Competition and facilitation between a native and a domestic herbivore: trade-offs between forage quantity and quality

摘要: Potential competition between native and domestic herbivores is a major consideration influencing the management conservation of in rangeland ecosystems. In grasslands North American Great Plains, black-tailed prairie dogs (Cynomys ludovicianus) are widely viewed as competitors with cattle but also important for biodiversity due to their role creating habitat other species. We examined spatiotemporal variation dog effects on growing-season forage quality quantity using measurements from three colony complexes Colorado South Dakota previous study fourth complex Montana. At two experiencing below-average precipitation, availability both off colonies was so low (12-54 g/ m 2 ) that daily intake rates were likely constrained by instantaneous foraging time. Under these dry conditions, (1) substantially reduced availability, thus further limiting rates, (2) had either no or small positive effect digestibility. such compete direct proportion abundance. For above-average (77-208 g/m sufficient be limited digestion rather than intake. one where enhanced digestibility (N) while having quantity, predicted facilitate mass gains regardless second can vary facilitation depending Our findings show high vegetation dynamics characteristic semiarid paralleled variability magnitude grazers. Competitive interactions evident during periods may partially wholly offset when does not limit rate cattle.