Gunnison's Prairie Dog Use of Resource Pulses in a Chihuahuan Desert Grassland at the Sevilleta National Wildlife Refuge, New Mexico: Capture Data

Seasonal environments experience cyclical or unpredictable pulses in plant growth that provide important resources for animal populations, and may affect the diversity and persistence of animal communities that utilize these resources. The timing of breeding cycles and other biological activities must be compatible with the availability of critical resources for animal species to exploit these resource pulses; failure to match animal needs with available energy can cause population declines. Adult Gunnison’s prairie dogs emerge from hibernation and breed in early spring, when plant growth is linked to cool-season precipitation and is primarily represented by the more nutritious and digestible plants that utilize the C3 photosynthetic pathway. In contrast, summer rainfall stimulates growth of less nutritious plants using the C4 photosynthetic pathway. Prairie dogs should therefore produce young during times of increased productivity from C3 plants, while pre-hibernation accumulation of body fat should rely more heavily upon C4 plants. If seasonal availability of high-quality food sources is important to Gunnison’s prairie dog population growth, projected changes in climate that alter the intensity or timing of these resource pulses could result in loss or decline of prairie dog populations. This project will test the hypothesis that population characteristics of Gunnison's prairie dog, an imperiled grassland herbivore, are associated with climate-based influences on pulses of plant growth.

季节性环境中，植物生长会出现周期性或不可预测的脉冲式增长，这类增长为动物种群提供了重要资源，同时也会对依赖这些资源的动物群落的多样性与存续能力产生影响。动物的繁殖周期及其他生命活动的时间节点，必须与可利用这类资源脉冲的关键资源的可获得性相匹配；若动物的生存需求与可获取的能量无法适配，便可能引发种群数量下滑。成年冈尼森草原犬鼠（Gunnison's prairie dog）会在早春结束冬眠并开始繁殖，此时的植物生长与冷季降水相关，且主要由利用C3光合途径（C3 photosynthetic pathway）的高营养、易消化植物构成。相反，夏季降雨会促使用C4光合途径（C4 photosynthetic pathway）的低营养植物生长。因此，草原犬鼠应在C3植物生产力提升的时段繁育幼崽，而冬眠前的体脂积累则应更多依赖C4植物。若优质食物来源的季节性可获得性对冈尼森草原犬鼠的种群增长至关重要，那么预计会改变这类资源脉冲强度与时间节点的气候变化，便可能导致草原犬鼠种群数量减少甚至消亡。本项目将验证这一假说：作为一种受胁的草原植食性动物，冈尼森草原犬鼠的种群特征，与气候对植物生长脉冲的调控作用存在关联。