Browsing by Author "Gaxiola, Aurora"

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Biotic and abiotic drivers of carbon, nitrogen and phosphorus stocks in a temperate rainforest
    (2021) Perez-Quezada, Jorge F.; Perez, Cecilia A.; Brito, Carla E.; Fuentes, Juan P.; Gaxiola, Aurora; Aguilera-Riquelme, David; Lopatin, Javier
    Forest ecosystems are recognized for their large capacity to store carbon (C) in their aboveground and belowground biomass and soil pools. While the distribution of C among ecosystem pools has been extensively studied, less is known about nitrogen (N) and phosphorus (P) pools and how these stocks relate to each other. There is also a need to understand how biotic and abiotic ecosystem properties drive the magnitude and distribution of CN-P stocks. We studied a temperate rainforest in southern South America to answer the following questions: 1) how are C-N-P total stocks distributed among the different ecosystem pools?, 2) how do C:N, C:P and N:P ratios vary among ecosystem pools?, and 3) which are the main biotic and abiotic drivers of C-N-P stocks? We established 33 circular plots to estimate C, N, and P stocks in different pools (i.e. trees, epiphytes, understory, necromass, leaf litter, and soil) and a set of biotic (e.g., tree density and richness) and abiotic variables (e.g., air temperature, humidity and soil depth). We used structural equation modeling to identify the relative importance of environmental drivers on C-N-P stocks. We found that total ecosystem stocks (mean +/- SE) were 1062 +/- 58 Mg C ha-1, 28.8 +/- 1.5 Mg N ha-1, and 347 +/- 12.5 kg P ha-1. The soil was the largest ecosystem pool, containing 68%, 92%, and 73% of the total C, N, and P stocks, respectively. Compared to representative temperate forests, the soil of this forest contains the largest concentrations and stocks of C and N. The low P stock and wide soil C:P and N:P ratios suggest that P may be limiting forest productivity. The ecosystem C-N-P stocks were mainly driven by abiotic properties measured in the study area, however for N stocks, variables such as plant diversity and canopy openness were also relevant. Our results provide evidence about the importance not only of understanding the differences in C, N, and P stocks but also of the factors that drive such differences. This is key to inform conservation policies related to preserving old-growth forests in southern South America, which indeed are facing a rapid land-use change process.
  • No Thumbnail Available
    Item
    Azorella Cushion Plants and Aridity are Important Drivers of Soil Microbial Communities in Andean Ecosystems
    (2021) Rodriguez-Echeverria, Susana; Delgado-Baquerizo, Manuel; Morillo, Jose A.; Gaxiola, Aurora; Manzano, Marlene; Marquet, Pablo A.; Gonzalez, Leticia; Cavieres, Lohengrin A.; Pugnaire, Francisco I.; Armas, Cristina
    Cushion plants are specialized keystone species of alpine environments that can have a positive effect on ecosystem structure and function. However, we know relatively little about how cushion plants regulate the diversity and composition of soil microbial communities, major drivers of soil processes and ecosystem functioning. Identifying what factors drive the diversity and composition of soil microbial communities in high-elevation ecosystems is also fundamental to predict how global changes will affect their conservation and the services and functions they provide. Thus, we sampled four sites along the southern Andes following the vegetation belt of Azorella cushion species. The field sites spread along a latitudinal gradient and had contrasting levels of aridity, UV-B radiation, mean temperature and soil properties. Overall, Azorella, as well as aridity and UV-B radiation, were the major drivers of the distribution, composition and diversity of soil microbial communities in the studied ecosystems of the Chilean Andes. UV-B radiation affected particularly soil fungi, while soil properties such as pH, total C and N content, essential predictors of microbial diversity globally, had a much lower effect on the composition of soil microbial communities. Understanding the factors driving the structure and composition of microbial communities, particularly the role of cushion plants and the feedbacks between plant, climate and soil is of uttermost importance for the preservation of the functionality of high-elevation ecosystems threatened by climate change.
  • 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.
  • No Thumbnail Available
    Item
    Variability in terrestrial litter decomposition can be explained by nutrient allocation strategies among soil decomposer communities
    (2023) Murua, Jose M.; Gaxiola, Aurora
    1. Leaf litter decomposition is a key process for nutrient cycling with broad ecosystem-level consequences. However, we still cannot explain an important amount of the observed variability in decomposition rates. Therefore, a mechanistic model of how litter quality impacts the metabolic capacity of microbial decomposers to degrade litter at a given rate could improve our understanding of litter decomposition.
  • Thumbnail Image
    Item
    Young People Are Changing Their Socio-Ecological Reality to Face Climate Change: Contrasting Transformative Youth Commitment with Division and Inertia of Governments
    (MDPI, 2022) Pena-Vega, Alfredo; Cohen, Marianne; Manuel Flores, Luis; Le Treut, Herve; Lagos, Marcelo; Carlos Castilla, Juan; Gaxiola, Aurora; Marquet, Pablo
    This paper contributes to a critical re-reading of the notion of climate services. It does so by problematizing the discontinuity between young people's commitment to climate change, and the lack of a common vision regarding climate policy among governments. In this essay, youth commitment is characterized in terms of participation in the Global Youth Climate Pact (GYCP, 2015-2022). Here, young people share projects from their own high schools and communities and participate in a citizen consultation. Most projects have achieved a good success score, increasing over the years, especially for those carried out in emerging and developing countries. Some of them were presented at the COPs. In contrast, a textual analysis of intended nationally determined contributions (INDC) illustrates divergent understandings of the Paris Agreement and exemplifies the poor results of governmental climate diplomacy. This study establishes the need to closely monitor early warning signs of climate change in conjunction with high schools and school communities. The initiatives of young people are building a civic and planetary awareness for climate change in contrast with governmental division and inertia. In this sense, climate services, directed to young people, could contribute to design a sustainable future. We approach the practices, attitudes, and commitments of young people from the angle of cooperation rather than a moral vision of responsibility. Particularly, we propose a dialogical link between the treatment of climate issues and its effects on the constitution of networks, notably as they relate to practices of action, that is, the way in which distinct groups of young people develop relationships with their environments, organize themselves, and act and transform reality.