The effects of fire on grassland bird communities of Barberspan, North West Province, South Africa
TL;DR: For at least five months after two controlled and one accidental fire at the Barberspan Nature Reserve in South Africa, birds in an area larger than that burned were affected as mentioned in this paper.
Abstract: Considering the frequent nature of fires and resultant drastic change in habitat following fire, research on the effects of fire on birds in the grasslands of South Africa is surprisingly scarce. For at least five months after burns we followed the changes in bird species composition, species richness and densities of two controlled burns and one accidental fire at the Barberspan Nature Reserve in grasslands that had not been burned or grazed in 10 years. Compared with the control areas, species richness and densities increased in the burned areas immediately following the burns, with more species and birds recruited to the burned areas than were lost. Immediate post-burn opportunists tended to be larger species, and the biomass increase mirrored the increases in species richness and densities in burned areas. Avian species richness, densities and biomass tended to return to the initial conditions after a number of months. Although the bird communities from two controlled-burns differed before the burns, they converged to a characteristic immediate post-burn composition. Five months after the burns however, the bird communities reflected a pre-burn composition. Indications were that birds in an area larger than that burned were affected. Mosaic burning, with shifting large and small patches, should be considered on a landscape scale. Ostrich 2007, 78(3): 591–608
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TL;DR: It is raised a concern that generally longer living birds in warmer climates, laying fewer eggs per clutch, might be at increased risk when compared with trophically similar birds exposed to equivalent levels of pollution in colder climates.
Abstract: During the last 15 years, no research has been published on the levels of pesticides in bird eggs from South Africa, despite the high levels found previously. We analysed eggs from African darter, cattle egret, reed cormorant, African sacred ibis, as well as single eggs from some other species, and found HCB, DDTs, HCHs, chlordanes and PCBs at detectable levels. The presence of mirex in all species was unexpected, since this compound was never registered in South Africa. It also seemed as if terrestrial feeding birds had higher DDE:PCB ratios when compared with aquatic feeding birds. Except for chlordane, the African darter eggs had the highest levels of all other compounds (mean 370 and 300 ng g −1 ww Σpesticides and ΣPCBs, respectively). Multivariate analysis clearly distinguished the aquatic and terrestrially feeding birds on pollution profile. The African darter (aquatic feeding) and the cattle egret (terrestrial feeding) would be good indicator candidates. Eggshell thinning was detected in the African darter, and was associated with most of the compounds, including DDE and PCBs. We raise a concern that generally longer living birds in warmer climates, laying fewer eggs per clutch, might be at increased risk when compared with trophically similar birds exposed to equivalent levels of pollution in colder climates. Given the scarcity of water and the high biodiversity in Southern Africa, climate change will exert strong pressure, and any additional anthropogenic contamination at levels that can cause subtle behavioural, developmental and reproductive changes, can have serious effects.
90 citations
Cites background from "The effects of fire on grassland bi..."
...These birds follow cattle in grasslands, feeding on disturbed insects, follow closely behind fire fronts feeding on burned prey (Bouwman and Hoffman, 2007), and also feed on chicks of nesting birds (own observations)....
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TL;DR: In this article, the authors compared spatially heterogeneous fire and grazing treatments to spatially homogeneous fire treatments on grazed rangeland along a precipitation gradient in the North American Great Plains.
Abstract: Summary 1. Many rangelands evolved under an interactive disturbance regime in which grazers respond to the spatial pattern of fire and create a patchy, heterogeneous landscape. Spatially heterogeneous fire and grazing create heterogeneity in vegetation structure at the landscape level (patch contrast) and increase rangeland biodiversity. We analyzed five experiments comparing spatially heterogeneous fire treatments to spatially homogeneous fire treatments on grazed rangeland along a precipitation gradient in the North American Great Plains. 2. We predicted that, across the precipitation gradient, management for heterogeneity increases both patch contrast and variance in the composition of plant functional groups. Furthermore, we predicted that patch contrast is positively correlated with variance in plant functional group composition. Because fire spread is important to the fire– grazing interaction, we discuss factors that reduce fire spread and reduce patch contrast despite management for heterogeneity. 3. We compared patch contrast across pastures managed for heterogeneity and pastures managed for homogeneity with a linear mixed effect (LME) regression model. We used the LME model to partition variation in vegetation structure to each sampled scale so that a higher proportion of variation at the patch scale among pastures managed for heterogeneity indicates patch contrast. To examine the relationship between vegetation structure and plant community composition, we used constrained ordination to measure variation in functional group composition along the vegetation structure gradient. We used the meta-analytical statistic, Cohen’s d, to compare effect sizes for patch contrast and plant functional group composition. 4. Management for heterogeneity increased patch contrast and increased the range of plant functional group composition at three of the five experimental locations. 5. Plant functional group composition varied in proportion to the amount of spatial heterogeneity in vegetation structure on pastures managed for heterogeneity. 6. Synthesis and applications. Pyric-herbivory management for heterogeneity created patch contrast in vegetation across a broad range of precipitation and plant community types, provided that fire was the primary driver of grazer site selection. Management for heterogeneity did not universally create patch contrast. Stocking rate and invasive plant species are key regulators of heterogeneity, as they determine the influence of fire on the spatial pattern of fuel, veg etation structure and herbivore patch selection, and therefore also require careful management.
77 citations
Cites background from "The effects of fire on grassland bi..."
...Management for heterogeneity has been shown to increase the diversity of invertebrates, small mammals, large ungulates and birds in several ecosystems world-wide (Archibald & Bond 2004; Fuhlendorf et al. 2006, 2009; Bouwman & Hoffman 2007; Coppedge et al. 2008; Engle et al. 2008; Doxon et al. 2011)....
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01 Jan 2017
TL;DR: In this paper, the authors highlight the broad importance of heterogeneity to rangelands and focus more specifically on (1) animal populations and production, (2) fire behavior and management, and (3) biodiversity and ecosystem function.
Abstract: Rangeland management, like most disciplines of natural resource management, has been characterized by human efforts to reduce variability and increase predictability in natural systems (steady-state management often applied through a command-and-control paradigm). Examples of applications of traditional command and control in natural resource management include wildfire suppression, fences to control large ungulate movements, predator elimination programs, and watershed engineering for flood control and irrigation. Recently, a robust theoretical foundation has been developed that focuses on our understanding of the importance of variability in nature. This understanding is built upon the concept of heterogeneity, which originated from influential calls to consider spatial and temporal scaling in ecological research. Understanding rangeland ecosystems from a resilience perspective where we recognize that these systems are highly variable in space and time cannot be achieved without a focus on heterogeneity across multiple scales. We highlight the broad importance of heterogeneity to rangelands and focus more specifically on (1) animal populations and production, (2) fire behavior and management, and (3) biodiversity and ecosystem function. Rangelands are complex, dynamic, and depend on the variability that humans often attempt to control to ensure long-term productivity and ecosystem health. We present an ecological perspective that targets variation in rangeland properties—including multiple ecosystem services—as an alternative to the myopic focus on maximizing agricultural output, which may expose managers to greater risk. Globally, rangeland science indicates that heterogeneity and diversity increase stability in ecosystem properties from fine to broad spatial scales and through time.
77 citations
TL;DR: The concentration of DDE measured in eggs of the cattle egret suggests the need for monitoring this contaminant in other bird species at different trophic levels.
Abstract: In this study, residual concentration of organochlorine pesticides (OCPs) in the sediments, prey, and eggs of Bubulcus ibis were measured from three breeding heronries from the Punjab province of Pakistan. Pattern of contamination in eggs followed the order: DDTs > HCHs > heptachlor > aldrin. Overall, pesticide residual concentrations were greater in eggs of cattle egrets collected from heronry on the River Ravi. Among HCHs, γ-HCH was more prevalent in eggs, whereas DDTs followed the order: DDD > DDE > p,p
′-DDT > o,p
′-DDT. Eggshell thinning was detected which showed negative relationship with residual concentration of DDE. In prey samples, residual concentration of POPs followed the order: DDTs > HCHs > dicofol > heptachlor; however, contamination pattern in sediments followed a slightly different order: DDTs > heptachlor > dicofol > HCHs > dieldrin > aldrin. Concentration of β-HCH was more prevalent in sediments and comparatively greater concentrations of POPs were measured in sediments collected from the River Ravi. Dicofol was found for the very first time in the biological samples from Pakistan, and its concentration was measured as relatively high in eggs from heronry from the River Chenab. Residual concentrations measured in eggs were below the levels that could affect egret populations. Biomagnification of the total OCPs through the food chain was evident in three breeding heronries. The concentration of DDE measured in eggs of the cattle egret suggests the need for monitoring this contaminant in other bird species at different trophic levels.
72 citations
Cites background from "The effects of fire on grassland bi..."
...These birds follow cattle in grasslands, feeding on disturbed insects, follow closely behind fire fronts feeding on burned prey (Bouwman and Hoffman 2007), and even feed on chicks of nesting birds (Bouwman et al. 2008)....
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TL;DR: Using recent paleoenvironmental reconstructions, models from optimal foraging theory are used to hypothesize benefits that this fire‐altered landscape provided to ancestral hominins and link these benefits to steps that transformed the authors' ancestors into a genus of active pyrophiles whose dependence on fire for survival contributed to its rapid expansion out of Africa.
Abstract: Members of genus Homo are the only animals known to create and control fire. The adaptive significance of this unique behavior is broadly recognized, but the steps by which our ancestors evolved pyrotechnic abilities remain unknown. Many hypotheses attempting to answer this question attribute hominin fire to serendipitous, even accidental, discovery. Using recent paleoenvironmental reconstructions, we present an alternative scenario in which, 2 to 3 million years ago in tropical Africa, human fire dependence was the result of adapting to progressively fire-prone environments. The extreme and rapid fluctuations between closed canopy forests, woodland, and grasslands that occurred in tropical Africa during that time, in conjunction with reductions in atmospheric carbon dioxide levels, changed the fire regime of the region, increasing the occurrence of natural fires. We use models from optimal foraging theory to hypothesize benefits that this fire-altered landscape provided to ancestral hominins and link these benefits to steps that transformed our ancestors into a genus of active pyrophiles whose dependence on fire for survival contributed to its rapid expansion out of Africa.
53 citations
References
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TL;DR: A new and simple method to find indicator species and species assemblages characterizing groups of sites, and a new way to present species-site tables, accounting for the hierarchical relationships among species, is proposed.
Abstract: This paper presents a new and simple method to find indicator species and species assemblages characterizing groups of sites The novelty of our approach lies in the way we combine a species relative abundance with its relative frequency of occurrence in the various groups of sites This index is maximum when all individuals of a species are found in a single group of sites and when the species occurs in all sites of that group; it is a symmetric indicator The statistical significance of the species indicator values is evaluated using a randomization procedure Contrary to TWINSPAN, our indicator index for a given species is independent of the other species relative abundances, and there is no need to use pseudospecies The new method identifies indicator species for typologies of species releves obtained by any hierarchical or nonhierarchical classification procedure; its use is independent of the classification method Because indicator species give ecological meaning to groups of sites, this method provides criteria to compare typologies, to identify where to stop dividing clusters into subsets, and to point out the main levels in a hierarchical classification of sites Species can be grouped on the basis of their indicator values for each clustering level, the heterogeneous nature of species assemblages observed in any one site being well preserved Such assemblages are usually a mixture of eurytopic (higher level) and stenotopic species (characteristic of lower level clusters) The species assemblage approach demonstrates the importance of the ''sampled patch size,'' ie, the diversity of sampled ecological combinations, when we compare the frequencies of core and satellite species A new way to present species-site tables, accounting for the hierarchical relationships among species, is proposed A large data set of carabid beetle distributions in open habitats of Belgium is used as a case study to illustrate the new method
7,449 citations
"The effects of fire on grassland bi..." refers methods in this paper
...PC-Ord was also used to conduct non-hierarchical indicator species analysis for burned or unburned areas (deriving Indicator Values/IV), using the method of Legendre (1997), with a Monte Carlo test of significance of the observed maximum indicator values of the species, using 1 000 permutations....
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Book•
01 Aug 2002
7,234 citations
"The effects of fire on grassland bi..." refers methods in this paper
...…used this method in preference to Nonmetric Multidimensional Scaling (NMS) in this case, as the former analysis is well suited for evaluating problems with conceptual reference points (in this case defined temporal data), within an experimental design (McCune and Beals 1993, McCune and Grace 2002)....
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TL;DR: An environmental patchwork which exerts powerful influences on the distri butions of organisms, their interactions, and their adaptations is considered.
Abstract: discon tinuities on many scales in time and space. The patterns of these discontinuities produce an environmental patchwork which exerts powerful influences on the distri butions of organisms, their interactions, and their adaptations. Consideration of this environmental patch structure is critical to both the theory and management of populations. Despite the obvious heterogeneity of natural sys te.ms, most of the models that form the theoretical fabric of population biology and ecology (and that are increasingly conditioning our perception of reality) tell mathe matical stories of populations
1,019 citations
"The effects of fire on grassland bi..." refers background in this paper
...…in food availability, shelter, vegetation structure, nest site availability, nesting materials, floristic and faunistic composition, and micro-climate (Wiens 1976, Brawn et al. 2001, Jones 2001), and the ability to use more than one type of habitat for different purposes (Law and Dickman 1998)....
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...…preferential (or disproportionate: Jones 2001) use of different patches (habitat selection due to patch profitability because of incapacitated prey: Wiens 1976, Begon et al. 2006) combined with intermediate disturbance (reduced competition in areas with intermediate frequency of disturbance:…...
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...Wiens (1976) suggested one aspect of patches that could be investigated: does a patch environment allow both course-grained and finegrained strategies to be pursued by different populations within a guild, thereby allowing close tracking of changes in the environment?...
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...Our opinion is that many studies de facto consider the ‘fit’ of animal species into habitat parameters as ‘habitat correlation’ (or ‘habitat use’ (Jones 2001), rather than ‘habitat selection’ (Wiens 1976, Jones 2001)....
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TL;DR: Concerns about habitat use and selection in birds are addressed through a survey of recent literature and areas where improvements or advances can be made in avian habitat ecology are highlighted.
Abstract: The study of habitat use and selection in birds has a long tradition (Grinnell 1917, Kendeigh 1945, Svardson 1949, Hild6n 1965; Block and Brennan 1993). Early habitat-selection theory was characterized by correlative models of habitat characteristics and species abundance (MacArthur and Pianka 1966, Verner et al. 1986, Rosenzweig 1991), which subsequently evolved into models that involved density dependence: the "ideal-free distribution" and "ideal-despotic distribution" models (Fretwell and Lucas 1970, Fretwell 1972). More recently, habitat-selection studies have shown that many factors, such as landscape structure, can influence exactly how "ideal" and "free" animals are while moving through a landscape and selecting habitats (Karr and Freemark 1983, Pulliam and Danielson 1991, Petit and Petit 1996). Habitat-selection studies have recently assumed a new urgency, partially as a result of the importance of incorporating both habitat and demographic information into conservation planning (Caughley 1994). Nevertheless, ornithologists tend to be inconsistent in their conceptual framework and terminology with regard to (1) what constitutes habitat use versus selection, (2) the behavioral and evolutionary context of their findings, and (3) the order or scale of their study, from microhabitat to geographic range (Johnson 1980, Orians and Wittenberger 1991). The purpose of this review is to address those concerns through a survey of recent literature and highlight areas where improvements or advances can be made in avian habitat ecology. Three Areas of Concern.-Definitions.-The semantic and empirical distinctions between the terms habitat use and habitat selection are often unclear (Hall et al. 1997). Habitat refers to a distinctive set of physical environmental factors that a species uses for its survival and reproduction (Block and Brennan 1993). Habitat use refers to the way in which an individual or species uses habitats to meet its life history needs (Block and Brennan 1993). The study of habitat-use patterns describes the actual distribution of individuals across habitat types (Hutto 1985). Habitat selection refers to a hierarchical process of behavioral re-
688 citations
"The effects of fire on grassland bi..." refers background in this paper
...…in food availability, shelter, vegetation structure, nest site availability, nesting materials, floristic and faunistic composition, and micro-climate (Wiens 1976, Brawn et al. 2001, Jones 2001), and the ability to use more than one type of habitat for different purposes (Law and Dickman 1998)....
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...Overall, it seems that preferential (or disproportionate: Jones 2001) use of different patches (habitat selection due to patch profitability because of incapacitated prey: Wiens 1976, Begon et al. 2006) combined with intermediate disturbance (reduced competition in areas with intermediate frequency…...
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...Our opinion is that many studies de facto consider the ‘fit’ of animal species into habitat parameters as ‘habitat correlation’ (or ‘habitat use’ (Jones 2001), rather than ‘habitat selection’ (Wiens 1976, Jones 2001)....
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TL;DR: It is demonstrated that increasing spatial and temporal heterogeneity of disturbance in grasslands increases variability in vegetation structure that results in greater variability at higher trophic levels, suggesting that management that creates a shifting mosaic using spatially and temporally discrete disturbances in Grasslands can be a useful tool in conservation.
Abstract: In tallgrass prairie, disturbances such as grazing and fire can generate patchiness across the landscape, contributing to a shifting mosaic that presumably enhances biodiversity. Grassland birds evolved within the context of this shifting mosaic, with some species restricted to one or two patch types created under spatially and temporally distinct disturbance regimes. Thus, management-driven reductions in heterogeneity may be partly responsible for declines in numbers of grassland birds. We experimentally altered spatial heterogeneity of vegetation structure within a tallgrass prairie by varying the spatial and temporal extent of fire and by allowing grazing animals to move freely among burned and unburned patches (patch treatment). We contrasted this disturbance regime with traditional agricultural management of the region that promotes homogeneity (traditional treatment). We monitored grassland bird abundance during the breeding seasons of 2001-2003 to determine the influence of altered spatial heterogeneity on the grassland bird community. Focal disturbances of patch burning and grazing that shifted through the landscape over several years resulted in a more heterogeneous pattern of vegetation than uniform application of fire and grazing. Greater spatial heterogeneity in vegetation provided greater variability in the grassland bird community. Some bird species occurred in greatest abundance within focally disturbed patches, while others occurred in relatively undisturbed patches in our patch treatment. Henslow's Sparrow, a declining species, occurred only within the patch treatment. Upland Sandpiper and some other species were more abundant on recently disturbed patches within the same treatment. The patch burn treatment created the entire gradient of vegetation structure required to maintain a suite of grassland bird species that differ in habitat preferences. Our study demonstrated that increasing spatial and temporal heterogeneity of disturbance in grasslands increases variability in vegetation structure that results in greater variability at higher trophic levels. Thus, management that creates a shifting mosaic using spatially and temporally discrete disturbances in grasslands can be a useful tool in conservation. In the case of North American tallgrass prairie, discrete fires that capitalize on preferential grazing behavior of large ungulates promote a shifting mosaic of habitat types that maintain biodiversity and agricultural productivity.
513 citations
"The effects of fire on grassland bi..." refers background or result in this paper
...Robel et al. (1998) found lower bird densities but higher species diversity on rangelands in Kansas, USA (where burning was used for the control of invasive plants), and ascribed the reduction to reduced structural complexity....
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...There is therefore a shortterm succesional cycle within burned grasslands, as was also deemed to be the case in grasslands in the USA (Brawn et al. 2001)....
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...All birds seen or heard making use of the control or burned areas were identified and counted (van’t Hul et al. 1997, Herrando et al. 2002, Mills 2004, Blake 2005, Fuhlendorf et al. 2006, O’Reilley et al. 2006)....
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...Similar differences in species composition were also found in tall-grass prairie in Oklahoma, USA (Fuhlendorf et al. 2006)....
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...Similar findings have been made in other studies on the impacts of fire (van’t Hul et al. 1997, Davis et al. 2000, Herrando et al. 2002, Blake 2005, Smucker et al. 2005, Fuhlendorf et al. 2006, Powell 2006)....
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