Fernández-Giménez, M. E., D. J. Augustine, L. M. Porensky, H. Wilmer, J. D. Derner, D. D. Briske, and M. Olsgard Stewart. 2019. Complexity fosters learning in collaborative adaptive management. Ecology and Society 24(2):29. https://doi.org/10.5751/ES-10963-240229

Aboveground net primary productivity (ANPP) in grasslands is an important integrator of terrestrial ecosystem function, a key driver of global biogeochemical cycles, and a critical source of food for wild and domesticated herbivores. ANPP exhibits high spatial and temporal variability, driven by a suite of factors including precipitation amount and pattern, biotic and abiotic legacies, and topographic heterogeneity. Global climate models forecast an altered hydrological cycle due to climate change, including higher precipitation variability and more extreme events, which may further increase spatiotemporal variability in ANPP. Therefore, it is essential to understand the sensitivity of this central ecosystem function to various precipitation metrics, legacies, and topographic positions to better inform sustainable grassland management. In this study, we analyzed long‐term (36‐yr) ANPP data collected across a topographic sequence in the semiarid shortgrass steppe of North America to examine patterns and drivers of spatiotemporal variability in ANPP. We observed that (1) ANPP varied substantially by topographic position, with greater divergence during years with high production, (2) ANPP variability was higher temporally (16‐fold maximum difference across years) than spatially (4‐fold maximum difference across topographic positions), (3) warm‐season perennial grasses were the dominant plant functional type across all topographic positions and strongly influenced total ANPP dynamics, and (4) ANPP had strong sensitivities to current year precipitation amount and pattern that varied by plant functional type, as well as weaker sensitivities to precipitation and productivity legacies. Overall, the lowest topographic position had the highest sensitivity to precipitation, likely due to higher resource availability via the downhill movement of water and nutrients during years with high precipitation and large rainfall events. These results suggest that temporal and spatial ANPP variability in shortgrass steppe is primarily driven by the combined effects of precipitation amount and pattern during the current year, with the dominant warm‐season perennial grasses governing these responses.

Ecotones, or transitional zones between ecosystems, are often hotspots for biodiversity and targets for conservation. Where the Great Plains meet the sagebrush ( Artemisia spp.) steppe, an opportunity exists to conserve habitat for the two most imperiled avian guilds in North America, grassland and shrub‐steppe birds. This ecotone creates a unique challenge with respect to the management of disturbance processes, such as fire and grazing, because grassland and sagebrush‐shrubland birds respond quite dissimilarly to disturbance. To address this management challenge and maximize conservation opportunities, we examined the responses of grassland and sagebrush bird communities to disturbance at a grassland–sagebrush ecotone in northeast Wyoming, USA . Specifically, we surveyed bird communities on active black‐tailed prairie dog ( Cynomys ludovicianus ) colonies and burned areas, as well as on paired undisturbed points in 2016 and 2017. Bird community structure varied in response to both the presence and type of disturbance. Although alpha diversity of avian species was highest on undisturbed sites and burned areas, only prairie dog colonies provided breeding habitat for the imperiled shortgrass‐obligate mountain plover ( Charadrius montanus ), and species turnover (beta diversity) was greatest between on‐colony and off‐colony points. Furthermore, bird communities were shaped by both disturbance‐dependent (e.g., disturbance age) and disturbance‐independent (e.g., topography and soils) landscape features. Managers must balance the benefits of high species diversity in undisturbed sagebrush with habitat requirements of other imperiled species like the mountain plover. This may entail prioritizing the amount and distribution of disturbances in relation to population goals for species of conservation concern while simultaneously maintaining a mosaic of all three patch types in this landscape.