Abstract
The occurrence of short-interval, severe wildfires are increasing drastically at a global scale, and appear as a novel phenomenon in areas where fire historically returns in large time lapses. In forest ecosystems, these events induce drastic changes in population dynamics, which could dramatically impact species diversity. Here, we studied the effect on diversity of recent short-interval, severe wildfires (SISF), which occurred in rapid succession in the summers of 2002 and 2015 in Chilean Northern Patagonian Araucaria–Nothofagus forests. We analyzed the diversity of deadwood-dependent (i.e., saproxylic) and fire-sensitive beetles as biological indicators across four conditions: 2002-burned areas, 2015-burned areas, SISF areas (i.e., burned in 2002 and again in 2015), and unburned areas. Saproxylic beetles were collected using window traps in 2017 to 2019 summer seasons. To investigate the mechanisms underpinning the fire-related disturbance of the assemblage, we evaluated the effects of post-fire habitat quality (e.g., dead wood decomposition) and quantity (e.g., burned dead wood volume and tree density) on the abundances and species richness of the entire assemblage and also multiple trophic groups. Compared with the unburned condition, SISF drastically reduced species richness, evenness, and Shannon’s diversity and altered the composition of the saproxylic beetle assemblages. The between-condition variation in composition was accounted for by a species replacement (turnover) between SISF and 2015-burned areas, but both species replacement and extinction (nestedness) between SISF and unburned areas. Dead wood decomposition and tree density were the variables with the strongest effects on the abundance and species richness of the entire saproxylic beetle assemblage and most trophic groups. These results suggest that SISF, through degraded habitat quality (dead wood decomposition) and quantity (arboreal density), have detrimental impacts on diversity and population dynamics of saproxylic beetle assemblages. Therefore, habitat loss is a central mechanism underpinning fire-related biodiversity loss in these forest ecosystems.
Highlights
Climate change and human activities have induced significant alterations in wildfire dynamics at the global scale
All analyses were pIenrftohrme 7ed9 isnamR vp.3li.n6.g3s(RacCroorsesTtehaemb, u20r2n0e)d. , reburned, and unburned Araucaria–Nothofagus forest, we collected a total of 7957 individuals of saproxylic beetles belonging to 42 families.3I.nReasdudltistion, we registered a total of 253 species/morpho-species, where the most abun3.d1.aSnatpsropxeycliiceBsewetleerCeaAtcrhaucarius minor Kuschel, 1966 (Curculionidae; 3315 individuals) and EnicImn uthsetr7a9nssavmeprsliinthgosraacxroDssatjohezb1u9r6n7ed(L, raetbruidrniiedda, ea;n1d1u8n5biunrdnievdidAuraaulcsar(isae–eNSotuhpofpagluesmentary forest, we collected a total of 7957 individuals of saproxylic beetles belonging to 42 families
This work provides novel evidence of the negative effects of short-interval, severe wildfires on forests that are not well-adapted to resist these disturbances
Summary
Climate change and human activities have induced significant alterations in wildfire dynamics at the global scale. The occurrence of high-severity events in forest ecosystems has steeply increased over the last few decades [1–4]. The time interval between consecutive fires (“fire return”) is becoming shorter across different forest ecosystems [5,6]. Such short-interval, severe wildfires (hereafter referred to as SISF) constitute a compound disturbance in reburned areas [7–9]. Fire returns are crucial for the population dynamics in many forest ecosystems [10]. The response capacity of these ecosystems has been largely exceeded under the current global warming scenario [11,12]. Wildfires are becoming more frequent in areas where large fires have been historically less frequent, resulting in an increased risk of habitat loss [12,13]. SISF have recently become a focus of interest for ecology due to their additive effects on forest ecosystems [8,12,14–16]
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