牦牛粪沉积下高寒草甸植物群落种间关联研究

植物群落构成和种间关联,反映物种在空间上的分布及相互依存和制约关系。为探究牦牛粪沉积和植被斑块互作下草地植物群落演变趋势及稳定性机制,以青藏高原东北缘高寒草甸禾草/杂类草斑块和嵩草/杂类草斑块为对象,分析牦牛粪沉积下两种斑块中主要植物种的重要值(IV)、Jaccard种间关联指数和Spearman秩相关系数的变化规律。结果表明,1)粪沉积使禾草/杂类草斑块的建群种扁穗冰草的IV增加和西北针茅的IV降低,嵩草/杂类草斑块的建群种线叶嵩草的IV降低;2)禾草/杂类草斑块中,粪沉积(DP)和对照(CK)的正负关联种对比为0.61和0.63,显著联结种对为6.6%和6.4%;嵩草/杂类草斑块中,DP和CK的正负关联种对比为0.90和0.72,显著联结种对为2.8%和14.5%;且二者显著联结的种对多存在于优势种或亚优势种与伴生种之间;3)两种斑块中多数种对间联结性弱,群落处于不稳定阶段;粪沉积使嵩草/杂类草斑块的稳定性增强,利于禾草/杂类草斑块的演变;4)依据优势种对环境的适应方式和主导生态因子,将两种斑块的群落植物种划分为喜阳耐旱植物、喜阴喜湿植物和喜阳喜湿植物三大生态种组。     

Functional Resource Heterogeneity Increases Livestock and Rangeland Productivity

Most of the world's rangelands are subject to large spatial and temporal variation in forage quantity and quality, which can have severe consequences for the stability and profitability of livestock production. Adaptive foraging movements between functional seasonal resources can help to ameliorate the destabilizing effects on herbivore body stores of spatial and temporal variability of forage quantity and quality. Functional dry-season habitats (key resources) provide sufficient nutrients and energy to minimize reliance on body stores and are critical for maintaining population stability by buffering the effects of drought. Functional wet-season habitats dominated by short, nutritious grasses facilitate optimal intake of nutrients and energy for lactating females, for optimal calf growth rates and for building body stores. Adaptive foraging responses to high-quality focal patches induced by rainfall and disturbance further facilitate intake of nutrients and energy. In addition, focused grazing impact in high-quality patches helps to prevent grassland maturing and losing quality. In this regard, the design of many rotational grazing systems is conceptually flawed because of their inflexible movement of livestock that does not allow adaptation to spatial and temporal variability in forage quantity and quality or sufficient duration of stay in paddocks for livestock to benefit from self facilitation of grazing. Similarly the fixed intraseasonal resting periods of most rotational grazing systems might not coincide with the key pulses of nitrogen mineralization and rainfall in the growing season, which can reduce their efficiency in providing a functional recovery period for grazed grasses. This might explain why complex rotational grazing systems on average have not out-performed continuous grazing systems. It follows, therefore, that ranchers need to adopt flexible grazing management practices that allow adaptation to spatial and temporal variability in forage quantity and quality, allow facilitation of grazing (season-long grazing), and allow more effective recovery periods (season-long resting).     

Understanding Landscape Use Patterns of Livestock as a Consequence of Foraging Behavior

Many grazing-management challenges stem from poor livestock distribution resulting in overuse of some areas and low utilization of others. Managing livestock-distribution patterns requires knowledge of pasture characteristics and animal behavior patterns. Behavioral patterns result from recognizable processes that include inherited attributes, individual and social learning systems, cue-consequence specificity, predispositions toward novel stimuli, and spatial memory. Through these behavioral mechanisms, animals form and revise preferences and aversions for specific locations in their foraging landscape. To accomplish habitat selection, domestic herbivores use sight and sound cues to seek and return to high-quality foraging locations. Nested within habitat selection are learned diet preferences and aversions by which ungulate herbivores associate taste with positive or negative postingestive feedback. The deliberate and careful modification of animal attributes and habitat characteristics could yield options for adaptive rangeland management. In this article, we describe the basic principles that underlie how animals make decisions about where to forage and how long to stay in a particular habitat. We also suggest management practices designed to modify animal behavior and alter habitat-use patterns.     

Foraging Behavior Development of Foals in Natural Grassland

Early relationships between young mammalian herbivores and social models (e.g., mothers or peers) have been proposed as playing a major role in the process of diet learning. Diet selection is an important factor influencing animal development and ecology, especially in natural and seminatural grasslands, with a large diversity of plant species. To explore the learning process of foraging behavior and diet selection choices by foals, six free-ranging Criollo foals and their respective mares were monitored through continuous bite monitoring from birth to 130 d old, in the Pampas Grasslands of southern Brazil. Cumulative suckling time decreased exponentially from birth to 130 d old, while dry matter intake, foraging time, and bite mass of foals increased continuously. It was possible to identify three marked periods in the foal’s foraging behavior development: 1) an exploratory phase (from 0 to 40 d old) marked by limited forage intake from a large diversity of plants; 2) a specialization phase (from 40 to 110 d old) with a marked increase in forage intake and a specialization around the same plants as the ones selected by the mares; and 3) a stabilization phase (after 110 d old) in which forage intake still increases but diet composition of foals stabilized similarly to the one of the respective mares. The higher diversity at young ages could be explained by exploratory hypothesis, where foals test different forages to discover their environment, given that their nutritional needs are fulfilled by milk consumption, not by forage intake. As requirements shift toward solid items, bite mass and foraging time increase and diet choices become similar to that of the mares. Our results detail how young foals develop their foraging behavior and suggest, without testing it and under the circumstances of this study, that they learn their diet through social transmission from their mothers.     

黄河首曲沙化草地恢复重建模式研究

通过对青草沙障、草方格 山生柳Salix oritrepha密植扦插 种草、羊粪生物结皮 种草、卵石方格 种草、遮荫网 种草、山生柳密植扦插6种草地恢复重建模式研究,结果表明:效果由大到小依次为草方格 山生柳密植扦插 种草模式、羊粪生物结皮 种草促进恢复重建模式、卵石方格 种草模式、遮荫网 种草模式、青草沙障、山生柳密植扦插模式。草方格 山生柳密植扦插 种草模式,山生柳插穗成活率为92.3%,保存率为83.1%,平均生长量为12.4 cm,平均草高12 cm,覆盖度为78%,此模式值得推广。羊粪生物结皮 种草模式,各种草平均生长量为5.3 cm,覆盖度为43%~48%,是玛曲沙化草地最有前途的恢复重建模式之一,山生柳密植扦插效果最差,此模式难以推广。     

Positive effect of spring advance on the diet quality of an alpine herbivore

Changes in vegetation phenology related to global warming are having alarming effects on the life history traits of many herbivore species. Such changes are particularly critical in alpine ecosystems, where strong climate limitations on plant growth make seasonal synchronization imperative for the growth, reproduction and survival of herbivores. However, despite the pivotal role of resource-use strategies on the performances of such species, few studies have explicitly assessed the mechanistic impact of climate change on their diets. We aimed to fill this gap by studying the effect of spring onset on the dietary composition and quality of a medium-size alpine herbivore while considering density-dependent processes and age- and sex-specific differences in foraging behavior. Using an exceptional, long-term (24 years) direct individual-based dietary monitoring of a Pyrenean chamois population (Rupicapra pyrenaica pyrenaica), we showed that ongoing earlier onsets of spring are leading to an earlier access to high-quality forage and therefore a higher diet quality at a fixed date, without apparent changes in diet composition. We also showed that at high densities, intraspecific competition reduced diet quality by driving animals to feed more on woody plants and less on nutritious forbs and graminoids. By assessing the mechanistic effects of global warming on the dietary patterns of species at the center of trophic networks, this study is an essential step for predictive models aiming at understanding the ongoing ecosystem consequences of the global climatic crisis.     

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.     

添加物料和菌剂对日喀则地区马铃薯茎叶青贮品质的影响

以日喀则地区马铃薯(Solanum tuberosum)茎叶为原料制作青贮饲料,分别与玉米(Zea mays)面、小麦(Triticum aestivum)麸、聚合草(Symphytum officinale)、紫花苜蓿(Medicago sativa)、青饲玉米、燕麦草(Arrhenatherum elatius)、干青稞(Hordeum vulgare)秸秆、干油菜(Brassica napus)壳等材料混贮,以甲酸、尿素、食盐和6种生物菌剂(A,活性乳酸菌冻干粉;B,益加益秸秆发酵剂;C,千牧EM菌原种;D,百益宝EM菌种;E,微特美益生菌种;F,粗饲料降解剂)为添加剂,聚乙烯袋真空包装分别于发酵30、60、90d后进行感官评定及生化分析,采用隶属函数法综合评价青贮品质。结果表明,日喀则地区马铃薯茎叶青贮饲料在制作后30d已经基本完成发酵进入青贮稳定阶段,能长期有效保持饲料的水分及营养物质。单独的马铃薯茎叶青贮效果差,添加生物菌剂、甲酸、麦麸、玉米面、青饲玉米秸秆、燕麦草可以改善青贮品质,其中添加麦麸的效果优于玉米面,添加青饲玉米优于添加燕麦草。聚合草含水量高、紫花苜蓿营养丰富,但是与马铃薯茎叶混贮发酵效果差。干油菜壳不适于与马铃薯茎叶混贮。菌剂A、B的青贮效果要优于E、F。研究得出,马铃薯茎叶+30%麦麸,马铃薯茎叶+0.3%尿素+0.4%食盐+30%麦麸+D,茎叶+30%麦麸+B这3个青贮处理效果较好。     

Short-term effects on productivity and egg quality in nutrient-restricted versus non-restricted organic layers with access to different forage crops

Abstract

Two experiments were conducted to study the effects of different forage crops on productivity and some egg quality parameters of small flocks of organic laying hens fed whole wheat or concentrates. Each experiment was carried out in a split plot design with two different forage crops and two types of supplementary feed (typical concentrate for organic layers versus whole wheat) with three replications. In the first experiment the tested forage crops were of a well-established grass/clover and a mixture of forbs (Fagopyrum esculentum, Phacelia tanacetifolia and Linum usitatissimum). In the second experiment the tested forage crops were a well-established grass/clover and chicory (Cichorium intybus cv. Grassland Puna). The results on productivity and egg quality suggest that laying hens consume large amounts of foraging material when accessible. In nutrient restricted hens (wheat-fed) the forage may yield a substantial contribution to the requirements of amino acids and metabolizable energy although productivity parameters and measurements on dry matter in albumen showed that wheat-fed hens, on a short-term basis, were not able to fully compensate for the lack of protein and amino acids by increased foraging. Of the forage crops investigated especially chicory seems to contribute to the nutrition of the hens. Measurements on eggshell parameters showed that oyster shells together with foraging material were sufficient to meet the hens’ calcium requirements. Yolk colour clearly revealed that laying hens consume large quantities of green fodder irrespective of the type of supplementary feed. Yolk colour from hens with access to chicory tended to be darker, of a redder and less yellow hue compared with grass/clover fed hens, which is considered a positive quality.     

Predatory Plants and Patchy Cows: Modeling Cattle Interactions with Toxic Larkspur Amid Variable Heterogeneity

The most common explanations for the evolution and persistence of herd behavior in large herbivores relate to decreased risk of predation. However, poisonous plants such as larkspur (Delphinium spp.) can present a threat comparable to predation. In the western United States, larkspur diminishes the economic and ecological sustainability of cattle production by killing valuable animals and restricting management options. Recommendations for mitigating losses have long focused on seasonal avoidance of pastures with larkspur, despite little evidence that this is practical or effective. Our ongoing research points to the cattle herd itself as the potential solution to this seemingly intractable challenge and suggests that larkspur and forage patchiness may drive deaths. In this paper, we present an agent-based model that incorporates neutral landscape models to assess the interaction between plant patchiness and herd behavior within the context of poisonous plants as predator and cattle as prey. The simulation results indicate that larkspur patchiness is a potential driver of toxicosis and that highly cohesive herds may greatly reduce the risk of death in even the most dangerous circumstances. By placing the results in context with existing theories about the utility of herds, we demonstrate that grouping in large herbivores can be an adaptive response to patchily distributed poisonous plants. Lastly, our results hold significant management-relevant insight, both for cattle producers managing grazing in larkspur habitat and in general as a call to reconsider the manifold benefits of herd behavior among domestic herbivores.     

牛鞭草种质资源在中国的分布及其人工草地建植技术

牛鞭草为一种高大型C4禾草,其分布较广,主要分布在热带、亚热带和北半球的温带湿润地区。牛鞭草在我国已知的有4种,各种的分布有所不同。牛鞭草由于适应性广、耐刈割、产量高、品质好,被广泛种植,但由于长期单一种植造成草地严重退化,从而影响了该草的产量和品质,因此本文还从牛鞭草的建植和管理技术方面作了一定的论述。     

Burning and Climate Interactions Determine Impacts of Grazing on Tallgrass Prairie Systems

Tallgrass prairie may respond differently to prescribed burning and subsequent preferential grazing, termed pyric herbivory, under variable climate conditions. This 6-yr study (2011−2016) compared tallgrass prairie pastures that were subjected to burned and unburned conditions while exposed to grazing under differing climate conditions in the Southern Great Plains of the United States. The study area consisted of six pastures, three burned and three unburned. Each burned pasture was further divided into three patches and subjected to a 3-yr rotational burning cycle. The Enhanced Vegetation Index (EVI) derived from Landsat 7/8 (EVI_LS) and Moderate Resolution Imaging Spectroradiometer (MODIS, EVI_MOD) was used to indicate vegetation production depending on size of pastures. On the basis of EVI_LS, most burned patches (11 of 18) had lesser production (overall difference of 3%) than unburned patches within the same pasture. The differences were larger (13%) in a drought yr (2011) compared with normal (3% in 2013) and wet (<1% in 2015) yrs. The distribution of precipitation controlled EVI_LS for periods during and after grazing. The burned patches tended to have lower EVI_LS during grazing periods than the unburned patches within the same pasture, probably because of selective grazing of newly grown grass in recently burned patches. In contrast, the differences in EVI_LS between during and after grazing periods were mostly (78%) smaller in burned than unburned patches. However, more variations in EVI_LS existed among pasture comparisons due to landscape heterogeneity. Similar results were observed with EVI_MOD. Overall, results demonstrated that pyric herbivory management and climate determine the impacts of grazing on tallgrass prairie systems. The contrasting seasonal forage availabilities in burned and unburned patches, indicated by different seasonality of EVI, also suggests that patch burning might better balance the quantity and quality of the grass available for cattle grazing.     

Polyethylene glycol influences selection of foraging location by sheep consuming quebracho tannin

Tannins are a heterogeneous group of phenolic polymers that can induce detrimental effects when consumed by herbivores. Polyethylene glycol (PEG) binds to tannins and thus attenuates their negative effects. Our objective was to determine whether sheep actively seek PEG when fed tannins and thus modify their foraging location as a function of the spatial distribution of PEG. Lambs were first trained to recognize the beneficial effects of PEG by offering a meal high in quebracho tannin (QT), which presumably caused malaise, and then PEG (MW, 3,350), which presumably led to recovery from malaise. Animals were then tested in an experimental area where they could forage at two different locations that contained in Trial 1 1) PEG and QT in adjacent food boxes (PEG+QT) or 2) QT and in Trial 2 1) PEG or 2) QT. Preference for foraging locations was tested under three conditions: 1) no preload meal, 2) a meal high in quebracho tannin 1 h before testing, and 3) a basal diet high in quebracho tannin. Lambs spent more time (P = 0.012) and ate more tannin-containing food (P = 0.022) at locations where PEG was present (PEG+QT) than where it was absent (QT; Trial 1). Lambs responded to increased tannins in their bodies (Conditions 2 and 3) by reducing intake (P = 0.0001; Trial 2) at sites containing only QT and by increasing intake (P = 0.0001, Trial 1; P = 0.001, Trial 2) and foraging time (P = 0.072, Trial 1; P = 0.0001, Trial 2) at locations where PEG was available. Thus, PEG influenced foraging location by sheep consuming quebracho tannin. Accordingly, it may be possible to formulate range blocks that enable herbivores to ingest PEG in tannin-rich habitats. Strategic distribution of PEG in those habitats may attract animals to underutilized feeding sites.     

青干草调制技术

青干草调制是把天然饲草或人工种植的饲草进行适时收割,干燥和贮藏、切短的过程。青干草由于养分保存好,适口性好,消化率高,使用方便被大多数养殖户接受,调制的青干草,能较完善地保持青绿饲料的营养成分。据有关资料报道,人工干燥法制成的优质青干草,可保存90%～93%的养分,还可调节青饲草供应的季节性,是牛羊等草食动物优质的饲料之一。贮藏的青干草要求含水量14%～17%,超过17%容易发霉变质。     

Is Hand Plucking an Accurate Method of Estimating Bite Mass and Instantaneous Intake of Grazing Herbivores?

Instantaneous intake is central to the understanding of large herbivore foraging strategies and rangeland ecology. Unfortunately, its measurement under field conditions remains challenging because of the difficulty of estimating bite mass. The hand plucking method provides a simple, noninvasive method of estimating bite masses and thus instantaneous intake of grazing herbivores. However, many authors questioned its accuracy and interobserver repeatability. In this study, we tested the accuracy and the repeatability of the hand plucking method using four observers and two herbivore species (i.e., cattle and goats). We compared hand plucked bite mass estimates to actual bite mass of bites taken by the herbivores on natural patches of grass. Training of the observers was fundamental to obtaining accurate bite mass measurements. The mean daily accuracy of the observers’ bite mass estimates increased from 60–80% to 80–94% within 5 d. After training, the relationship between bite mass estimates and actual bite mass was linear and not significantly different from a Y = X relationship. This means that individual bite mass estimates were centered on the real values and thus positive and negative errors canceled each other when combined. As a result, estimates of cumulative intake over about 10 feeding stations had accuracies of over 95%. Furthermore, neither the observer identity nor the herbivore species affected the accuracy of the measurements. The categorization of bites into different size categories proved to be essential in achieving accurate measurements. When observers are trained, hand plucking is a reliable and accurate method of estimating bites mass and instantaneous intake of grazing herbivores. This has important implications for rangeland research and management, as hand plucking is often the only practicable method available for estimating instantaneous intake of free-ranging herbivores.     

划区轮牧与草地可持续性利用的研究进展

划区轮牧是一种充分利用饲草生长旺季而进行的集约、区块式放牧管理系统。本文总结了近年来国内外轮牧制度的发展现状,概括了划区轮牧的优势包括:提高草地生态系统的功能性、草地生产力;降低草食动物肠胃线虫感染率;分析了其与传统连续放牧相比所具有的局限性。进一步从放牧类型的延展、放牧策略的改进、人为因素的投入、生态模型研究等多角度综合考究,提出综合协调生物因素与环境、平衡生态与经济以及优化牧企合作现状的轮牧策略,以期为轮牧对于生态恢复和草地可持续性利用的生产实践应用提供科学依据和优化管理的决策参考。     

若尔盖高原典型草地灌丛化对植被特征和土壤养分的影响

本文以若尔盖高原高山绣线菊(Spiraea alpina)、管花忍冬(Lonicera tubuliflora)、高山柳(Salix cupularis)三类典型灌丛为研究对象,分析其林下灌丛斑块与邻近草地斑块植被特征和土壤养分差异。结果显示：相较于各自草地斑块,高山柳灌丛斑块内植被总盖度、生物量、丰富度指数、多样性指数、优势度指数均显著下降(P<0.05),土壤全量养分与速效养分含量上升;高山绣线菊灌丛斑块除丰富度指数外各项指数均上升,其中总盖度显著上升(P<0.05),土壤全量养分与速效钾含量均上升,而有效磷含量显著下降(P<0.05);管花忍冬灌丛斑块除丰富度指数外,其余植被特征指标均上升,且土壤全钾、全磷、碱解氮、有效磷、有机质含量同样上升,而土壤全氮与速效钾含量下降。本研究可为不同优势灌木的高寒草地灌丛化控制与利用提供参考。     

The influence of urine and dung deposition on patch grazing patterns of cattle and sheep in the Southern Tall Grassveld

Abstract

The effect of urine and dung deposition on the patch grazing patterns of cattle and sheep in the Southern Tall Grassveld was investigated using an experiment with four treatments, viz. artificial urine, fresh cattle dung, fresh sheep dung, and a control. Cattle and sheep preferentially grazed the sward surrounding and within urine deposits for six months after deposition. Cattle rejected herbage from both cattle and sheep dung patches for six months after deposition. Sheep initially rejected the herbage from cattle dung patches, but their grazing patterns were no longer affected at six months after deposition. Sheep grazing tended not to be influenced by sheep dung. Urine deposition may consequently be an important factor in patch initiation and patch development.     

低温和干旱胁迫下牧草的抗逆性机制

低温和干旱是限制牧草生长发育和产量的两个非生物胁迫因子。掌握牧草抗逆性机制,选育具有强抗寒性和抗旱性的牧草是寒旱地区草牧业高质量发展和退化草地生态系统恢复的重要基础。在形态学层面,低温和干旱胁迫条件下牧草会形成多种抗逆性形态结构,这些结构的变化能很好地反映牧草对逆境的响应和适应能力。在生理生化层面,牧草通过调节超氧化物歧化酶、过氧化物酶、过氧化氢酶、游离脯氨酸、可溶性糖、可溶性蛋白质、脱落酸、乙烯、赤霉素和细胞分裂素等的响应,以适应低温和干旱胁迫。在分子水平层面,牧草通过信号转导、应答和抵御基因的表达等综合作用,以适应寒旱胁迫。总之,本研究从牧草形态学、生理生化和分子水平三个层面综述了牧草对低温和干旱胁迫的响应和适应机制,以期为全面认识牧草抗逆机制提供重要参考。     

草地施肥对草食家畜生产能力的影响

草地施肥直接改变牧草的营养元素(氮、磷、钾、钙、镁等)含量水平,从而间接影响草食家畜的生长能 力,需根据牧草生长情况合理施肥。在本试验中需增施钙、镁和锌肥,才能满足草食家畜的正常生长。