Journal Article

Human activities modulate reciprocal effects of a subterranean ecological engineer rodent, Tachyoryctes macrocephalus, on Afroalpine vegetation cover

Miehe, Georg, Reuber, Victoria, Wube, Tilaye, Schabo, Dana G., Wraase, Luise, Farwig, Nina, Asefa, Addisu

2023

Overview

Human activities, directly and indirectly, impact ecological engineering activities of subterranean rodents. As engineering activities of burrowing rodents are affected by, and reciprocally affect vegetation cover via feeding, burrowing and mound building, human influence such as settlements and livestock grazing, could have cascading effects on biodiversity and ecosystem processes such as bioturbation. However, there is limited understanding of the relationship between human activities and burrowing rodents. The aim of this study was therefore to understand how human activities influence the ecological engineering activity of the giant root‐rat (Tachyoryctes macrocephalus), a subterranean rodent species endemic to the Afroalpine ecosystem of the Bale Mountains of Ethiopia. We collected data on human impact, burrowing activity and vegetation during February and March of 2021. Using path analysis, we tested (1) direct effects of human settlement on the patterns of livestock grazing intensity, (2) direct and indirect impacts of humans and livestock grazing intensity on the root‐rat burrow density and (3) whether human settlement and livestock grazing influence the effects of giant root‐rat burrow density on vegetation and vice versa. We found lower levels of livestock grazing intensity further from human settlement than in its proximity. We also found a significantly increased giant root‐rat burrow density with increasing livestock grazing intensity. Seasonal settlement and livestock grazing intensity had an indirect negative and positive effect on giant root‐rat burrow density, respectively, both via vegetation cover. Analysing the reciprocal effects of giant root‐rat on vegetation, we found a significantly decreased vegetation cover with increasing density of giant root‐rat burrows, and indirectly with increasing livestock grazing intensity via giant root‐rat burrow density. Our results demonstrate that giant root‐rats play a synanthropic engineering role that affects vegetation structure and ecosystem processes. In our study, we tested how human activities in terms of livestock grazing and settlements affect the reciprocal effects between vegetation and giant root‐rats. Our results show that increasing livestock grazing intensity causes increases in giant root‐rat burrow density indirectly through decreased vegetation cover. Reciprocally, the root‐rat's engineering activities resulted in decreased vegetation cover.

• Publisher: John Wiley & Sons, Inc,John Wiley and Sons Inc,Wiley
• Subject: Biodiversity / Biodiversity Ecology / Bioturbation / Community Ecology / Density / Ecological effects / Ecological Engineering / Ecosystem Ecology / Ecosystems / Endemic species / Engineers / Environmental engineering / Flowers & plants / Grazing / Grazing intensity / Habitats / Human Ecology / Human impact / Human influences / human settlement / Human settlements / Land settlement / Livestock / Livestock grazing / Mountains / rodent burrow / Rodents / synanthropic association / Tachyoryctes macrocephalus / Urination / Vegetation / Vegetation cover