The range of influence between cattle herds is of importance for the local spread of Salmonella Dublin in Denmark

The objective of the study was to estimate the range of influence between cattle herds with positive Salmonella Dublin herd status. Herd status was a binary outcome of high/low antibody levels to Salmonella Dublin in bulk-tank milk and blood samples collected from all cattle herds in Denmark for surveillance purposes. Two methods were used. Initially, a spatial generalised linear mixed model was developed with an exponential correlation function to estimate the range of influence simultaneously with the effect of potential risk factors. An iteratively reweighted generalised least squares procedure was used as a second method for verifying the range of influence estimates. With this iterative procedure, deviance residuals were calculated based on a generalised linear model and the range of influence was estimated based on the residuals using an exponential semivariogram. The range of influence was estimated for six different regions in Denmark using both methods. The analyses were performed on data collected during 1 year after initiation of the Salmonella Dublin surveillance program providing herd classifications for the 4th year-quarter of 2003 and 2 years later for the 4th year-quarter of 2005. The prevalence of dairy herds with a positive Salmonella Dublin herd classification status in this period had decreased from 22.1 to 17.0%. In non-dairy herds, the prevalence was nearly unchanged during the same period (3.4 and 3.7% in 4th quarter of 2003 and 2005, respectively). For all cattle herds, the range of influence was 2.3–6.4 km in 2003 and 1.5–8.3 km in 2005. There seemed to be no association between the range of influence and the density of herds in the different regions.     

Colonisation as a common denominator in plant metapopulations and range expansions: effects on genetic diversity and sexual systems

Colonisation plays a central role in both the initial occupancy of a region through range expansions as well as in metapopulations, where local extinctions are balanced by re-colonisations. In this paper, we review the effects that colonisation is expected to have on patterns of genetic variation within a species, and we draw attention to the possibility of interpreting these patterns as signatures of colonisation in the past. We briefly review theoretical predictions for the effect of colonisation on both neutral genetic diversity and on variation at genetic loci that regulate the sexual system of plant populations. The sexual system represents a particularly important trait in this context because it is affected by both selection during colonisation, and because it influences gene flow amongst populations. Finally, we introduce four case studies of plant species that show variation in their sexual systems that is consistent with theoretical predictions.     

Land ownership and landscape structure: a spatial analysis of sixty-six Oregon (USA) Coast Range watersheds

Patterns of land ownership and forest cover are related in complex and ecologically significant ways. Using a Geographic Information System and regression analysis, we tested for spatial relationships between the structure of land ownership and forest cover across 66 watersheds in the state of Oregon (USA), Coast Range mountains. We found that in these watersheds (1) forest cover diversity increased with land ownership diversity, (2) size of forest patches increased with size of land ownership patches, and (3) connectivity of forest cover increased with connectivity of land ownership. Land ownership structure explained between 29% and 40% of the variability of forest cover structure across these watersheds. Driving this relationship are unique associations among particular ownership classes and various forest cover classes. The USDA Forest Service and the USDI Bureau of Land Management were associated with mature forest cover; private industry was associated with young forest cover; nonindustrial private forest owners were associated with a wide diversity of cover classes. Watersheds with mixed ownership appear to provide greater forest cover diversity, whereas watersheds with concentrated ownership provide less diverse but more connected forest cover. Results suggest that land ownership patterns are strongly correlated with forest cover patterns. Therefore, understanding landscape structure requires consideration of land ownership institutions, dynamics, and patterns.This revised version was published online in May 2005 with corrections to the Cover Date.     

Stretching Exercises for Horses: Are They Effective?

This article aims to present research in both animals and humans that support the use of stretching exercises in horses as a means of increasing range of motion, improving body flexibility and posture, and preventing injury by strengthening the supportive tissues. Too often veterinarians may overlook the importance of stretch exercises. This could partially be due to a lack of familiarity of what type of exercises to recommend, how to perform them, or where to obtain the desired information. Studies demonstrate the beneficial effects of stretching, warm-up, and temperature on the mechanical properties of muscle, potentially reducing the risk of strain injury to muscles. Evidence demonstrates that various approaches to conditioning that include warm-up and stretching along with other techniques such as strength training and proprioceptive training enhance performance and prevent certain types of injury. In addition, stretching of specific muscles and articulations for specific activities might enhance the effectiveness of these other pre-exercise activities, which is consistent with a multifactorial model for injury prevention. Stretches are either dynamic (having motion) or static (having no motion). Dynamic stretching involves moving parts of the body and gradually increasing reach, speed of movement, or both. It is controlled movement or swings that gently take the limb to the limits of range of motion. Static stretching consists of stretching a muscle (or group of muscles) to its farthest point and then maintaining or holding that position. Passive or relaxed and isometric stretching are both types of static stretches. Passive or relaxed is where a position is maintained by holding it with some other part of your body, or with the assistance of a partner or some other apparatus. This type of stretching is the most common type used with stretching exercises in horses as we control the motion and positioning desired. Slow, relaxed stretching is useful in relieving spasms in muscles that are healing after an injury. Relaxed stretching is also good for “cooling down” after a workout and helps reduce postworkout muscle fatigue and soreness. A case study and an example of a stretch exercise program and what to look for in a “how to” guide is also presented.     

中国草地资源的可持续利用

本文论述了我国草原利用的现状,草原与牧业之关系及其可持续发展的途径,牧业与农业两个系统的组合,草原资源的改良和保护,保持保护与利用的动态平衡。同时对我国草原管理提出了-些建议。     

Influence of Cattle Stocking Rate on Browsing of Norway Spruce in Subalpine Wood Pastures

In the Swiss Alps, 15% of Swiss mountain forests are grazed during summer, mainly by cattle. The forest laws of various Swiss cantons characterise forest grazing as a detrimental form of land use and stipulate that this grazing practice should be restricted. However, little is known about tree damage actually caused by cattle. Seven subalpine ranges in the Swiss Canton Grisons, grazed by cattle at different stocking rates, were investigated. The condition of naturally regenerated young trees (Picea abies (L.) Karst.) was assessed before and after the cattle grazing period. In order to characterise the influence of wild ungulates on the young trees during winter, the assessment of tree condition was repeated in the proximate spring. In total, 4% of the young trees were browsed on the apical shoot, 10% were browsed on lateral shoots, 13% of the trees showed other damage. The variation among ranges could almost completely be explained by the cattle stocking rate (livestock units per hectare). During winter, wild ungulates browsed 3 times as many young trees as the cattle during summer. The results suggest that cattle stocking rates on subalpine wood pastures should not exceed one livestock unit per hectare in order to avoid intensive browsing and other damage by cattle on young Norway spruces.     

论城市森林的范围及经营对策

工业发展与城市化使城市环境恶化,城市对森林的需要增加。建设完善的城市森林生态体系,合理划分城市森林的范围,并进行高效经营已是当务之急。本文对影响划分城市森林范围的森林类型、划分原则、为协调城市与林区关系及在市场经济条件下的经营对策进行探讨。     

Integration of Northern spotted owl habitat and fuels treatments in the eastern Cascades,Washington, USA

The restoration of natural fire regimes has emerged as a primary management objective within fire-prone forests in the interior western US. However, this objective becomes contentious when perceived to be in conflict with the conservation of rare wildlife species. For example, the integration of fire ecology in disturbance-prone forests of eastern Washington with the recovery of the Northern spotted owl has been described as a management dilemma. We intersected modeled spotted owl habitat with mapped priority fuels treatment areas in order to determine the magnitude of the potential conflict between fuels management and owl conservation. Our results show that there is considerable overlap within dry forests between high suitability spotted owl habitat and moderate-high priority fuels treatment areas (34% overlap). However, there is also considerable overlap of lower suitability spotted owl habitat with moderate-high priority fuels treatment areas (35% overlap) providing opportunities to accomplish multiple management objectives if one considers a landscape perspective. We propose that a conservation strategy for the Northern spotted owl in the eastern Cascades consider the following: emphasize landscape restoration of dry forests within which spotted owl habitat is embedded; landscapes considered for restoration need to be large enough to accomodate the effects of fire disturbances and still retain sufficient habitat to support spotted owl populations; and include adaptive management allowing for adequate monitoring and feedback for managers to make needed adjustments.     

Thinning and chipping small-diameter ponderosa pine changes understory plant communities on the Colorado Front Range

Novel fire mitigation treatments that chip harvested biomass on site are increasingly prescribed to reduce the density of small-diameter trees, yet the ecological effects of these treatments are unknown. Our objective was to investigate the impacts of mechanical thinning and whole tree chipping on Pinus ponderosa (ponderosa pine) regeneration and understory plant communities to guide applications of these new fuel disposal methods. We sampled in three treatments: (1) unthinned forests (control), (2) thinned forests with harvested biomass removed (thin-only), and (3) thinned forests with harvested biomass chipped and broadcast on site (thin + chip). Plots were located in a ponderosa pine forest of Colorado and vegetation was sampled three to five growing seasons following treatment. Forest litter depth, augmented with chipped biomass, had a negative relationship with cover of understory plant species. In situ chipping often produces a mosaic of chipped patches tens of meters in size, creating a range of woodchip depths including areas lacking woodchip cover within thinned and chipped forest stands. Thin-only and thin + chip treatments had similar overall abundance and species richness of understory plants at the stand scale, but at smaller spatial scales, areas within thin + chip treatments that were free of woodchip cover had an increased abundance of understory vegetation compared to all other areas sampled. Relative cover of non-native plant species was significantly higher in the thin-only treatments compared to control and thin + chip areas. Thin + chip treated forests also had a significantly different understory plant community composition compared to control or thin-only treatments, including an increased richness of rhizomatous plant species. We suggest that thinning followed by either chipping or removing the harvested biomass could alter understory plant species composition in ponderosa pine forests of Colorado. When considering post-treatment responses, managers should be particularly aware of both the depth and the distribution of chipped biomass that is left in forested landscapes.     

Integrating wild mushrooms use into a model of sustainable management for indigenous community forests

Recently, the importance of fungal resources has been brought to the forefront due to their ecological and economical importance. There have been many efforts to record their diversity at local and regional scales. However, few studies deal with the potential value of fungi for the development of local communities, particularly in developing countries. The present study presents the results of a five-year inventory of useful mushrooms in the communal land of Ixtlan de Juarez, Oaxaca. We use the species list to analyze the real possibility of local communities incorporating these resources into a model of local development exploiting wood and non-wood forest products in the context of Smart wood certification. The model discusses three main strategies for mushroom management (diversification of forest exploitation, incorporation of soil function to forestry and fungal technology development); in each case we also discuss the viability and infrastructure necessary to implement it. We identified a total of 159 taxa of useful mushrooms and provide information on their habit, substrate, abundance and recorded use. Thirteen taxa were Ascomycetes and 146 Basidiomycetes; belonging to 42 families and 73 genera. A total of 38 taxa (23.9%) were new records for the state of Oaxaca. This is, to date, the most comprehensive list of useful mushrooms presented in Mexico. It demonstrates the huge mycological diversity of these resources present in the Juarez’ Mountain Range. A total of 113 species are edible, 38 species have direct applications in forest management, 19 species have medicinal properties, 12 are toxic and 12 species have recorded biotechnological applications. The diversity and heterogeneity of potential uses of these resources represent a challenging opportunity for local communities. Product diversification is a fundamental strategy to integrate a model of sustainable forest exploitation. We concluded that communities developing forestry activities must be aware of the functional properties of ectomycorrhizal and saprotrophic fungi to include them in their own forest management plans. We also outline a set of common steps for initiating sustainable and diversified forestry practices which include: awareness-raising targeted to local authorities and forestry technicians on the ecological importance of mushrooms; illustrated catalogues on useful species accessible to all the communities, which would allow taxonomic identification for all species; local technical capacity to obtain and disseminate strains of mycorrhizal and saprotrophic fungi; obtaining resources to develop infrastructure to cultivate mushrooms, among many others projects.