Ecosystem Services of Grazed Grasslands in the Flooding Pampa

The Flooding Pampa grasslands are the last remnant of the Rio de la Plata grasslands in Argentina.Anthropo-genic interventions have led to severe degradation and,as a result,the ecosystem services provided by the grass-lands are declining,in terms of provisioning,regulating,and supporting services.We synthesized the existing literature on the ecosystem goods and services provided by these grasslands under grazing in different conditions and conservation status.We found that plant and animal diversity and primary production are the most studied ecosystem services,while climate regulation,water supply,nutrient cycling,meat production and erosion control,in that order,are less studied.Cultural services are under-researched.Continuous grazing and glyphosate spraying are the main drivers of grassland degradation.Controlled grazing and conservative stocking rates have been shown to reverse degradation and demonstrate that livestock production is compatible with ecosystem conserva-tion by maintaining regulating and provisioning services.As these management strategies are poorly integrated,improving their implementation will require important changes in farmers’decisions and the development of policies that create the economic conditions for this to happen.Research is needed to understand the conditions that prevent the knowledge generated from being transferred to producers and translated into practices that would improve the provision of ecosystem services.

Improving remote sensing-based net primary production estimation in the grazed land with defoliation formulation model

Remote sensing(RS) technologies provide robust techniques for quantifying net primary productivity(NPP) which is a key component of ecosystem production management. Applying RS, the confounding effects of carbon consumed by livestock grazing were neglected by previous studies, which created uncertainties and underestimation of NPP for the grazed lands. The grasslands in Xinjiang were selected as a case study to improve the RS based NPP estimation. A defoliation formulation model(DFM) based on RS is developed to evaluate the extent of underestimated NPP between 1982 and 2011. The estimates were then used to examine the spatiotemporal patterns of the calculated NPP. Results show that average annual underestimated NPP was 55.74 gC·m^(-2)yr^(-1) over the time period understudied, accounting for 29.06% of the total NPP for the Xinjiang grasslands. The spatial distribution of underestimated NPP is related to both grazing intensity and time. Data for the Xinjiang grasslands show that the average annual NPP was 179.41 gC·m^(-2)yr^(-1), the annual NPP with an increasing trend was observed at a rate of 1.04 gC·m^(-2)yr^(-1) between 1982 and 2011. The spatial distribution of NPP reveals distinct variations from high to low encompassing the geolocations of the Tianshan Mountains, northern and southern Xinjiang Province and corresponding with mid-mountain meadow, typical grassland, desert grassland, alpine meadow, and saline meadow grassland types. This study contributes to improving RS-based NPP estimations for grazed land and provides a more accurate data to support the scientific management of fragile grassland ecosystems in Xinjiang.

Effects of Non-protein Nitrogen Supplement on Growth Performance of Graze Cattle

[Objective] The experiment was conducted to investigate the growth performance of graze cattle fed on non-protein nitrogen （NPN） supplement. [ Method] The experiment was conducted in late spring and early summer before grazing. Thirty Chinese SimmentaI-Taihang taxa bulls at the age of 9-10 months weighing 150-170 kg were divided into the control group, experimental group 1 and experimental group 2, 10 in each group, Each cattle in the experimental group 1 fed on the basal diet supplemented 1.0 kg cornmeal every day. Each cattle in the experimental group 2 fed on the basal diet supplemented 1.0 kg cornmeal and 0.25 kg NPN supplement every day. Those in the control group were fed on the basal di- et. The experiment was performed for 100 d. [Result] The average daily gain of the experimental group I was 217 g larger than that of the control group, while the average daily gain of the experimental group 2 was 429 g larger than that of the control group. The differences in the average daily gain were significant between the three groups. [ Conclusion ] The growth performance of cattle grazed in northern slopes was obviously improved by supplementing a small amount of concentrate in feed. The improvement was more remarkable if a small amount of NPN supplement was also added in feed.

Effects of Feces on Spatial Distribution Patterns of Grazed Grassland Communities

Animals excrete feces during grazing. The uneven distribution of feces causes a spatial heterogeneity in grassland communities. In this study, we attempted to clarify the effects of feces on spatial distribution patterns of plant species. A field study was conducted on four grasslands each grazed by a single cow. These four grasslands were defined as Poa pratensis （Kentucky bluegrass） dominated grassland without feces （PoF-）, Poa pratensis dominated grassland with feces （PoF＋）, Zoysia japonica Steud. （Japanese lawngrass） dominated grassland without feces （ZyF-）, and Zoysia japonica Steud. dominated grassland with feces （ZyF＋）. A 50 m line that transects 100 equally spaced quadrats （L-quadrats） was drawn on each of the four grasslands. Each quadrat was 0.50 m × 0.50 m in size and consisted of four equal-area cells of 0.25 m ×0.25 m （S-quadrats）. The occurrences of all plant species were recorded in each S-quadrat. The binomial distribution （BD） and beta-binomial distribution （BBD） were used to represent the variation in spatial patterns. The BBD provided a significant description of the frequency distribution of plants per quadrat. A power law was used to calculate the spatial heterogeneity of each species together with the community heterogeneity. The results revealed that the plants on each of the four grasslands were aggregatively distributed. The ZyF＋ exhibited greater spatial heterogeneity than the ZyF-due to the uneven deposition of feces by cows grazing on the grasslands. Additionally we also found that the feces had effect on the heterogeneity inZyF＋ and did not have effect in PoF＋.

Analysis of Characteristics of Grazed Artificial Pastures in the South of Guizhou

＂Ryegrass, orchard grass, Festuca arundinacea and Trifolium repens＂ were researched in Dushan County, Guizhou Province, in order explore grass characteristics by different grazing methods in seasons. The results show that grass community height in different groups was of little differences（P0.05）; the group of moderate grazing in spring, summer and autumn dominated in grass cover; grass density showed insignificant variations among different treatment groups（P0.05） and in the groups of heavy grazing in spring and autumn and moderate grazing in summer and of moderate grazing in spring, summer and autumn, grass community density was higher compared with the other groups（P0.05）; as for above-ground biomass, the group of moderate grazing in spring and autumn and heavy grazing in summer and of moderate grazing in spring, summer and autumn dominated.

Grasshopper Species-Area Relationship on Ungrazed and Overgrazed Grasslands

The species richness and abundance of rangeland grasshoppers were investigated at 6 sites of ungrazed and overgrazed pastures in Inner Mongolia during the autumn of 1994.The ungrazed sites supported higher richness and density of grasshoppers than the overgrazed sites.The effects of overgrazing and ungrazing on the species-area relationships of grasshoppers were directty measured.The grasshopper assemblages from the 6 sites differed significantly in the intercept or in the slopes of their species-area regressions.The greater intercept and slope values of their species-area regression were found in grasshopper assemblages on ungrazed sites.In contrast to species-area relationship regression,the species increase rate with individual number was more rapid at overgrazed sites.Implications for conservation are discussed.

Response of understory vegetation over 10 years after thinning in an old-growth cedar and cypress plantation overgrazed by sika deer in eastern Japan

Background： Forest management strategies such as thinning have long been used to enhance ecosystem functions, especially in plantations.Thinning in plantations with high deer density, however, may not yield a desired increase in understory vegetation because deer graze on germinating plants after thinning.Here, we examine the changes in understory vegetation after thinning in plantations that have been overgrazed by sika deer to provide insight into the effects of thinning on ecosystem functions such as soil conservation and biological diversity.Methods： We conducted our survey in the Tanzawa Mountains of eastern Japan.We surveyed the change in understory vegetation within and outside of three deer exclosures on a single slope with three levels of understory vegetation cover： sparse（1%, exclosure ＂US＂）, moderate（30%, exclosure ＂MM＂）, and dense（80%, exclosure ＂LD＂） over10 years after a 30% thinning of an old-growth cedar and cypress plantation which was overgrazed by sika deer.Results： Understory vegetation cover, biomass and species richness increased within and outside the ＂US＂ and＂MM＂ exclosures after thinning, and biomass was greater within than outside the exclosures at 10 years after thinning.Unpalatable species dominated both ＂US＂ and ＂MM＂ exclosures before thinning, and trees and shrubs dominated within the exclosures over time after thinning.In contrast, unpalatable, grazing-tolerant, perennial,and annual species increased outside the ＂US＂ and ＂MM＂ exclosures.No noticeable changes were observed within and outside the ＂LD＂ exclosure when compared with the ＂US＂ and ＂MM＂ exclosures.Conclusions： Our results suggest that thinning a stand by 30% based on volume resulted in an increase in understory vegetation cover mainly composed of both unpalatable and grazing-tolerant species in a plantation forest where understory vegetation is sparse or moderate and sika deer density is high.We emphasize that establishing deer exclosures or controlling deer is essential to maintaining similar understory vegetation both within and outside exclosures.

Seed rain and soil seed bank compensatory roles on Nassella tenuis(Phil.)Barkworth seedling recruitment in ungrazed and grazed sites

In semi-arid lands,vegetation is distributed in shrub patches immersed in a less vegetated interpatch matrix.Grazing affects perennial grass seed bank through a decrease in seed rain and an increase in seed predation and soil compaction.Nevertheless,some species with anchorage mechanisms in their seeds might overcome this,such as Nassella tenuis(Phil.)Barkworth.This is an important species in grazing paddocks because it has an intermediate palatability and its relatively tolerant to grazing.These characteristics allow N.tenuis to increase its abundance in grazed sites.Our objective was to assess how grazing affects the key palatable species from seeds to seedlings:i.e.,seed rain,soil seed bank,and seedling recruitment in different microsites along a windward-leeward transect across shrub canopy.We hypothesized that:(1)the negative effects of grazing on N.tenuis fructification are reflected in its seed rain,soil seed bank,and seedling recruitment,especially in interpatches;(2)Nassella tenuis seed rain reduction,soil compaction by cattle in grazed sites,and removal of seeds by wind decrease its soil seed bank,especially in microsites exposed to the predominant wind;and(3)the decrease in N.tenuis soil seed bank and cover increase in annual species in grazed sites have negative effects on its seedling recruitment,especially in microsites exposed to predominant wind.We placed seed traps,collected soil samples,and monitored seedling recruitment in different locations around shrub canopy to address our hypotheses.Also,we established a manipulative experiment in which we sow N.tenuis seeds and followed its recruitment in different microsites.We compared the seed rain,soil seed bank,natural seedling recruitment,and sown seeds recruitment of N.tenuis between grazed and ungrazed sites.We analyzed differences between microsites along a windward-leeward transect across shrubs patches.Seed rain and soil seed bank had the same density in patches and interpatches both in ungrazed and grazed sites.But seed rain was higher,and soil seed bank was lower in ungrazed sites than in grazed sites.Almost all under-canopy microsites showed greater soil seed bank abundance and natural seedling recruitment in ungrazed sites.Sown seeds recruitment was the same between grazed and ungrazed sites,but it showed protective effects of shrubs in leeward microsites under grazed sites.As a conclusion,seed rain and soil seed bank are complementary under grazed sites.

Virally-Mediated Versus Grazer-Induced Mortality Rates in a Warm-Temperate Inverse Estuary (Spencer Gulf, South Australia)

We investigated the seasonal dynamics of flow cytometrically-defined populations of viruses, heterotrophic bacteria, and the picoeukaryotic and prokaryotic phytoplankton at three sites in the temperate oligotrophic inverse estuary of Spencer Gulf (South Australia). We consistently identified two sub-populations of viruses, three sub-populations of heterotrophic bacteria, one population of picoeukaryotic phytoplankton and two populations of prokaryotic phytoplankton (cyanobacteria Prochlorococcus and Synechococcus). Both the cytometric community composition and the abundance of viruses, heterotrophic bacteria and both prokaryotic (Synechococcus and Prochlorococcus) and eukaryotic picophytoplankton were consistent with previous observations conducted in South Australian continental shelf waters. Noticeably LDNA bacteria (i.e. inactive or dormant cells) were consistently significantly the most abundant group of heterotrophic bacteria (totaling from 29% to 68% of total bacterial abundance) and were up to 10-fold more abundant than that previously reported in South Australian continental shelf waters, including the nearby Saint Vincent Gulf. These results suggest an overall low activity of the microbial community, and are consistent with previous evidence that LDNA cells may play a greater role in heterotrophic processes than HDNA cells in oligotrophic waters. In an attempt to further assess the qualitative and quantitative nature of the mortality of these organisms, we used a specific dilution assay to assess the relative contribution of viruses and microzooplankton grazers to the mortality rates of heterotrophic bacteria, and picoeukaryotic and prokaryotic phytoplankton. We consistently reported site-specific, population specific and sea-son-specific viral lysis and grazing rates of heterotrophic bacteria and the picoeukaryotic and prokaryotic (cyanobacteria Prochlorococcus and Synechococcus) phytoplankton across sites and seasons. Specifically, both viral lysis and micro-zooplankton grazing rates of heterotrophic bacteria were consistently relatively low across sites and seasons, even though their seasonality suggested an overall dominance of grazing over viral lysis in both summer and winter. In contrast, no seasonality is found in either lysis or grazing rates of prokaryotic and eukaryotic picophytoplankton, which are comparable to previous observations conducted in oligotrophic waters, suggesting the mortality dynamics of these populations is similar to those encountered in other oligotrophic waters. The observed patterns of mortality rates of heterotrophic bacteria and both prokaryotic and eukaryotic picophytoplankton are consistent with the low chlorophyll concentration and production previously observed in the waters of the Spencer Gulf.

春季不同放牧强度对高寒草甸土壤氮利用的影响

为探究春季(3—6月)不同放牧强度对高寒草甸土壤氮转化速率和氮利用的影响,以祁连山区高寒草甸为研究对象,通过牦牛和藏系羊交替放牧方法,调查分析了禁牧(CK),轻度放牧(LG),中度放牧(MG),重度放牧(HG),极重度放牧(SG)5个放牧强度下高寒草甸植被特征,土壤理化性质及土壤氮含量变化特征。结果表明:随着放牧强度增加植被盖度、高度、地上生物量和土壤含水量均呈降低趋势,地下生物量、土壤容重、紧实度和土壤温度增加;土壤全氮和铵态氮含量均在LG处理下最高,硝态氮整体呈下降趋势;不同放牧强度土壤净氮矿化速率、氨化速率和硝化速率均在LG处理下最高;土壤氮利用与植被特征和土壤性状冗余分析结果显示:土壤因子是氮利用的主要驱动因子。熵权-TOPSIS排序结果:土壤氮利用从高到低依次是LG>MG>HG>CK>SG。综上所述,在高寒草甸春季草场轻度放牧处理下土壤氮利用最高。

荒漠草原春季休牧后优势种群重要值与物种多样性的关联性分析

本试验在内蒙古锡林郭勒盟短花针茅荒漠草原进行,旨在探究春季休牧后放牧利用方式对荒漠草原植物群落优势种群重要值和物种多样性的影响,研究结果发现:按照CK(全年不放牧)、SA1(春季休牧+夏季重牧+秋季适牧)和SA2(春季休牧+夏季适牧+秋季重牧)的顺序,植物群落物种多样性指数降低。放牧会增强不同优势物种重要值与植物群落物种多样性的关联度。由优势种群重要值与物种多样性的整体关联性看出,虽然SA1和SA2的放牧利用方式存在相似的影响过程,但优势种群和物种多样性对植物群落的作用整体表现为SA1>SA2。因此,春季休牧+夏季重牧+秋季适牧的放牧处理方式能够使得优势种群重要值和物种多样性通过相互之间较强的关联关系维持草地植物群落结构和功能。

中国季风边缘区表土孢粉分布特征及其影响因素

研究中国季风边缘区表层土壤孢粉分布特征及其影响因素,有助于提高化石孢粉重建区域植被和古季风演变的可靠性。通过对中国季风边缘区的38个样点(年降水量区间30~650 mm)的表土样品进行孢粉分析,研究了表土孢粉组合特征与气候、人类活动之间的关系。结果表明:(1)在低海拔、温带草原地区,气候相对温暖干燥,孢粉组合以苋科和蒿属为主,且蒿藜比(A/C比值)与年均降水量变化趋势基本一致。(2)中国季风边缘区的高海拔、高寒草原草甸地区,气候相对寒冷湿润,孢粉组合以莎草科、菊科和禾本科为主导,蒿属和苋科花粉的百分比之和平均为25.8%,并且该区域A/C比值与年均降水量未呈现明显相关性。(3)乔灌木孢粉总百分比与年均气温/最热月气温之间的相关性要强于与年均降水量之间的相关性。(4)这些孢粉组合特征反映了中国季风边缘区植被和水热条件在海拔上的分布特征,孢粉数据冗余分析(RDA)结果也清晰揭示了孢粉组合及主要花粉类型在最热月气温和海拔梯度上的分布。此外,真菌孢子在研究区高寒地区土壤表层中大量出现,反映了该区域放牧强度大、伴随土壤侵蚀速率高的环境特征。

黄河源区4种不同禁牧条件对草地根-土复合体力学特征的影响

[目的]探讨黄河源区高寒环境禁牧条件对原生草地和退化草地根-土复合体力学强度影响,阐明禁牧对植被恢复的作用,为黄河源区草地恢复以及地质灾害防治提供理论参考。[方法]选取黄河源河南县地区未禁牧、禁牧期1 a、禁牧期4 a、禁牧期10 a这4种工况下的草地作为研究对象,通过直剪试验得到复合体黏聚力和内摩擦角,环刀称重法得到密度,烘干法得到含水率,采用SPSS软件分析了不同禁牧期草地植物根径、土体密度、土体含水率、含根量与根-土复合体黏聚力之间的相关关系。[结果](1)根-土复合体黏聚力与含水率之间呈显著负相关关系(p<0.05),未禁牧草地植物根径与根-土复合体黏聚力之间呈现极显著正相关关系(R=0.68,p<0.01),根数与根-土复合体黏聚力之间呈极显著正相关关系(R=0.85,p<0.01);1 a禁牧期土体密度与根-土复合体黏聚力c值之间呈显著正相关关系(R=0.56,p<0.05)。(2)随着禁牧年限增加,原生与退化草地土体平均黏聚力c值呈增大的变化趋势,其中10 a禁牧期原生草地黏聚力c值较未禁牧原生草地平均黏聚力增加幅度为6.39%;10 a禁牧期退化草地黏聚力c值较未禁牧平均黏聚力增加幅度为8.16%。[结论]实施禁牧提高黄河源区草地根-土复合体黏聚力,有利于防治黄河源区草地退化及水土流失。

牦牛和藏羊暖季放牧对青藏高原高寒草地不同组分碳、氮的影响

土壤碳、氮是植物生长主要的养分来源,对于维持土壤肥力,提高土壤微生物活性以及对缓解全球气候变化具有重要意义。本研究依托青海省高寒草地-家畜系统适应性管理技术平台(https://ghcd.agiot.cn)研究不同放牧方式对不同组分碳、氮的影响。结果表明:牦牛、藏羊单独放牧显著增加了微生物生物量碳,混合放牧显著降低了微生物生物量碳;对微生物生物量氮而言,单独放牧和混合放牧均显著降低了微生物生物量氮含量,放牧对土壤总碳和土壤总氮无显著影响。放牧对微生物生物量碳、微生物生物量氮、可溶性有机碳和可溶性有机氮的影响大于对土壤总碳和土壤总氮的影响。从微生物生物量的角度分析,高寒草地以混合放牧为优,单独放牧会加剧高寒草地土壤微生物碳限制。本试验确定了不同放牧方式下高寒草地土壤不同组分碳、氮含量,可以为该区域草地的可持续管理提供科学依据。

放牧牲畜行为对草地土壤氮转化的影响研究进展

氮是草地植物生长必需的营养元素,其在草地土壤的含量动态和迁移转化易受到放牧牲畜行为的直接或间接影响,探明不同牲畜行为与草地土壤氮转化的关系对于系统揭示放牧干扰下草地氮素迁移转化的响应特性至关重要。现有研究多侧重于分析放牧活动的综合作用对草地土壤氮含量及动态的影响,导致关于不同牲畜行为对土壤氮转化作用机制和差异性的认识较为不足。因此,本文通过分析3种主要牲畜行为(采食、践踏、排泄)与草地土壤、植物和微生物的关系,探究不同牲畜行为下草地土壤氮素的迁移转化特性及影响因素,指出牲畜采食行为增强植物-土壤间的碳周转,有助于促进土壤氮转化;践踏行为通过改变土壤氧化还原条件间接调控氮转化过程中的硝化与反硝化作用,但对不同质地土壤的影响差异较大;排泄行为通过粪尿氮素输入为氮转化过程提供较多的底物和有效碳源,使其对草地土壤氮转化的影响更为直接和复杂。气候变化和人类活动干扰加剧背景下,利用15N同位素示踪和分子生物学技术等从多角度定量解析放牧牲畜行为对不同类型天然草地土壤-植物系统氮素迁移转化的影响效应、作用机制和关键因素势在必行。研究结论为优化牧区放牧牲畜管理模式和促进草地生态系统高质量与可持续发展提供参考。

放牧干扰下两河源牧区草地群落多样性与生物量的关系及变化

放牧会影响植物群落特征及地上生物量与多样性之间的关系,是近年来草地生态系统研究的热点问题。本研究以两河源牧区草地为例,基于60个采样点,采用样方法对该牧区的草地植被进行调查,使用α-多样性指数测度分析了放牧对植物群落结构特征的影响,探讨植物群落物种多样性与地上生物量之间的关系及变化。结果表明:1)在自然放牧条件下,两河源牧区植物科属种数量降低,植物群落高度和盖度呈下降趋势(P<0.01),密度呈上升趋势(P<0.01)。2)放牧显著降低了植物群落地上生物量(P<0.01)。其中,禾草类植物群落地上生物量降低,杂草类植物群落地上生物量提高,豆科类植物群落地上生物量的变化不大。3)放牧对两河源牧区植物群落产生了显著的影响,导致植物群落物种丰富度、优势度和多样性降低,但群落物种数量的分布更加均匀。4)植物群落地上生物量与Margalef丰富度指数、Shannon-Wiener多样性指数和Alatalo均匀度指数呈极显著正相关关系(P<0.01),与Simpson优势度指数呈极显著负相关关系(P<0.01)。放牧干扰下,植物群落地上生物量与物种多样性之间的关系依然显著。因此,在草地的管理和维护中,应考虑放牧对植物群落结构特征的影响,根据当地实际情况做出合理的应对政策。研究结果为两河源牧区草地维护、管理及生态系统的可持续发展提供理论依据。

放牧对荒漠草原区植被、土壤及根系的影响研究综述

荒漠草原区是我国北方防沙带的重要组成部分,因气候变化和人类活动等因素的综合影响,导致该区域出现生产力下降、草场沙化、风蚀沙害等突出问题。国内专家学者围绕草地生产力、放牧梯度实验、草场沙化恢复等方面开展了大量研究,但仍存在部分科学技术难题尚未解决,如放牧对土壤及根系的潜在影响、放牧-土壤-风蚀-水蚀间的联动机制等问题。文章通过梳理国内外相关文献,明确已有研究基础,挖掘研究薄弱点,提出未来荒漠草原区关于放牧与植被-根系间的关键科学问题,为制定合理的草地资源利用政策提供理论依据。

代谢正常型肥胖症患者放牧饮食行为的影响因素分析:一项质性研究

背景在肥胖率日益增长的现况下,代谢正常型肥胖通过早期干预可以获得良好结局,此类人群出现放牧饮食行为是体质量管理的一个明确障碍因素。了解出现放牧饮食行为的影响因素,有助于提升肥胖症的饮食依从性,但目前缺少相关的质性研究。目的探索代谢正常型肥胖者放牧饮食行为发生的影响因素。方法基于能力、机会、动机-行为模型(COM-B)和理论域框架(TDF)制订访谈提纲,2023年6—9月采用目的抽样法选取江苏省苏北人民医院内分泌科就诊的17例代谢正常型肥胖者进行半结构式访谈,访谈资料以COM-B和TDF为编码框架,采用归纳主题法和演绎框架法分析。结果分析归纳出包括缺乏饮食管理知识、认知资源不足、感知和实践影响、不良应对方式、缺乏反思/自发动机、环境与社会影响6个核心主题。结论代谢正常型肥胖者由于自身、医护、社会环境等诸多因素影响导致出现放牧饮食行为,应根据患者多维度需求采取相应干预措施,以帮助患者建立健康饮食行为习惯。

荒漠草原混牧牛羊的放牧行为特征

荒漠草原混合放牧家畜的行为特征对草地资源的可持续利用具有重要意义。本研究在内蒙古自治区锡林郭勒盟镶黄旗的荒漠草原牛羊混合放牧牧场开展。试验选取了畜群中的4头牛与8只羊,通过分别佩戴载有三轴加速度传感器的GPS定位项圈,分析了混牧牛羊放牧时间(GTIME)与放牧活动水平(GODBA)的时间动态,并探讨了牛羊放牧行为特征对草地资源月份变化的响应模式。结果表明,荒漠草原混牧牛羊的GTIME与GODBA呈显著正相关关系(R2>0.60),且牛羊的GODBA对草地资源的响应模式存在差异。其中,牛受到地上生物量的正向调控(P<0.05),受到Shannon指数的负向调控(P<0.01)。而羊则受到地上生物量与毒杂草重要值的负向调控(P<0.001),以及Shannon指数与牧草粗蛋白含量的正向调控(P<0.001)。并且,混牧牛羊24 h的行为模式均表现出“多峰”特征,且随月份变化有收缩的趋势。同时,牛羊不同行为之间的活动水平存在显著差异,且羊的活动水平整体高于牛(P<0.05)。

Preventive treatments for the invasion of Leucanthemum vulgare Lam.:exploring effects in rangeland ecosystems of Iran

Invasive species are increasingly spreading,particularly in rangeland ecosystems.It is essential to evaluate the effectiveness of different methods for controlling invasive plants in these ecosystems.This study aimed to investigate the effects of three strategies-21-year grazing exclusion(21-YES),mowing-grazing in rotation in alternate years(MGRS),and moderate grazing(MGS)-on the change in cover,density,and biomass of Leucanthemum vulgare Lam.(Ox-eye Daisy=OED)and the plant community.To accomplish this,three sites selected for each treatment.In 2021,270 vegetation plots were sampled using a random systematic method.Subsequently,we recorded the density and canopy cover of all growth forms(forbs,grasses,and ferns),the OED biomass,and the ground cover.The results indicated that MGS reduced OED density,OED canopy,and OED biomass.Furthermore,this strategy demonstrated the highest density and canopy cover of the plant community(including total,forbs,grasses,and ferns).Additionally,the strongest correlation was observed between the total canopy and the OED density(R2=-0.91,-0.95,-0.94 in 21-YES,MGRS,and MGS,respectively),as well as between the total canopy and the OED canopy(R2=-0.51,-0.98,-0.97 in 21-YES,MGRS,and MGS,respectively).The MGS led to an increase in diversity indices.In general,the grazing strategy has proven to be effective in controlling the spread of invasive OED and has also resulted in an increase in canopy cover,density,and diversity indices of the plant community.The study highlights the importance of ongoing management efforts to control invasive species,with moderate grazing potentially serving as a more practical,culturally accepted,and costeffective short-term control strategy for widespread rangeland weed infestations.