DISSERTATION RESEARCH: Microbial Responses to Elevation in a Tropical Montane Cloud Forest

University Of California-Irvine, Irvine CA

Investigators

Abstract

Tropical montane cloud forests are characterized by persistent low-level cloud cover. These clouds alter light, temperature, and precipitation. They also support a large community of plants living on the branches and trunks of trees. Over time, dead plant material collects and decomposes on these branches, forming ?canopy soil?. Few studies have investigated the microbial communities within canopy soils. Nevertheless, this is important because microbial communities decompose organic material from plants and release CO2 (a greenhouse gas) into the atmosphere. This process has primarily been measured in soils on the forest floor. Based on these forest floor measurements, we estimate that microbes in tropical ecosystems can contribute greatly to global production of CO2. However, these estimates do not account for canopy soil. Determining how canopy soils contribute to microbial diversity and carbon cycling will allow us to better determine the role of tropical ecosystems in the global carbon cycle. In turn, this knowledge will allow us to make more accurate predictions of how these ecosystems may respond to future changes in the environment. Moreover, international research and collaborations are important to promote environmental stewardship and create networks of researchers with common goals. The project involves a multidisciplinary collaboration with another researcher and will help build a stronger, international research network. This research will incorporate canopy soil into the investigation of microbial diversity in tropical montane cloud forests. To obtain a full assessment of the diversity within canopy soils and how they compare to terrestrial soils, the researchers will measure both fungal and bacterial diversity. Greater abiotic stress within tropical canopies should select for different microbial communities than are present in terrestrial soil. Therefore, the researchers hypothesize that canopy and terrestrial soils will harbor distinct microbial communities. In addition, extracellular enzymatic activity of C-targeting enzymes will be higher in canopy soils due to increased organic matter. Canopy and terrestrial soils will be collected along two elevation transects each on the Atlantic and Pacific slopes of the Cordillera de Tilarán within the Monteverde Cloud Forest Reserve. Collections will occur during the dry (January to April) and wet (May to November) seasons to explore differences in seasonality within this ecosystem. Fungal and bacterial diversity and extracellular enzymatic activity will be measured.