Ecosystem services of tropical dry forests : insights from longterm ecological and social research on the Pacific coast of Mexico

In the search for an integrated understanding of the relationships among productive activities, human well-being, and ecosystem functioning, we evaluated the services delivered by a tropical dry forest (TDF) ecosystem in the Chamela Region, on the Pacific Coast of Mexico. We synthesized information gathered for the past two decades as part of a long-term ecosystem research study and included social data collected in the past four years using the Millennium Ecosystem Assessment (MA) conceptual framework as a guide. Here we identify the four nested spatial scales at which information has been obtained and emphasize one of them through a basin conceptual model. We then articulate the biophysical and socio-economic constraints and drivers determining the delivery of ecosystem services in the Region. We describe the nine most important services, the stakeholders who benefit from those services, and their degree of awareness of such services. We characterize spatial and temporal patterns of the services&rsquo; delivery as well as trade-offs among services and stakeholders. Finally, we contrast three alternative future scenarios on the delivery of ecosystem services and human well-being. Biophysical and socioeconomic features of the study site strongly influence human&minus;ecosystem interactions, the ecosystem services delivered, the possible future trajectories of the ecosystem, and the effect on human well-being. We discuss future research approaches that will set the basis for an integrated understanding of human&minus;ecosystem interactions and for constructing sustainable management strategies for the TDF.<br /

A Tale of Two Species: Speculation on the Introduction of Pachycereus pringlei in the Sierra Libre, Sonora, Mexico by Homo sapiens

Desert Plants is published by The University of Arizona for the Boyce Thompson Southwestern Arboretum. For more information about this unique botanical journal, please email the College of Agriculture and Life Sciences Publications Office at [email protected]

Relationships among climate, stem growth, and biomass δ13C in the giant saguaro cactus (Carnegiea gigantea)

Giant saguaro (Carnegiea gigantea) is one of the longest-lived and massive cacti species in the Americas. They occur throughout the Sonoran Desert region with a distribution spanning a five-fold gradient in mean annual precipitation. Relationships between fitness traits, including stem growth, and spatio-temporal climate patterns are still poorly understood in saguaro, but are assumed to be largely coupled to summer precipitation. To better understand patterns of climate sensitivity in giant saguaro, annual stem growth, carbon isotope ratios (δ13C) in spine tissues, and seasonal variation in stem volume, a proxy for stem water storage, were evaluated over a single growing season (2014) in six widely distributed populations in the northern Sonoran Desert, and over four consecutive growing seasons (2013–2016) in two populations with differences in mean annual precipitation and site moisture (Mi), defined as precipitation amount divided by mean atmospheric vapor pressure deficit. We hypothesized that saguaro growth and δ13C would be coupled to a complex suite of climate conditions that include winter precipitation and aridity. Annual stem growth of all populations was generally better correlated to Mi than precipitation alone and was best correlated with Mi measured over the hydrologic year, October 2013–September 2014 (F = 39.8, P < 0.0001). Likewise, mean δ13C increased with Mi, with the highest correlation with Mi calculated for July 2013–August 2014 (F = 38.4.0, P < 0.0001). Annual stem growth measured across all populations was well correlated to δ13C in spines produced during the current year of growth (F = 36.3, P < 0.0001). Annual variation in stem growth appeared to reflect annual variation in mean stem volume measured monthly from the summer of the previous year to the summer of the current year of growth. Results suggest that stem growth and photosynthetic physiology recorded by δ13C are coupled to a complex suite of climate conditions with a strong legacy effect from the previous summer and winter. These findings provide new insight on the effects of summer and winter drought and a warming climate on the photosynthesis, growth, and fitness of giant saguaro. © 2018 The Authors

Plant biotic interactions in the Sonoran Desert: Conservation challenges and future directions.

Biotic interactions are vital to ecosystem functioning. Interactions among individuals lie at the core of population and community dynamics, and therefore play a central role in the existence and persistence of species. Plants form the food base of most terrestrial ecosystems and are therefore not surprisingly involved in a substantial portion of biotic interactions. Plants, animals, and microbes face great challenges to survival in the desert environment, and these interactions play a critical role in the survival of many species.Fil: Marazzi, Brigitte. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Nordeste. Instituto de Botánica del Nordeste (i); ArgentinaFil: Bronstein, Judith L..Fil: Sommers, Pacifica N..Fil: López, Blanca R..Fil: Bustamante Ortega, Enriquena.Fil: Búrquez, Alberto.Fil: Medellín, Rodrigo A..Fil: Aslan, Clare.Fil: Franklin, Kim