prairies; espèces invasives; formation de patchs; dynamique des communautés; interactions sol-plantes; utilisation des terres; fonctionnement de l'écosystème
Chuong Julie, Huxley Jared, Spotswood Erica N., Nichols Liana, Mariotte Pierre, Suding Katharine N. (2016), Cattle as Dispersal Vectors of Invasive and Introduced Plants in a California Annual Grassland, in Rangeland Ecology & Management
, 69, 52-58.
Mariotte Pierre, Spotswood Erica, Farrer Emily, Suding Katharine, Positive litter feedbacks of an introduced species reduce native diversity and promote invasion in Californian grasslands, in Applied Vegetation Science
Spotswood Erica N., Mariotte Pierre, Farrer Emily C., Nichols Liana, Suding Katharine N., Separating sources of density-dependent and density-independent establishment limitation in invading species, in Journal of Ecology
The occurrence of alternative states and thresholds has become a central issue at the interface of basic and applied ecology. Alternative states represent major shifts in ecosystem function due to changes in abundance and composition of dominant species, and associated biological and physical processes. Recent evidence suggests that cross-scale interactions may be critical to understanding catastrophic spread in patchy systems, including invasive species. The objectives of this project are to determine how feedbacks between fine-scale processes, landscape level transitions and threshold dynamics influence the establishment of noxious weed invasion. In this project, we will use the noxious weed Medusahead (Taeniatherum caput-medusae) that is target for management intervention in Californian rangelands. Indeed, weed infestations by Medusahead on annual rangeland can reduce forage production by 75-80%, severely comprising the economic vitality of these agroecosystems. In this study, we will utilize seed addition experiments, in the Sierra Foothills Research Extension Center, to establish populations of different densities. Then, we will follow population dynamics, spatial spread and movement of livestock in order to uncover how processes at fine and landscape scales interact to create conditions under which pastures can become invaded. In addition, we will manage fire experiments, with five levels, at four different plant patch sizes to evaluate burn effectiveness at different scales. Overall, we will test the generalities and predictability of patch formation and spatial contagion, widely thought to be critical components of abrupt and sudden threshold effects, in weed invasion. Our goal is to identify key pasture conditions under which transitions to pasture wide dominance are most likely, so that managers can avoid land use practices most likely to trigger difficult to reverse shifts.