophic level of many terrestrial and aquatic food webs (Swift et al. 1979; Moore et al. 2004; Benbow et al. 2015). In terrestrial ecosystems, detritus may consist of plant-derived matter (e.g. leaf litter, dead wood, root exudates), dead microbes, fecal matter and animal tissue (carrion) (Swift et al. 1979). Plantderived detritus comprises the majority of the resources that undergo decomposition in terrestrial ecosystems but they are nutrient poor and very recalcitrant (Swift et al. 1979; Carter et al. 2007). Contrary, carrion is much more nutrient-rich and decomposes at much faster rates than plant detritus, and, as such, its role in nutrient cycling may be highly relevant (Swift et al. 1979; Barton et al. 2013). Indeed, carrion decomposition is usually associated with the activity of microbes, invertebrate and vertebrate detritivores and scavengers (Carter et al. 2007; Barton et al. 2013). The combined activity of microbes and invertebrates increases the nutrients released from the carrion into the soil; however, vertebrates may reduce this contribution by direct consumption or dispersion (Carter et al. 2007; Barton et al. 2013). In terrestrial ecosystems where carrion releases nutrients into the soil, plants may ultimately mobilize these nutrients entering the belowground detrital pathway (Moore et al. 2004; Carter et al. 2007). Despite its potential importance, only very recently the scientific community has started to acknowledge the role of carrion decomposition in nutrient recycling (DeVault et al. 2003; Carter et al. 2007; Wilson and Wolkovich 2011). Detrital inputs enter any ecosystem via allochthonous or autochthonous sources (Moore et al. 2004). Allochthonous inputs are resources that originate in one habitat but move into another, while autochthonous inputs originate and are consumed in the same habitat (Polis et al. 1997). Many ecosystems experience spatial subsidies as regular seasonal events, but subsidies can also result from sporadic episodes of resource superabundance, named resource pulses (Ostfeld and Keesing 2000; Anderson et al. 2008b; Yang et al. 2008). Examples of resource pulses include periodical cicadas’ emergence in North American forests (e.g. Yang 2004, 2008), El Nin˜o rainfalls in arid ecosystems (e.g. Polis et al. 1997; Meserve et al. 2003; Letnic et al. 2005), seed or fruit mast events (e.g. Woff 1996; Curran and Leighton 2000), and massive spawning events by migratory fish (e.g. Woff and Hershey 1999; Yanai and Kochi 2005). Despite their ecological importance, these studies focused mostly on aboveground processes and just a few assessed belowground effects (Yang 2004; Yang et al. 2010).