Device for the standard measurement of shoot flammability in the field

Fire ecology has been hindered by the lack of comparable, affordable protocols to quantify the flammability of whole plants over large numbers of species. We describe a low‐tech device that can be carried to the field and that allows highly standardized measurement of the flammability of whole individuals or portions up to 70 cm long. We illustrate its potential with results for 34 species belonging to different growth forms from central Argentina. The device consists of an 85 × 60 cm half‐cut metallic barrel placed horizontally and mounted on a removable metallic structure. It contains three parallel burners, a grill with an attached gauging thermometer and a blowtorch. Burners and blowtorch are connected to a propane–butane gas cylinder. Plant samples are placed on the grill and preheated with the burners for 2 min at 150°C. They are then ignited for 10 s with the blowtorch while the burners are kept on. Four parameters are measured for each sample: maximum temperature reached, burning time, burnt length and burnt biomass percentage. These parameters are used to construct a compound index of flammability for each sample that ranges between 0 (no flammability) and around 3 (maximum flammability). We obtained a wide range of values for flammability and all its components. Most of this variability was accounted for by differences between growth forms and species, rather than by differences at the level of replicates. This suggests that the device and protocol are sensitive enough to detect flammability differences among plants with different functional traits, and at the same time robust enough to produce consistent results among samples with similar traits. A major advantage is that plant architecture is kept almost intact, providing a flammability measure much closer to that of whole individuals in the field than those obtained by other standard protocols in use. The device and protocol presented here should facilitate the acquisition of comparable flammability data over large numbers of species from different floras and ecosystems, potentially contributing to several fields of research, such as functional ecology, evolutionary ecology and vegetation‐atmosphere modelling.     

Mating success of the endemic Des Murs’ Wiretail (Sylviorthorhynchus desmursii,Furnariidae) in fragmented Chilean rainforests

Abstract: We studied the effects of fragment size, vegetation structure and presence of habitat corridors on the reproductive success of the Des Murs’ Wiretail (Sylviorthorhynchus desmursii Des Murs, Furnariidae), a small (10 g) understorey bird, endemic to South American forests. In a rural landscape of Chiloé Island, southern Chile (42°S; 70°W), we determined the mating and nesting success of wiretails in 28 territories distributed in seven small (1–20 ha) and two large (>300 ha) forest fragments during the 1997–1998 breeding season. Wiretails inhabited dense bamboo thickets in the understorey of forest patches, dense shrublands covering old fields, and dense early successional forest vegetation. Wiretails avoided open pastures. Reproductive success depended solely on the probability of finding mates, and the main factor affecting mating success was the presence of corridors. Mated individuals occupied 72% of the territories in forest patches <20 ha connected by corridors, 73% of the territories in large (>300 ha) fragments, but only 20% of territories in isolated fragments surrounded by pastures. Because of the rapid expansion of pastures in southern Chile, the conservation of wiretails and other understorey birds will depend on the maintenance of travel corridors with dense understorey vegetation between forest fragments.