An Examination of Soil Microbial Communities and Litter Decomposition along an Urbanization Gradient

Urban landscape managers increasingly recognize the critical role of soil organisms in regulating plant nutrient availability through decomposition. Naturalized forested soils are regarded as being balanced in annual organic contributions and the microorganisms responsible for nutrient cycling. Unfortunately, land conversion processes such as urbanization can potentially alter the ability of microorganisms to supply nutrients to plants by changing the organic additions and edaphic properties of soil. However, because the degree of variation in the composition and structure of soil biological communities is not clear in urban areas, baseline information regarding the impact of urban land management practices on soil microbial communities is essential to improve our ability to manage urban soils and the plants they support. This study explored soil bacterial and fungal communities along an urbanization gradient over five urban land-uses: street side terraces, new (< 5 years) residential landscapes receiving intensive management, old (> 25 years) residential landscapes receiving intensive management, old residential landscapes receiving minimal management, and rural forested lands in metropolitan Milwaukee, WI, USA. The objectives were to: 1) determine if urbanization initiates changes bacterial and fungal community composition and microbial biomass across five urban land-uses, 2) determine if urbanization initiates changes biological activity across five urban land-uses, 3) determine if urbanization initiates changes the soil physical and chemical environment across five urban land-uses, and 4) determine if differences in the bacterial and fungal compositions are related to differences in the soil’s physical and chemical characteristics. Microbial biomass did not differ along the urbanization gradient. The PLFA/FAME produced microbial communities showed statistical differences in biodiversity index values by land-use; however, analysis of similarities (ANOSIM) and multidimensional scaling (MDS) indicated highly similar communities with limited separation. The TRFLP inferred bacterial and fungal communities showed some land-use differences based on ANOSIM, MDS, and analysis of biodiversity indices. However, the discrete land-use clusters grouped closely from large-scale similarities in community profiles. Therefore, observed differences in microbial community composition reflected only a small portion of the total microbial biomass. The decomposition of transposed leaf litter showed significant decline in C:N ratio over time, but no statistical differences by land-use were observed. The soil edaphic properties (bulk density, soil organic matter, pH, Mg, Na, total N, and C:N ratio) displayed significant differences across the urbanization gradient. Additionally, Mg and total N we correlated to changes in the bacterial communities. Consequently, in locations where parent material and soil forming processes are homogeneous, urbanization and landscape management appears to have less impact on soil microbiology than initially expected.The International Society of Arboriculture John Hyland Gran

The genetic composition of wild recruits in a recovering lake trout population in Lake Michigan

Strain performance evaluations are vital for developing successful fishery management and restoration strategies. Here, we utilized genotypes from 36 microsatellites to investigate hatchery strain contribution to collections of naturally produced lake trout (Salvelinus namaycush) sampled across Lake Michigan. Strain composition varied by area, with recoveries of Seneca Lake strain exceeding expectations based on stocking records in northern Lake Michigan but performing similarly to other strains in southern Lake Michigan. Interstrain hybrids were present at moderate frequencies similar to expectations based on simulations, suggesting that strains are interbreeding randomly. We hypothesize that the superior performance of the Seneca Lake strain in northern Lake Michigan is partially due to adaptive advantages that facilitate increased survival in areas with high mortality from sea lamprey (Petromyzon marinus) predation, such as northern Lake Michigan. However, when this selective pressure is lessened, the Seneca Lake strain performs similarly to other strains. Our study demonstrates that strain performance can vary across small spatial scales and illustrates the importance of conducting thorough strain evaluations to inform management and conservation.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The range of passive arm circumduction in primates: Do hominoids really have more mobile shoulders?

Hominoids and lorines are assumed to possess greater shoulder mobility than other primates. This assumption is based on morphological characteristics of the shoulder, rather than on empirical data. However, recent studies have shown that the glenohumeral joint of hominoids is not more mobile than that of other primates (Chan LK. 2007. Glenohumeral mobility in primates. Folia Primatol (Basel) 78(1): 1-18), and the thoracic shape of hominoids does not necessarily promote shoulder mobility (Chan LK. 2007. Scapular position in primates. Folia Primatol (Basel) 78(1): 19-35). Moreover, lorines differ significantly from hominoids in both these features, thus challenging the assumption that both hominoids and lorines have greater shoulder mobility. The present study aims to test this assumption by collecting empirical data on shoulder mobility in 17 primate species. Passive arm circumduction (a combination of glenohumeral and pectoral girdle movement) was performed on sedated subjects (except humans), and the range measured on the video images of the circumduction. The motion differed among primate species mostly in the craniodorsal directions, the directions most relevant to the animal's ability to brachiate and slow climb. Hylobatids possessed the highest craniodorsal mobility among all primate species studied. However, nonhylobatid hominoids did not have greater craniodorsal mobility than arboreal quadrupedal monkeys, and lorines did not have greater craniodorsal mobility than arboreal quadrupedal prosimians. Nonhylobatid hominoids and lorines had similar craniodorsal mobility, but this was due to a longer clavicle, more dorsal scapula, and lower glenohumeral mobility in the former, and a shorter clavicle, less dorsal scapula, and greater glenohumeral mobility in the latter. This study provides evidence for the reexamination of the brachiation, slow climbing, and vertical climbing hypotheses. ©2008 Wiley-Liss, Inc.link_to_subscribed_fulltex