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The impacts of fire on birds in Australia’s tropical savannas

Abstract

The ecology of Australia's tropical savannas is shaped by the near-pervasive influence of fire. Constituting ∼20% of Australia's land area, tropical savannas contribute >75% of the area burnt in Australia each year. Across most of Australia's tropical savannas, components of biodiversity are declining, including many species of birds. This review seeks to assess whether that decline is linked to current fire regimes. However, relevant studies are few, short-term and opportunistic, and indicate rather than demonstrate the effects of fire. There is no set of agreed paradigms for contextualising the relationship between birds and fire regimes in this region or for any management consequences. We conclude that the current fire regime is suboptimal for many species of birds, particularly for granivores, frugivores, hollow-dependent species and those that nest on or near the ground. For conservation reserves, we recommend that fire management protocols include the explicit targets that: (1) at least 25% of the savanna landscape is at least 3 years unburnt; (2) at least 5% is at least 10 years unburnt; (3) fire-sensitive non-savanna vegetation types are increasing or stable and (4) populations of selected hollow-nesting, ground-nesting, frugivorous and granivorous birds are increasing or stable. We also identify key knowledge gaps that currently inhibit conservation management.


Ano de Publicação: 2013

Spatial pattern and severity of fire in areas with and without buffel grass (Cenchrus ciliaris) and effects on native vegetation in central Australia

Abstract The spread of buffel grass (Cenchrus ciliaris) in semi-arid Australia in recent decades has substantially
increased ground cover and fuel loads, particularly in open woodland vegetation communities. The resulting
alteration of fire regimes may be the most significant impact of buffel invasion on ecological communities in these
areas. Broad scale management of buffel grass is currently not an option in Australia but it is becoming increasingly
relevant to assess the benefits of restoring areas of native vegetation where preventing buffel grass invasion is
no-longer possible.We managed buffel grass in a series of experimental plots from 2008–2012. In June and August
2011, two unplanned fires burnt through the plots providing a unique opportunity to compare the outcome of
wildfire, including the spatial pattern of fire, and the effect on ground vegetation and on a long-lived, perennial
overstorey species, in replicated managed and unmanaged plots. The area of ground that remained unburnt was
much greater in managed plots (with predominantly native vegetation) than unmanaged (predominantly buffel
grass) plots and where the managed plots did burn the fire was more patchy. This had direct implications for the
richness of ground layer plant taxa following fire and the extent to which overstorey trees were exposed to fire. Fire
increased pre-existing differences in the number of taxa in the ground level vegetation, an effect that persisted for
the duration of our study, suggesting that fire accelerates direct negative competitive effects between buffel grass and
native grasses and forbs. Hakea divaricata (fork-leafed corkwood) trees in unmanaged buffel grass sites suffered
higher burn intensities, and their long-term viability at this location is likely to be threatened if fires fuelled by buffel
grass continue. Our results demonstrate clear benefits of removing fire-enhancing invasive plants from areas of high
conservation value.
Key words: buffel grass, Cenchrus ciliaris, fire, Hakea divaricata, invasive grass, restoration.

Ano de Publicação: 2013

Perspectives on prescribed burning

Fire – both natural and anthropogenic – is an inevitable and often essential component of ecosystem processes and landscape management in many parts of the world. The deliberate and accidental use of fire defines us as a species and has helped shape our evolutionary path. Today, the prescribed use of landscape fire is not without controversy and while debates rage in many densely populated fire‐prone regional settings, we are also coming to appreciate the global significance of interactions between fire regimes in fire‐prone biomes (eg boreal, Mediterranean, and modified tropical forests; savanna woodlands and grasslands) and the Earth–climate system.

Long‐standing debates beset the complex world of prescribed fire management: what is the natural or historical fire regime (ie the combination of frequency, seasonality, intensity, and type of fire) for a region or ecosystem, and what relevance, if any, may that have for contemporary land uses? How do we reconcile often competing management demands for ensuring public safety with maintaining ecosystem services and cultural and biodiversity values? How do we operationally deliver effective fire management in increasingly densely populated, fragmented landscapes and increasingly risk‐averse, regulated, and litigious societal settings? How do we know if such practices are delivering against multiple desired objectives? Is there any capacity to be adaptive, especially with changing land‐use, climatic, and biotic (eg invasive flammable plants) conditions?

The seven papers in this online special issue of Frontiers explore this complex management environment in two parts. First, we look at the development and challenges associated with prescribed burning as practiced in fire‐prone southern Europe (Fernandes et al.), North America (Ryan et al.), southwestern Australia (Burrows and McCaw), and South Africa (van Wilgen). The latter two papers, in particular, also address fire management in spectacularly biodiverse systems. Contemporary prescribed burning practices in all four regions have evolved, only since the mid‐20th century, from northern European‐influenced fire suppression policies, providing a legacy of enhanced fuel accumulation and increased density of woody vegetation that has amplified the fire hazard in fire‐prone systems. Today, despite inter‐ and intraregional differences, common challenges to the wider application of prescribed burning relate more to societal risk aversion and misunderstanding, a lack of supportive policies, and inadequate funding (especially for adaptive management systems) than to a deficiency in fundamental and applied fire‐ecology knowledge. To summarize the findings of these respective papers, it seems that the status of prescribed burning is still in its infancy in southern Europe, technically well‐informed but lacking broader community acceptance in North America, well‐advanced and mostly publicly supported in southwestern Australia, and technically well‐informed but operationally ineffective in South Africa's biodiverse shrublands. Common to all is the need to inform and engage with local and regional communities, especially given that prescribed fire management ultimately involves numerous (often unpalatable) trade‐offs and decisions.

The second part of the issue presents three case studies illustrating innovative prescribed burning approaches to a few seemingly intransigent management problems – conspicuously, two of those studies draw heavily on traditional knowledge systems. The first (Nigh and Diemont) challenges the stereotypical view that all swidden (or “slash‐and‐burn”, “shifting cultivation”) agricultural or agroforestry practices result in highly degraded ecosystems. No one can deny that unregulated burning associated with much contemporary agricultural or forest plantation practice in tropical and subtropical systems is unsustainable, but it is important to remember that many societies have developed highly sustainable practices over many generations. This paper examines the Maya milpa agroforestry system that, in one form or another, was once widespread throughout Mesoamerica. The second paper (Russell‐Smith et al.) describes the application of traditional Aboriginal burning practices in north Australian savannas to the successful implementation of a commercial “savanna burning” carbon emissions mitigation program that also provides local employment and biodi‐versity benefits. Savanna fires contribute as much as 10% of annual total global carbon emissions and, although intentional burning is officially prohibited in most countries containing savanna systems, fire is a requisite management tool in many local livelihood applications. The third paper (Twidwell et al.) describes an important, and still developing, fire management initiative in the US Great Plains, specifically the formation of community‐based prescribed burning cooperatives that are charged with reclaiming grasslands from invading shrubs. The program resonates with other community‐based fire management initiatives around the world, with the aim of empowering and giving responsibility back to local communities.

We are not suggesting that these seven examples adequately cover the field of prescribed burning – far from it – but we trust that they provide an informed overview of the complex challenges associated with contemporary prescribed fire management.


Ano de Publicação: 2013

Long-term effects of fire frequency and season on herbaceous vegetation in savannas of the Kruger National Park, South Africa

Abstract

ABSTRACT
Aims:

The long-term effects of changing fire regimes on the herbaceous component of savannas are poorly understood but essential for understanding savanna dynamics. We present results from one of the longest running (>44 years) fire experiments in savannas, the experimental burn plots (EBPs), which is located in the Kruger National Park (South Africa) and encompasses four major savanna vegetation types that span broad spatial gradients of rainfall (450–700 mm) and soil fertility.

Methods:

Herbaceous vegetation was sampled twice in the EBPs using a modified step-point method, once prior to initiation of the experiment (1954) and again after 44–47 years. Different combinations of three fire frequency (1-, 2- and 3-year return intervals) and five season (before the first spring rains, after the first spring rains, mid-summer, late summer and autumn) treatments, as well as a fire exclusion treatment, were applied at the plot level (∼7 ha each), with each treatment (n = 12 total) replicated four times at each of the four sites (n = 192 plots total). The effects of long-term alterations to the fire regime on grass community structure and composition were analyzed separately for each site.

Important Findings:

Over the 44+ years duration of the experiment, fires were consistently more intense on sites with higher mean annual rainfall (>570 mm), whereas fires were not as intense or consistent for sites with lower and more variable rainfall (<510 mm) and potentially higher herbivory due to greater soil fertility. Because the plots were open to grazing, the impacts of herbivory along with more variable rainfall regimes likely minimized the effects of fire for the more arid sites. As a consequence, fire effects on grass community structure and composition were most marked for the higher rainfall sites and generally not significant for the more arid sites. For the high-rainfall sites, frequent dry season fires (1- to 3-year return intervals) resulted in high grass richness, evenness and diversity, whereas fire exclusion and growing season fires had the lowest of these measures and diverged the most in composition as the result of increased abundance of a few key grasses. Overall, the long-term cumulative impacts of altered fire regimes varied across broad climatic and fertility gradients, with fire effects on the grass community decreasing in importance and herbivory and climatic variability likely having a greater influence on community structure and composition with increasing aridity and soil fertility.


Ano de Publicação: 2013

Indigenous Burning as Conservation Practice: Neotropical Savanna Recovery amid Agribusiness Deforestation in Central Brazil

Abstract
International efforts to address climate change by reducing tropical deforestation increasingly rely on indigenous reserves
as conservation units and indigenous peoples as strategic partners. Considered win-win situations where global
conservation measures also contribute to cultural preservation, such alliances also frame indigenous peoples in diverse
ecological settings with the responsibility to offset global carbon budgets through fire suppression based on the presumed
positive value of non-alteration of tropical landscapes. Anthropogenic fire associated with indigenous ceremonial and
collective hunting practices in the Neotropical savannas (cerrado) of Central Brazil is routinely represented in public and
scientific conservation discourse as a cause of deforestation and increased CO2 emissions despite a lack of supporting
evidence. We evaluate this claim for the Xavante people of Pimentel Barbosa Indigenous Reserve, Brazil. Building upon
23 years of longitudinal interdisciplinary research in the area, we used multi-temporal spatial analyses to compare land
cover change under indigenous and agribusiness management over the last four decades (1973–2010) and quantify the
contemporary Xavante burning regime contributing to observed patterns based on a four year sample at the end of this
sequence (2007–2010). The overall proportion of deforested land remained stable inside the reserve (0.6%) but increased
sharply outside (1.5% to 26.0%). Vegetation recovery occurred where reserve boundary adjustments transferred lands
previously deforested by agribusiness to indigenous management. Periodic traditional burning by the Xavante had a large
spatial distribution but repeated burning in consecutive years was restricted. Our results suggest a need to reassess
overreaching conservation narratives about the purported destructiveness of indigenous anthropogenic fire in the cerrado.
The real challenge to conservation in the fire-adapted cerrado biome is the long-term sustainability of indigenous lands and
other tropical conservation islands increasingly subsumed by agribusiness expansion rather than the localized subsistence
practices of indigenous and other traditional peoples.

Citation: Welch JR, Brondı´zio ES, Hetrick SS, Coimbra CEA Jr (2013) Indigenous Burning as Conservation Practice: Neotropical Savanna Recovery amid Agribusiness Deforestation in Central Brazil. PLoS ONE 8(12): e81226. doi:10.1371/journal.pone.0081226

Ano de Publicação: 2013

Fire management in species-rich Cape fynbos shrublands

The management of fire-dependent biodiversity hotspots must be based on sound ecological knowledge and a
pragmatic approach that accommodates the constraints within which fire managers must operate. South Africa’s
fynbos biome (shrubland or heathland vegetation found in the Western Cape of South Africa) is one such
hotspot. In this region, the implementation of prescribed burning to conserve biodiversity must take into
account the area’s rugged and inaccessible terrain and recurrent wildfires, the presence of fire-adapted invasive
alien plants, and the imperatives for ensuring human safety. These constraints limit the potential for prescribed
burning to be effective everywhere, and prioritization and trade-offs will be needed to ensure the efficient use of
limited funding and management capacity. In such environments, management must be adaptive, based on
clearly defined and shared goals, monitoring, and assessment, and should be flexible enough to adjust as new
lessons are learned.

Ano de Publicação: 2013

Landscape structural analysis of the Lençóis Maranhenses national park: implications for conservation

Our work evaluated the anthropic effects on the landscape structure of the Lençóis Maranhenses National Park (LMNP) and its Buffer Zone, and proposed strategies for the region’s conservation. LMNP is an important protected area in Brazilian north coast which protects a unique wetland ecosystem composed of sand dunes fields and a coastal vegetation called restinga. Supervised mapping of LMNP and a surrounding buffer of 3 km was carried out through high resolution and fine scale (1:5000) satellite images. The mapped area was subdivided in 1000 ha hexagonal Analysis Units (AU) and the following landscape metrics were calculated for each one of them: cover area (CA) of each soil cover class - dune fields (CA-DUNES), water bodies (CA-WATER), dense restinga (CADENSE), scattered restinga (CA-SCATTER), grassland (CA-SANDY), mangroves (CA-MANG), anthropogenic activity (CA-ANTRO) and, secondary vegetation (CA-SECOND); Landscape Shannon Diversity Index (SHDI), and; percentage of native vegetation cover (NV−COV). Pearson correlations were performed between the CA of each class and SHDI to identify the classes most correlated to CA-ANTRO. Our results showed that anthropic classes (crops, trails, and villages) had a stronger correlation (Pearson Correlation, r ≈ 0.65) with phytophysiognomies of dense restinga, secondary vegetation and SHDI, thus indicating that the land use conversion occurs in dense restinga areas and promotes vegetation secondarization, as well as increasing fragmentation. At least, 42% of the dense restinga habitats was destroyed due to human activities. Five conservation and restoration strategies were proposed in a local scale depending on the percentage of native vegetation cover on each AU, from the most to less conserved: (a) only conservation; (b) conservation with management; (c) management; (d) management and restoration; and, (e) restoration. The implementation of Agroforestry Systems with agro-successional restoration goals was recommended as an alternative for land use.

Keywords:Land use, Territorial planning,Landscape metrics,Conservation strategies


https://reader.elsevier.com/reader/sd/pii/S1617138118303108?token=1E133DD41AB611A5DB97426EFB32BBDABC19DB7AD0359970DA0A6F9EDD129658E32C80E33214545E23956F5A37353057


Ano de Publicação: 2019

Can savanna burning projects deliver measurable greenhouse emissions reductions and sustainable livelihood opportunities in fire-prone settings?

Abstract

Savannas constitute the most fire-prone vegetation type on earth and are a significant source of greenhouse gas emissions. Most savanna fires are lit by people for a variety of livelihood applications. ‘Savanna burning’ is an accountable activity under the Kyoto Protocol, but only Australia, as a developed economy, accounts for emissions from this source in its national accounts. Over the past decade considerable effort has been given to developing savanna burning projects in northern Australia, combining customary indigenous (Aboriginal) approaches to landscape-scale fire management with development of
scientifically robust emissions accounting methodologies. Formal acceptance by the Australian Government of that methodology, and its inclusion in Australia’s developing emissions trading scheme, paves the way for Aboriginal people to commercially benefit from savanna burning projects. The paper first describes this Australian experience, and then explores options for implementing community-based savanna burning emissions reduction projects in other continental savanna settings, specifically in Namibia and Venezuela. These latter examples illustrate that savanna fire management approaches
potentially have broader application for contributing to livelihood opportunities in other fire-prone savanna regions.

Ano de Publicação: 2013

The Management of Fire-Adapted Ecosystems in an Urban Setting: the Case of Table Mountain National Park, South Africa

ABSTRACT.

The Table Mountain National Park is a 265-km² conservation area embedded within a city of 3.5 million people.
The highly diverse and unique vegetation of the park is both fire prone and fire adapted, and the use of fire forms an integral
part of the ecological management of the park. Because fires are both necessary and dangerous, fire management is characterized by uncertainty and conflict. The response of vegetation to fire is reasonably well understood, but the use of fire for conservation purposes remains controversial because of key gaps in understanding. These gaps include whether or not the vegetation is resilient to increases in fire frequency, how to deal with fire-sensitive forests embedded in fire-prone shrublands, and how to integrate fire and invasive alien plant control. National legislation emphasizes the need to protect communities from dangerous wildfires, and this compels fire managers to adopt a cautious approach to the application of fire. Ecological outcomes are optimized under a fire regime of relatively high-intensity, dry-season fires. Obtaining permission to burn under such conditions is not possible, and so the practice of prescribed burning is constrained, and this results in a fire regime dominated by wildfires. Ecological uncertainties, and the divergent requirements for maintaining healthy ecosystems on the one hand, and ensuring human safety on the other, result in a complex fire management environment. These complexities could be, and in some cases are being, alleviated by raising awareness, increasing fire management capacity, improving ecological monitoring of the effects of fire, and prioritizing areas for integrated fire and invasive alien plant management.
Key Words: biodiversity conservation; ecosystem management; forestry; fynbos; pines; wildland–urban interface

Ano de Publicação: 2012

The influence of prescribed fire on the extent of wildfire in savanna landscapes of western Arnhem Land, Australia

Abstract.

Fire regimes in many north Australian savanna regions are today characterised by frequent wildfires occurring
in the latter part of the 7-month dry season. A fire management program instigated from 2005 over 24 000 km2 of
biodiversity-rich Western Arnhem Land aims to reduce the area and severity of late dry-season fires, and associated
greenhouse gas emissions, through targeted early dry-season prescribed burning. This study used fire history mapping
derived mostly from Landsat imagery over the period 1990–2009 and statistical modelling to quantify the mitigation of
late dry-season wildfire through prescribed burning. From 2005, there has been a reduction in mean annual total proportion
burnt (from 38 to 30%), and particularly of late dry-season fires (from 29 to 12.5%). The slope of the relationship between
the proportion of early-season prescribed fire and subsequent late dry-season wildfire was,–1. This means that imposing
prescribed early dry-season burning can substantially reduce late dry-season fire area, by direct one-to-one replacement.
There is some evidence that the spatially strategic program has achieved even better mitigation than this. The observed
reduction in late dry-season fire without concomitant increase in overall area burnt has important ecological and
greenhouse gas emissions implications. This efficient mitigation of wildfire contrasts markedly with observations reported
from temperate fire-prone forested systems.
Additional keywords: fire management, greenhouse gas emissions, Leverage, planned fire, unplanned fire.

Ano de Publicação: 2012