State-and-Transition Models for Heterogeneous Landscapes: A Strategy for Development and Application

Interpretation of assessment and monitoring data requires information about how reference conditions and ecological resilience vary in space and time. Reference conditions used as benchmarks are often specified via potential-based land classifications (e.g., ecological sites) that describe the plant communities potentially observed in an area based on soil and climate. State-and-transition models (STMs) coupled to ecological sites specify indicators of ecological resilience and thresholds. Although general concepts surrounding STMs and ecological sites have received increasing attention, strategies to apply and quantify these concepts have not. In this paper, we outline concepts and a practical approach to potential-based land classification and STM development. Quantification emphasizes inventory techniques readily available to natural resource professionals that reveal processes interacting across spatial scales. We recommend a sequence of eight steps for the co-development of ecological sites and STMs, including 1) creation of initial concepts based on literature and workshops; 2) extensive, low-intensity traverses to refine initial concepts and to plan inventory; 3) development of a spatial hierarchy for sampling based on climate, geomorphology, and soils; 4) stratified medium-intensity inventory of plant communities and soils across a broad extent and with large sample sizes; 5) storage of plant and soil data in a single database; 6) model-building and analysis of inventory data to test initial concepts; 7) support and/or refinement of concepts; and 8) high-intensity characterization and monitoring of states. We offer a simple example of how data assembled via our sequence are used to refine ecological site classes and STMs. The linkage of inventory to expert knowledge and site-based mechanistic experiments and monitoring provides a powerful means for specifying management hypotheses and, ultimately, promoting resilience in grassland, shrubland, savanna, and forest ecosystems.     

Recent progress in the study of behavior and management in grazing cattle

Recent progress in studies concerning behavior of, and management for, grazing cattle are reviewed. Since 1950, much study has been conducted on ‘How’, ‘When’, ‘Where’ and ‘How long’ regarding grazing. After the 1980s, grazing ecology introduced the concept of hierarchy at different spatial and temporal scales, and since then grazing behavior has been investigated on the foraging hierarchy of large grazing herbivores: bite, feeding station (FS), patch, feeding site, camp and home range. From the sequence of activities, FS is grouped within a feeding patch, and movement of grazing cattle has been studied between FSs, feeding patches, feeding sites and between camps. Grazing behavior and production relates closley with defoliation, and grazing management should control both grazing behavior and vegetation according to three rules: planning, operational and adaptation rules. Planning rules relate the stocking rate of cattle; operational rules relate to defoliation; and adaptation rules vary with regional situations. Recent studies on grazing have been carried out in the fields of animal diversity and welfare. Future studies in this field should be conducted on the ecology, neurophysiology and psychology of grazing. Nonlinear analysis will also be significant in this field. Grazing cattle production should also utilize supplementation by roughage and/or grains.     

祁连山东段不同放牧强度下高原鼢鼠栖息地选择分析

本研究以祁连山东段高寒草甸栖息的高原鼢鼠为研究对象,探讨不同放牧强度下高原鼢鼠栖息地特征及选择因素,为合理控制草原鼠害及保护草地生物多样性提供科学依据。本研究选择4个不同放牧强度小区,调查每个小区的高原鼢鼠相对种群密度、土壤紧实度和容重、植物学组成、植物物种丰富度、地上生物量、可食牧草产量及各植物功能群产量,并分析高原鼢鼠相对种群密度与这些要素之间的关系。结果表明,放牧强度与高原鼢鼠相对种群密度有正相关关系但不显著(P>0.05),重度放牧区下高原鼢鼠相对种群密度最高,禁牧区高原鼢鼠相对种群密度最低;高原鼢鼠相对种群密度与土壤紧实度呈显著负相关(P<0.05),与土壤容重和地上生物量呈负相关但不显著(P>0.05);高原鼢鼠相对种群密度与杂类草产量有正相关关系但不显著(P>0.05),与可食牧草产量、禾草产量和物种丰富度有负相关关系但不显著(P>0.05);多元线性回归方程表明影响高原鼢鼠栖息地选择的主要因素是土壤紧实度(Y=205.36-0.145X₁,X₁为土壤紧实度)。     

不同放牧制度对土壤种子库的影响——以青藏高原东缘高寒草甸为例

以青藏高原玛曲地区高寒草甸为研究对象,通过对暖季牧场与冷季牧场不同放牧强度的比较分析,探讨了可萌发土壤种子库的密度、垂直分布规律及其与地上植被的关系。结果表明,1)暖季牧场土壤种子库中,轻度放牧有12种,种子密度为2 307.66粒·m~(-2),重度放牧有6种,种子密度为1 065.08粒·m~(-2),禁牧有5种,种子密度为828.38粒·m~(-2),轻度放牧的物种丰富度及密度都显著大于重度放牧草地(P0.05);冷季牧场轻度放牧有12种,种子密度为3 786.88粒·m~(-2),重度有8种,种子密度为5 621.15粒·m~(-2),禁牧有5种,种子密度为532.53粒·m~(-2),轻度放牧种子密度小于重度放牧。2)无论是暖季牧场还是冷季牧场轻度放牧土壤种子库的多样性指数、均匀度指数、优势度指数和丰富度指数均大于重度放牧,土壤种子库与地上植被的相似性在不同的放牧强度下都小于0.3,其中不放牧时的相似性最小,轻度放牧时的相似性最高。而暖季牧场和冷季牧场的轻度放牧和重度放牧两种放牧强度之间的相似性系数都最大,分别为0.63和0.67。3)土壤种子库在不同处理间随着土层的加深数量都呈现迅速减少的趋势,大部分集中在0-5cm。     

Intake and Selection of Goats Grazing Heterogeneous Vegetation: Effect of Gastrointestinal Nematodes and Condensed Tannins

Feeding behavior is a multifactorial process with pivotal relevance for the maintenance and survival of ruminants. This study evaluated the effect of gastrointestinal nematodes (GIN), condensed tannin (CT) content of plants, and their possible interaction on the intake and selection of feed resources by Criollo goats in a heterogeneous vegetation. An 8-wk field experiment was conducted in the tropical deciduous forest (TDF) during the rainy season with adult Criollo goats (35.1 ± 6.7 kg body weight [BW]). Goats were assigned to four groups (n = 6): 1) MOX: suppressive treatment with moxidectin (Cydectin 0.4 mg/kg BW subcutaneous every 4 wk), 2) INF: with natural GIN infection, 3) MOX + PEG: treated with moxidectin and dosed with a CT-neutralizing agent (50 g of polyethylene glycol [PEG] diluted in 50 mL of water, per os), and 4) INF + PEG: with natural GIN infection and PEG dosage. Intake was measured using a direct observation method in a 2.2-ha TDF plot. Plant availability was obtained from 30 exclusion quadrants (2 × 2 m). Selection was estimated with the Cheeson index using the ratio of consumed plants and their availability by grouping plant species as shrubs and herbs (with high CT [> 10%], medium CT [> 3% to < 10%], or low CT [< 3%]), vines, and grasses. Neither GIN infection nor CT neutralization influenced intake or selection of feed resources. All groups showed high selection toward grass species (P < 0.001), which may represent a strategy to reduce intake of crude protein and CT from shrubs and herbs. In conclusion, GIN infection and CT neutralization do not influence intake or selection of goats with browsing experience in the TDF. Selection toward grass suggested a trade-off between nutrient harvest optimization and the health risk of GIN infective larvae consumption. Thus, it is necessary to revalorize the TDF as a sustainable feed resource for goats.     

Orthopaedic case management: A balancing act

Balancing the activities of a foal with an orthopaedic injury can be challenging. Physeal fractures also provide additional complexities to consider. This commentary examines both the juxtaposition of confinement and reduced activity, and the complex features of physeal injuries.     

A field study comparing a pregrazing treatment with the morantel sustained release bolus with a strategic deworming program in first year grazing cattle

A field trial was designed to compare the efficacy of a pregrazing treatment with a morantel sustained release bolus and two strategic treatments of levamisole in the prevention and control of gastrointestinal parasitism in first year grazing cattle. The infection of calves, pasture contamination and the subsequent effects on performance were recorded.     

Dormant Season Grazing: Effect of Supplementation Strategies on Heifer Resource Utilization and Vegetation Use

Grazing dormant forage under low-input heifer development strategies typically exposes cattle to low-quality forage. Protein supplementation while grazing dormant range can enhance heifer growth and reproductive performance. We examined resource utilization of heifers and the effects of dormant season grazing on residual vegetation characteristics under two supplementation management strategies. Approximately 100 weaned composite heifer calves were randomly selected and placed into one of two supplementation treatments in each of 2 yr, one receiving a free access 62% crude protein self-fed concentrate and the other receiving a daily hand-fed 20% crude protein cake. Grazing occurred from December (2015 and 2016) through March (2016 and 2017). Thirty transects were randomly located within each pasture for measuring vegetation quality and structure before and after grazing. Daily space use and behavior was evaluated for 21 individuals within each treatment using global positioning system (GPS) collars and resource utilization functions. Heifers supplemented with concentrated protein spent more time grazing per day than heifers supplemented with cake (6.92 ± 0.18, 6.24 ± 0.17 h). Relative use by heifers in the cake treatment was negatively related to horizontal distance from the supplement delivery site early to midwinter ($\stackrel{?}{\overline{\beta }}$ = ? 0.41 ± 0.16, ? 0.53 ± 0.17). Both treatments selected grazing locations relative to standing biomass of perennial grasses ($\stackrel{?}{\overline{\beta }}$ = 0.0005 ± 0.00004) and crude protein ($\stackrel{?}{\overline{\beta }}$ = 0.12 ± 0.007). However, resource selection was highly variable among individuals for both supplementation treatments. We found no treatment effects on pre-post grazing differences in residual cover of litter, grass, forbs and shrubs (P > 0.24). However, the time period when grazing occurred had an effect on residual vegetation conditions (P < 0.01). Our results indicate high levels of variability in grazing site selection by heifers, suggesting future research should incorporate individual animal measurements in an attempt to account for individual animal variability.     

甘南高寒草地放牧系统生态风险的AHP决策分析及管理对策

本研究从生态经济学角度,系统探讨了制约高寒草地畜牧业可持续发展的主要风险因素及其时空变化特征,剖析了生态风险分析内涵,应用多层次的AHP(analytichierarchyprocess)决策分析方法,对甘南玛曲高寒草地放牧系统的生态风险进行了综合评价分析。结果表明,在导致高寒草地植被退化、土地沙漠化的诸风险因素中,长期超载放牧是主要风险因素,其权重达0.4803;其次是全球气候变化造成的降水减少风险和鼠害、虫害风险,其权重分别为0.2902和0.1558;人类其他不当活动(挖药材、采矿等)的风险影响较小,其权重仅为0.0737。在研究区风险防范的诸管理措施中,围栏轮牧(降低放牧强度)措施和针对严重退化草地实施的补播、施肥、封育等综合措施的效果最佳,其相应组合权重分别为0.3060和0.2661;灭鼠和建植人工草地等措施均有一定的效果。基于上述风险评价分析,提出了高寒草地放牧系统生态风险防范的主要管理对策与措施,为草地资源保护与可持续利用提供定量依据。     

The grazing capacity of Sweetveld: 1 A technique to record grazing capacity

A technique is proposed for measuring the grazing capacity of sweet grassveld. The suggested procedure is to record the parameter on plots simulating individual camps in rotational grazing systems. This allows considerably smaller experimental areas to be used than in conventional stocking rate trials. Grazing capacity is assumed to be the number of grazing days per hectare that can be obtained on a sward, provided animals perform at their maximum capabilities for that sward. This is determined from the point where the rate of herbage disappearance deviates from linearity during periods of occupation. The technique was tested, and found to work well, under two simulated grazing management systems in the False Thornveld of the Eastern Cape.     

关于退牧还草的意义和技术标准问题探讨

退牧还草是一项长期而又复杂的系统工程,需要统筹考虑、科学规划、合理安排.但各地在实际操作中对究竟怎么退、如何退,缺乏规范和技术标准,这集中表现在没有明确什么样的草地需要禁牧、什么样的草地需要休牧、什么样的草地需要轮牧等问题上.禁牧、休牧和轮牧的工程标准和技术措施缺乏,给当前正在进行的退牧还草工作带来很多混乱和困难.因此,规范退牧还草的技术标准是当前退牧还草工作首先要解决的问题.     

基于遥感数据的呼伦贝尔草原放牧强度研究

呼伦贝尔草甸草原是我国主要的畜牧业基地,放牧强度直接影响着该草原生态系统的稳定和可持续发展。本文首先建立了研究区草地地上生物量的遥感估算经验模型,然后结合净初级生产力(NPP),研究了草地放牧强度估算方法;基于该方法,利用2014年6月到7月多期Landsat遥感数据计算谢尔塔拉牧场草地地上生物量变化和放牧强度。研究结果表明:所使用方法可较好用于放牧强度的估算,估算结果与实际情况基本吻合,决定系数R²达0.7996;谢尔塔拉牧场的公共放牧区放牧强度范围为1~2.5 Au/hm²,属于过度放牧状态,重度放牧区多位于小型湖泊周围和草地面积较少但牛相对较多的生产队,轻度放牧区多位于围封地;将尺度扩展到海拉尔区分析:所使用方法能够准确地将轻度、中度和重度放牧区分开,且海拉尔区东北方向的放牧强度明显高于西南地区。     

Equine conidiobolomycosis: A review and case study

Conidiobolus coronatus is one of the most commonly identified upper respiratory fungal pathogens in horses. This article includes a review of clinical signs, diagnostics, treatment and outcomes in previously reported cases of equine conidiobolomycosis, as well as six additional cases seen at our hospital. Each of the six horses presented with a complaint of serosanguinous or haemorrhagic nasal discharge and conidiobolomycosis was confirmed by histopathology and fungal culture. Five horses recovered after administration of antifungal drugs alone (n = 4) or in combination with extensive nasal septum resection (n = 1). Surgical treatment alone was ineffective. One horse was euthanised without treatment because of the extent of the disease.     

科尔沁草地家庭生态牧场模式探讨

针对目前科尔沁天然草地超载过牧、普遍退化的实际,论述了家庭生态牧场的概念和建设家庭生态牧场的重要意义,探讨了建设家庭生态牧场的可行性,提出了家庭生态牧场的总体规划模式,确定了每个家庭生态牧场家畜饲养规模控制在300个羊单位以内、出栏率达到100%;各类可食饲草料年生产能力208 065 kg;天然放牧场113.3 hm2,打草场20 hm2,多年生豆科人工草地6.7 hm2,青贮饲料地3.3 hm2的草畜平衡规划模式.