Current projects

In Madagascar, one of the world’s biodiversity “hotspots," I work chiefly within the “protected area” strategy. The government of Madagascar announced at the 2003 World Parks Congress that it plans to triple the area protected for conservation in Madagascar. This news set the conservation world buzzing. Madagascar is one of the most biologically unique and rich areas in the world. It is home to all of the world’s lemur species, as well as several families of endemic birds and plants, 50% of the world’s chameleon species, and the list goes on and on. Given this fantastic opportunity to protect Madagascar’s unique biodiversity, how do we allocate the additional area among sites in order to maximize the number of species that will receive protection, as well as the long-term viability of the reserve network? One problem with making this allocation is that the biota of Madagascar is still poorly known, like many other tropical countries with rich biotas and inaccessible landscapes.

I am leading a large, international group of colleagues to make the most out of the data that we have. The first step is status assessment for species. Often we know the least about the rare species that we care the most about. The second step is modeling of species distributions. We are using new modeling techniques that avoid many of the problems inherent to some popular distribution modeling techniques. The third step is to use modeled distributions as inputs for making decisions about siting new reserves, thus gaining information (with a given level of uncertainty) on areas for which we have no data. We are using new reserve design algorithms recently developed by colleague Dr. Atte Moilanen (University of Helsinki), in one of the first application of these algorithms to a real-world problem. These algorithms allow us to design reserve networks that represent all species while (2) maximizing the proportion of species’ ranges, (3) maximizing connectivity of reserves across the landscape, and (4) incorporating uncertainty, a significant advance over many prior algorithms. We are also exploring the synergistic effects of global climate change and habitat loss on species extinction probabilities. With a new grant from the MacArthur Foundation, we are working with conservation partners at Wildlife Conservation Society, World Wildlife Fund and Conservation International to generate strategies for reserve design in Madagascar, and develop local capacity to store, manage and utilize biodiversity data. Working with these organizations ensures that our findings will be channeled directly to the governmental authorities responsible for establishing new protected areas.

In Northern California and New Jersey, I am investigating the inter-relationship between land use practices, wild bee communities and pollination services that these bees provide to crops on farms. What is the value of these native bees in providing pollination services on farms, and what, in consequence, are the values of the natural habitats and alternative farming practices? Could pollination services be enhanced through altered land management practices, conservation, and restoration? This work has suddenly become more topical due to large die-offs (called Colony Collapse Disorder) of the managed European honey bees that supply pollination services to many crops in the US. By working with governmental and non-governmental agencies, we are bringing our results to the attention of farmers and policy-makers. Through it, we are also developing conceptual and modeling frameworks that apply broadly to other ecosystems.

In California, our recent findings show that a diverse community of native bee pollinators can provide sufficient pollination services for crops without the addition of managed colonies of honey bees (Kremen et al. 2002), but that this service critically depends on the availability of natural habitat in proximity to the farm site (Kremen et al. 2004). Farm management (organic versus conventional) may also influence the diversity and abundance of native bees found on farms. Interestingly, agricultural intensification simultaneously reduces richness, abundance and biomass of bees, and promotes local extinction of the most efficient bee pollinators, thus destroying the “insurance policy” provided by native bees for pollination of crops (Larsen et al. 2005). The value provided by the native bees is an argument in favor of protecting and/or restoring natural habitat. In the California and New Jersey systems, we are documenting the critical floral and nesting resources provided in both natural areas and farmlands, and are using this information to develop protocols for restoring natural habitat and managing farmlands to promote bee diversity, abundance, and the pollination services these bees provide across the landscape. We are modeling what configuration of local and landscape habitat factors are required to maintain population persistence and pollination function of wild bee communities. I am also co-leading, with Dr. Neal Williams, former post-doc in the lab, a group of international scientists at the National Center for Ecological Analysis and Synthesis (NCEAS) on a series of meta-analyses that extends this modeling approach to a wider array of landscapes, systems and services.


To find out more about some of the ongoing projects, click on the link below. (PDF document)

Hedgerow Native Bee Project