Dataset Information

Empirical relationships between tree fall and landscape-level amounts of logging and fire.

ABSTRACT: Large old trees are critically important keystone structures in forest ecosystems globally. Populations of these trees are also in rapid decline in many forest ecosystems, making it important to quantify the factors that influence their dynamics at different spatial scales. Large old trees often occur in forest landscapes also subject to fire and logging. However, the effects on the risk of collapse of large old trees of the amount of logging and fire in the surrounding landscape are not well understood. Using an 18-year study in the Mountain Ash (Eucalyptus regnans) forests of the Central Highlands of Victoria, we quantify relationships between the probability of collapse of large old hollow-bearing trees at a site and the amount of logging and the amount of fire in the surrounding landscape. We found the probability of collapse increased with an increasing amount of logged forest in the surrounding landscape. It also increased with a greater amount of burned area in the surrounding landscape, particularly for trees in highly advanced stages of decay. The most likely explanation for elevated tree fall with an increasing amount of logged or burned areas in the surrounding landscape is change in wind movement patterns associated with cutblocks or burned areas. Previous studies show that large old hollow-bearing trees are already at high risk of collapse in our study area. New analyses presented here indicate that additional logging operations in the surrounding landscape will further elevate that risk. Current logging prescriptions require the protection of large old hollow-bearing trees on cutblocks. We suggest that efforts to reduce the probability of collapse of large old hollow-bearing trees on unlogged sites will demand careful landscape planning to limit the amount of timber harvesting in the surrounding landscape.

SUBMITTER: Lindenmayer DB

PROVIDER: S-EPMC5825053 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Empirical relationships between tree fall and landscape-level amounts of logging and fire.

Lindenmayer David B DB Blanchard Wade W Blair David D McBurney Lachlan L Stein John J Banks Sam C SC

PloS one 20180223 2

Large old trees are critically important keystone structures in forest ecosystems globally. Populations of these trees are also in rapid decline in many forest ecosystems, making it important to quantify the factors that influence their dynamics at different spatial scales. Large old trees often occur in forest landscapes also subject to fire and logging. However, the effects on the risk of collapse of large old trees of the amount of logging and fire in the surrounding landscape are not well un ...[more]

PMID: 29474487

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Project description:Wildland fires are a dominant disturbance on Earth. On the local scale, fire activity is also influenced by species-specific fire behaviour of leaf litter beds. Thus, researchers strive to identify plant functional traits governing fire behaviour. The currently accepted relationships between morphological characteristics of the individual particles, fuel bed structure and resulting fire behaviour have been established on freshly constructed leaf litter beds. To investigate to what degree these relationships are altered upon exposure of constructed leaf litter beds to outside weather conditions, a novel testing system was designed. It enables outdoor exposure of the constructed litter beds, their subsequent retrieval and fire behaviour testing without disturbing the sample structure. Two treatments were applied on seven monospecific leaf litters. "Fresh treatment" corresponded to the common practice of testing fire behaviour directly after fuel bed construction. In the "settled treatment" constructed fuel beds were exposed for 30 days to outside weather conditions before being tested. The "settled treatment" was designed to address physical changes in the fuel bed structure which occur due to repeated wetting of the fuel bed. Thus, to minimise the effects of decomposition and fragmentation, winter exposure was chosen. Within the "fresh treatment" previously established relationships between size, curl, bulk density and fire behaviour characteristics could be confirmed. In the "settled treatment" the majority of these relationships lost their significance. The "settled treatment" had significantly lower bulk density (BD), rate of spread, maximum flame height and maximum sand temperature at 1 cm depth; and significantly higher flaming duration and amount of unburned residues compared to the "fresh treatment". Species with low initial BD were more affected by the treatment than species with high initial BD. The abrupt change in the fire behaviour of some leaf litter beds and the loss of numerous relationships between morphological characteristics of the individual particles and fire behaviour characteristics upon settled treatment indicate that fast occurring changes in the fuel bed structure should be taken into consideration if we are to understand the relationships between functional traits and local fire activity.

Dataset Information

Empirical relationships between tree fall and landscape-level amounts of logging and fire.

Publications

Empirical relationships between tree fall and landscape-level amounts of logging and fire.

Similar Datasets

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