Direct and indirect disturbance impacts on forest biodiversity

Abstract

Understanding the responses of biodiversity to forest disturbance is critical for maintaining ecosystem integrity and key ecological functions. Ecological research in forests after major disturbance typically focuses on the direct responses of individual species or communities, often with only limited consideration of the interactions between forest structure and biodiversity. Despite this, these interactions can mediate indirect disturbance impacts throughout forest ecosystems. Using data from a decade of extensive, empirical research, we employ structural equation modeling to quantify the direct and indirect impacts of multiple stand-replacing disturbances on elements of forest structure (basal area (BA) of dominant plant lifeforms and number of hollow-bearing trees) and on biodiversity (plant diversity, arboreal marsupials, and avifauna) in the southeastern Australian montane-ash forests. The number of stand-replacing disturbances resulted in a lower species richness and lower functional dispersion of avifauna and had a strong negative influence on the number of hollow-bearing trees. In contrast, the number of stand-replacing disturbances increased plant species richness in the understory, after controlling for the influence of stand age. In this ecosystem, we also found evidence of ecological interactions that mediated indirect impacts. For instance, disturbance-induced declines in the number of hollow-bearing trees had negative impacts on the richness of arboreal marsupials. Moreover, disturbance-induced increases in the richness of understory plants had positive impacts on avian richness, partially mitigating direct disturbance impacts. Our novel integrative study provides new insights into the mechanisms that underpin disturbance impacts in forests at the ecosystem level. This has enabled the development of a new conceptual model on forest responses to the number of stand-replacing disturbances. By exploring interactions between elements of biodiversity, forest structure, and disturbance, our model demonstrates how disturbance-induced changes in one measure can have cascading effects on another. This understanding will provide for an integrative approach to management and planning.

Rapid bird species recovery following high‐severity wildfire but in the absence of early successional specialists

“…This includes vigorous growth of Acacia spp. trees (Bowd, Blair, et al, 2021), which can be associated with the richness and functional diversity of birds (Bowd, Blanchard, et al, 2021). Species of Acacia provide foraging substrates and support populations of insect prey for some bird species (Woinarski & Cullen, 1984).…”

“…We summarized data on one morphological trait (body mass) and four life history traits: (1) diet (invertebrates, nectar, other), (2) foraging substrate (canopy/ understorey, ground), (3) social system (flocking or non‐flocking), and (4) migratory status (migratory, non‐migratory/resident) (see Table S4). We selected these traits because they can reflect the ability of species to respond to environmental change (Ikin et al, 2019; Rainsford et al, 2021), and because they relate to important ecological functions such as seed dispersal, pollination, insect control (diet and foraging substrate) (Bowd, Blanchard, et al, 2021; Ikin et al, 2019). We note that many bird life history traits are highly correlated (Ikin et al, 2019) and we therefore limited the number of life history attributes tested and examined each of them individually.…”

“…This includes vigorous growth of Acacia spp. trees (Bowd, Blair, et al, 2021), which can be associated with the richness and functional diversity of birds (Bowd, Blanchard, et al, 2021).…”

“…in the case of birds, foraging guild, body size, movement patterns) occurring among sets of species in a given ecosystem (Keddy & Laughlin, 2021). Disturbances such as wildfires may lead to species with disturbance-tolerant traits dominating an assemblage, lowering functional dispersion (the "breadth" of functional roles) (Bowd, Blanchard, et al, 2021). This contrasts with less disturbed communities where the distribution of traits may be more uniform (Ikin et al, 2019).…”

Historial de incendios basado en técnicas dendrocronológicas para un bosque de coníferas en la región sureste de Jalisco, México

“…Disturbance regimes, characterized by disturbance intensities and frequencies (Keeley & Pausas, 2019;Safford, Hayward, Heller, & Wiens, 2012), modify the structure and function of forest ecosystems and their resilience to future disturbances (Bowd, Blanchard, McBurney, & Lindenmayer, 2021;Keeley & Pausas, 2019;McLauchlan et al, 2020;Quintero-Gradilla, Jardel-Peláez, Cuevas-Guzmán, García-Oliva, & Martínez-Yrizar, 2019). In recent years, disturbance regimes in forests worldwide have been altered by varying climate conditions (Bowd et al, 2021;Seidl et al, 2017), anthropogenic interactions (Bowd et al, 2021;Watson et al, 2018), pathogen attacks (Sturrock et al, 2011), invasive species (Wardle & Peltzer, 2017) and increased fire frequency (Bowd et al, 2021;Keeley & Pausas, 2019;Schoennagel et al, 2017;Seidl, Schelhaas, Rammer, & Verkerk, 2014). According to Seidl et al (2017), future changes in disturbance are likely to be more prominent in coniferous forests and the boreal biome.…”