Prairie dog decline reduces the supply of ecosystem services and leads to desertification of semiarid grasslands

Abstract

Anthropogenic impacts on North American grasslands, a highly endangered ecosystem, have led to declines of prairie dogs, a keystone species, over 98% of their historical range. While impacts of this loss on maintenance of grassland biodiversity have been widely documented, much less is known about the consequences on the supply of ecosystem services. Here we assessed the effect of prairie dogs in the supply of five ecosystem services by comparing grasslands currently occupied by prairie dogs, grasslands devoid of prairie dogs, and areas that used to be occupied by prairie dogs that are currently dominated by mesquite scrub. Groundwater recharge, regulation of soil erosion, regulation of soil productive potential, soil carbon storage and forage availability were consistently quantitatively or qualitatively higher in prairie dog grasslands relative to grasslands or mesquite scrub. Our findings indicate a severe loss of ecosystem services associated to the absence of prairie dogs. These findings suggest that contrary to a much publicize perception, especially in the US, prairie dogs are fundamental in maintaining grasslands and their decline have strong negative impacts in human well - being through the loss of ecosystem services.

Figure 1. The study area was located in the Janos Biosphere Reserve, in northern Chihuahua, close to the Mexico – US (New Mexico) international border.

Figure 2. Ecosystem services were evaluated in grasslands with prairie dogs, grasslands and mesquite scrubs that have lost prairie dog colonies in the last 10 years, in the Janos region, Chihuahua, Mexico.

Our results clearly show the positive effect of prairie dogs on the provision of these ecosystem services. Color bars indicate the relative magnitude of each of the services in the different treatments with respect to grasslands with prairie dogs.

Figure 3. Groundwater recharge variation among treatments in the Janos region, Chihuahua, Mexico.

Related to the foraging and burrowing activities of prairie dogs, among other physical and biological factors, the supply of this service was statistically higher in grasslands with prairie dogs than in grasslands and mesquite.

Figure 4. Variation in the regulation of soil erosion among treatments in the Janos region, Chihuahua, Mexico.

Soils in prairie dog grasslands were less prone to erosion, because they showed more than 60% of plant cover, while mesquite soils had more than 30% bared and prone to erosion.

Figure 5. Regulation of soil productive potential service among treatments in the Janos region, Chihuahua, Mexico.

Penetration resistance was higher in mesquite scrubs sites when compared with prairie dog grasslands and grasslands, indicating that soils are more compacted making more difficult the establishment of herbs and grasses.

Figure 6. Forage availability among treatments in the Janos region, Chihuahua, Mexico.

Contrary to a common lay and scientific assumption, forage availability was statistically higher in grasslands with prairie dogs than in grasslands and mesquite scrubs.