Browsing by Author "Kelt, Douglas A."

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Exclusion of small mammals and lagomorphs invasion interact with human-trampling to drive changes in topsoil microbial community structure and function in semiarid Chile
    (2018) Alfaro, Fernando D.; Manzano, Marlene; Abades T., Sebastián R.; Trefault Carrillo, Nicole Natalie; De la Iglesia Cabezas, Rodrigo Alonso; Gaxiola Alcantar, Aurora; Marquet, P. A. (Pablo A.); Gutiérrez, Julio R.; Meserve, Peter L.; Kelt, Douglas A.; Belnap, Jayne; Armesto, Juan J.
  • Thumbnail Image
    Item
    Long-term field studies on rodents
    (2017) Hayes, Loren D.; Ebensperger Pesce, Luis Alberto; Kelt, Douglas A.; Pillay, Neville; Viblanc, Vincent A.; Schradin, Carsten; Meserve, Peter L.
  • No Thumbnail Available
    Item
    Long-term research in Bosque Fray Jorge National Park: Twenty years studying the role of biotic and abiotic factors in a Chilean semiarid scrubland
    (2010) Gutierrez, Julio R.; Meserve, Peter L.; Kelt, Douglas A.; Engilis, Andrew, Jr.; Previtali, M. Andrea; Milstead, W. Bryan; Jaksic, Fabian M.
    Since 1989, we have conducted a large-scale ecological experiment in semiarid thorn scrub of a national park in north-central Chile. Initially, we focused on the role of biotic interactions including predation, interspecific competition, and herbivory in small mammal and plant components of the community. We utilized a reductionist approach with replicated 0.56 ha fenced grids that selectively excluded vertebrate predators and/or larger small mammal herbivores such as the degu, Octodon degas. Although we detected small transitory effects of predator exclusions on degu survival and numbers, other species failed to show responses. Similarly, interspecific competition (i.e., degus with other small mammals) had no detectable numerical effects (although some behavioral responses occurred), and degu-exclusions had relatively small effects on various plant components. Modeling approaches indicate that abiotic factors play a determining role in the dynamics of principal small mammal species such as O. degas and the leaf-eared mouse (Phyllotis darwini). In turn, these are mainly related to aperiodic pulses of higher rainfall (usually during El Nino events) which trigger ephemeral plant growth; a food addition experiment. in 1997-2000 verified the importance of precipitation as a determinant of food availability. Since 2004, we have expanded long-term monitoring efforts to other important community components including birds and insects in order to understand effects of abiotic factors on them; we report some of the first results of comprehensive surveys on the former in this region. Finally, we recently shifted focus to documenting effects of exotic lagomorphs in the park. We installed additional treatments selectively excluding small mammals, lagomorphs, or both, from replicated grids in order to evaluate putative herbivore impacts. In conjunction with increased annual rainfall since 2000, we predict that introduced lagomorphs will have increasing impacts in this region, and that more frequent El Ninos in conjunction with global climatic change may lead to marked changes in community dynamics. The importance of long-term experimental studies is underscored by the fact that only now after 20 years of work are some patterns becoming evident.
  • No Thumbnail Available
    Item
    Species interactions across trophic levels mediate rainfall effects on dryland vegetation dynamics
    (2021) Farias, Ariel A.; Armas, Cristina; Gaxiola, Aurora; Cea, Alex P.; Luis Cortes, Jose; Lopez, Ramiro P.; Casanoves, Fernando; Holmgren, Milena; Meserve, Peter L.; Gutierrez, Julio R.; Kelt, Douglas A.
    Arid ecosystems are strongly limited by water availability, and precipitation plays a major role in the dynamics of all species in arid regions, as well as the ecosystem processes that occur there. However, understanding how biotic interactions mediate long-term responses of dryland ecosystems to rainfall remains very fragmented. We report on a unique large-scale field experiment spanning 25 yr and three trophic levels (plants, small mammal herbivores, predators) in a dryland ecosystem in the northern Chilean Mediterranean Region where we assessed how biotic interactions influence the long-term plant community responses to precipitation. As the most persistent ecological changes in dryland systems may result from changes in the structure, cover, and composition of the perennial vegetation, we emphasized the interplay between bottom-up and top-down controls of perennial plants in our analyses. Rainfall was the primary factor affecting the dynamics of, and interactions among, plants and small mammals. Ephemeral plant cover dynamics closely tracked short-term annual rainfall, but seemed unaffected by top-down controls (herbivory). In contrast, the response of the perennial plant cover to precipitation was mediated by (1) a complex interplay between subtle top-down (herbivory) controls that become more apparent in the long-term, (2) competition with ephemeral plants during wet years, and (3) an indirect effect of predators on subdominant shrubs and perennial herbs. This long-term field experiment highlights how climate-induced responses of arid perennial vegetation are influenced by interactions across trophic levels and temporal scales. In the face of global change, understanding how multi-trophic controls mediate dryland vegetation responses to climate is essential to properly managing the conservation of biodiversity in arid systems.
  • Thumbnail Image
    Item
    The avifauna of Bosque Fray Jorge National Park and Chile's Norte Chico
    (2016) Kelt, Douglas A.; Cofré, Hernán; Cornelius, Cintia; Engilis Jr, Andrew; Gutiérrez, Julio R.; Marquet, P. A. (Pablo A.); Medel Sierralta, Rodrigo Miguel; Meserve, Peter L.; Quirici, Verónica; Samaniego, Horacio; Vásquez, Rodrigo A.