Interactive Effects of White-Tailed Deer, an Invasive Shrub, and Exotic Earthworms on Leaf Litter Decomposition

Mahon, Michael B.; Fisk, Melany C.; Crist, Thomas O.

doi:10.1007/s10021-020-00485-9

Cited by 7 publications

(7 citation statements)

References 45 publications

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“…By going beyond analyzing categorical invasion status and deliberately including invasion intensity, these results provide novel insights into how earthworm invasion impacts soil fauna after an invasion has been started and how much they change over the gradient of invasive earthworm biomass. Our results nicely complement earlier studies investigating the impact of earthworm‐invasion intensity on ecosystem processes such as, for example, nutrient cycling and leaf‐litter decomposition (Suárez et al 2006, Crumsey et al 2013, Chang et al 2016, Mahon et al 2020), by extending these findings to the responses of the soil‐fauna communities which are responsible, at least in part, for the change in ecosystem processes. Interestingly, some of these changes in relation to earthworm‐invasion intensity appear to happen at relatively low earthworm biomass levels (e.g.…”

Section: Discussionsupporting

confidence: 88%

“…Moreover, while most of our knowledge on ecosystem responses to earthworm invasion is based on comparing high‐invasion to low‐invasion areas, less is known about the effects of invasion intensity. Despite increasing attention to the effects of invasive earthworm density (Suárez et al 2006), biomass (Mahon et al 2020) or community composition (Crumsey et al 2013, Chang et al 2016), most of these studies focus on responses in leaf litter decomposition or nutrient dynamics while knowledge on soil‐fauna responses to invasion intensity remains limited.…”

Section: Introductionmentioning

confidence: 99%

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Earthworm invasion causes declines across soil fauna size classes and biodiversity facets in northern North American forests

Eisenhauer

Ferlian

Thakur

et al. 2021

Oikos

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Anthropogenic pressures alter the biodiversity, structure and organization of biological communities with severe consequences for ecosystem processes. Species invasion is such a human-induced ecosystem change with pronounced impacts on recipient ecosystems. Around the globe, earthworms invade habitats and impact abiotic soil conditions and a wide range of above-and belowground organisms. In northern North America, where earthworms have been largely absent since the last glaciation period and most earthworm species present today have only been (re-)introduced a few hundred years ago, invasion impacts have been intensively studied. However, despite several studies assessing impacts of invasive earthworms on soil fauna, studies have rarely investigated the simultaneous responses of different soil-fauna size groups and biodiversity facets which might respond differently to earthworm invasion and independently affect ecosystem processes. Our study goes beyond previously-established knowledge on earthworm-invasion effects by simultaneously assessing differences in four biodiversity facets, namely the abundance, biomass, richness and Shannon index of soil invertebrate macro-, mesoand microfauna communities between high-and low-invasion status plots (n = 80) and in relation to invasion intensity measured as earthworm biomass across four northern North American forests sampled between 2016 and 2017. Across forests and soil-fauna groups, we found reduced abundance (−33 to −45%) and richness (−18 to −25%) in high compared to low-invasion status areas. Additionally, meso-(−14%) and microfauna biomass (−38%) and macro-(−7%) and microfauna Shannon index (−8%) were reduced. Higher invasion intensity (earthworm biomass) was additionally related to reduced soil-fauna biodiversity. While the studied biodiversity facet was important for the soil fauna response, soil-fauna size group was comparably unimportant. Given the global ubiquity of earthworm invasion and the importance of soil fauna for key ecosystem processes, our observational results help to assess future impacts of this invasion and the consequences for anthropogenically-altered ecosystem functioning.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Earthworm invasion causes declines across soil fauna size classes and biodiversity facets in northern North American forests

Eisenhauer

Ferlian

Thakur

et al. 2021

Oikos

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“…However, these linked disturbances may have a compounding effect on ecosystem nutrients and vegetation, leading to understory dominance of ruderal species and altered successional trajectories (Powers & Nagel, 2009). In a recent study showing how combined deer and earthworms could change ecosystems, Mahon et al (2020) found that deer increased earthworm populations, which then increased leaf litter decomposition rates and changed soil nutrient dynamics. However, more research is needed on the combined effects of earthworms and deer, considering their many indirect effects on ecosystems (Frelich et al, 2019; Rooney & Waller, 2003).…”

Section: Discussionmentioning

confidence: 99%

Linked disturbance in the temperate forest: Earthworms, deer, and canopy gaps

Reed

Bronson

Forrester

et al. 2023

Ecology

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Despite the large body of theory concerning multiple disturbances, relatively few attempts have been made to test the theoretical assumptions of how and if disturbances interact. Of particular importance is whether disturbance events are linked, as this can influence the probability and intensity of ecological change. Disturbances are linked when one disturbance event increases or decreases the likelihood or extent of another. To this end, we used two long-term, multi-disturbance experiments in northern Wisconsin to determine whether earthworm invasion is linked to canopy gap creation and white-tailed deer browsing. These three disturbances are common and influential within North American temperate forests, making any interactions among them particularly important to understand. We expected both deer and canopy gaps to favor invasive earthworms, particularly species that live close to or on the soil surface. However, we found only partial support of our hypotheses, as both deer exclosures and canopy gaps decreased earthworms in each experiment. Further, earthworm density increased the most over time in areas far from the gap center and in areas with deer present. Deer exclosures primarily decreased Aporrectodea and Lumbricus species, while gaps decreased Dendrobaena and Lumbricus species. Our findings show that earthworm invasion is linked to deer presence and gap-creating disturbances, which provides new insight in multiple disturbance theory, aboveground-belowground dynamics, and temperate forest management. K E Y W O R D S aboveground-belowground interactions, canopy gaps, invasive earthworms, linked disturbance, temperate forest, ungulates, white-tailed deer Peter B. Reich and Lee E. Frelich share co-advisership and equal guidance on research development.

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“…However, another study performed in the hardwood forests in North America found that a positive interaction between white‐tailed deer Odocoileus virginianus and invasive earthworms (e.g. Aporrectodea tuberculata ) occurred, which led to more rapid litter decomposition compared to either group of animal present alone (Mahon et al., 2020). Consistent with the results from that study, the large combined impact of cattle and ants on litter decomposition in our experiment was likely a result of facilitative interactions between them.…”

Section: Discussionmentioning

confidence: 99%

A facilitation between large herbivores and ants accelerates litter decomposition by modifying soil microenvironmental conditions

Risch

Sanders

et al. 2021

Functional Ecology

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Large herbivores and insects commonly coexist and play important functional roles in grassland ecosystems. The interactive effects of these two animal groups in shaping ecosystem processes and functioning are poorly understood. In a semi‐arid grassland of northeastern China, we previously found a reciprocal facilitation between large herbivores (cattle; Bos tarurs) and ants: cattle grazing led to a twofold increase in ant mound abundance compared with ungrazed sites, while the presence of ant mounds, in turn, increased the foraging of cattle during the peak of the growing season. Here, by using a large‐scale, 4‐year (2010–2013) manipulative experiment, we further investigated how such a facilitation between large herbivores and ants can affect a key ecosystem process, litter decomposition. Using a set of small‐scale reciprocal translocation litterbag experiments, we separated the effects of litter quality and soil microenvironmental factors altered by cattle and ants on litter decomposition rates. A significant interaction between the experimental factors, cattle grazing and ant presence, showed that litter decomposition rate was at the highest levels when both cattle and ants were present, with only a small impact when each was present on its own. Mechanistically, cattle and ants exerted limited effects on litter quality (litter C:N ratio). However, these animals greatly altered soil microenvironments by increasing soil N availability, which in turn increased soil microbial biomass and accelerated decomposition process. Synthesis. Our results demonstrate how positive interactions between two groups of animals, large herbivores and ants, can affect decomposition rates, with important consequences for ecosystem carbon and nutrient cycling. Large herbivores, either domestic or wild, often coexist and interact frequently with a diverse of other fauna in terrestrial ecosystems. Assessing their interactive effects will help us to better understand their role in shaping ecosystem processes and functioning with important management implications. A free Plain Language Summary can be found within the Supporting Information of this article.

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Interactive Effects of White-Tailed Deer, an Invasive Shrub, and Exotic Earthworms on Leaf Litter Decomposition

Cited by 7 publications

References 45 publications

Earthworm invasion causes declines across soil fauna size classes and biodiversity facets in northern North American forests

Earthworm invasion causes declines across soil fauna size classes and biodiversity facets in northern North American forests

Linked disturbance in the temperate forest: Earthworms, deer, and canopy gaps

A facilitation between large herbivores and ants accelerates litter decomposition by modifying soil microenvironmental conditions

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