Post-fire salvage logging alters species composition and reduces cover, richness, and diversity in Mediterranean plant communities

Arco-Aguilar

et al. 2017

Forests

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Post-fire salvage logging (SL) is a common management action that involves the harvesting of burnt trees. As a consequence, a large amount of biological legacies in the form of logs and other coarse woody debris are removed from the post-fire habitat, creating a more simplified landscape. Therefore, SL could act as an additional disturbance over that produced by fire. In this study, we seek to determine the effect of SL on the regeneration of the bryophyte community of a laurel forest from the Canary Islands (Spain). We hypothesized that SL will act as an additional disturbance and, consequently, salvaged areas will have a higher difference in community composition with respect to a reference ecosystem (RE). Mosses and liverworts were sampled 22 months after the salvage operations in salvaged plots, non-salvaged, and in an RE represented by areas of the original forest. Species richness did not differ between salvage and non-salvaged treatments. However, multivariate analysis and species-indicator analysis showed that non-salvaged plots had a composition closer to that of the RE, with a higher proportion of closed-canopy, perennial, and long-lived species, as well as some epiphytes. By contrast, salvaged plots were dominated by early-successional terrestrial species and species preferring open habitats. We conclude that post-fire SL represents an additional disturbance that further delays succession, a result that is consistent with previous studies using other taxonomic groups. SL should therefore be avoided or, if implemented, the possibility of leaving part of the post-fire biological legacies in situ should be considered.

Section: Discussionmentioning

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Post-Fire Salvage Logging Imposes a New Disturbance that Retards Succession: The Case of Bryophyte Communities in a Macaronesian Laurel Forest

Hernández-Hernández

Arco-Aguilar

et al. 2017

Forests

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“…, Leverkus et al. ). The treatments created four habitats that differed in vertical structure, a parameter that exerts a strong effect on the foraging behavior of the European jay (Gómez , Castro et al.…”

Section: Methodsmentioning

confidence: 99%

Shifting demographic conflicts across recruitment cohorts in a dynamic post‐disturbance landscape

Leverkus

Benayas

2016

Ecology

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Seed dispersal effectiveness, which measures the number of adult plant individuals produced by seed dispersal, is the product of the number of seeds dispersed and the probability a seed produces an adult. Directed dispersal to certain habitat types may enhance some stages of recruitment but disfavor others, generating demographic conflicts in plant ontogeny. We asked whether temporal changes in habitat features may affect the distribution of seedlings recruited from dispersed acorns, and whether this could induce shifts in the life-stage conflicts experienced by successive cohorts of naturally recruited plants. As early successional habitats are characterized by rapid change, we used a burnt pine stand in southern Spain to monitor the recruitment and performance of a major tree species (Quercus ilex) across 7 yr in four types of post-fire habitats. These differed in structure and included patches of unburnt forest and three management alternatives of burnt trees: logging, partial cutting, and nonintervention. Young oaks that resprouted after the fire were mainly located near acorn sources, while new seedlings initially emerged mostly in habitats with standing snags due to habitat selection by European jays, Garrulus glandarius, for dispersal. The dead pines gradually collapsed and attracted less dispersal, so subsequent seedling cohorts mainly recruited within patches of unburnt pines. These live pines enhanced the survival of the oaks located beneath their canopy but greatly reduced their growth as compared to the other post-fire habitats, thus representing a demographic conflict that was absent elsewhere. As a consequence of the directional shift in the habitat where seedlings recruited, successive seedling cohorts experienced a gradual improvement in their likelihood of survival but a reduction in growth. The progressive intensification of this life-stage conflict hinged on the reduction of vertical structures in the habitat with standing burnt pines. Recruitment success thus involved temporal variation in the habitat where recruitment occurred, likely resulting from changes in the direction of seed dispersal, and spatial variation in habitat suitability for seedling establishment and growth. Temporal changes in habitat structure can indirectly change the environment in which recruitment occurs, and consequently seed dispersal effectiveness, by shifting the direction of seed dispersal.

“…It was a high-intensity crown fire that consumed all the leaves, twigs, and litter and charred the bark of the trunks [30]. After the fire, the Forest Service established three plots across an elevational gradient within the context of a long-term research program devoted to study the effect of salvage logging with respect to other post-fire burnt wood management alternatives on ecosystem restoration and regeneration ( [17,26,44]; Table 1). The three plots were similar in terms of pre-fire tree density (1000-1500 trees ha −1 ), fire intensity (high), bedrock (micaschist), aspect (southwest), soil type (haplic phaeozems), and other soil characteristics ( [30,45]; Table 1).…”

Section: Study Sitementioning

confidence: 99%

“…Throughout the time of decomposition, decaying wood provides shelter and habitat for a large number of organisms [1][2][3][4], guarantees nutrient availability and turnover [5][6][7], defines carbon residence time and sequestration [8,9], enhances soil moisture [10], and determines the vertical and horizontal physical structure of the habitat as snags or fallen logs [11][12][13][14]. All these processes, both singly and in synergic combination, deeply influence other ecosystem processes, ranging from the performance of individual plants to landscape-scale biodiversity and even biogeochemical cycles [15][16][17][18][19][20]. Knowledge of the factors that determine the rate of wood decomposition is therefore relevant for understanding the residence time of logs, with broad implications for numerous ecosystem functions and services [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Deadwood Decay in a Burnt Mediterranean Pine Reforestation

Molinas-González

Leverkus

2017

Forests

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Dead wood remaining after wildfires represents a biological legacy for forest regeneration, and its decay is both cause and consequence of a large set of ecological processes. However, the rate of wood decomposition after fires is still poorly understood, particularly for Mediterranean-type ecosystems. In this study, we analyzed deadwood decomposition following a wildfire in a Mediterranean pine plantation in the Sierra Nevada Natural and National Park (southeast Spain). Three plots were established over an elevational/species gradient spanning from 1477 to 2053 m above sea level, in which burnt logs of three species of pines were experimentally laid out and wood densities were estimated five times over ten years. The logs lost an overall 23% of their density, although this value ranged from an average 11% at the highest-elevation plot (dominated by Pinus sylvestris) to 32% at an intermediate elevation (with P. nigra). Contrary to studies in other climates, large-diameter logs decomposed faster than small-diameter logs. Our results provide one of the longest time series for wood decomposition in Mediterranean ecosystems and suggest that this process provides spatial variability in the post-fire ecosystem at the scale of stands due to variable speeds of decay. Common management practices such as salvage logging diminish burnt wood and influence the rich ecological processes related to its decay.