Soil Erosion and Vegetation Succession in Alpine Kobresia Steppe Meadow Caused by Plateau Pika——A Case Study of Nagqu County, Tibet

This paper evaluated the impacts of mounds created by the plateau pika （Ochotona curzoniae） on the vegetation composition, structure, and species diversity of an alpine Kobresia steppe meadow in Nagqu County, Tibet Autonomous Region, China. Based on mound height or the depth of erosion pit, we defined five stages of erosion and compared the floristic features of communities at these stages with those in undisturbed sites. In the study area, the mounds and pits covered up to 7% of the total area. Lancea tibetica, Lamiophlomis rotata, and Potentilla biflarca were the dominant species in erosion pits, and Kobresia pygmaea, the dominant species in undisturbed sites, became a companion species in eroded areas. In the process of erosion, the original vegetation was covered by soil ejected by the pika, then the mounds were gradually eroded by wind and rain, and finally erosion pits formed. The vegetation coverage increased with increasing erosion stages but remained significantly lower than that in undisturbed sites. Improved coverage eventually reduced soil erosion, and pit depth eventually stabilized at around 20cm. Aboveground biomass increased with increasing erosion stage, but the proportion of low-quality forage reached more than 94%. The richness index and Shannon-Wiener index increased significantly with increasing erosion stage, but the richness index in mound and pit areas was significantly lower than that in undisturbed sites.

The Influence of Fence on Body Mass and Population Dynamics of Plateau Pika

To determine the influence of the fence on plateau pika (Ochotona curzoniae), we measured the body mass, breeding status, population densities, using live-trapping and line-transect sampling in April and September 2006. In April, body mass of both male and female plateau pika inside of fence were significant higher than that outside of fence (♀: F = 6.583, df = 1.20, p = 0.019;♂: F = 6.49, df = 1.17, p = 0.021). The ratio of spermary drop of an adult male was also higher (92.31% vs 57.14%). In September, body mass of adult male in both study sites showed no significant difference (F = 0.001, df = 1.23, p = 0.975), but were all significant higher than that of April (F = 121.713, df = 1.22, p < 0.001;F = 105.819, df = 1.20, p < 0.001). In April, the population densities of both study sites showed on significant difference (F = 2.388, df = 1.38, p = 0.131), but the population density inside of fence was much higher than that outside of fence (F = 7.534, df = 1.38, p = 0.009) in September. Our results show that the changes of quality and quantity of food that available to plateau pika in winter, can depress the range of reducing body mass of plateau pika, make breeding season ahead, and then promote the increase of population.

Plateau pikas near roads are bold and silent when facing a potential predator

Human disturbance,particularly road traffic,is one of the greatest threats to wildlife.Considering the association between alerting behavior and the survival of animals,it is important to study the effects of road traffic on alerting behavior of wildlife.Previous studies assessing the shortterm impact of road traffic on alerting behavior of wildlife have focused on vigilance distances.However,studies on the use of alarm calls are scarce,and it is unclear whether such behavioral responses change after repeated exposure to road traffic.We assessed the alerting behavior of plateau pikas(Ochotona curzoniae)who were near or far from roads when facing a potential predator.We found that pikas near roads exhibited shorter vigilance and tolerance distances,and produced fewer alarm calls than those relatively far away from roads.Furthermore,both vigilance and tolerance distances of plateau pikas were significantly positively correlated with the distance from the burrow to the road.Road traffic reduced antipredator responses and shaped alerting behavior;that is,pikas near roads were bolder and more silent compared to those far away from roads.Our findings suggest that increasing urbanization will have corresponding effects on animal behavior,which may have significant fitness effects in the future.

Altitude-dependent metabolite biomarkers reveal the mechanism of plateau pika adaptation to high altitudes

The harsh environment in the Tibetan plateau,the highest place in the world,poses thermoregulatory challenges and hypoxic stress to animals.The impacts of plateau environment on animal physiology and reproduction include external factors such as strong ultraviolet radiation and low temperature,and internal factors such as animal metabolites and gut microbiota.However,it remains unclear how plateau pika adapt to high altitudes through the combination of serum metabolites and gut microbiota.To this end,we captured 24 wild plateau pikas at the altitudes of 3400,3600,or 3800 m a.s.l.in a Tibetan alpine grassland.Using the machine learning algorithms(random forest),we identified five biomarkers of serum metabolites indicative of the altitudes,that is,dihydrotestosterone,homo-l-arginine,alpha-ketoglutaric-acid,serotonin,and threonine,which were related to body weight,reproduction,and energy metabolism of pika.Those metabolic biomarkers were positively correlated with Lachnospiraceae_Agathobacter,Ruminococcaceae,or Prevotellaceae_Prevotella,suggesting the close relationship between metabolites and gut microbiota.By identifying the metabolic biomarkers and gut microbiota analysis,we reveal the mechanisms of adaptation to high altitudes in plateau pika.

Seasonal variations in the composition and functional profiles of gut microbiota reflect dietary changes in plateau pikas

Seasonal variations in gut microbiota of small mammals and how they are influenced by environmental variables are relatively poorly understood.We sampled 162 wild plateau pikas(Ochotona curzoniae)in 4 seasons over 2 and a half years and recorded the air temperature,precipitation,and nutrient content in edible vegetation at the sampling site.After conducting 16S rRNA and shotgun metagenomic sequencing,we found that the highest alpha diversity,the relative abundance of Firmicutes,and the simplest co-occurrence network occurred in winter,whereas the highest relative abundance of Proteobacteria and the most complex network structure were observed in spring.The highest relative abundance of Verrucomicrobiota and Spirochaetota was seen in summer and autumn,respectively.Air temperature,precipitation,and the contents of crude protein,crude fiber,and polysaccharide in vegetation had significant effects on the seasonal changes in gut microbiota.Diet contributed more to microbial variation than climatic factors.Metagenomic analysis revealed that the amino acid metabolism pathway and axillary activity enzymes were most abundant in summer,while abundance of carbohydrate-binding modules and carbohydrate esterases was highest in spring.These microbial variations were related to the changes in dietary nutrition,indicating that gut microbiota of plateau pika contribute to the efficient use of food resources.This study provides new evidence of how external environmental factors affect the intestinal environment of small mammals.

The plateau pika has multiple benefits for alpine grassland ecosystem in Qinghai–Tibet Plateau

The plateau pika(Ochotona curzoniae)has been engaged in pest control for many years based on the logic that the plateau pika is responsible for alpine grassland degradation and competes with livestock for forage resources.However,the plateau pika is an important species which has multiple benefits in Qinghai-Tibetan Plateau,as it(i)makes burrows that are the primary homes for lizards and a variety of small birds;(ii)creates microhabitat disturbance that promotes the increase of plant species richness;(iii)serves as the principal prey for almost all of the plateau predator species;and(iv)contributes positively to the dynamic equilibriumof alpine ecosystems.

不同干扰强度高原鼠兔对高寒草甸土壤温室气体通量变化的影响

高原鼠兔通过取食植物、排泄粪尿及掘土等行为对土壤理化性质及土壤微生物产生广泛干扰,进而可能会影响高寒草甸土壤温室气体排放。本研究选择高密度组(H)、低密度组(L)、对照组(CK)3种鼠兔干扰强度的高寒草甸为研究对象,揭示温室气体排放速率对不同高原鼠兔干扰强度的响应规律及主要调控因素。结果表明,H组高寒草甸土壤CO_(2)排放速率为596.66 mg·(m^(2)·h)^(-1),显著低于CK组的695.45 mg·(m^(2)·h)^(-1)(P<0.05)。高原鼠兔干扰强度、地上生物量、土壤pH和土壤含水量是影响CO_(2)排放速率的主要调控因素。H组高寒草甸CH_(4)吸收速率为-43.46mg·(m^(2)·h)^(-1),显著低于L组的4.92mg·(m^(2)·h)^(-1)(P<0.05),H和L组高寒草甸N_(2)O排放速率分别为8.03、-2.39μg·(m^(2)·h)^(-1),均显著高于CK组的-16.69μg·(m^(2)·h)^(-1)(P<0.05)。土壤硝态氮和铵态氮含量、pH和含水量是影响CH_(4)吸收和N_(2)O排放的重要因素。因此,高原鼠兔干扰强度是影响温室气体排放速率的因素之一,进一步研究高原鼠兔对高寒草甸土壤温室气体排放速率的影响具有重要意义。

青海省东部高原鼠兔不同年限裸斑处土壤碳氮磷储量的变化

土壤碳氮磷储量是评价草地稳定和健康的有效指标,但目前关于生物干扰对草地土壤碳氮磷储量的研究尚不清楚,特别是在不同时间范围内土壤碳氮磷储量的变化过程以及局部对整体的影响研究相对较少。本研究于高原鼠兔(Ochotona curzoniae)干扰区内通过针对性取样和随机取样分别确定不同年限高原鼠兔裸斑处和高原鼠兔干扰区内土壤碳氮磷储量,分析高原鼠兔干扰区内植被覆盖区、高原鼠兔新裸斑、旧裸斑和废弃裸斑处土壤碳氮磷储量的差异,以及不同年限高原鼠兔裸斑对高原鼠兔干扰区内土壤碳氮磷储量的影响。结果表明:土壤全碳和全磷含量在高原鼠兔新裸斑处显著低于植被覆盖区域(P<0.05),土壤全碳和全氮储量在植被覆盖区域显著高于高原鼠兔新裸斑、旧裸斑和废弃裸斑处(P<0.05),但土壤容重、全氮和全磷储量在高原鼠兔不同年限的裸斑处没有差异。高原鼠兔新裸斑处土壤全碳、全氮含量以及全碳和全氮储量分别对高原鼠兔干扰区内土壤全碳和全氮含量以及全碳和全氮储量均有极显著影响(P<0.01),植被覆盖区的土壤容重对高原鼠兔干扰区内土壤容重有极显著影响(P<0.01)。而土壤含水量和有机碳含量对植被覆盖区域的土壤碳氮磷储量、高原鼠兔新裸斑处氨态氮含量对土壤碳氮磷储量以及高原鼠兔旧裸斑处全钾含量对土壤碳氮磷储量均有显著影响(P<0.05)。综上,本研究证实了高原鼠兔新裸斑对高寒草甸土壤碳氮磷储量变化的影响最大,因此在治理高原鼠兔造成的裸斑性高寒草甸时,应对高原鼠兔新裸斑重点修复。

青海省果洛州高原鼠兔宜生区分布及其对气候变化的响应

研究高原鼠兔的地理分布及其对气候变化的响应,对进一步了解高原鼠兔在生态系统中作用意义重大。本研究利用青海省果洛州高原鼠兔存在点和环境因子数据,采用物种分布模型预测在3种排放背景下,当前与未来高原鼠兔宜生分布区。结果表明:极度梯度提升树(eXtreme Gradient Boosting, XGBoost)的ROC和TSS值最高,模型表现最佳;最湿季降水量对高原鼠兔分布的影响最大,其次为气温年较差和最湿月降水量,且高原鼠兔当前生境适宜度随海拔和降水量的增加而降低,而随气温的增加呈先增加后降低的趋势;当前气候条件下高原鼠兔主要分布在果洛州西北部,未来气候影响下高原鼠兔适宜生境面积逐渐减少,且适宜生境集中在玛多县西北部;在3种排放情景下,高原鼠兔适宜度随海拔和降雨量的增加而降低,而随着气温的升高,低排放背景下高原鼠兔适宜度增加,高排放背景下其适宜度降低。

食物中蛋氨酸含量对高原鼠兔肠道微生物群落的影响

过度放牧引起的退化草地为高原鼠兔(Ochotona curzoniae)提供了丰富的蛋白质食物资源,而食物中必需氨基酸(尤其是蛋氨酸)含量的变化会影响宿主体内肠道微生物群落。本研究依据不同退化草地高原鼠兔胃内容物中的蛋氨酸含量,使用0.26%和0.45%蛋氨酸含量的兔颗粒饲料分组饲喂高原鼠兔,50 d后收集粪便,利用宏基因组学以及非靶向代谢组学分析,评估高蛋氨酸处理对高原鼠兔肠道微生物群落及其代谢产物的影响。结果表明,与低蛋氨酸组相比,高蛋氨酸组高原鼠兔肠道微生物群落的α、β多样性均无显著差异,但Candida⁃tus_Saccharibacteria、软壁菌门(Tenericutes)等菌群的丰度显著增加,丁酸代谢、牛磺酸和次牛磺酸代谢等菌群功能显著表达,其上调的代谢产物主要在初级胆汁酸合成、抗坏血酸和醛酸代谢、Th17细胞分化、牛磺酸和次牛磺酸代谢、B细胞受体信号通路、T细胞受体信号通路、NF⁃κB途径等通路富集;而低蛋氨酸组高原鼠兔菌群的糖类代谢功能显著表达,其上调的代谢产物主要在氨基酸代谢相关通路富集。上述结果表明,高蛋氨酸食物可改变高原鼠兔肠道微生物及其代谢产物,进而可能增强宿主的免疫和繁殖性能,对提高高原鼠兔个体适合度及其种群数量有重要的作用。

高原鼠兔筑巢行为形成的裸露斑块对土壤动物多样性的影响

为探究高原鼠兔筑巢行为对土壤动物多样性的影响,于2022年7月,在念青唐古拉山利用土钻法和干漏斗法进行土壤动物采集和分离,开展高原鼠兔筑巢行为形成的裸露斑块对土壤动物多样性影响的研究。此次调查共采集土壤动物311头,隶属3门,6纲,13目,32科,优势类群为隐颚螨科占所采样本20.26%。与原生草地相比,高原鼠兔筑巢行为形成的裸露斑块中土壤动物类群数、个体数、密度、多样性、丰富度、均匀度均减少,优势类群个体数和优势度则无显著差异。Pearson相关性分析得出土壤动物多样性与植被地上地下生物量、盖度、丰富度、多样性指数、土壤紧实度、土壤湿度呈正相关。结构方程模型进一步表明植被地上地下生物量减少对土壤动物多样性影响最为显著(P<0.01)。因此,高原鼠兔筑巢行为形成的裸露斑块内植被退化和土壤理化性质改变会导致裸露斑块中土壤动物多样性降低。

高原鼠兔洞穴对土壤入渗的影响及机制

[目的]探究高原鼠兔洞穴对高寒草甸土壤入渗性能及其相关因素的影响,以揭示其对高寒草甸生态系统水分循环和土壤水文功能的潜在作用。[方法]以高寒草甸高原鼠兔洞穴不同部位作为研究对象,包括洞口(PE)与洞道(PB),对照为无高原鼠兔洞穴分布的未扰动高寒草甸(AM),用单环法对土壤入渗速率进行测定。[结果](1)高原鼠兔洞穴促进高寒草甸土壤入渗速率,相比于未扰动高寒草甸,洞口和洞道初始入渗速率分别升高377.63%和189.47%,稳定入渗速率分别升高314.29%和220.00%(p<0.05);(2)高原鼠兔洞穴破坏高寒草甸土壤结构,相比于原生高寒草甸,洞口表层土壤总孔隙度和毛管孔隙度分别显著降低4.69%和16.27%,但非毛管孔隙度显著升高22.47%,洞口和洞道团聚体平均重量直径分别显著降低20.09%和9.45%,土壤有机质含量显著降低,各部位大小依次为未扰动高寒草甸>洞道>洞口(p<0.05);(3)高原鼠兔洞穴主要通过影响高寒草甸草毡层根系促进土壤入渗,根系生物量是影响初始入渗速率和稳定入渗速率的主导因子,标准化总效应分别为-0.717和-0.539。[结论]鼠兔洞穴一定程度上有利于高寒草甸生态系统的水分循环,但同时也破坏了高寒草甸原本的土壤结构,加剧高寒草甸退化风险。

高原鼠兔发情周期性激素与性器官变化特征

为研究雌性高原鼠兔(Ochotona curzoniae)的发情表征变化及其与性激素含量、生殖器官发育之间的关系,选取繁殖期与非繁殖期雌性高原鼠兔,通过外阴形态观察与阴道细胞涂片检测阴道的周期性变化,确定繁殖期鼠兔的发情周期在7~11 d,发情期持续3~4 d,而非繁殖期鼠兔的阴道维持在接近发情前期的状态。采集发情期、发情间期与非繁殖期雌性高原鼠兔的血清与尿液样本,使用酶联免疫吸附法检测雌二醇和孕酮含量。结果显示,发情期高原鼠兔血清雌二醇含量显著高于发情间期与非繁殖期(P=0.0338),而非繁殖期血清孕酮含量显著高于发情期与发情间期(P=0.0195)。尿液检测的灵敏度整体弱于血清,仅在发情期与非繁殖期间存在尿液雌二醇含量的显著差异(P=0.0009)。发情期卵巢重量极显著高于发情间期与非繁殖期(P<0.0001),且发情间期卵巢重量也显著高于非繁殖期(P=0.0072)。苏木精-伊红染色显示,高原鼠兔卵巢在发情期以有腔卵泡为主,在发情间期则同时分布次级卵泡、有腔卵泡与黄体,而在非繁殖期卵巢皮质区分布有大量的原始与初级卵泡。高原鼠兔子宫内膜、肌层与外膜三层结构区分明显,发情期子宫内膜较厚,固有层分布大量腺体,外膜区域血管丰富;发情间期子宫腺体与血管数量均大幅减少;非繁殖期子宫明显退化,内膜上皮变薄,腺体与血管基本消失。本研究确定了阴道细胞涂片法在高原鼠兔发情阶段判定中的有效性,描述了不同发情阶段高原鼠兔性激素与性器官变化特征,为雌性高原鼠兔季节性繁殖调控机制研究提供了重要基础数据。

基于文献计量的高原鼠兔研究现状与热点分析

高原鼠兔爆发式增长严重威胁着草地生态系统,也造成了不可估量的经济损失。通过文献计量方法,统计了WOS(Web of Science)数据库和CNKI(中国知网)数据库中1992—2022年高原鼠兔研究领域的文献,同时利用CiteSpace从发文趋势、学科、国家、机构、作者、研究热点等角度,定性定量地开展文献可视化分析。结果表明,高原鼠兔研究领域的相关文献数量整体上表现为随年份的增加呈上升趋势,并可以划分为初步萌芽期、平稳发展期、高速发展期;高原鼠兔研究的学科领域进一步扩大,在原来学科基础上交叉融合出新的6个学科;21个国家进行了高原鼠兔相关研究,其中CNKI中有94个机构展开了130次合作,WOS中有174个机构展开362次合作;CNKI数据库中形成了4个明显的作者团体,WOS数据库中形成了2个明显的作者团体,群体内大多以核心作者为纽带,交流频繁,群体间交流较少;CNKI和WOS中的研究热点可以概括为2个方面,分别是从分子水平、生态方面去揭示高原鼠兔与环境之间的关系。

指向学科核心素养的高中生物学情境套题命制及改进

本文以区级原创情境套题“高原鼠兔”为例,阐述了指向学科核心素养的试题情境选择、有价值的试题素材的搜集和选择、情境套题的情境材料和问题串编写、初稿情境材料中的数据和图的修改、试题中逻辑问题的发现和修改等试题命制的路径和改进方法,使试题表现较好的核心素养水平的进阶梯度,提高指向学科核心素养的命题质量。

高原鼠兔对于青藏高原生态系统的影响

高原鼠兔(Ochotona curzoniae)是青藏高原上一种小型的穴居哺乳动物。一定数量的高原鼠兔可以对生态系统产生如食物链稳定等积极作用,而过多的数量则会造成消极影响。为探究高原鼠兔对青藏高原生态系统所造成的影响,本研究主要从为高原动物提供住所,作为食物网的关键组成为高原肉食动物提供食物等行为对青藏高原的积极影响,以及数量过度而造成的消极作用2个方面来阐述高原鼠兔对于青藏高原生态系统的影响,诠释了高原鼠兔在生态系统中的地位,并对未来的研究方向进行了展望。

The genomic characteristics and pathogenicity of a mammalian orthoreovirus within a new lineage from wild pika in plateau

Emerging and re-emerging viruses from wild animals have seriously threatened the health of humans and domesticated animals in recent years.Herein,we isolated a new mammalian orthoreovirus(MRV),Pika/MRV/GCCDC7/2019(PMRV-GCCDC7),in the Qinghai-Tibet Plateau wild pika(Ochotona curzoniae).Though the PMRVGCCDC7 shows features of a typical reovirus with ten gene segments arranged in 3:3:4 in length,the virus belongs to an independent evolutionary branch compared to other MRVs based on phylogenetic tree analysis.The results of cellular susceptibility,species tropism,and replication kinetics of PMRV-GCCDC7 indicated the virus could infect four human cell lines(A549,Huh7,HCT,and LoVo)and six non-human cell lines,including Vero-E6,LLCMK2,BHK-21,N2a,MDCK,and RfKT cell,derived from diverse mammals,i.e.monkey,mice,canine and bat,which revealed the potential of PMRV-GCCDC7 to infect a variety of hosts.Infection of BALB/c mice with PMRVGCCDC7 via intranasal inoculation led to relative weight loss,lung tissue damage and inflammation with the increase of virus titer,but no serious respiratory symptoms and death occurred.The characterization of the new reovirus from a plateau-based wild animal has expanded our knowledge of the host range of MRV and provided insight into its risk of trans-species transmission and zoonotic diseases.

多年鼠类防控对高原鼠兔种群数量及植物群落结构的影响

高原鼠兔对草地生态系统的影响备受关注,而多年鼠类防控对高原鼠兔种群数量与植物群落结构影响的研究鲜见。本研究通过对青海省河南县鼠类种群密度较高的高寒草甸进行了连续九年、每年三次的鼠类防控和监测,研究多年鼠类防控对高原鼠兔种群数量及植物群落结构的影响。结果表明:前四年连续的鼠类防控显著地降低了高原鼠兔种群密度,而后五年高原鼠兔种群密度下降趋势并不明显;随着鼠类防控年份的增加,植物群落盖度,高度和地上生物量均显著增加,且它们与鼠兔种群密度呈显著的负相关关系,一定程度上说明高密度的鼠兔种群数量不利于植物盖度和地上生物量的维持;气候因子比鼠兔种群大小更能解释植物地上生物量的变化,其对鼠兔种群密度的影响也大于持续鼠类防控的影响。因此,对于鼠害严重的高寒草甸,鼠类防控协同气候因子共同影响着高原鼠兔种群大小和植物群落结构及功能。

高原鼠兔干扰对高寒草甸植物物种多样性与土壤生态化学计量比间关系的影响

植物物种多样性和土壤生态化学计量比间的关系,是草地植物群落结构维持的关键。高原鼠兔干扰虽被证实能够影响植物物种多样性、土壤有机碳、全氮和全磷的含量,但是否影响高寒草甸植物物种多样性和土壤生态化学计量比间的关系,尚不清楚。本研究以甘南和青海湖流域为对象,采用配对设置样地的方法,分析了高原鼠兔干扰对高寒草甸植物物种多样性和土壤生态化学计量比间关系的影响。结果表明:高原鼠兔干扰显著增加了物种丰富度指数、土壤有机碳、全氮和全磷含量,以及土壤C∶N和C∶P(P<0.05),但没有显著影响物种多样性指数、物种均匀度指数和土壤N∶P。高原鼠兔干扰增加了物种丰富度指数和物种多样性指数与土壤C∶N间的正相关性(P<0.05),减弱了物种丰富度指数与土壤C∶P间的正相关性(P<0.01);物种多样性指数与土壤C∶P间的关系从高原鼠兔未干扰生境的对数关系转变为干扰生境的二次函数关系(P<0.05),而物种丰富度指数与土壤N∶P间的关系从高原鼠兔未干扰生境的不显著相关,改变为干扰生境的显著负相关二次函数(P<0.01);物种多样性指数与土壤N∶P间的关系从未干扰生境的显著正相关二次函数(P<0.05),变为干扰生境的不显著相关,这确证了高原鼠兔干扰能够改变植物物种多样性与土壤生态化学计量比间的关系,为全面解释高原鼠兔干扰下草地植物群落结构的维持提供了基础信息。

高原鼠兔和高原鼢鼠种群暴发区干扰斑块空间分布格局与演替规律

高原鼠兔(Ochotona curzoniae)和高原鼢鼠(Myospalax baileyi)是两种在高寒草甸广泛分布的小型哺乳动物,其暴发活动可能造成高寒草甸的严重退化。使用无人机分别拍摄典型的高原鼠兔和高原鼢鼠种群暴发区图像,解译高原鼠兔洞口、高原鼢鼠土丘和它们的干扰斑块,获得干扰斑块的周长和面积信息,计算干扰斑块形状指标,确定高原鼠兔与高原鼢鼠暴发活动对高寒草甸的影响。研究表明:(1)高原鼠兔与高原鼢鼠暴发活动形成的干扰斑块周长与面积比(PARA)、形状指数(SHAPE)和分形维数(FRAC)差异显著(P<0.05),其中高原鼢鼠斑块的FRAC是1.0124±0.0091,属于普通的规则几何圆形分布格局,高原鼠兔斑块的FRAC是1.1203±0.0546,属于分形几何不规则的分布格局。(2)高原鼠兔洞口数量与其斑块面积没有线性相关关系(P=0.9677),高原鼢鼠土丘数量与其斑块面积呈显著正相关(P<0.05)。(3)高原鼢鼠斑块面积统计学上呈长尾分布,不符合正态分布(P<0.01)。根据高原鼠兔斑块面积分布格局可将斑块演替分为三个阶段:土丘形成阶段、斑块连通阶段和斑块扩散阶段。高原鼠兔土丘形成阶段斑块的形状和分布,与高原鼢鼠干扰斑块相似;在演替初期阶段融合连通阶段斑块的面积分布呈指数分布,形状趋于分形几何(FRAC=1.1161);在跨尺度扩散阶段斑块面积较大且形状复杂(SHAPE=4.4202),呈现不规则分布格局。三个阶段斑块的周长与面积比、形状指数和分形维数差异显著(P<0.05)。高原鼠兔在退化高寒草甸的觅食活动促进了融合连通阶段斑块的形成,呈现分形几何斑块演替规律。由此得出结论,引起高寒草甸退化的主要原因是过度放牧下高原鼠兔暴发活动,造成跨尺度扩散斑块演替阶段出现的结果,并非高原鼢鼠的暴发活动形成的。因此,控制高原鼠兔数量并恢复高原鼠兔干扰斑块植被相比高原鼢鼠更重要。