Browsing by Author "Ibarra, Jose Tomas"

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    Becoming tree, reconstructing memory: biocultural networks in pewen (Araucaria araucana) landscapes of the southern Andes
    (2024) Ibarra, Jose Tomas; Cortes, Josefina; Petitpas, Robert; Barreau, Antonia; Caviedes, Julian; Orrego, Gabriel; Riquelme-Maulen, Wladimir; Altamirano, Tomas A.
    Relationships between people and trees are continually unfolding in the contexts of si-tuated social-ecological systems. In current studies on social-ecological systems linked with trees, we commonly find two approaches: the first focuses on 'biological entities', examining the ecological dynamics of tree species and associated biodiversity. The se-cond approach focuses on people, analyzing 'human agency' along with historical and contemporary political or other forces shaping human-tree relationships. In this paper, we explore social-ecological systems associated with the Pewen (Araucaria araucana), one of the most iconic and sacred trees from the southern Andes. We first describe some of our own research findings on Pewen for both approaches described above. We then develop a third perspective, that we call 'relational', which highlights biocultural rela-tions and has the potential to overcome both the 'ecological/social' and the 'biological entity/human agency' dichotomies. Our relational approach allows a closer enquiry on how actors (e.g. trees and their seeds, wildlife, and people, among others) interact in complex and sympoietic biocultural networks, recognizing the biocultural memory of the system that emerges as an on-going complex of dynamics relations that must be enacted and performed on a daily basis. Furthermore, it stresses that people-pewen networks are continuously built and rebuilt in open systems subjected to historical and contemporary drivers of change
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    Ecosystem engineers show variable impacts on habitat availability for cavity nesters in South American temperate forests
    (2024) Lima, Cecilia Cuatianquiz; Altamirano, Tomas A.; Jara, Rocio; Price, Edwin R.; Novoa, Fernando J.; Ibarra, Jose Tomas
    Ecosystem engineers are organisms that impact their environment and co-existing species by creating or modifying habitats, and thus they play important roles as drivers of community assembly. We examined whether cavity characteristics and/or habitat attributes associated with cavities provided by 4 ecosystem engineers influence the presence of nests of 3 secondary cavity-nesting birds-Aphrastura spinicauda (Thorn-tailed Rayadito), Tachycineta leucopyga (Chilean Swallow), and Troglodytes aedon (Southern House Wren)-and whether these variations influence their reproductive success. We tested this by: (1) assessing nest presence in cavities supplied by ecosystem engineers and (2) quantifying the reproductive success of secondary cavity nesters as a function of cavity characteristics and habitat attributes supplied by ecosystem engineers. Between 2009 and 2022, we recorded 757 cavities in 546 trees in old-growth and second-growth forests in a Global Biodiversity Hotspot in the Andes of southern Chile. Insect/fungi and Pygarrhichas albogularis (White-throated Treerunner) play a key role as the primary producers of cavities. Insect/fungi generated the cavities for 82% of A. spinicauda nests and 95% of T. aedon nests; in contrast, 57% of T. leucopyga nests were cavities excavated by P. albogularis. Characteristics of cavities (size of cavity entrance, volume, and height above ground) were associated with nest presence of secondary cavity nesters and with reproductive success of A. spinicauda and T. aedon. Habitat attributes such as tree density and canopy cover influenced nest presence for A. spinicauda and T. leucopyga, but did not correlate with the reproductive success of any secondary cavity nester. Bamboo density and forest type were related to reproductive success of A. spinicauda and T. aedon. Diameter at Breast Height of trees was related to the reproductive success of T. leucopyga. This study contributes to understanding the importance of various ecosystem engineers for the conservation of secondary cavity-nesting birds in temperate forests and beyond.
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    Seed exchange networks: metrics for examining the resilience of social-ecological agricultural systems
    (2024) Barrera, Maria Guadalupe; Ibarra, Jose Tomas
    Agricultural systems are dynamic social-ecological systems which are rarely examined under relational approaches. The analysis of seed exchange networks represents a growing empirical pathway to relational thinking for examining the resilience of social-ecological agricultural systems and their dynamic cycles. We conducted a literature review to (i) explore the advances of seed exchange network research, and (ii) identify and synthesize the network metrics used for examining social-ecological structures linking human and other-than-human actors to understand the resilience of agricultural systems. Complementarily, we explored what a relational approach to seed exchange network analysis might entail. Our work shows a growing use of network analysis to explore coupled social-ecological relations in agricultural systems. However, in the past quarter century, most seed exchange case studies often omitted the inherent relational nature of network data and lacked recognition of the agency of other-than-human entities in seed exchange networks. We identified over 20 network metrics broadly used in network analysis, including structural and locational metrics such as 'density', 'modularity', and 'centrality'. These metrics have the potential to inform about the dynamics that may either enhance or constrain the resilience of agricultural systems. For example, 'density' and 'centrality' can reveal pathways of agrobiodiversity access and key actors, respectively. This information may enhance the efficiency of agrobiodiversity flows in agricultural systems. Finally, we discuss some practical implications of adopting a relational approach to seed exchange network analysis to better understand people-agrobiodiversity relations under local, regional, and global changes.
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    Social-ecological resilience: Knowledge of agrobiodiversity by campesinos and migrants in the face of global changes
    (2024) Ibarra, Jose Tomas; Caviedes, Julian; Monterrubio-Solis, Constanza; Barreau, Antonia; Marchant, Carla
    There is concern that agrobiodiversity is being irreversibly eroded in the face of agricultural industrialization. While academic and policy debates stress loss of landraces, little attention has been paid to evaluating how agricultural knowledge systems endure in response to broader social-ecological changes (i.e., "system's resilience"). For being resilient, agricultural knowledge systems should incorporate new information (modern seed varieties) whilst maintaining its traditional components (landraces) and functions. However, the loss or continuing utilization of landraces may be influenced by several social-ecological filters, which are processes that selectively remove varieties according to their phenotype, local uses, or value. We examined the resilience of agricultural knowledge systems in the southern Andes. These systems include the knowledge of landraces and modern varieties by campesinos and lifestyle migrants. We further assessed the association of social-ecological filters with the knowledge of agrobiodiversity. Over four years (2018-2022), we used mixed-methods including semi-structured interviews with gardener experts and conducted knowledge exercises of seed varieties and surveys of gardeners (n = 132). We assessed the association of 'knowledge score on varieties' (general, landraces, and modern) with a priori-defined social-ecological filters. Gardeners with more proficient knowledge of landraces were more knowledgeable of modern varieties too. The general knowledge of agrobiodiversity and the knowledge of landraces, but not of modern varieties, was higher for campesinos than migrants. The main seed source of gardeners, the participation in seed exchanges, gardeners' origin, and gardeners' age were the social-ecological filters that influenced gardeners ' knowledge of agrobiodiversity. We highlight that socialecological, small-scale farming systems, are being resilient when they have the capacity of incorporating new information (knowledge of modern varieties) whilst maintaining their identity (knowledge of landraces) without undergoing a major shift in their basic structures and functions in this Important Agricultural Heritage Site and Global Biodiversity Hotspot, and beyond.