Effects of digging by a native and introduced ecosystem engineer on soil physical and chemical properties in temperate grassy woodland

Abstract

Temperate grasslands and woodlands are the focus of extensive restoration efforts worldwide. Reintroduction of locally extinct soil-foraging and burrowing animals has been suggested as a means to restore soil function in these ecosystems. Yet little is known about the physical and chemical effects of digging on soil over time and how these effects differ between species of digging animal, vegetation types or ecosystems. We compared foraging pits of a native reintroduced marsupial, the eastern bettong (Bettongia gaimardi) and that of the exotic European rabbit (Oryctolagus cuniculus). We simulated pits of these animals and measured pit dimensions and soil chemical properties over a period of 2 years. We showed that bettong and rabbit pits differed in their morphology and longevity, and that pits had a strong moderating effect on soil surface temperatures. Over 75% of the simulated pits were still visible after 2 years, and bettong pits infilled faster than rabbit pits. Bettong pits reduced diurnal temperature range by up to 25 °C compared to the soil surface. We did not find any effects of digging on soil chemistry that were consistent across vegetation types, between bettong and rabbit pits, and with time since digging, which is contrary to studies conducted in arid biomes. Our findings show that animal foraging pits in temperate ecosystems cause physical alteration of the soil surface and microclimatic conditions rather than nutrient changes often observed in arid areas.

Identifying important environmental variables in the niche partitioning of two keystone ecosystem engineers (Bettongia gaimardi and Potorous tridactylus) in Tasmania

“…The higher number (254) and more varied sources of B. gaimardi records used by Proft et al (2021) in constructing their Species Distribution Model (SDM) is likely to be the reason for any discrepancies. Examples from the literature support our modelled B. gaimardi climate range (Taylor 1992;Davies et al 2019;Ross et al 2019).…”

“…Examples from the literature support our modelled B. gaimardi climate range (Taylor 1992; Davies et al . 2019; Ross et al . 2019).…”

“…An increase in spore production and dispersal ensures that fungi will be spread widely, ready to rapidly inoculate regenerating plants. Finally, B. gaimardi and P. tridactylus are true ecosystem engineers in their ability to improve soil quality through turn-over, aeration, moderation of soilsurface temperature, and by providing a germination niche for native seedlings (Davies et al 2019;Munro et al 2019;Ross et al 2019Ross et al , 2020.…”

Trends in animal translocation research

“…beaver, Law et al 2017, e.g. eastern bettong, Ross et al 2019), can be a catalyst for trophic cascades and restore ecosystem processes and functions (e.g. seed dispersal, nutrient cycling, hydrology).…”

“…The field of translocation science (also known as reintroduction biology), is wide-ranging, with numerous sub-disciplines that, combined, provide evidence-based knowledge informing on-the-ground management actions and decision-making (Ewen et al 2012). Translocation science encompasses ecological impacts (Ross et al 2019), genetics (White et al 2018(White et al , 2020, tactics and adaptive management that improve translocation success (Batson et al 2015, Wilson et al 2020, threat mitigation (e.g. exotic predators (Manning et al 2021)), and, more recently, the adaptation of translocated species to novel threats (Muralidhar et al 2019, Evans et al 2021b, 2022b, Tay et al 2021.…”