Nurturing resilient forest biodiversity: nest webs as complex adaptive systems

Abstract

Forests are complex adaptive systems in which properties at higher levels emerge from localized networks of many entities interacting at lower levels, allowing the development of multiple ecological pathways and processes. Cavity-nesters exist within networks known as "nest webs" that link trees, excavators, e.g. woodpeckers, and nonexcavators (many songbirds, ducks, raptors, and other organisms) at the community level. We use the idea of panarchy (interacting adaptive cycles at multiple spatio-temporal scales) to expand the nest web concept to levels from single tree to biome. We then assess properties of nest web systems (redundancy, heterogeneity, memory, uncertainty, and nonlinearity) using examples from our studies in temperate, subtropical, and tropical forests of the Americas. Although nest webs from Chile, Canada, Argentina, and Ecuador have independent evolutionary histories, structures, and disturbance regimes, they share the main properties of complex adaptive systems. Heterogeneity, redundancy, and memory allow nest web systems to absorb some degree of disturbance without undergoing a regime shift; that is, without changing their basic structures and functions, i.e., the system's identity. Understanding nest webs as complex adaptive systems will inform management practices to nurture the resilience of forest biodiversity in the face of local, regional, and global social-ecological changes.

Large trees and decay: Suppliers of a keystone resource for cavity‐using wildlife in old‐growth and secondary Andean temperate forests

“…We found that tree density was much higher in secondary than in old-growth forest stands and the density of dead trees was comparable for both forest types. However, the density of cavity-bearing trees was much higher in old-growth forests, indicating the importance of these structurally complex stands as habitat for cavity-using wildlife in temperate ecosystems (Zenner 2004;Bunnell 2013;Caviedes & Ibarra 2017;Ibarra et al 2020).…”

“…However, the density of cavity‐bearing trees was much higher in old‐growth forests, indicating the importance of these structurally complex stands as habitat for cavity‐using wildlife in temperate ecosystems (Zenner 2004; Bunnell 2013; Caviedes & Ibarra 2017; Ibarra et al . 2020).…”

Coupling people and nature: social-ecological filters of beetle functional diversity in local campesino and migrant homegardens of the southern Andes

“…This result associates with the observed steep relationship between beetle species richness and functional richness, in relation to a random expectation, that started to saturate with relatively high beetle richness 48,49 . This nding suggest that homegardens with high functionally redundancy will be more resilient to shifts in social-ecological lters [50][51][52] .…”

“…Structurally complex homegardens will not only increase the functional niche space lled by species in beetle communities and enhance bene cial organisms, such as pest-control predators, pollinators, and seed dispersers 13 , they will also be more important carbon sinks than those that are structurally simpli ed and lack trees 73 . In a complexity science context, this result suggests that these small-scale systems have a social-ecological memory in which older and structurally complex homegardens act as long-lived system entities whose presence continues to in uence compositional, structural, and functional states of the system over time 51 .…”

Construction and Metabolism of Cultural Landscapes for Sustainability in the Anthropocene

“…In the last 50 years, a paradigm shift has occurred in science with the emergence of the paradigm of complexity [9], and so-called complexity science, in which the study object evolved from separate components to a focus on the whole [10][11][12]. This shift has meant that many researchers no longer focus on linear and deterministic processes but rather on self-organized networks of interactive actors that give rise to complex systems [13][14][15]. This approach tried to overcome the limitations of mainstream scientific knowledge, which posits the objectivity of scientific truths, acknowledging the need for a comprehensive and contextual approach dealing with uncertainties [8,10,16,17].…”