Soil characteristics and CO2 emissions of ex-burnt peatland in Kubu Raya District, West Kalimantan, Indonesia

Astiani D, Widiastuti T, Latifah S, Simatupang D. 2020. Soil characteristics and CO2 emissions of ex-burnt peatland in Kubu Raya District, West Kalimantan, Indonesia. Biodiversitas 21: 3691-3698. West Kalimantan, Indonesia has a large extent of tropical peatland with total ​​1.74 million ha with only 44.5% of such areas remaining as peat forest, while the rests have been converted into plantations, agricultural lands, and shrubs. The conversion of peat forest often uses fires to clear the vegetation and is followed by building canal to drain the water. The lack of vegetation combined with drought soil trigger uncontrolled escaped fire, especially in the dry season or El-Nino events, which is likely to affect soil characteristics and emit carbon dioxide. The purpose of this study is to examine the changes in soil characteristics both physical and chemical properties and to investigate CO2 emissions from peat soil post-fire. As a comparison, similar parameters were also assessed in non-burnt sites. The results showed significant differences in some peat soil characters both physically and chemically between ex-burnt and non-burnt peatland. The ex-burnt site had higher pH, available phosphorus and C/N ratio than those in the non-burnt site. Conversely, the total nitrogen and carbon contents, and cation exchange capacity were lower which is likely due to leaching. Peat fires also impacted physical characteristics of the soil such as increasing soil bulk density, reducing soil water content, soil temperature, especially in wet conditions. Carbon dioxide emissions in the ex-burnt site were considered higher than non-burnt site. These results could be brought out as a part of baseline data in managing ex-burnt peatlands to maintain a balance between carbon output and input and efforts on preventing peatland fires from becoming continuous carbon sources.

Summer fire in steppe habitats: long-term effects on vegetation and autumnal assemblages of cursorial arthropods

Being an essential driving factor in dry grassland ecosystems, uncontrolled fires can cause damage to isolated natural areas. We investigated a case of a small-scale mid-summer fire in an abandoned steppe pasture in northeastern Ukraine and focused on the post-fire recovery of arthropod assemblages (mainly spiders and beetles) and vegetation pattern. The living cover of vascular plants recovered in a year, while the cover of mosses and litter remained sparse for four years. The burnt site was colonised by mobile arthropods occurring in surrounding grasslands. The fire had no significant impact on arthropod diversity or abundance, but changed their assemblage structure, namely dominant complexes and trophic guild ratio. The proportion of phytophages reduced, while that of omnivores increased. The fire destroyed the variety of the arthropod assemblages created by the patchiness of vegetation cover. In the post-fire stage they were more similar to each other than at the burnt plot in the pre- and post-fire period. Spider assemblages tended to recover their pre-fire state, while beetle assemblages retained significant differences during the entire study period.

Short term effects of wild fire on invertebrates in coastal heathland in southeastern Australia

Differences in the assemblages of terrestrial arthropod communities in burnt and adjacent unburnt areas of coastal heathland are reported. The burnt site experienced a wildfire 20 months prior to sampling. Collections of invertebrates from pitfall traps in winter indicated that there was no difference in total species richness or total numbers of individuals trapped between burnt and unburnt plots. However, at species level, 60 percent of the taxa showed a strong preference for either burnt areas or unburnt areas with only a few species trapped in around equal numbers in both areas. Twenty percent of species were only found on the unburnt plots. The implications of these results for fire management are discussed.

Observations on survival and early growth of natural regeneration in floodplain coolibah Eucalyptus victrix (Myrtaceae) in the Pilbara, Western Australia

Observations are presented on the natural regeneration of Eucalyptus victrix L. Johnson and K. Hill (coolibah), the dominant tree species of grassy woodlands on the floodplain of the Fortescue River, north of Newman in the Pilbara district of Western Australia. The main objectives of this study were to examine: (i) survival of newly recruited E. victrix seedlings on flooded and burnt sites, and (ii) growth and survival of established plants in a gilgaied landscape. Populations of newly-recruited seedlings following flooding or fire were monitored opportunistically at 'Marillana' and 'Ethel Creek' stations, for up to two years from tagging. A population of saplings at 'Roy Hill' station was observed over eight years. Seedling densities of E. victrix in flooded sites were 0.32 and 1.03 plants/m2 in 1995 and 1997 respectively. Locally high densities reached from 1.2 to 17.7 plants/m2 on areas of 28 and 6 m2 respectively. At the burnt site at 'Ethel Creek', 1.30 plants/m2 were observed where 58 seedlings were recorded on an area of 445 m2 a year after a natural fire. Many of these persisted well into their second year, whereas seedlings recruited in the flooded sites generally lasted less than a year (250-376 days). In contrast, persistence of a cohort of 100 established saplings < 2 m tall in a gilgaied landscape at 'Roy Hill' was high. During 8 years of observations, only one sapling was lost. Those found at the edges of gilgais had attained greater heights (3.91 � 1.14 m) than saplings located inside (3.16 � 0.95 m) or on top (3.12 � 0.93 m) of the gilgais. This study demonstrates that the seedling stage in E. victrix is critical, in that once newly recruited individuals reach the sapling stage (0.611 m), mortality rates are much reduced. Unfortunately, it was not possible during the course of this study to locate a cohort of young seedlings that did survive and so any consideration of the conditions necessary for their survival is purely speculative.

Effects of Fire on Soil Macroinvertebrates in a Mediterranean Phryganic Ecosystem

The effect of a summer wildfire on the abundance and community composition of soil macroinvertebrates of a phryganic ecosystem was studied. The numerical responses of macroinvertebrates to fire were variable, most notably the reduction of the saprophagous fauna. The magnitude of the changes in abundance due to fire was comparable or even lower than the variations imposed by the seasonality of the mediterranean climate. fire did not seem to affect strongly the community composition of the soil inhabiting fauna, but caused considerable changes in the composition of the litter-dwellers. Furthermore, seasonal changes in community composition were less pronounced in the burnt site compared to those in the control. The observed effects of fire should be attributed to the destruction of the litter layer and the above ground vegetation cover, rather than to the immediate death of the animals, since most of them were absent from the upper soil layers during summer, that is when fire occured.

Comparative Leaf Water Potentiais of Plants in Burnt and Unburnt Dry Sclerophyll Vegetation

Leaf (xylem) water potentials were measured in summer and autumn on four species, Eucalyptus fasciculosa, Pultenaea daphnoides, Platylobium obtusangulum and Acacia myrtifolia growing in the understorey of sclerophyll stringybark vegetation in the Mt Lofty Ranges, South Australia. Plants regenerating in an area burnt by bushfire 2 years previously were compared with plants in an adjacent unburnt area. The Acacia was killed by fire and subsequently regenerated from seed. The other three species survived and resprouted from basal or epicormic buds. It was expected that shrubs regenerating from basal buds would be better hydrated in summer, as a large intact root system would supply a reduced canopy, and that seedlings, with smaller root systems than unburnt adults, would be more stressed. The Acacia was indeed significantly more stressed during summer in the burnt area. However the Platylobium was also more stressed than the controls, while the Pultenaea showed no significant differences between burnt and control areas. The Eucalyptus showed no differences between sites, nor between any of the three sampling times. The more negative water potentials of some of the regenerating plants are explained by greater exposure of surface soil on the burnt site, leading to more rapid drying of the surface soil in summer.