One of the major potential effects of climate change across terrestrial biomes is an increase in climate-driven tree mortality, particularly mortality triggered by a combination of drought and hotter temperatures. Drought and heat impacts on trees include: reductions in leaf area and crown ‘‘dieback’’ where only a portion of a tree’s canopy dies (commonly referred to as ‘‘defoliation’’); increases in background tree mortality rates; and broad-scale forest die-off events. The general objective is to detect the environmental and functional conditions of the vegetation that allow to explain the mortality pattern in Nothofagus dombeyi (Coihue) registered in humid and diverse forests of northern Patagonia, after the occurrence of recent major droughts (2014/15).

Funded by the Agencia de Promoción Científica FONCyT (PICT 2017-3843). 

Climate change is increasing the frequency and intensity of extreme drought events, with profound consequences for forest ecosystems. In the temperate forests of northern Patagonia, tree growth and survival are strongly influenced by climatic anomalies, yet responses vary widely among individuals depending on species traits, site conditions, and interactions with neighboring trees. This project focuses on understanding how the native conifer Austrocedrus chilensis responds to recurrent extreme droughts across different forest compositions. In particular, it examines the relative importance of environmental conditions, stand structure, and neighborhood interactions in shaping tree growth responses to climatic stress. Using a dendroecological approach, the project analyzes tree-ring growth of A. chilensis individuals growing in pure, mixed, and diverse forest stands. By integrating information on tree neighborhood structure and canopy position, the study evaluates how local conditions influence resilience to drought and recovery following disturbance.

Ph.D thesis of Loreta Facciano

Ecological communities are often sustained by a small number of species and interactions that play a disproportionate role in maintaining ecosystem structure and function. In the temperate forests of Patagonia, a remarkable mutualistic interaction links the hummingbird Sephanoides sephaniodes, the marsupial Dromiciops gliroides, the mistletoe Tristerix corymbosus, and its main host plant Aristotelia chilensis. Together, these species support key ecological processes such as pollination and seed dispersal. However, this interaction is increasingly threatened by global change resulting in the removal of these species or disruption of key interactions. Understanding the ecological consequences of disrupting this mutualism is essential for conserving the structure and functioning of Patagonian forest communities. This project evaluates the ecological importance of the hummingbird–mistletoe–marsupial mutualism and examines how its disruption affects community interactions and stability. Using ecological network approaches, we analyze pollination and seed dispersal interactions across forests with and without this mutualism and in areas impacted by non-native ungulates. and reduces community resilience.

Ph.D thesis of Agustin Vitali.

Ungulates are important agents of natural selection in different ecosystems. Through herbivory, ungulates can alter the phenotype of plants and their fitness. In general, browsed plants tend to be smaller, produce fewer flowers and fruits, and often show higher mortality than plants protected from herbivory. In addition, herbivory by ungulates can alter the quality of remaining plant tissues as food and shelter for other organisms by selecting for traits associated with resistance or tolerance to herbivory. The main objective of this project is to evaluate evidence of divergence in response to herbivory by introduced ungulates in populations of Aristotelia chilensis (Maqui), one of the most abundant understory species in the temperate forests of Patagonia. We also examine the potential direct and indirect effects of these changes on the structure and composition of above- and below-ground arthropod communities, as well as on key ecosystem processes mediated by variation in plant tissue quality.

Funded by the Agencia de Promoción Científica FONCyT (FONCyT PICT 2016-6560). 

This project focuses on the spatial and temporal dynamics of aerial parasitic plants (mistletoes), which rely on host plants for establishment and are dispersed by animals. The spatial distribution of both host trees and parasitic plants can strongly influence the behavior of seed dispersers. In turn, the interaction between landscape structure and animal behavior can shape the future spatial distribution of parasitic plants. Moreover, parasite–host interactions generate reciprocal effects between both populations, creating an ideal system for studying the spatial dynamics of interacting species. Understanding these dynamics requires detailed empirical data collected at multiple spatial and temporal scales. The main objective of this project is to study the spatial and temporal population dynamics of parasites and hosts, focusing on the aerial parasitic plant Tristerix corymbosus (“Quintral”, Loranthaceae) and its host plants. This mistletoe is a keystone species, that interacts with numerous plant and animal species, and plays an important role in Patagonian temperate forests.

Funded by the Agencia de Promoción Científica FONCyT (PICT 2011-1899). PI: Yamila Sasal.

We study one of the major environmental challenges associated with exotic conifer plantations: the spread of wilding trees beyond plantation boundaries. The objective of this project was to generate baseline information on both the ecological impacts of these invasions and the effectiveness of their management. This knowledge is essential for the conservation of native ecosystems and for promoting the long-term sustainability of the regional forestry sector. To addressed these questions, we evaluated multiple ecosystem components in native forests, pine-invaded areas, and sites where invasive pines had been removed through management actions. Specifically, we assessed plant and insect biodiversity, fuel structure, pest incidence, soil aerobic respiration, and litter decomposition rates associated with pine invasions. 

Funded by Ministerio de Agricultura, Ganadería y Pesca de la Nación. 

Disturbances play an important role in shaping natural communities by influencing biodiversity and ecological interactions. These events can modify species richness, abundance, and composition across multiple trophic levels and, consequently, alter the intensity and structure of plant-animal interactions. Thus, disturbances affect not only community composition but also the relationships among species within ecological assemblages. Understanding how multiple disturbances interact is particularly important, as their combined effects cannot always be predicted from the study of individual disturbances alone. In the Andean-Patagonian forests of South America, the most frequent disturbances include wildfires and grazing by exotic mammals such as cattle. The main objective of my Ph.D. research was to evaluate the effects of fire and post-fire cattle grazing on several ecological processes. Specifically, I assessed their impacts on ground-dwelling arthropod biodiversity, levels of foliar herbivory by insects, plant-pollinator interactions, and fruit and seed predation. This research was conducted in Nahuel Huapi National Park, near “Lago Espejo” in a forest area that burned in 1999.

Founded by CONICET, UNCOMA, FONCyT (PICT).