堆肥对土壤重金属垂直分布的影响与污染评价

对不同畜禽粪便堆肥与土壤重金属垂直分布的关系进行了研究．结果表明,在畜禽粪便堆肥过程中,粪堆下土壤pH值和有机质显著增加,其pH和有机质含量的垂直分布表现为从表层到底层逐渐降低．各种畜禽粪便粪堆下土壤Zn、Cd含量明显增高,且从表层到底层呈逐渐减小的趋势．鸡粪和猪粪堆下土壤Cu含量随土层深度增加而降低;牛粪堆下土壤Cu含量随土层深度增加没有明显的变化．自然条件下Cd和Zn在土壤系统中的迁移能力大于Cu．各粪堆下的部分土层Cu、Zn、Cd含量超过我国土壤环境质量一级标准．应用地质积累指数法对各土层污染评价的结果表明,只有肉鸡粪堆下0～10cm土壤和蛋鸡粪堆下0～40cm土壤受到轻度Zn污染,其它粪堆下各土层均未受到Cu、Zn、Pb和Cd污染．     

Monitoring African buffalo (Syncerus caffer) and cattle (Bos taurus) movement across a damaged veterinary control fence at a Southern African wildlife/livestock interface

We test the extent to which fence damage or fence permeability (resulting from human and elephant damage) influences patterns of cattle and buffalo movement at the periphery of Gonarezhou National Park, Zimbabwe. We used spoor data to detect and compare the frequency of cattle and buffalo movement across the fence boundary. Results show that spoor proportions for cattle were significantly higher on fence partially damaged by humans than buffalo spoor. Conversely, buffalo spoor proportions were significantly higher on sections with totally removed fence as a result of elephant damage. Results suggest that cattle and buffalo use different sections of the damaged fence.     

Persistence of Native C4 Grasses under High-Intensity, Short-Duration Summer Bison Grazing in the Eastern Tallgrass Prairie

Disturbances such as burning or grazing maintain the herbaceous nature of eastern tallgrass prairie. These disturbances are also known to affect the relative abundance of warm-season (C4) and cool-season (C3) grasses in native prairie. Although burning is a commonly used tool, the utility of livestock grazing to manage restored prairie is less understood. We established five monocultures and one mixture of C4 grass species of the eastern tallgrass prairie in southern Wisconsin. To examine their persistence under high-intensity, short-duration summer grazing, we estimated cover of several functional groups and C4 species over a 6-year period (2000 through 2006) in a randomized complete block design. After a 2-year establishment phase (1998–1999), bison were rotated through paddocks two or three times annually during late June, July, or early August. All C4 grasses declined over time but at different rates depending on the species. Switchgrass ( Panicum virgatum ) decreased at the lowest rate, whereas Little bluestem ( Schizachyrium scoparium ) cover declined faster than Big bluestem ( Andropogon gerardii ), Indiangrass ( Sorghastrum nutans ), and Sideoats grama ( Bouteloua curtipendula ), whose rates of decline were not significantly different from each other. Succession followed a predictable trajectory with annual grasses initially colonizing interstitial space among C4 grasses, followed by legumes, which ultimately gave way to exotic C3 forage grasses. The focal C4 grasses remained the dominant functional group 8 years postseeding, but recolonization by non-native C3 grasses increased over the study period.     

Climate as a determinant of dung beetle response to native forest replacement by cattle pastures in South America

Anthropogenic disturbance in natural ecosystems reduces the number of species in biological communities and homogenizes their composition across different regions. Climate is one of the main abiotic determinants of species distributions and different factors were proposed as the main climatic drivers. Here we explored the role of regional climate on the local response of dung beetle assemblages to the replacement of native forest by cattle pastures in South America by simultaneously contrasting three climatic hypotheses: energy, seasonality and heterogeneity. We compiled a database by searching published studies comparing dung beetle richness and composition between both native forests and cattle pastures. We calculated the proportional difference in species richness and composition between habitat types. As explanatory variables, we used seven abiotic variables grouped into the three climatic hypotheses. Energy/Productivity: mean annual temperature (°C/year) and total annual precipitation (mm/year). Seasonality: annual thermal amplitude (°C/year), the average coefficient of variation of monthly precipitation and the coefficient of average monthly variation in temperature. Heterogeneity: coefficient of variation of mean annual temperature, coefficient of variation of mean annual precipitation. Using regression analyses and a model selection procedure, we found differences in species richness between native forests and cattle pastures were explained by the coefficient of variation of mean annual precipitation, whereas changes in species composition were explained by total annual precipitation and the coefficient of variation of mean annual precipitation. The response of dung beetle assemblages to livestock grazing in South American forests was associated with precipitation variation. The heterogeneity hypothesis better explained changes in species richness following forest replacement by cattle pastures, while both energy/productivity and heterogeneity hypotheses explained the changes in species composition.     

Evaluation of crude annual parturition rate estimates in a small-holder African ruminant farming system

Many parameters have been proposed for evaluating livestock reproduction performances in tropical farming systems. In tropical free-ranged and small-holder systems, where reproduction cycles cannot be individually observed without expensive field surveys, one of these parameters is the average number of parturitions (h) expected by reproductive female, if the female spends the whole year in the herd. A frequent approach for estimating h is to use the ratio hc = m/T, so-called 'crude annual parturition rate', where m is the observed number of parturitions and T is the total time of presence of the reproductive females in the herd during the year. The bias encountered when h is estimated by hc was evaluated in this paper. Six methods of estimation were used, where T was the exact observed time of presence (hc1) or approximated by monthly, quarterly, half-yearly and yearly averages or final size of the reproductive herd size (hc2 to hc6). Data came from long-term follow-up of cattle and small-ruminant herds (with data recorded at animal level) in extensive agro-pastoral systems in Senegal. In general, h was correctly estimated by hc1. Nevertheless hc1 was sensitive to competing risks (e.g. deaths, sales and slaughtering of reproductive females) and was seriously biased when intensive withdrawals of females occurred before or during the parturition peak. Reliability of crude rates progressively decreased from hc2 to hc6, corresponding to the degradation of information used for approximating T. This decrease was much lower for cattle (for which all methods had acceptable reliability) than for small ruminants. Among the compared methods, the lower reliability was observed for hc6 that we do not recommend for small ruminants. Methods hc5 and hc6 are currently used in rapid cross-sectional retrospective surveys based on the recall of the farmers on the demographic events which occurred in the herd over the last past 12 months. The study has showed that such surveys and estimates hc5 and hc6 can generate seriously biased results. More globally, annual parturition rates can be highly variable depending on the 12-month periods considered. Annual parturition rates estimated on short-term data, even with precise herd follow-up surveys, must be considered cautiously.     

Distribution of mosquito species in areas with high and low incidence of classic Kaposi's sarcoma and seroprevalence for HHV-8

The 'promoter-arthropod' hypothesis, which postulates that exposure to the bites of certain species of haematophagous arthropods is an environmental risk cofactor linked to human herpes virus 8 (HHV-8) and Kaposi's sarcoma, was investigated in the Po River valley, northern Italy. The presence and density of adult female mosquitoes (Diptera: Culicidae) was determined by CDC light trap catches in two adjacent districts, at variance with respect to Kaposi's sarcoma incidence and HHV-8 seroprevalence. A total of 3910 specimens belonging to 11 species was collected in 34 rural sites (six municipalities) representative of the two districts. Five of these species are considered to be possible 'promoters' because of the irritation their bites cause humans: Aedes vexans (Meigen) and Ae. caspius (Pallas) (87% of sampled promoters), Culex modestus Ficalbi, Culiseta annulata (Schrank) and Coquillettidia richiardii (Ficalbi). Six are probable 'non-promoters': Cx. pipiens s.l., Cx. martinii Medschid, Anopheles claviger (Meigen), An. maculipennis s.l., An. plumbeus Stephens and Uranotaenia unguiculata Edwards. The density of promoters by site was correlated with the incidence rates of Kaposi's sarcoma at the district level (Pearson's r = 0.33, P = 0.06) and at the municipal level (r = 0.50, P< 0.01). Similar correlations emerged for non-promoters (r = 0.48, P< 0.01 and r = 0.42, P = 0.01, respectively). The density of promoters was higher than that of non-promoters in sites with livestock (odds ratio, OR = 2.8, 95% CI 2.2-3.6) and in municipalities with Kaposi's sarcoma cases (OR = 2.5, 95% CI 1.7-3.5). The study provides additional evidence of the association between the density of some mosquito species and Kaposi's sarcoma.     

Phylogeography and origin of Indian domestic goats

The Indian subcontinent contains 20 well-characterized goat breeds, which vary in their genetic potential for the production of milk, meat, and fibre; disease resistance; heat tolerance; and fecundity. Indian goats make up 20% of the world's goat population, but there has been no extensive study of these economically important animals. Therefore, we have undertaken the present investigation of 363 goats belonging to 10 different breeds from different geographic regions of India using mtDNA sequence data from the HVRI region. We find evidence for population structure and novel lineages in Indian goats and cannot reconcile the genetic diversity found within the major lineage with domestication starting 10,000 years ago from a single mtDNA ancestor. Thus, we propose a more complex origin for domestic goats.     

Food habits of the world's grey wolves

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Political Change and Factors Limiting Numbers of Wild and Domestic Ungulates in Kazakhstan

We examine factors regulating numbers of domestic livestock and saiga antelopes during the major periods of Kazakhstan's history. In the pre-Soviet period livestock migrations were relatively unrestricted and covered huge distances. Little winter feed or veterinary care was provided for domestic livestock and numbers were regulated largely by winter snow or ice cover. Drought affected fecundity but did not cause large-scale mortality. During the Soviet period the provision of winter feed shielded domestic livestock from winter mortality while hunting controls allowed saiga numbers to recover from overhunting. Livestock and saiga numbers during this period were high and there is evidence that productivity was affected. However, there were no crashes in livestock numbers linked to high densities, probably because rainfall variability is relatively low and catastrophic droughts are rare. Today livestock numbers in Kazakhstan have crashed because of the withdrawal of state support and the use of animals as currency. The collapse of the state also meant the end of hunting controls and increased poverty, which has lead to widespread saiga poaching and dramatic population declines.