Browsing by Author "Barbosa, Olga"

Now showing 1 - 4 of 4
  • No Thumbnail Available
    Item
    Assessing Ecological Indicators for Remnant Vegetation Strips as Functional Biological Corridors in Chilean Vineyards
    (2021) Diaz-Forestier, Javiera; Abades, Sebastian; Pohl, Nelida; Barbosa, Olga; Godoy, Karina; Svensson, Gabriella L.; Undurraga, Maria, I; Bravo, Camila; Garcia, Camila; Root-Bernstein, Meredith; Armesto, Juan J.; Celis-Diez, Juan L.
    Mediterranean central Chile is globally recognized as a hotspot for terrestrial biodiversity due to its high endemism and massive habitat loss. However, within the rural landscape of central Chile, significant extents of natural areas remain, especially on less productive, steep slopes, and vegetation strips extending from the surrounding hills to agricultural areas. Accordingly, vegetation strips or corridors, within lowland farms, constitute key elements to support the conservation of biodiversity in rural landscapes. To assess the ecological performance of corridors in 22 commercials vineyards in central Chile, we characterized them in terms of width-, length-, area-, and perimeter-to-area ratios, as well as the number of connections with natural areas. Based on a set of previously defined ecological indicators (species, functional groups, and structural components), we compared their occurrence in corridors within vineyards and in the surrounding natural areas. We evaluated the effects of corridor attributes on the occurrence of the selected ecological indicators, using a generalized linear mixed model with each vineyard as a random factor. The area, width, and length of vegetation corridors varied widely (1.2-86.3 ha, 10.5-95 m, and 380-5000 m, respectively). We found significant differences in the occurrence of indicators between corridors and natural areas. All sampled ecological indicators in corridors showed a negative relationship with the distance to the nearest natural area. Vegetation strips within vineyards represent important opportunities for biodiversity conservation that significantly enhance habitat quality in the agricultural landscape for biodiversity and habitat connectivity.
  • Thumbnail Image
    Item
    Patrones de urbanización en la biodiversidad de humedales urbanos en Concepción metropolitano
    (2015) Rojas Quezada, Carolina Alejandra; Sepúlveda Zúñiga, Einer; Barbosa, Olga; Rojas, Octavio; Martínez Reyes, Carolina del Pilar
  • Thumbnail Image
    Item
    Patterns of bird diversity and habitat use in mixed vineyard-matorral landscapes of Central Chile
    (2017) Steel, Zachary L.; Steel, Anna E.; Williams, John N.; Viers, Joshua H.; Marquet, P. A. (Pablo A.); Barbosa, Olga
  • No Thumbnail Available
    Item
    Regeneration patterns and persistence of the fog-dependent Fray Jorge forest in semiarid Chile during the past two centuries
    (2008) Gutierrez, Alvaro G.; Barbosa, Olga; Christie, Duncan A.; Del-Val, Ek; Ewing, Holly A.; Jones, Clive G.; Marquet, Pablo A.; Weathers, Kathleen C.; Armesto, Juan J.
    The persistence of rainforest patches at Fray Jorge National Park (FJNP) in semiarid Chile (30 degrees 40'S), a region receiving approximately 147 mm of annual rainfall, has been a source of concern among forest managers. These forests are likely dependent on water inputs from oceanic fog and their persistence seems uncertain in the face of climate change. Here, we assessed tree radial growth and establishment during the last two centuries and their relation to trends in climate and canopy disturbance. Such evaluation is critical to understanding the dynamics of these semiarid ecosystems in response to climate change. We analyzed forest structure of six forest patches (0.2-22 ha) in FJNP based on sampling within 0.1 ha permanent plots. For the main canopy species, the endemic Aextoxicon punctatum (Aextoxicaceae), we used tree-ring analysis to assess establishment periods, tree ages, growing trends and their relation to El Nino Southern Oscillation (ENSO), rainfall, and disturbance. The population dynamics of A. punctatum can be described by a continuous regeneration mode. Regeneration of A. punctatum was sensitive to different canopy structures. Growth release patterns suggest the absence of large scale human impact. Radial growth and establishment of A. punctatum were weakly correlated with rainfall and ENSO. If water limits forests patch persistence, patches are likely dependent on the combination of fog and rain water inputs. Forest patches have regenerated continuously for at least 250 years, despite large fluctuations in rainfall driven by ENSO and a regional decline in rainfall during the last century. Because of the positive influence on fog interception, forest structure should be preserved under any future climate scenario. Future research in FJNP should prioritize quantifying the long-term trends of fog water deposition on forests patches. Fog modeling is crucial for understanding the interplay among physical drivers of water inputs under climate change.