@article {JRN53911, title = {Constraints and time lags for recovery of a keystone species (Dipodomys spectabilis) after landscape restoration}, journal = {Landscape Ecology}, volume = {29}, year = {2014}, month = {02/2014}, pages = {665-675}, chapter = {665}, abstract = {

Habitat restoration is typically focused on reestablishing suitable conditions at a local scale, but landscape constraints may be important for keystone species with limited dispersal. We tested for time lags and examined the relative importance of local and landscape constraints on the response of the banner-tailed kangaroo rat (Dipodomys spectabilis) to restoration of Chihuahuan Desert grasslands in New Mexico, USA. Dipodomys spectabilis is a keystone species that creates habitat heterogeneity and modifies the structure of plant and animal communities. We selected 21 sites and compared density of D. spectabilis between areas treated with herbicide to control shrubs (treated areas) and paired untreated areas. We evaluated whether density of D. spectabilis depended on treatment age, local habitat quality (vegetation and soil structure), and landscape factors (treatment area and spatial connectivity). Density was greater at treated areas than at untreated areas due to a direct effect of reduced shrub cover. However, the response of D. spectabilis to restoration was lagged by a decade or more. Structural equation modeling indicated the time lag reflected a dispersal constraint as opposed to a temporal change in habitat quality. This inference was corroborated by a positive relationship between density at treated areas and connectivity to source populations. Our results indicate that density of D. spectabilis depended strongly on the spatial configuration of treated areas, which supports a landscape mosaic approach to restoration. If keystone species commonly exhibit limited dispersal ability, landscape constraints may be broadly important for shaping ecosystem structure and function after habitat restoration.

}, keywords = {colonization, connectivity, conservation, desertification, Dipodomys spectabilis, dispersal, ecosystem engineer, grassland, kangaroo rat, shrub encroachment}, doi = {10.1007/s10980-014-0003-5}, url = {/files/bibliography/14-007.pdf}, author = {Brad Cosentino and Robert L. Schooley and Brandon T Bestelmeyer and J.F. Kelly and John M. Coffman} } @article {50485, title = {Woody Plant Invasion at a Semi-arid Transition Zone: Importance of Ecosystem Type to Colonization and Patch Expansion}, journal = {Journal of Vegetation Science}, volume = {17}, year = {2006}, note = {Duplicate of ARIS $\#$ 182512}, month = {June 15, 2006}, pages = {389-396}, abstract = {Our objective was to evaluate how patterns in colonization and patch expansion of an invasive woody plant, Larrea tridentata (creosotebush) differ between two grassland ecosystems at a biome transition zone. We sampled frequency of occurrence, height, and surface area of saplings (n=134) and patches of adult plants (n=247) of creosotebush within a mosaic of ecosystems dominated either by the Chihuahuan Desert species, black grama, or the shortgrass steppe species, blue grama, located within 1 km of the creosotebush-dominated ecosystem. Distances between patches and patch area were used to estimate connectivity and propagule pressure. Sapling height and distance to the creosotebush dominated ecosystem were used to estimate patterns in dispersal. Our results show that creosotebush saplings (<1\%) and patches of adults (15\%) occur less frequently in black grama than blue grama-dominated ecosystems. Propagule pressure did not differ with distance from the core creosotebush ecosystem. Evidence was found for both local and long distance dispersal. We conclude that spatial variation in creosotebush saplings and adults at this biome transition zone is related to the different susceptibilities to invasion by the two grassland ecosystems. The persistence of grasslands at this site despite region-wide expansion by creosotebush may be related to the spatial distribution of blue grama-dominated ecosystems that resist or deter invasion by this species.}, keywords = {colonization, ecosystem, semi-arid, transition, woody}, url = {/files/bibliography/06-024.pdf}, author = {Debra C. Peters and Jin Yao and J. R. Gosz} } @conference {50626, title = {Endophytic fungi associated with shrubs and grasses of the northern Chihuahuan Desert and a potential role in drought tolerance}, booktitle = {Annual Meeting, Canadian Botanical Association}, year = {2004}, month = {June 26-30, 2004}, pages = {p. 10}, address = {Winnipeg, Manitoba, Canada }, abstract = {Native grasses and shrubs of the northern Chihuahuan Desert are predominantly colonized by dark septate endophytes. Methods using stains that target fungal chitin and internal lipids with high-magnification, light microscopy and scanning electron microscopy revealed a much greater incidence of colonization than was previously thought. In-vitro-regenerated plants from meristematic stem cells were also found to be colonized with the same fungi observed in plants from native populations. Originally thought to be restricted to roots, they are conspicuously present in meristems, sieve elements, xylem vessels of roots and leaves and in photsynthetic cells and stomata. Differing from pathogens and mycorrhizal fungi that have localized patterns of colonization, they systemically inhabit the entire apoplastic network of below- and aboveground organs. They encapsulate host cell protoplasts and are vertically transmitted by seed. Hyphal networks and biofilms that encapsulate all cells and tissues of micropropagated and native plants prevent their direct exposure to harsh external environments. The intimate nature of the association with all plant cells and organs indicates that these native desert shrubs and grasses function as composite plant-fungus organisms. A potential role in managing basic physiological processes that positively enhance plant survival in arid ecosystems is suggested.}, keywords = {Chihuahuan Desert, colonization, endophytes, fungi}, author = {J.R. Barrow and Aaltonen, R.E. and P. Osuna-Avila and I. Reyes-Vera} }