The Cooperative Ecosystem Studies Unit Network promotes, conducts, and provides research, technical assistance and education services nationwide in support of the missions of participating federal agencies and their partners concerning natural and cultural resource management on federal and/or private lands and waters. Each CESU project is cooperative, substantially involving and benefitting both federal and non-federal partners. A CESU project is consistent with the goals of the respective CESU which administers the project. The proposed agreement would incorporate the terms and conditions of the one of the following CESU Cooperative and Joint Venture Agreements -Californian master agreement L13AC00082 - to which the Bureau of Land Management is a party to. The established Network overhead charge is set at 17.5 percent. Prospective universities and non-governmental research organizations with membership in the CESUs are eligible to apply for funding under this announcement. Positive interactions in plant communities are particularly important in arid and semi-arid systems as they frequently shape patterns of diversity and localized productivity (Brooker and Callaway 2009, Butterfield 2009, Cavieres and Badano 2009, Cavieres and Badano 2010, Xiao, et al. 2009). Importantly, positive interactions can also lead to long-term evolutionary changes in the dynamics within a community (Bronstein 2009, Brooker, et al. 2008, Kikvidze and Callaway 2009, Thorpe, et al. 2011). The consequences of plant facilitation are however generally restricted to single trophic levels, to plant-plant interactions and not seeds, and to the study of direct interactions only (Brooker, et al. 2008, Lortie and Callaway 2009). These research gaps are not only intriguing but also relate to habitat restoration and a more inclusive perspective on the community-level effects of positive interactions for other organisms in addition to plants, such as the endangered blunt-nosed leopard lizard. Accordingly, facilitation in arid/semi-arid systems may have the capacity to mediate species loss within these systems and provide resilience to the structure and function of these communities.