Ecological engineers’ nests benefit plant recovery following fire in a semiarid grassland, New Mexico, USA

• Published in: Journal of vegetation science 2019-07, Vol.30 (4), p.709-719
• Main Authors: Nicolai, Nancy, Overbeck, Gerhard
• Format: Article
• Language: English
• Subjects: ants; community ecology; Density; dicots; Dispersal; Ecosystems; Engineers; Functional groups; Granivory; Grasses; grassland restoration; Grasslands; herbaceous community structure; Magnoliopsida; Mounds; Nests; plant recovery facilitation; plant‐animal interactions; Recovery; Regeneration; rodent burrow; Rodents; Seed dispersal; Species richness; wildfire; Wildlife; Wildlife conservation; Wildlife habitats; Wildlife refuges
• ISSN: 1100-9233; 1654-1103
• DOI: 10.1111/jvs.12755

Questions Ants and rodents are recognized as ecosystem engineers worldwide creating soil‐modified nests and adjacent edges with superior resources. The influence of Dipodomys spectabilis (rat) and Pogonomyrmex rugosus (ant) on nests and edges would be similar in burned and unburned habitat on functional groups’ cover, density, number of inflorescences and species number. We hypothesize that annual and perennial dicots would recover faster on rat patches than on burned grassland, dicots and grasses would recover faster on ant patches than on burned grassland, and annual dicots would recover faster on rat than on ant patches, whereas grasses would recover faster on ant than on rat patches. Location Semiarid grassland, Sevilleta National Wildlife Refuge, New Mexico, USA. Methods We analyzed annual and perennial dicots, grasses and subshrubs in burned and unburned plots at 80 nests during cool‐ and warm‐seasons two years post‐fire. Data were collected at nest top (mound), edge, and 20 m (control) from the edge. Results Cover, density and species richness of different functional groups were low on animal mounds in unburned and burned plots. Ant edges had greater perennial dicot cover, grass cover and richness while rat edges had lower grass density and richness than control sites at unburned and burned plots. Perennial dicot density and richness recovered faster at rat mounds and edges than control. Ant edges yielded faster recovery of grass inflorescences than control. Dicots recovered faster on rat than ant mounds whereas grasses grew faster on ant edges. Conclusions Rats create nests enhancing density of recovering dicots and ant edges facilitate reproduction of recovering grasses. Equal regeneration between animal nests and grassland occurred commonly when fire reduced grass competition. Dysochory, granivory and fire intensity may influence recovery. Nests may be sources of reestablishment and seed dispersal. Recovery of grassland may be amplified as plants infill from engineered nests. After fire, perennial forb density and number of species recovered faster on the burrows of banner‐tailed kangaroo rat than in surrounding grassland. Recovering grasses produced more seed stalks on rough harvester ant nests. Nests may facilitate grassland recovery as plants infill from these sources of recolonization.