Conservation of prairie dog ecosystem engineering may support arthropod beta and gamma diversity

Ecosystem engineering by animals can create new habitats and increase the heterogeneity of the habitat mosaic that in turn can increase plant and animal diversity. Prairie dogs in North America alter both the above- and below-ground structure of the landscape and create novel habitats in grassland ecosystems. The ground-dwelling arthropod community associated with Gunnison’s prairie dog modified habitats is compositionally different from that found in the surrounding grassland. Individual arthropod families and species have different distributions in both active prairie dog towns and inactive towns, compared to unmodified grasslands. These different responses to ecosystem engineering increase beta (between-habitat) and gamma (regional) diversity. This study suggests that simple measures of alpha diversity (species richness) may not adequately quantify overall diversity and that measures of beta diversity may be necessary to assess the role of prairie dogs as keystone engineers. Thus, conservation of prairie dogs and the engineering process may have positive effects for numerous species both locally and regionally

Prairie dog engineering indirectly affects beetle movement behavior

Previous studies have shown that landscape structure influences animal movement and population structure. In this study, we show an indirect interaction between beetles and prairie dogs due to prairie dog ecosystem engineering. Gunnison\u27s prairie dog (Cynomys gunnisoni Hollister) towns have more bare ground and are structurally less complex than adjacent unmodified grasslands. This results in bare ground facilitating beetle movement. Differences in landscape structure between prairie dog towns and unmodified grasslands had a significant effect on the movement of the darkling beetle, Eleodes hispilabris Say. Beetle movement tended to be more linear (pathway fractal dimension approached 1) on prairie dog habitats and more sinuous on adjacent grasslands. Beetle velocity was 44% greater and net displacement 63% farther on the prairie dog habitat. These differences were also evident at fine scales when beetles moved between grass and bare ground patches regardless of habitat. Beetles moved 2.3 times faster and displaced 3.0 times farther after making this microhabitat transition. Beetles avoided grass and selected bare ground for movement 12–22% more than the percent of bare ground on the landscape. Since beetles exhibited directed movements and grasslands inhibit movement, it might be expected that beetles would accumulate in this habitat upon encounter. However, beetles were approximately twice as abundant on prairie dog towns as on adjacent grasslands. A difference in beetle movement behavior, between prairie dog towns and grasslands, suggests that prairie dog towns are an important component of this desert grassland landscape for these beetles

Conservation of prairie dog ecosystem engineering may support arthropod beta and gamma diversity

Ecosystem engineering by animals can create new habitats and increase the heterogeneity of the habitat mosaic that in turn can increase plant and animal diversity. Prairie dogs in North America alter both the above- and below-ground structure of the landscape and create novel habitats in grassland ecosystems. The ground-dwelling arthropod community associated with Gunnison’s prairie dog modified habitats is compositionally different from that found in the surrounding grassland. Individual arthropod families and species have different distributions in both active prairie dog towns and inactive towns, compared to unmodified grasslands. These different responses to ecosystem engineering increase beta (between-habitat) and gamma (regional) diversity. This study suggests that simple measures of alpha diversity (species richness) may not adequately quantify overall diversity and that measures of beta diversity may be necessary to assess the role of prairie dogs as keystone engineers. Thus, conservation of prairie dogs and the engineering process may have positive effects for numerous species both locally and regionally

The Gunnison’s prairie dog structures a high desert grassland landscape as a keystone engineer

The influence of landscape spatial structure on ecological processes has recently received much attention. Comparisons are made here between the spatial structure of grasslands, and active and extirpated Gunnison\u27s prairie dog (Cynomys gunnisoni Hollister) towns at the Petrified Forest National Park, Arizona, U.S.A. The spatial structure of bare ground was quatified using a box-counting technique to extract landscape fractal dimensions, D, and bare-ground patch size. These landscapes are fractal, and active prairie dog towns had higher fractal dimensions, i.e. a more homogeneous spatial structure as D approaches 2, than inactive towns, which had higher fractal dimensions than unmodified grasslands. Morisita\u27s index suggested that shrubs were more randomly distributed on prairie dog towns and more aggregated on grassland habitats. The different spatial distributions of bare ground and shrubs have the potential to influence resource distributions between these habitats for both prairie dogs and other fauna. Consequently, the presence of prairie dogs in these grasslands increases grassland landscape heterogeneity at large spatial scales, potentially enhancing beta diversity

Unique arthropod communities on different host-plant genotypes results in greater arthropod diversity

Studies on the effect of plant-species diversity on various ecological processes has led to the study of the effects of plant-genetic diversity in the context of community genetics. Arthropod diversity can increase with plant-species or plant-genetic diversity (Wimp et al. in Ecol Lett 7:776-780, 2004). Plant diversity effects can be difficult to separate from other ecological processes, for example, complementarity. We asked three basic questions: (1) Are arthropod communities unique on different host-plant genotypes? (2) Is arthropod diversity greater when associated with greater plant-genetic diversity? (3) Are arthropod communities more closely associated with host-plant genetics than the plant neighborhood? We studied canopy arthropods on Populus fremontii trees randomly planted in a common garden. All trees were planted in a homogeneous matrix, which helped to reduce P. fremontii neighborhood effects. One sample was comprised of few P. fremontii genotypes with many clones. A second sample was comprised of many P. fremontii genotypes with few clones. A second data set was used to examine the relationships between the arthropod community with P. fremontii genetic composition and the neighborhood composition of the focal host plant. Unique arthropod communities were associated with different P. fremontii genotypes, and arthropod community diversity was greater in the sample with greater P. fremontii genotypic diversity. Arthropod community similarity was negatively correlated with P. fremontii genetic distance, but arthropod community similarity was not related to the neighborhood of the P. fremontii host plant. © 2012 Springer Science+Business Media B.V

The Society for the Study of Evolution

Abstract. Understanding the genetic basis to landscape vegetation structure is an important step that will allow us to examine ecological and evolutionary processes at multiple spatial scales. Here for the first time we show that the fractal architecture of a dominant plant on the landscape exhibits high broad-sense heritability and thus has a genetic basis. The fractal architecture of trees is known to influence ecological communities associated with them. In a unidirectional cottonwood-hybridizing complex (Populus angustifolia ϫ P. fremontii) pure and hybrid cottonwoods differed significantly in their fractal architecture, with phenotypic variance among backcross hybrids exceeding that of F 1 hybrids and of pure narrowleaf cottonwoods by two-fold. This result provides a crucial link between genes and fractal scaling theory, and places the study of landscape ecology within an evolutionary framework

Data from: Tree genetics strongly affect forest productivity, but intraspecific diversity-productivity relationships do not

Numerous studies have demonstrated biodiversity–productivity relationships in plant communities, and analogous genetic diversity–productivity studies using genotype mixtures of single species may show similar patterns. Alternatively, competing individuals among genotypes within a species are less likely to exhibit resource-use complementarity, even when they exhibit large differences in their effects on ecosystem function. In this study, we test the impact of genotype diversity and genetic identity on ecosystem function using an ecosystem-scale common garden experiment. Distinct tree genotypes were collected across the entire natural range of the riparian tree Populus fremontii in the USA, and grown in 1–16 genotype combination forest stands. Due to the warm climate and irrigation of the planting location along the Colorado River (AZ, USA), mature forest physiognomy with trees up to 19 m tall was achieved in just five years. Several key patterns emerged: (i) genotype richness did not predict forest productivity, suggesting a lack of net biodiversity effects; (ii) we found differences among genotype monoculture stands comparable to differences in average productivity across all forest biomes on Earth; (iii) productivity was predicted based on genetic marker similarity in trees; (iv) genetic-based differences in leaf phenology (early leaf-on and late leaf-fall timing) were correlated with >80% of the variation in tree and forest productivity irrespective of home-site conditions. Large differences in productivity among genotypes can result in dramatic differences in forest productivity without resulting in diversity–productivity relationships that are present in species-scale biodiversity studies

Raw data for tree sizes, blocks, and treatments in the Cibola Tree Genetics and Productivity Experiment

This file contains the raw data for the sizes of trees in the Cibola tree genotype diversity and productivity experiment. Treatments and block locations are also indicated