机构地区:[1]青海大学农牧学院,西宁810016 [2]河南县草原工作站,黄南州811599
出 处:《生态学报》2023年第7期2949-2958,共10页Acta Ecologica Sinica
基 金:国家自然科学基金项目(31872999,U21A20191);青海省科学技术厅项目(2020-ZJ-904);高等学校学科创新引智计划(D18013)。
摘 要: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。Plateau pika(Ochotona curzoniae)and plateau zokor(Myospalax baileyi)are two species of small mammal widely distributed in alpine meadow.The main difference between the two animals is that plateau zokor mainly lives underground and plateau pika mainly lives on the surface of grassland.Their outbreak activities may cause serious degradation of alpine meadow.The disturbance patches formed by the two animals have different effects on the alpine meadow.Which kind of animal outbreak can lead to the cross-scale succession of disturbance patches is a scientific problem that needs to be solved.The patch shape and pattern metric in the field of landscape ecology can be used to compare the patch distribution patterns,thereby understanding the differences in the formation process of various patches.In this study,Unmanned aerial vehicle(UAVs)were used to capture typical images of plateau pika and plateau zokor population outbreak areas.Plateau pika holes,plateau zokor mounds and their disturbance patches were interpreted.The perimeter and area information of the disturbance patch was obtained.The shape and pattern metrics of disturbance patch were calculated and analyzed.The effects of outbreak activities of plateau pika and plateau zokor on the degradation of alpine meadow were determined.The results indicated that(1)there were significant differences in perimeter-area ratio(PARA),shape index(SHAPE)and fractal dimension index(FRAC)between plateau pika and plateau zokor disturbance patches formed by their outbreak activities(P<0.05).The FRAC of plateau zokor patches was 1.0132±0.0103,which belongs to ordinary regular geometry(circle),and the FRAC of plateau pika patches was 1.1007±0.0576,which belongs to fractal geometry.(2)There was no correlation between the number of plateau pika holes and the patch area of plateau pika(P=0.9677).There was a significantly positive correlation between the number of mounds and the patch area of plateau zokor(P<0.05).(3)The area of plateau zokor patch showed a long tail distribution at stat
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