A roadmap for pyrodiversity science Steel, Zachary L.; Miller, Jesse E. D.; Ponisio, Lauren C. ...
Journal of biogeography,
February 2024, 2024-02-00, 20240201, Letnik:
51, Številka:
2
Journal Article
Recenzirano
Background
Contemporary and projected shifts in global fire regimes highlight the importance of understanding how fire affects ecosystem function and biodiversity across taxa and geographies. ...Pyrodiversity, or heterogeneity in fire history, is often an important driver of biodiversity, though it has been largely overlooked until relatively recently. In this paper, we synthesise previous research to develop a theoretical framework on pyrodiversity–biodiversity relationships and propose future research and conservation management directions.
Theoretical Framework
Pyrodiversity may affect biodiversity by diversifying available ecological niches, stabilising community networks and/or supporting diverse species pools available for post‐fire colonisation. Further, pyrodiversity's effects on biodiversity vary across different spatial, temporal and organismal scales depending on the mobility and other life history traits of the organisms in question and may be mediated by regional eco‐evolutionary factors such as historical fire regimes. Developing a generalisable understanding of pyrodiversity effects on biodiversity has been challenging, in part because pyrodiversity can be quantified in various ways.
Applying the Pyrodiversity Concept
Exclusion of Indigenous fire stewardship, fire suppression, increased unplanned ignitions and climate change have led to dramatic shifts in fire regimes globally. Such shifts include departures from historic levels of pyrodiversity and add to existing challenges to biodiversity conservation in fire‐prone landscapes. Managers navigating these challenges can be aided by targeted research into observed contemporary pyrodiversity–biodiversity relationships as well as knowledge of historical reference conditions informed by both Indigenous and local ecological knowledge and western science.
Future Research Directions
Several promising avenues exist for the advancement of pyrodiversity science to further both theoretical and practical goals. These lines of investigation include but are not limited to (1) testing the increasing variety of pyrodiversity metrics and analytical approaches; (2) assessing the spatial and temporal scale‐dependence of pyrodiversity's influence; (3) reconstructing historical pyrodiversity patterns and developing methods for predicting and/or promoting future pyrodiversity; and (4) expanding the focus of pyrodiversity science beyond biodiversity to better understand its influence on ecosystem function and processes more broadly.
Cognitive interventions involving visuospatial tasks, such as the game "Tetris" have demonstrated efficacy in reducing the frequency of intrusive memories. However, it remains unclear whether these ...tasks also reduce the perceived intensity and distress of these memories. We investigated whether either of two visuospatial tasks: a Tetris intervention or Digital Corsi task, following the viewing of an analog trauma (film) resulted in decreased intensity and distress for intrusive memories over the following week, when compared to a control condition. Participants (
= 110) were randomly assigned to task conditions after viewing the film. Linear mixed models indicated no between-group differences for reductions in intensity or distress over the course of the week. These findings highlight an important boundary to the benefits of such visuospatial tasks, in that while they may be associated with reductions in intrusion memory frequency, individuals may nonetheless continue to experience distress when intrusions do occur.
Budgets for species conservation limit actions. Expending resources in areas of high human density is costly and generally considered less likely to succeed. Yet, coastal California contains both a ...large fraction of narrowly endemic at-risk plant species as well as the state's three largest metropolitan regions. Hence understanding the capacity to protect species along the highly urbanized coast is a conservation priority. We examine at-risk plant populations along California's coastline from San Diego to north of San Francisco to better understand whether there is a relationship between human population density and: i) performance of at-risk plant populations; and ii) conservation spending. Answering these questions can help focus appropriate strategic conservation investment. Rare plant performance was measured using the annualized growth rate estimate between census periods using the California Natural Diversity Database. Human density was estimated using Census Bureau statistics from the year 2000. We found strong evidence for a lack of a relationship between human population density and plant population performance in California's coastal counties. Analyzing US Endangered Species expenditure reports, we found large differences in expenditures among counties, with plants in San Diego County receiving much higher expenditures than other locations. We found a slight positive relationship between expenditures on behalf of endangered species and human density. Together these data support the argument that conservation efforts by protecting habitats within urban environments are not less likely to be successful than in rural areas. Expenditures on behalf of federally listed endangered and threatened plants do not appear to be related to proximity to human populations. Given the evidence of sufficient performance in urban environments, along with a high potential to leverage public support for nature in urban environments, expenditures in these areas appear to be an appropriate use of conservation funds.
Frequent‐fire forests were once heterogeneous at multiple spatial scales, which contributed to their resilience to severe fire. While many studies have characterized historical spatial patterns in ...frequent‐fire forests, fewer studies have investigated their temporal dynamics. We investigated the influences of fire and climate on the timing of conifer recruitment in old‐growth Jeffrey pine‐mixed conifer forests in the Sierra San Pedro Martir (SSPM) and the eastern slope of the Sierra Nevada. Additionally, we evaluated the impacts of fire exclusion and recent climate change on recruitment levels using statistical models with realized as well as fire suppression and climate change‐free counterfactual scenarios. Excessive soil drying from anthropogenic climate change resulted in diminished recruitment in the SSPM but not in the Sierra Nevada. Longer fire‐free intervals attributable to fire suppression and exclusion resulted in greater rates of recruitment across all sites but was particularly pronounced in the Sierra Nevada, where suppression began >100 years ago and recruitment was 28 times higher than the historical fire return interval scenario. This demonstrates the profound impact of fire's removal on tree recruitment in Sierra Nevada forests even in the context of recent climate change. Tree recruitment at the SSPM coincided with the early‐20th‐century North American pluvial, as well as a fire‐quiescent period in the late 18th and early 19th centuries. Episodic recruitment occurred in the SSPM with no “average” recruitment over the last three centuries. We found that temporal heterogeneity, in conjunction with spatial heterogeneity, are critical components of frequent‐fire‐adapted forests. Episodic recruitment could be a desirable characteristic of frequent‐fire‐adapted forests, and this might be more amenable to climate change impacts that forecast more variable precipitation patterns in the future. One key to this outcome would be for frequent fire to continue to shape these forests versus continued emphasis on fire suppression in California.
Wildfires in many western North American forests are becoming more frequent, larger, and severe, with changed seasonal patterns. In response, coniferous forest ecosystems will transition toward ...dominance by fire‐adapted hardwoods, shrubs, meadows, and grasslands, which may benefit some faunal communities, but not others. We describe factors that limit and promote faunal resilience to shifting wildfire regimes for terrestrial and aquatic ecosystems. We highlight the potential value of interspersed nonforest patches to terrestrial wildlife. Similarly, we review watershed thresholds and factors that control the resilience of aquatic ecosystems to wildfire, mediated by thermal changes and chemical, debris, and sediment loadings. We present a 2‐dimensional life history framework to describe temporal and spatial life history traits that species use to resist wildfire effects or to recover after wildfire disturbance at a metapopulation scale. The role of fire refuge is explored for metapopulations of species. In aquatic systems, recovery of assemblages postfire may be faster for smaller fires where unburned tributary basins or instream structures provide refuge from debris and sediment flows. We envision that more‐frequent, lower‐severity fires will favor opportunistic species and that less‐frequent high‐severity fires will favor better competitors. Along the spatial dimension, we hypothesize that fire regimes that are predictable and generate burned patches in close proximity to refuge will favor species that move to refuges and later recolonize, whereas fire regimes that tend to generate less‐severely burned patches may favor species that shelter in place. Looking beyond the trees to forest fauna, we consider mitigation options to enhance resilience and buy time for species facing a no‐analog future.
Wildfires in many western North American forests are becoming more frequent, larger, and more severe due to changes in climate and past fire suppression. We propose a new life history framework for wildlife response to frequency, intensity, and patch size of wildfire disturbances. Finally, we consider forest management strategies that might enhance the resilience of wildlife under transient future conditions.
Ecological disturbance regimes across the globe are being altered via direct and indirect human influences. Biodiversity loss at multiple scales can be a direct outcome of these shifts. Fire, ...especially in dry forests, is an ecological disturbance that is experiencing dramatic changes due to climate change, fire suppression, increased human population in fire‐prone areas, and alterations to vegetation composition and structure. Dry western conifer forests that historically experienced frequent, low‐severity fires are now increasingly burning at high severity. Relatively little work has been done looking at the effects of this novel disturbance type on affected plant communities, and little is known about how these impacts change over time. To fill in these knowledge gaps, we examined a fire that burned in a yellow pine and mixed conifer forest in the central Sierra Nevada in California, USA. We sampled at five time steps across the nine years following the fire (1, 3, 5, 8, and 9 years postfire). We found a generally unimodal relationship between fire severity and plant alpha and gamma diversity, but found that areas that burned at high severity supported progressively lower plant diversity as time since fire increased. Similarly, beta diversity decreased drastically through time for the high‐severity areas, while remaining more static in the other severity classes. The combination of these findings indicates that significant floristic homogenization can result from high‐severity fire in this ecosystem type. We also saw consistently lower diversity in unburned areas in comparison to area burned at low and moderate severity, underlining that both lack of fire and high‐severity fire can have negative impacts on postfire plant diversity. Unburned areas that experienced forest thinning after the first sample year saw an increase in plant diversity over time, suggesting that some—but not all—of the effects of fire on plant diversity can be approximated through forest management.
Children and adolescents, who account for most of the world's refugees, have an increased prevalence of psychological disorders. The mental health of refugee children is often associated with the ...severity of post-traumatic stress disorder (PTSD) in their caregivers. Despite the potential for refugee caregivers' PTSD to affect child mental health, little evidence exists concerning the underlying mechanisms of this association. This study tested the effect of refugee caregivers' previous trauma and levels of ongoing stressors on current PTSD, and in turn how this influences parenting behaviour and consequent child psychological health.
This cohort study recruited participants from the Building a New Life in Australia study, a population-based prospective cohort study of refugees admitted to 11 sites in Australia between October, 2013, and February, 2014. Eligible participants were aged 18 years or older and the principal or secondary applicant (ie, the refugee applicant within a migrating family unit) for a humanitarian visa awarded between May, 2013, and December, 2013. Primary caregiver PTSD and postmigration difficulties were assessed at Wave 1 (in 2013), and caregiver PTSD was reassessed at Wave 2 (in 2014). At Wave 3, between October, 2015, and February, 2016, primary caregivers repeated measures of trauma history, postmigration difficulties, probable PTSD, and harsh and warm parenting style, and completed the Strengths and Difficulties Questionnaire for their child. We used path analysis to investigate temporal patterns in PTSD, trauma history, postmigration stressors, parenting style, and children's psychological difficulties.
The current data comprised 411 primary caregivers who provided responses in relation to at least one child (660 children). 394 primary caregivers with 639 children had data on independent variables and were included in the final model. Path analyses revealed that caregivers' trauma history and postmigration difficulties were associated with greater subsequent PTSD, which in turn was associated with greater harsh parenting and in turn, higher levels of child conduct problems (β=0·049, p=0·0214), hyperactivity (β=0·044, p=0·0241), emotional symptoms (β=0·041, p=0·0218), and peer problems (β=0·007, p=0·047). There was also a direct path from primary caregiver PTSD to children's emotional problems (β=0·144, p=0·0001).
PTSD in refugees is associated with harsh parenting styles, leading to adverse effects on their children's mental health. Programmes to enhance refugee children's mental health should account for PTSD in parents and caregivers, and the parenting behaviours that these children are exposed to.
National Health and Medical Research Council.
High-income countries like Australia play a vital role in resettling refugees from around the world, half of whom are children and adolescents. Informed by an ecological framework, this study ...examined the post-migration adjustment of refugee children and adolescents 2-3 years after arrival to Australia. We aimed to estimate the overall rate of adjustment among young refugees and explore associations with adjustment and factors across individual, family, school, and community domains, using a large and broadly representative sample.
Data were drawn from Wave 3 of the Building a New Life in Australia (BNLA) study, a nationally representative, longitudinal study of settlement among humanitarian migrants in Australia. Caregivers of refugee children aged 5-17 (N = 694 children and adolescents) were interviewed about their children's physical health and activity, school absenteeism and achievement, family structure and parenting style, and community and neighbourhood environment. Parent and child forms of the Strengths and Difficulties Questionnaire (SDQ) were completed by caregivers and older children to assess social and emotional adjustment.
Sound adjustment according to the SDQ was observed regularly among young refugees, with 76-94% (across gender and age) falling within normative ranges. Comparison with community data for young people showed that young refugees had comparable or higher adjustment levels than generally seen in the community. However, young refugees as a group did report greater peer difficulties. Bivariate and multivariate linear regression analyses showed that better reported physical health and school achievement were associated with higher adjustment. Furthermore, higher school absenteeism and endorsement of a hostile parenting style were associated with lower adjustment.
This is the first study to report on child psychosocial outcomes from the large, representative longitudinal BNLA study. Our findings indicate sound adjustment for the majority of young refugees resettled in Australia. Further research should examine the nature of associations between variables identified in this study. Overall, treating mental health problems early remains a priority in resettlement. Initiatives to enhance parental capability, physical health, school achievement and participation could assist to improve settlement outcomes for young refugees.
What are the deleterious effects of mass trauma on the psychological wellbeing of refugees and other war-affected populations? Most epidemiological data are for short-to-medium term effects, leaving ...the possibility that early psychological reactions could reduce naturally over time. We aimed to assess the long-term effects of trauma on mental health and disability in Vietnamese refugees resettled in Australia.
In a population-based study, we identified a community sample of 1413 adult Vietnamese from census collection areas in Sydney, Australia. Participants were interviewed by trained bilingual workers who administered questionnaires to assess the frequency of international classification of disease, version 10 (ICD-10) mental disorders in the 12 months before interview; psychiatric symptoms, by use of a culturally-sensitive symptom measure; exposure to psychologically traumatic events; disability and use of health services; and social, economic, and cultural factors since migration. We did multivariate analyses with adjustment for stressors since migration to establish the risk factors for mental illness.
1161 (82%) adults completed the interview. Mean length of residence in Australia was 11·2 years (SD 14·4) and mean time since the most severe traumatic event was 14·8 years (SD 10·8). 95 (8%) and 75 (7%) of participants had mental disorders defined by ICD-10 and the culturally-sensitive measure, respectively. Trauma exposure was the most important predictor of mental health status. Risk of mental illness fell consistently across time. However, people who had been exposed to more than three trauma events (199) had heightened risk of mental illness (23, 12%) after 10 years compared with people with no trauma exposure (13, 3%) (odds ratio 4·7, p<0·0001, 95% Cl 2·3–9·5).
Most Vietnamese refugees were free from overt mental ill health. Trauma-related mental illness seemed to reduce steadily over time, but a subgroup of people with a high degree of exposure to trauma had long-term psychiatric morbidity. Our findings support the need to develop specialised mental health services to reduce disability in refugees whose exposure to extreme trauma puts them at risk of chronic psychiatric disability.
•Diversity is higher in remnant habitats and ecotones than large vineyard blocks.•Landscape composition and patch shape are important predictors of species presence.•Fragmenting vineyard blocks and ...Increasing edge habitat may benefit many species.•Some species likely require large tracts of intact natural habitat to persist.
The Mediterranean climate region of central Chile is rich in biodiversity and contains highly productive agricultural lands, which creates challenges for the preservation of natural habitats and native biodiversity. Ecological data and studies for the region are also limited, making informed conservation in agricultural landscapes difficult. The increasing availability of remotely sensed data provide opportunities to relate species occurrences to measures of landscape heterogeneity even when field measures of habitat structure are lacking. When working with such remotely sensed data, it’s important to select appropriate measures of heterogeneity, including common metrics of landscape composition as well as frequently overlooked shape metrics. In this contribution we combine bird surveys with multispectral satellite imagery to develop boosted regression tree models of avian species richness, and of habitat use for 15 species across a mixed vineyard-matorral landscape in central Chile. We found a range of associations between individual species and land cover types, with the majority of species occurring most frequently in remnant habitats and ecotones rather than the interiors of large vineyard blocks. Models identified both metrics of landscape composition and patch shape as being important predictors of species occurrence, suggesting that shape metrics can complement more commonly used metrics of landscape composition. Vineyards that include corridors or islands of remnant habitat among vine blocks may increase the amount of area available to many species, although some species may still require large tracts of intact natural habitat to persist.
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