Animal foraging pit soil enhances the performance of a native grass under stressful conditions

Abstract

Background and Aims In line with the Stress Gradient Hypothesis, studies of facilitation have tended to focus on plant-plant interactions (biotic nurses), while the relative role of abiotic nurses has been little studied. We assessed the role of biotic and abiotic nurses, and their interaction, on soil enhancement and the consequential performance of a native annual grass, Dactyloctenium radulans. Methods We used a growth chamber study with two levels of water application to compare the performance of D. radulans growing in soil from foraging pits of the Short-beaked echidna (Tachyglossus aculeatus;abiotic nurse) and non-pit soil from either under tree canopies (biotic nurse) or surrounding open areas. Results All measures of plant performance were more pronounced under the high than the low water treatment. The greatest differences between pit and surface Microsites occurred under the low water application, reinforcing our view that facilitatory effects are greater in resource-limited environments. Despite tree canopy soil having greater N, there was no significant effect on plant performance, nor any significant interaction with Microsite. Conclusions Our study provides strong evidence that foraging pits enhance soil properties and this soil, in turn, facilitates plant growth; and supports previous work documenting the positive effect of nurse-protégé interactions under greater levels of abiotic stress.

Restoration potential of threatened ecosystem engineers increases with aridity: broad scale effects on soil nutrients and function

“…Australian soil-disturbing mammals such as echidnas Tachyglossus aculeatus, bettongs Bettongia spp. and greater bilbies Macrotis lagotis increase soil moisture, soil carbon and nitrogen and alter bacterial communities at the scale of individual pits measured within single landscapes (Garkaklis et al 2000, Eldridge and Mensinga 2007, Eldridge and James 2009, Travers et al 2012, but the question of whether their impacts change with environmental variables or are important at larger spatial scales remains unanswered.…”

A burrowing ecosystem engineer positively affects its microbial prey under stressful conditions

“…Other groups of organisms may modify physical conditions through their activities (i.e., allogenic engineering) rather than via their body shape. Only a few authors have addressed the potential application of the stress-gradient hypothesis to species with this form of environmental modification (Barrio, Hik, Bueno, & Cahill, 2012;Daleo & Iribarne, 2009;Donadi et al, 2013;Travers, Eldridge, Koen, & Soliveres, 2011). The best-studied mechanism of allogenic engineering is burrowing.…”

The foraging pits of the nine-banded armadillo, Dasypus novemcinctus (Mammalia: Xenarthra: Dasypodidae), and implications for interpreting conical trace fossils

“…Foraging pits of such terrestrial vertebrates as armadillos, rodents, echidnas, and monitor lizards (Varanus sp.) have been observed to be conical or subconical in shape (Chamberlain, 1980;McBee and Baker, 1982;Loope, 2008;Eldridge and Mensinga, 2007;Chapman, 2012), but most studies of modern foraging pits have focused on their impact on alteration of soil biogeochemistry and ecosystem engineering (Eldridge and Mensinga, 2007;Eldridge et al, 2012;Travers et al, 2012).…”