Relationships Between Landscape Greenness and Condition of Elk,Mule Deer,and Pronghorn in New Mexico

Nutritional condition drives large herbivore population performance and is related to precipitation and forage quality in the arid Southwest. Because precipitation is difficult to measure at home-range scales, we tested whether satellite-derived vegetation indices of landscape greenness (i.e., indices of vegetation phenology or photosynthetic activity including normalized difference vegetation index [NDVI], soil-adjusted vegetation index [SAVI], and enhanced vegetation index [EVI]) were correlated to the condition of three species of large herbivores (elk, mule deer, pronghorn). We used canonical correlation analysis to relate seasonal landscape greenness with several measures of large herbivore condition. We also used linear mixed models to relate each measure of condition to seasonal landscape greenness separately for each herbivore population-year to see if any patterns were masked by multivariate analysis. Landscape greenness indices were only weakly related to condition of large herbivores, and the effect of landscape greenness on condition was always weaker than lactation status with the exception of pronghorn, an income breeder. Different indices also frequently gave highly variable and conflicting relationships between seasonal landscape greenness and condition of large herbivores. Overall, expected positive relationships between herbivore condition and landscape greenness indices were seen in only 8% of 2 988 possible outcomes. Because indices of landscape greenness are increasingly being used to relate wildlife population demographics to precipitation through a presumed effect on forage quality and resultant nutritional condition, we caution this use in arid environments unless a direct landscape greenness-forage quality or greenness-condition link is demonstrated.     

论山区草地资源人口容量开放模型

山区草地资源是我国草地资源的主体,其生态环境和社会经济效应均不容忽视.通过构建山区草地资源人口容量开放模型,探索草地资源退化的根源和制定不同山区的发展战略依据对于实现国家的可持续发展和生态文明建设具有重要意义.     

论山区草地资源人口容量开放模型

山区草地资源是我国草地资源的主体,其生态环境和社会经济效应均不容忽视。通过构建山区草地资源人口容量开放模型,探索草地资源退化的根源和制定不同山区的发展战略依据对于实现国家的可持续发展和生态文明建设具有重要意义。     

Effects of Plant Secondary Compounds on Nutritional Carrying Capacity Estimates of a Browsing Ungulate

Carrying capacity estimates based on digestible protein (DP) and energy (DE) are useful in comparing effects of land management practices or the ability of different vegetation communities to support herbivores. Plant secondary compounds that negatively affect forage quality would be expected to change nutritionally based estimates of carrying capacity. We evaluated the effect of plant secondary compounds on nutritionally based carrying capacity estimates of white-tailed deer (Odocoileus virginianus Zimmerman) in Tamaulipan thorn scrub of northern Mexico. Forage biomass, nutrient concentration, and tannin concentration (protein-precipitating capacity) were measured for 23 forage items during spring and summer in three replicate pastures. Nitrogen in phenolic amines was estimated for the two principal woody browse species in deer diets and was assumed to be unavailable for amino acid synthesis. Carrying capacity estimates were calculated based on three dietary concentrations of DP and DE. Nutritional carrying capacity estimates that accounted for antinutritional compounds were reduced 50 ± 6%, 28 ± 8%, and 0 ± 0% (mean ± SE) for diets of high, medium, and low DE concentration, respectively, compared to estimates from models that ignored the effects of these compounds. Accounting for effects of plant secondary compounds reduced DP-derived carrying capacity estimates 4 ± 3%, 47 ± 9%, and 9 ± 8% for diets with high, medium, and low concentrations of DP, respectively. High variation in percent reduction in carrying capacity estimates occurred because of site and seasonal variation in plant species composition and biomass, making application of a single correction factor to account for plant secondary compound effects on carrying capacity infeasible. Protein-precipitating capacity of tannins accounted for > 98% of the reductions in carrying capacity estimates based on DP. Our results clearly demonstrate the need to consider effects of tannins on ungulate carrying capacity estimates based on DP and DE. Estimates can be further refined by accounting for nonprotein nitrogen and other antinutritional compounds in all forage items.     

祁连山国家公园生态承载力年际变化特征及其影响因素分析

基于2000—2019年祁连山国家公园境内的卫星遥感和社会经济统计数据,综合运用DPSIR、TOPSIS和障碍度模型,构建生态承载力评价指标体系,分析生态承载力年际变化特征,量化生态承载力状况,揭示影响生态承载力的主要障碍因素。结果表明：研究时段内生态承载力状况较差,经济发展与生态环境保护矛盾突出。2000—2014年生态承载力降低,2014—2019年生态承载力增加。驱动力和压力子系统变化是导致2014年之前生态承载力降低的主要因素,2014年以后生态承载力增加是驱动力、压力和响应子系统共同作用的结果。响应子系统是影响现阶段生态承载力的主要障碍因素,其次是驱动力和压力子系统。随时间推移,响应子系统对生态承载力的影响减弱,驱动力子系统对生态承载力的影响增强。未来应将国家公园纳入区域发展,耦合协调生态环境保护与社会经济发展的关系。     

三江源区嵩草草地枯草期牧草营养价值评定及载畜量研究

为探究三江源区枯草期嵩草(Kobresia)草地营养供给潜力和载畜量,采用概略养分分析法和体外产气法,结合产草量对枯草期牧草综合评定并确定其载畜量.结果表明:可食产草量为64.14 g· m-2;以风干样为基础测定的水分、灰分(Ash)、钙(Ca)、磷(P)、钙磷比(Ca/P)、粗纤维(CF)、酸性洗涤纤维(ADF)、中性洗涤纤维(NDF)、粗脂肪(EE)和粗蛋白(CP)分别为7.16％,5.66％,1.13％,0.04％,38.47,28.41％,44.31％,63.33％,2.32％和3.37％;体外发酵pH和氨氮浓度均在正常范围内,体外干物质消化率(IVDMD)、消化能(DE)和代谢能(ME)为36.10％,4.50MJ·k-1和2.92 MJ·k-1;水分,Ash,Ca,P,Ca/P,CF,ADF,NDF,EE和CP输出量分别为:4.62 g·m-2,3.59 g·m-2,0.79 g·m-2,0.02 g·m-2,42.51,19.37g·m-2,28.46 g ·m-2,39.25 g·m-2,1.42g·m 2和2.35 g· m-2;数量载畜量、可消化蛋白(DCP)载畜量和ME载畜量分别为1.06,0.37和0.74SU· hm-2.研究证实嵩草草地空间异质性大,牧草中P和CP严重匮乏,营养成为限制家畜生产的关键因素.     

门源马骨营养状况的检测

对门源县 3 8匹马的骨营养状况指标进行了检测。结果发现 :门源马的血清钙浓度为 2 .68mmol L ,血清无机磷浓度为 1.3 6mmol L ,血清碱性磷酸酶活性为 66.0 4IU L ,血清羟脯氨酸含量为 15 .2 6μmol L ,均处于正常的范围。按性别组间比较 ,公马的血清钙浓度显著高于母马的 (P <0 .0 5 ) ,其他各项指标均无显著性差异 (P >0 .0 5 )。     

甘肃省各草原生态区盛草期可食牧草养分含量及营养承载力评价

为了解甘肃不同草原生态区盛草期可食牧草及养分含量变化,评价不同区域草地的营养承载力,分区域选择代表性样地进行地面调查并采样进行常规营养成分检测.结果表明,盛草期青藏高寒区和河西南部山区可食牧草平均CP含量分别为11.74％和11.18％,Ca含量分别为0.81％和0.78％,牧草营养价值相对较高.河西荒漠区CP和Ca含...     

水貂营养状况评价方法研究进展

营养状况直接影响水貂的生长发育和繁殖性能,准确评价水貂的营养状况是养殖生产中制定饲喂制度和管理措施的重要依据。介绍了目前水貂养殖生产和科研中常见的几种评价方法,旨在为我国水貂营养状况评价提供依据。     

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 依据2010年海南省畜禽养殖数据,采用排污系数法估算了畜禽粪尿排泄量,同时结合农地面积,分析评价了海南省农地畜禽粪便承载力现状,并计算了海南省畜禽养殖环境容量。结果表明,2010年海南省以猪粪当量计的农地土壤畜禽粪便负荷量平均值为10.33 t/hm²,农地畜禽粪便承载力的预警值平均值为0.20,级别为Ⅰ级,对环境无污染风险,但海口市和东方市预警值分别为0.51和0.45,对环境稍有污染;2010年海南省最大畜禽饲养容量为5237.35万头猪标准动物,剩余饲养容量为2643.17万头猪标准动物,但海口市和东方市已超出当地最大畜禽饲养容量,应适当控制畜禽饲养规模。     

放牧草地载畜量与放牧率研究方法分析

放牧草地载畜量与放牧率是草地生态系统的研究重点。近年来研究人员针对放牧草地载畜量与放牧率的研究方法进行了大量研究。文章分析了目前有关放牧草地载畜量和放牧率研究方法的研究现状及发展趋势。     

畜禽养殖环境承载力特征研究

畜禽养殖环境承载力研究有利于科学规划畜牧业发展、优化畜禽养殖污染防治,推动我国畜禽养殖业和区域生态社会的可持续发展。与一般区域环境承载力和行业环境承载力相比,畜禽养殖环境承载力是一个独特的行业环境承载力。除了具有环境承载力的一般特征之外,畜禽养殖环境承载力还具有承载对象和承载体的独特性、环境系统的多层次系统性、空间异质性与管制性以及动态性与产业可调控性等特征。     

Polymerase chain reaction techniques for differentiating cytotoxic and noncytotoxic Pasteurella trehalosi from Rocky Mountain bighorn sheep.

OBJECTIVE: To evaluate 2 polymerase chain reaction (PCR)-based methods for differentiating cytotoxic and noncytotoxic Pasteurella trehalosi from Rocky Mountain bighorn sheep (Ovis canadensis canadensis). SAMPLE POPULATION: 23 isolates of P. trehalosi from bighorn sheep in Colorado, including 18 from free-ranging herds and 5 from a captive herd. PROCEDURE: Using a sequence of the leukotoxin gene region of P. haemolytica serotype 1, 7 PCR primers were designed. A PCR amplification was performed on a sample of bacterial cell suspensions from pure cultures of P. trehalosi with known in vitro cytotoxic effects. The 2 most promising primer pairs were used in a study of 23 P. trehalosi isolates. Results were analyzed for association with cytotoxicity and 3 distinct ribotypes (Eco, Aco, and Bco). RESULTS: Significant associations were observed between in vitro cytotoxicity and PCR results for coding region, between ribotype Eco classification and PCR results for coding region, and between ribotype Eco classification and PCR results for promoter region. There was a negative association between ribotype Aco classification and PCR results for coding and promoter regions. CONCLUSIONS AND CLINICAL RELEVANCE: The PCR for the leukotoxin A coding region may be useful in differentiating cytotoxic from noncytotoxic P. trehalosi isolates recovered from bighorn sheep. It may be useful for studying epidemiologic features of pasteurellosis in bighorn sheep and for designing vaccines to protect wild sheep against pneumonia caused by P. trehalosi and P. haemolytica.     

旅游环境容量模型的改进及应用探讨

通过对旅游环境容量传统量测模型进行评价，认为传统模型未考虑旅游者在景区内时空分布不均衡的问题。传统模型量测所得结果可能导致容量指标的过高估值，容易引起景区超载问题，不利于资源合理利用。在前人研究基础上，根据旅游环境容量自身静态和动态结合的特点，充分考虑到旅游者在时间、空间分布的不平衡，提出了旅游环境容量的改进模型。模型既注重整个景区又不忽视局部景点，计算所得旅游环境容量不管是在宏观，还是微观方面都更趋于合理。模型的应用结合景区先进的经营管理模式，能有效保证热点景点在旅游高峰时刻不超载。从而使整个景区的经济效益和生态效益在一定阶段内达到最大化。最后，以浙江金华双龙景区为例，进行了实证研究。     

草原生态载畜量测算核定方法研究

合理确定草地载畜量对有效保护草地资源并高效利用有重要的指导意义,传统方法计算的载畜量只表明了核定时段内的平均载畜量,没有明确载畜量核定的具体时间,开展载畜量核定容易引起混淆和争执,核查工作量大,耗时长,实际操作难度大。为此,本文综合近年来草地载畜量的相关研究结果、结合草原生态气候变化和草牧业的发展趋势,提出了以秋末入冬为载畜量核定时间,以能繁母畜数量作为核定主要指标的新草地生态载畜量计算方法,并提出了加强畜牧业基础设施和人工草地建设,加大牲畜出栏,开展划区轮牧和春季草地禁牧试点示范,合理利用牲畜补偿代谢特点,利用牧草再生特点提高牧草产量和贮备等技术措施,以期为提高草地载畜能力,增加牧民经济收入,实现草原畜牧业的可持续发展提供参考。     

Implications of presumptive fatal Rocky Mountain spotted fever in two dogs and their owner

A dog was examined because of petechiation, an inability to stand, pale mucous membranes, a possible seizure, and thrombocytopenia. Tick-borne illness was suspected, but despite treatment, the dog died. Eight days later, a second dog owned by the same individual also died. The dog was not examined by a veterinarian, but Rocky Mountain spotted fever (RMSF) was suspected on the basis of clinical signs. Two weeks after the second dog died, the owner was examined because of severe headache, fever, nausea, vomiting, decreased appetite, lethargy, and a fine rash on the body, face, and trunk. Despite intensive treatment for possible RMSF, the owner died. Although results of an assay for antibodies to Rickettsia rickettsii were negative, results of polymerase chain reaction assays of liver, spleen, and kidney samples collected at autopsy were positive for spotted fever group Rickettsia spp. These cases illustrate how dogs may serve as sentinels for RMSF in humans and point out the need for better communication between physicians and veterinarians when cases of potentially zoonotic diseases are seen.     

Comparison of Nutrient Digestibility Between Adult and Aged Horses

There is little published work comparing digestibility in healthy adult versus healthy aged horses. Researchers hypothesized that there would be no differences in macronutrient digestibility between eight adult (5–12 years) and nine aged (19–28 years) horses fed three diets in a Latin square design. Seventeen stock-type mares were randomly assigned for a 5-week period to one of three diets: hay only (HAY), hay plus a starch- and sugar-rich concentrate (CHO), or hay plus a fat- (oil) and fiber-rich concentrate (FF). Each diet period comprised 3 weeks of outdoor group drylot feeding, 2 weeks of indoor stalled individual feeding, followed by a 72-hour digestibility trial including total urine and fecal collection. Feed, fecal, and/or urine samples were analyzed to determine dry matter, crude protein, fat, energy, calcium, and phosphorus apparent retention as well as apparent digestibility. Neutral detergent fiber digestibility was also determined. Mean body weight was lower in aged than in adult horses (455 ± 12 kg vs. 500 ± 13 kg; P = .02), but body condition score (BCS) did not differ between groups (aged horses, 4.8 ± 0.2 BCS and adult horses, 5.1 ± 0.2 BCS; P = .20). No age differences in digestibility, apparent digestibility, or apparent retention were seen for any of the variables measured. Based on the results of this study, total tract macronutrient digestibility appears to be similar between healthy adult and aged horses.     

Plant Age and Growing Season Nutritional Content Relationships of Three Artemisia tridentata Subspecies

The effect of plant age on growing season chemical compositions and rumen fermentation characteristics was determined for three subspecies of big sagebrush: basin (Artemisia tridentata [Nutt.] subsp. tridentata), mountain (A. tridentata subsp. vaseyana [Rybd.] Beetle), and Wyoming (A. tridentata subsp. wyomingensis [Beetle and Young]). In vitro dry matter (IVDMD) and organic matter (IVOMD) disappearance, ammonia nitrogen (NH₃N), and volatile fatty acid (VFA) content were determined at the end of two fermentation periods (24 h and 48 h) by combining rumen inocula with age-classified vegetative samples from each sagebrush subspecies. An additional one-way analysis of variance was performed to investigate potential differences among subspecies in IVDMD, IVOMD, total VFA, and NH₃N following a 48-h fermentation period. Crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) components were also compared among sagebrush subspecies. Age class responses were variable across the spectrum of sagebrush subspecies and response variables. Where plant age effects were indicated, the small numeric differences probably have little biological or ecological significance. Mountain sagebrush was lower in IVOMD and total VFA concentrations (P < 0.0001) than basin and Wyoming. NH₃N concentration and CP were higher (P < 0.0001) in basin sagebrush than the other two subspecies, while Wyoming sagebrush was higher in NDF, ADF, and ADL than basin and mountain subspecies (P < 0.0001). NH₃N concentration for all three subspecies was lower than the minimum level (20 mg · 100 mL^?1) required for uninhibited rumen activity. Overall, this research questions the contention that older sagebrush plants offer less nutritional value than younger ones, at least for growing season conditions. The results also provide information that can be utilized in designing supplementation strategies for domestic animals on diets with characteristically high utilization of big sagebrush.     

A Basis for Relative Growth Rate Differences Between Native and Invasive Forb Seedlings

The ability of invasive plants to achieve higher relative growth rates (RGR) than their native counterparts has been widely documented. However, the mechanisms allowing invasives to achieve higher RGR are poorly understood. The objective of this study was to determine the basis for RGR differences between native and invasive forbs that have widely invaded nutrient-poor soils of the Intermountain West. Six native and 6 invasive forbs were seeded in pots in a greenhouse, and 4 harvests were conducted over a 2-month period. These 4 harvests were used to calculate RGR and the components of RGR, net assimilation rate (rate of dry matter production per unit leaf area), leaf area ratio (LAR, leaf area per unit total plant mass), leaf mass ratio (the proportion of biomass allocated to leaves), and specific leaf area (SLA, leaf area per unit leaf biomass). Mean RGR of the 12 study species ranged between 0.04 and 0.15 g · g⁻¹ · d⁻¹ but was significantly higher for invasive forbs compared to native forbs (P = 0.036). The higher RGR achieved by invasive forbs was due mainly to a greater SLA and LAR. This indicates that invasive forbs achieved higher RGR than natives primarily by creating more leaf area per unit leaf mass, not by allocating more biomass to leaf tissue or by having a higher net rate of dry matter production. A high degree of variation in RGR, SLA, and LAR was observed in native forbs, suggesting that the ability to design weed-resistant plant communities may be improved by managing for specific functional traits as opposed to functional groups.