Habitat and Avifaunal Recovery from Livestock Grazing in a Riparian Meadow System of the Northwestern Great Basin

Abstract

Riparian habitats are centers of biological diversity in arid and semiarid portions of western NorthAmerica, but despite widespread loss and degradation of these habitats there is little quantitative information concerning restoration of native riparian biota. We examined the recovery of a riparian meadow system in the context of long-term versus short-term release from livestock grazing. We compared the structure and dynamics of plant and avian communities on 1.5-ha plots inside a long-term ( Ͼ 30 years) livestock exclosure ("exclosure plots"), with adjacent plots outside the exclosure ("open plots") for 4 years following removal of livestock from open plots. Throughout the study, sedge cover, forb cover, and foliage height diversity of herbs were greater on exclosure plots; bare ground, litter cover, shrub cover, and shrub foliage height diversity were greater on open plots. Forb, rush, and cryptogamic cover increased on open plots but not on exclosure plots. Grass cover increased, whereas litter and bare ground decreased on all plots in conjunction with increased availability of moisture. Sedge cover did not change. Avian species richness and relative abundances were greater on exclosure plots; species composition differed markedly between exclosure and open plots ( Jaccard Coefficient ϭ 0.23-0.46), with exclosure plots dominated by wetland and riparian birds and open plots dominated by upland species. The appearance of key species of wet-meadow birds on open plots in the third and fourth years following livestock removal signaled the beginning of restoration of the riparian avifauna. We interpret the recovery of riparian vegetation and avifaunal composition inside the exclosure as a consequence of livestock removal, which led to a rise in the water table and an expansion of the hyporheic zone laterally from the stream channel. The lack of change in sedge and shrub cover on open plots suggests that restoration to a sedge-dominated meadow will not happen quickly. Hábitat y Recuperación de la Avifauna de Actividades de Pastoreo en un Sistema de Pradera Riparia en el Noroeste de Great BasinResumen: Los hábitats riparios son centros de diversidad ecológica en porciones áridas y semiáridas del Oeste de Norte América, sin embargo, a pesar de la ampia pérdida y degradación de estos hábitats, existe muy poca información cuantitativa referente al restablecimiento de la biota riparia nativa. Examinamos la recuperación de un sistema de pradera riperia en el contexto de su liberación de actividades de pastoreo a largo plazo contra uno a corto plazo. Comparamos la estructura y dinámica de comunidades de plantas y aves en lotes de 1.5 ha. dentro de una zona exluyente de ganado por largo plazo (30 años) "lotes excluyentes" con lotes adyacentes fuera de la zona de exclusión "lotes abiertos" durante cuatro años después de que el ganado fuera removido de los lotes abiertos. A lo largo del estudio, la cobertura de ciperáceas, cobertura de hierbas forrajeras (diferentes a pasto) y la diversidad de la altura del follage de las hie...

Grassland versus non-grassland bird abundance and diversity in managed grasslands: local, landscape and regional scale effects

“…In recent decades great attention have been paid to the population declines of farmland birds attributed to intensive agricultural management (Vickery et al 2001). Grazing generally has negative effect on bird species richness or abundance (Dobkin et al 1998;Fuller and Gough 1999;Verhulst et al 2004;Maron and Lill 2005). In the present study we showed effect of management on species richness and abundance of true grassland birds with higher species richness and abundance on the extensive sites, while on non-grassland species no effect was found.…”

Livestock Trampling Reduces the Conservation Value of Beetle Communities on High Quality Exposed Riverine Sediments

“…reduction in infiltration rates and increased bulk density) (Wheeler et al 2002), water table (e.g. lowering and contraction of the hyporheic zone) (Dobkin et al 1998), stream channels (e.g. enhanced width-depth ratios) (Clary 1999;Scrimgeour and Kendall 2003), stream banks (e.g.…”

“…nutrient enrichment) (Agouridis et al 2005). It has been associated with altered community composition and ecological function, and decreased diversity and conservation value for riparian vegetation (Clary 1999;Scott et al 2003), birds (Dobkin et al 1998;Scott et al 2003), aquatic macroinvertebrates (Scrimgeour and Kendall 2003) and small mammals (Giuliano and Homyack 2004). Therefore livestock grazing is likely to have several indirect influences on ERS beetle communities as a result of changes to sediment delivery, vegetation cover, habitat shading, and aquatic food supply (c.f.…”

Assessing the extent and diversity of riparian ecosystems in Sonora, Mexico

“…In addition to providing important ecological goods and services to human communities, these forests represent important stopover locations for Neotropical land birds that winter in Mexico or migrate between breeding and wintering grounds, which may extend from southern Canada to Central and South America (Skagen et al 1998;Yong et al 1998). In the western US, riparian ecosystems are estimated to occupy between 0.1% and 0.5% of the landscape (Knopf et al 1988;Webb and Leake 2006), yet they typically support a disproportionately large number of bird species and greater densities of birds than other habitats in the continental US (Dobkin et al 1998;Krueper et al 2003). Riparian ecosystems in the US and Canada have received considerable attention from researchers and conservationists (NRC (National Research Council) 2002;Naiman et al 2005).…”