Effects of an ENSO-related fire on birds of a lowland tropical forest in Sumatra

Comparisons of bird community composition in burned and unburned areas of a lowland tropical rainforest in Sumatra, Indonesia indicated the following during the first 5 years after burning: (1) original burn severity strongly affected bird community composition at both the genus and family levels; (2) bird community composition continued to change progressively away from immediate post-burn composition in medium and severely burned forest as well as adjacent unburned forest; and (3) the degree of impact was both taxon and guild specific, with understory insectivores most detrimentally affected. Although species richness may temporarily increase in burned areas, this study suggests that multiple wildfires will lead to a decline in diversity over a large scale as birds of open fields replace interior forest specialists.     

Fire effects on the composition of a bird community in an Amazonian savanna (Brazil).

The effects of fire on the composition of a bird community were investigated in an Amazonian savanna near Alter-do-Ch?o, Pará (Brazil). Mist-net captures and visual counts were used to assess species richness and bird abundance pre- and post-fire in an approximately 20 ha area. Visual counts along transects were used to survey birds in an approximately 2000 ha area in a nearby area. Results using the same method of ordination analysis (multidimensional scaling) showed significant effects of fire in the 20 ha and 2000 ha areas and strongly suggest direct effects on bird community composition. However, the effects were different at different spatial scales and/or in different years, indicating that the effects of fire vary spatially and/or temporally. Bird community composition pre-fire was significantly different from that found post-fire. Using multiple regression analysis it was found that the numbers of burned and unburned trees were not significantly related to either bird species richness or bird abundance. Two months after the fire, neither bird species richness nor bird abundance was significantly related to the number of flowering trees (Lafoensia pacari) or fruiting trees (Byrsonima crassifolia). Since fire is an annual event in Alter-do-Ch?o and is becoming frequent in the entire Amazon, bird community composition in affected areas could be constantly changing in time and space.     

Implications of grazing and burning of grasslands on the sustainable use of francolins (Francolinus spp.) and on overall bird conservation in the highlands of Mpumalanga province, South Africa

We investigated the densities of the Redwing Francolinus levaillantii and Greywing Francolins F. africanus and the diversity of grassland birds in general along a land-use gradient in the highlands of Mpumalanga province, South Africa. Redwing Francolins cannot tolerate intensive grazing and frequent burning and are confined largely to unburnt, ungrazed grasslands. Their density and the species richness of grassland birds in general are negatively correlated with grazing intensity. Redwing populations drop to densities that cannot be utilised by hunters on a sustainable basis in grasslands that are grazed at even moderate levels or burned annually. Nineteen bird species (including five threatened species) were confined to essentially pristine grassland and were never observed in grazed/annually burned grasslands. The Greywing Francolin is more evenly distributed (although always at sub-utilisation densities) along the grassland land-use gradient, and its density is positively correlated with grazing intensity. There are two assemblages of grassland bird species that appear to be indicative of the intensity of habitat utilisation. Populations of grassland birds in the study area are becoming increasingly dependent on isolated patches of pristine grassland and are threatened by management involving annual burning and high stocking rates on a landscape scale.     

Structure of ground‐dwelling ant communities in burned and unburned areas in Brazilian subtropical grasslands

Fire is frequently used in the management of pastures in southern Brazil, but its effects on ground‐dwelling ant communities in Brazilian subtropical grasslands is still poorly understood. Here, we compared ant species richness and composition between periodically burned and unburned areas in native grasslands of the Atlantic Forest biome. In total, we found 35 epigeic ant species in burned and unburned areas. There was slightly higher species richness in burned than in unburned areas, independent of the sampling period (season). There was a significant difference in richness over the sampling period (season effect). Species composition varied significantly between the areas, in which nine species (26%) occurred only in burned areas, eight (23%) occurred only in unburned areas, and 18 (51%) occurred in both. Four species showed a significant preference for burned sites (Camponotus crassus, Linepithema humile and two undetermined species of Pheidole and Solenopsis). Although this study did not separate fire effects on ground‐dwelling ant communities (due to sampling design), it provides new information regarding subtropical native grasslands that can be used as a baseline for future studies.     

Species reordering,not changes in richness,drives long‐term dynamics in grassland communities

Determining how ecological communities will respond to global environmental change remains a challenging research problem. Recent meta‐analyses concluded that most communities are undergoing compositional change despite no net change in local species richness. We explored how species richness and composition of co‐occurring plant, grasshopper, breeding bird and small mammal communities in arid and mesic grasslands changed in response to increasing aridity and fire frequency. In the arid system, grassland and shrubland plant and breeding bird communities were undergoing directional change, whereas grasshopper and small mammal communities were stable. In the mesic system, all communities were undergoing directional change regardless of fire frequency. Despite directional change in composition in some communities, species richness of all communities did not change because compositional change resulted more from reordering of species abundances than turnover in species composition. Thus, species reordering, not changes in richness, explains long‐term dynamics in these grass and shrub dominated communities.     

Long‐term Changes in Bird Communities after Wildfires in the Central Brazilian Amazon

We examined long‐term responses of an Amazonian bird assemblage to wildfire disturbance, investigating how understory birds reacted to forest regeneration 1, 3, and 10 years after a widespread fire event. The bird community was sampled along the Arapiuns and Maró river catchments in central Brazilian Amazonia. Sampling took place in 1998, 2000, and 2008 using mist‐nets in eight plots (four burned, four unburned sites). Species richness did not change significantly in unburned sites. In burned sites, however, we found significantly lower richness in 1998, higher richness in 2000, and similar richness in 2008. Multi‐dimensional scaling ordination showed consistent differences in bird communities both within burned sites sampled in different sampling years, and between burned and unburned sites in all years. Of the 30 most abundant species, 12 had not recovered 10 years after the fires, including habitat specialists such as mixed flocks specialists and ant‐followers. Fire‐disturbance favored three species (two hummingbirds and a manakin) in the short term only. All other species were either favored throughout the study (seven species of omnivores and small insectivores) or did not show a clear response (eight species). In burned sites, we also found significantly lower abundance of species sensitive to disturbances and habitat specialists over the entire study period. Although the bird community seems to be recovering in terms of richness, the overall community composition and abundance of some species in post‐burned and unburned sites remain very different, and have not recovered after 10 years of forest regeneration.     

Bird Community Changes in Response to Single and Repeated Fires in a Lowland Tropical Rainforest of Eastern Borneo

Our current understanding of bird community responses to tropical forest fires is limited and strongly geographically biased towards South America. Here we used the circular plot method to carry out complete bird inventories in undisturbed, once burned (1998) and twice burned forests (1983 and 1998) in East Kalimantan (Indonesia). Additionally, environmental variables were measured within a 25 m radius of each plot. Three years after fire the number of birds and bird species were similar for undisturbed and burned forests, but species diversity and turnover were significantly lower in the burned forests. The bird species composition also differed significantly between undisturbed and burned forests, with a strong decline of closed forest preferring bird species accompanied by a strong increase in degraded forest preferring species in burned forests. These differences were strongly related to differences in environmental conditions such as shifts in vegetation cover and layering and differences in ground and understorey vegetation structure. We also found significant shifts in body mass distribution, foraging height and feeding guilds between the bird communities in unburned and burned forests. Surprisingly, repeated burning did not lead to increasing impoverishment of the avifauna, and both once and twice burned forests still contained most of the bird species that were also present in undisturbed forest, even though their densities were considerably lowered.     

A comparison between aquatic birds of lakes and coastal rivers in Florida

Aquatic birds were counted on five Gulf coast Florida rivers to determine if these river systems supported densities, biomass and species richness similar to those found on Florida lakes. Forty-two species were identified and for the species that were found on both Florida streams and lakes similar densities and biomass were encountered. As with Florida lakes, stream bird abundance and species richness were higher in winter months than in summer months, a consequence of migratory bird populations. Total bird abundance, biomass per unit of phosphorus, and species richness per unit of area were similar to data collected on Florida lakes. Thus, Florida rivers are capable of supplying sufficient resources to maintain bird densities, biomass and species richness values similar to lakes of equal size and nutrient concentrations and are therefore important habitats for aquatic bird populations. An examination of individual habitat characteristics indicates that water depth was inversely correlated and submersed aquatic vegetation was positively correlated with bird density, biomass and species richness within the river systems. While both habitat characteristics are important they are also inversely related making it difficult to separate the individual significance of each characteristic.     

Bird Communities and Biomass Yields in Potential Bioenergy Grasslands

Demand for bioenergy is increasing, but the ecological consequences of bioenergy crop production on working lands remain unresolved. Corn is currently a dominant bioenergy crop, but perennial grasslands could produce renewable bioenergy resources and enhance biodiversity. Grassland bird populations have declined in recent decades and may particularly benefit from perennial grasslands grown for bioenergy. We asked how breeding bird community assemblages, vegetation characteristics, and biomass yields varied among three types of potential bioenergy grassland fields (grass monocultures, grass-dominated fields, and forb-dominated fields), and assessed tradeoffs between grassland biomass production and bird habitat. We also compared the bird communities in grassland fields to nearby cornfields. Cornfields had few birds compared to perennial grassland fields. Ten bird Species of Greatest Conservation Need (SGCN) were observed in perennial grassland fields. Bird species richness and total bird density increased with forb cover and were greater in forb-dominated fields than grass monocultures. SGCN density declined with increasing vertical vegetation density, indicating that tall, dense grassland fields managed for maximum biomass yield would be of lesser value to imperiled grassland bird species. The proportion of grassland habitat within 1 km of study sites was positively associated with bird species richness and the density of total birds and SGCNs, suggesting that grassland bioenergy fields may be more beneficial for grassland birds if they are established near other grassland parcels. Predicted total bird density peaked below maximum biomass yields and predicted SGCN density was negatively related to biomass yields. Our results indicate that perennial grassland fields could produce bioenergy feedstocks while providing bird habitat. Bioenergy grasslands promote agricultural multifunctionality and conservation of biodiversity in working landscapes.     

Responses of plant and bird communities to prescribed burning in tallgrass prairies

Historic losses and fragmentation of tallgrass prairie habitat to agriculture and urban development have led to declines in diversity and abundance of plants and birds associated with such habitat. Prescribed burning is a management strategy that has potential for restoring and rejuvenating prairies in fragmented landscapes, and through such restoration, might create habitat for birds dependent upon prairies. To provide improved data for management decision-making regarding the use of prescribed fire in tallgrass prairies, we compared responses of plant and bird communities on five burned and five unburned tallgrass prairie fragments at the DeSoto National Wildlife Refuge, Iowa, USA, from 1995 to 1997. Overall species richness and diversity were unaffected by burning, but individual species of plants and birds were affected by year-treatment interactions, including northern bobwhite (Colinus virginianus) and ring-necked pheasant (Phasianus colchicus), which showed time-delayed increases in density on burned sites. Analyses of species/area relationships indicated that, collectively, many small sites did make significant contributions to plant biodiversity at landscape levels, supporting the overall conservation value of prairie fragments. In contrast, most birds species were present on larger sites. Thus, higher biodiversity in bird communities which contain area-sensitive species might require larger sites able to support larger, more stable populations, greater habitat heterogeneity, and greater opportunity for niche separation.     

Passive restoration contributes to bird conservation in Brazilian Pampa grasslands

The global decline of biodiversity makes it important to find affordable ways to conserve and restore habitats. Restoration is useful for conserving native grasslands, with passive restoration defined as either natural colonization or unassisted recovery. Grasslands in southeastern South America have been transformed into croplands and impacted by other human activities. We describe the first assessment of passive restoration as a management tool to conserve birds in the Pampa grasslands of Brazil. We compared bird species richness using coverage‐based rarefaction and extrapolation, applying PERMANOVA for composition, and the abundance of bird communities between sites undergoing passive restoration (PR) and sites with native grasslands (NG). We employed fitted generalized linear mixed models (GLMM) to quantify relationships between bird occurrence and vegetation structure and cover. We recorded 61 species of birds during our study (45 in PR and 46 in NG) and 762 individuals (333 in PR and 429 in NG). Of these species, 15 were restricted to PR and 16 to NG. Grassland specialists and threatened species were found in both PR and NG, and only vegetation height differed between PR and NG. We detected eight species of conservation concern, including three recorded only in PR, three only in NG, and two in both PR and NG. The absence of marked differences in species richness and composition of bird communities between passive‐restoration and native grasslands in our study suggests that grasslands in the process of passive restoration can provide habitat for many species of grassland birds and that passive restoration is an appropriate management tool for biodiversity conservation in Brazilian grasslands.     

Vegetation responses to different spatial patterns of soil disturbance in burned and unburned tallgrass prairie

Pocket gopher (Geomyidae) disturbances are created in spatiallypredictable patterns. This may influence resource heterogeneity and affectgrassland vegetation in a unique manner. We attempt to determine the extent towhich density and spatial pattern of soil disturbances influence tallgrassprairie plant community structure and determine how these disturbances interactwith fire. To investigate the effects of explicit disturbance patterns we createdsimulated pocket gopher burrows and mounds in various spatial patterns.Simulated burrows were drilled into the soil at different densities inreplicated plots of burned and unburned prairie. Separate plots of simulatedmounds were created in burned and unburned prairie at low, medium, or high mounddensities in clumped, uniform, or random spatial dispersions. In both burned and unburned plots, increased burrow density decreasedgraminoid biomass and increased forb biomass. Total-plant and graminoid biomasswere higher in burned than unburned plots while forb biomass was higher inunburned plots. Total-plant species richness was not significantly affected byburrow density or burning treatments, but graminoid species richness increasedin unburned plots and forb species richness increased in burned plots. Plant species richness was temporarily reduced directly on mounddisturbances compared to undisturbed prairie. Over time and at larger samplingscales, the interaction of fire and mound disturbance patterns significantlyaffected total-plant and graminoid species richness. The principal effect inburned and unburned prairie was decreased total-plant and graminoid speciesrichness with increased mound disturbance intensity. Although species richness at small patch scales was not increased by anyintensity of disturbance and species composition was not altered by theestablishment of a unique guild of disturbance colonizing plants, our studyrevealed that interactions between soil disturbances and fire alter the plantcommunity dominance structure of North American tallgrass prairie primarily viachanges to graminoids. Moreover, these effects become increasingly pronouncedover time and at larger spatial sampling scales.     

Fire as a Recurrent Event in Tropical Forests of the Eastern Amazon: Effects on Forest Structure,Biomass, and Species Composition1

The effects of fire on forest structure and composition were studied in a severely fire-impacted landscape in the eastern Amazon. Extensive sampling of area forests was used to compare structure and compositional differences between burned and unburned forest stands. Burned forests were extremely heterogeneous, with substantial variation in forest structure and fire damage recorded over distances of <50 m. Unburned forest patches occurred within burned areas, but accounted for only six percent of the sample area. Canopy cover, living biomass, and living adult stem densities decreased with increasing fire inrensiry / frequency, and were as low as 10–30 percent of unburned forest values. Even light burns removed >70 percent of the sapling and vine populations. Pioneer abundance increased dramatically with burn intensity, with pioneers dominating the understory in severely damaged areas. Species richness was inversely related to burn severity, but no clear pattern of species selection was observed. Fire appears to be a cyclical event in the study region: <30 percent of the burned forest sample had been subjected to only one burn. Based on estimated solar radiation intensities, burning substantially increases fire susceptibility of forests. At least 50 percent of the total area of all burned forests is predicted to become flammable within 16 rainless days, as opposed to only 4 percent of the unburned forest. In heavily burned forest subjected to recurrent fires, 95 percent of the area is predicted to become flammable in <9 rain-free days. As a recurrent disturbance phenomenon, fire shows unparalleled potential to impoverish and alter the forests of the eastern Amazon.     

Bird assemblages in fragmented agricultural landscapes: the role of small brigalow remnants and adjoining land uses

Agricultural intensification typically leads to changes in bird diversity and community composition, with fewer species and foraging guilds present in more intensively managed parts of the landscape. In this study, we compare bird communities in small (2–32 ha) brigalow (Acacia harpophylla) remnants with those in adjacent uncultivated grassland, previously cultivated grassland and current cropland, to determine the contribution of different land uses to bird diversity in the agricultural landscape. Twenty remnant brigalow patches and adjacent agricultural (‘matrix’) areas in southern inland Queensland, Australia were sampled for bird composition and habitat characteristics. The richness, abundance and diversity of birds were all significantly higher in brigalow remnants than in the adjacent matrix of cropping and grassland. Within the matrix, species richness and diversity were higher in uncultivated grasslands than in current cultivation or previously cultivated grasslands. Forty-four percent of bird species were recorded only in brigalow remnants and 78% of species were recorded in brigalow and at least one other land management category. Despite high levels of landscape fragmentation and modification, small patches of remnant brigalow vegetation provide important habitat for a unique and diverse assemblage of native birds. The less intensively managed components of the agricultural matrix also support diverse bird assemblages and thus, may be important for local and regional biodiversity conservation.     

The responses of leaf litter ant communities to wildfires in the Brazilian Amazon: a multi-region assessment

Fire is frequently used as tool for land management in the Amazon, but often escapes into surrounding forests, with potentially severe impacts for forest biodiversity. We investigated the effects of single wildfires on ant communities in four geographically distinct regions of the Brazilian Amazon (Roraima, Pará, Acre and Mato Grosso) where forests had burned between 8 months and 10 years before our sampling. We established 7–12 transects, 500 m each, in burned and unburned forests in each region to investigate the effects of fire on forest structure and leaf litter ant communities, which were sampled using Winkler sacks. Fire effects on forest structure were more drastic in the most recently burned forests in Acre and Mato Grosso, while the impacts of older burns in Roraima and Pará were more subtle. Ant species richness was not different between burnt and unburned areas, but community composition differed between burned and control forests in all regions except Mato Grosso. At the species level, indicator species analysis showed that a limited number of species were significant indicators of unburned control forests in all regions, except Acre. Forests structure variables and leaf litter volume were all important in shaping ant communities, but their relative importance varied between regions. Our results indicate that burned forest have different ant species communities from unburned forests, and those differences are still apparent 10 years after the disturbance, highlighting the importance of effective policies for fire management in Amazon.     

Short-term invasibility patterns in burnt and unburnt experimental Mediterranean grassland communities of varying diversities

This paper reports the findings of a short-term natural invasibility field study in constructed Mediterranean herbaceous communities of varying diversities, under a fire treatment. Three components of invasibility, i.e. species richness, density and biomass of invaders, have been monitored in burnt and unburnt experimental plots with resident diversity ranging from monocultures to 18-species mixtures. In general, species richness, density and biomass of invaders decreased significantly with the increase of resident species richness. Furthermore, the density and biomass of invading species were significantly influenced by the species composition of resident communities. Although aboveground biomass, leaf area index, canopy height and percent bare ground of the resident communities explained a significant part of the variation in the success of invading species, these covariates did not fully explain the effects of resident species richness. Fire mainly influenced invasibility via soil nutrient levels. The effect of fire on observed invasibility patterns seems to be less important than the effects of resident species richness. Our results demonstrate the importance of species richness and composition in controlling the initial stages of plant invasions in Mediterranean grasslands but that there was a lack of interaction with the effects of fire disturbance.     

Woody elements benefit bird diversity to a larger extent than semi-natural grasslands in cereal-dominated landscapes

Increasing landscape complexity can mitigate negative effects of agricultural intensification on biodiversity by offering resources complementary to those provided in arable fields. In particular, grazed semi-natural grasslands and woody elements support farmland birds, but little is known about their relative effects on bird diversity and community composition. In addition, the relative importance of local habitat versus landscape composition remains unclear. We investigated how the presence of semi-natural grasslands, the number of woody elements and the composition of the wider agricultural landscape affect bird species richness, true diversity (exponential Shannon diversity) and species composition. Bird communities were surveyed four times on 16 paired transects of 250 m each with 8 transects placed between a crop field and a semi-natural grassland and 8 transects between two crop fields with no semi-natural grasslands in the vicinity. The number of woody elements around transects was selected as an important predictor in all models, having a positive effect on species richness and true diversity, while the local presence of semi-natural grasslands was not selected in the best models. However, species richness and true diversity increased with increasing cover of ley and semi-natural grasslands, whereas species composition was modified by the coverage of winter wheat at the landscape scale. Furthermore, bird species richness, true diversity and species composition differed between sampling dates. As bird diversity benefited from woody elements, rather than from the local presence of semi-natural grasslands as such, it is important to maintain woody structures in farmland. However, the positive effect of grassland at the landscape scale highlights the importance of habitat variability at multiple scales. Because species richness and true diversity were affected by different landscape components compared to species composition, a mosaic of land-use types is needed to achieve multiple conservation goals across agricultural landscapes.     

Fire mediated patterns of population densities in mountain big sagebrush bird communities

We employed a chronosequence approach to evaluate patterns of bird abundance in relation to post-fire vegetation recovery in mountain big sagebrush (Artemisia tridentata vaseyana). We estimated population density for 12 species of birds within the perimeters of 4 fires that had undergone 8–20 years of vegetation recovery and on adjacent unburned areas in the northwestern Great Basin, USA. Six species showed negative responses to fire persisting up to 20 years. Two species showed positive responses with effects persisting for <20 years. Understory vegetation was similar between burned and unburned areas irrespective of recovery time, and shrub canopy cover was similar between burned and unburned sites after 20 years of recovery. Persistent reductions in bird densities lead us to conclude that shrub canopy cover alone is not a sufficient metric for predicting recovery of songbird abundances following disturbance in mountain big sagebrush. © 2013 The Wildlife Society.     

Colonization of dynamic Mediterranean landscapes: where do birds come from after fire?

Aim Two main mechanisms may explain post‐disturbance species colonization patterns of early successional habitats such as those originated by wildfires. First, post‐disturbance colonization is not limited by the dispersal ability of the species to reach the newly created open areas and, secondly, colonization is limited by dispersal. Under the first hypothesis, we expect, at a regional scale, to find similar post‐disturbance communities to develop on recently burned sites. However, colonization limited by dispersal will lead to strong between‐site variations in species composition. Location To test these hypotheses, we studied the post‐fire colonization patterns of nine open‐habitat bird species in eight distantly located wildfires in the north‐eastern Iberian Peninsula. Methods We censused post‐fire bird composition by means of field transects and identified potential colonization sources from species–habitat suitability maps derived from atlas data. Results Our results showed strong significant differences in post‐fire species composition between burnt areas. Burnt areas located in areas with low probability of species presence before the fire event showed lower species occurrence and richness after the fire. Main conclusions These results do not support the idea that early successional stages and open habitats have a homogeneous community structure at regional scales and suggest that dispersal is a key constraint determining bird colonization of post‐fire habitats. Further attention should be paid to landscape heterogeneity as a key factor in determining population dynamics of open‐habitat species in the light of current and future land‐use changes in Mediterranean regions.     

Post-fire recovery of ant communities in Submediterranean Pinus nigra forests

This study analyzes the variations in the structure and composition of ant communities in burned Pinus nigra forests in central Catalonia (NE Spain). Pinus nigra forests do not recover after fire, changing to shrublands and oak coppices. For this reason, we suggest that ant communities of burned P. nigra forests will change after fire, because the post‐fire scenario, in particular with the increase of open areas, is different to the unburned one, and more favourable for some species than for others. In four locations previously occupied by P. nigra forests where different fires occurred 1, 5, 13 and 19 yr before the sampling, we sampled the structure and composition of ant communities with pitfall traps, tree traps and net sweeping in unburned plots and in plots affected by canopy and understory fire. The results obtained suggest that canopy and understory fire had little effect on the structure of ant communities. Thus, many variables concerning ant communities were not modified either by fire type (understory or canopy fire) or by time since fire. However, a number of particular species were affected, either positively or negatively, by canopy fire: three species characteristic of forest habitats decreased after fire, while eight species characteristic of open habitats increased in areas affected by canopy fire, especially in the first few years after fire. These differences in ant community composition between burned and unburned plots imply that the maximum richness is achieved when there is a mixture of unburned forests and areas burned with canopy fire. Moreover, as canopy cover in P. nigra forests burned with canopy fire is not completed in the period of time studied, the presence of the species that are characteristic of burned areas remains along the chronosequence studied, while the species that disappear after fire do not recover in the period of time considered. Overall, the results obtained indicate that there is a persistent replacement of ant species in burned P. nigra forests, as is also the case with vegetation.