Effects of Invasive Alien Plants on Fire Regimes

Brooks, Matthew L.; D’Antonio, Carla M.; Richardson, David M.; Grace, James B.; Keeley, Jon E.; DiTomaso, Joseph M.; Hobbs, Richard J.; Pellant, Mike; Pyke, David A.

doi:10.1641/0006-3568(2004)054[0677:eoiapo]2.0.co;2

Cited by 1,328 publications

(1,149 citation statements)

References 23 publications

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“…In particular, Parker et al (1999) opined the need for 'operational generalizations' about impact and stressed the difficulty of assessing the per capita effects of invaders. Not all invaders have a major impact because of their per capita effects; for example, many invasive plants, through their great abundance or biomass, affect fire regimes (Brooks et al 2004). Nonetheless, many invaders do generate impacts directly because of per capita effects, and a major obstacle to testing impact theories is the lack of standardized methods for determining such effects on use of resources, such as native prey .…”

Section: Introductionmentioning

confidence: 99%

Advancing impact prediction and hypothesis testing in invasion ecology using a comparative functional response approach

et al. 2013

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Invasion ecology urgently requires predictive methodologies that can forecast the ecological impacts of existing, emerging and potential invasive species. We argue that many ecologically damaging invaders are characterised by their more efficient use of resources. Consequently, comparison of the classical 'functional response' (relationship between resource use and availability) between invasive and trophically analogous native species may allow prediction of invader ecological impact. We review the utility of species trait comparisons and the history and context of the use of functional responses in invasion ecology, then present our framework for the use of comparative functional responses. We show that functional response analyses, by describing the resource use of species over a range of resource availabilities, avoids many pitfalls of 'snapshot' assessments of resource use. Our framework demonstrates how comparisons of invader and native functional responses, within and between Type II and III functional responses, allow testing of the likely population-level outcomes of invasions for affected species. Furthermore, we describe how recent studies support the predictive capacity of this method; for example, the invasive 'bloody red shrimp' Hemimysis anomala shows higher Type II functional responses than native mysids and this corroborates, and could -013-0550-8 have predicted, actual invader impacts in the field. The comparative functional response method can also be used to examine differences in the impact of two or more invaders, two or more populations of the same invader, and the abiotic (e.g. temperature) and biotic (e.g. parasitism) context-dependencies of invader impacts. Our framework may also address the previous lack of rigour in testing major hypotheses in invasion ecology, such as the 'enemy release' and 'biotic resistance' hypotheses, as our approach explicitly considers demographic consequences for impacted resources, such as native and invasive prey species. We also identify potential challenges in the application of comparative functional responses in invasion ecology. These include incorporation of numerical responses, multiple predator effects and trait-mediated indirect interactions, replacement versus non-replacement study designs and the inclusion of functional responses in risk assessment frameworks. In future, the generation of sufficient case studies for a meta-analysis could test the overall hypothesis that comparative functional responses can indeed predict invasive species impacts.Biol Invasions (2014) 16:735-753 DOI 10.1007/s10530

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Section: Introductionmentioning

confidence: 99%

Advancing impact prediction and hypothesis testing in invasion ecology using a comparative functional response approach

et al. 2013

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“…These woody invaders differ from the invasions by grasses in their effect on the fire regime. In contrast to the grass invaders in American and Australian systems, they often decrease fuel load and fire frequency by outshading native grasses, but increase the risk of high intensity canopy fires (Brooks et al 2004). The exotic scrambling shrub Chromolaena odorata, for example, is a species that has been reported to increase vertical continuity of fires in savannas, i.e.…”

Section: Introductionmentioning

confidence: 99%

Managing invasions at the cost of native habitat? An experimental test of the impact of fire on the invasion of Chromolaena odorata in a South African savanna

Beest

Cromsigt

Ngobese³

et al. 2011

Biol Invasions

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Successfully managing invasive plants in natural systems is extremely difficult. Recently however, progress has been made with an approach focused on changing ecosystem processes through the disturbance regime. We performed a large-scale (3 ha) full-factorial field experiment in densely invaded woodland in Hluhluwe-iMfolozi Park, a savanna reserve in South Africa, to study the effect of fire on the control of the pan-tropical invasive exotic shrub Chromolaena odorata in combination with the conventional method, i.e. manual clearing and herbicide application. We show how fire interacted with the conventional clearing of C. odorata and induced an intense canopy fire that caused a shift from woodland to grassland. After 2.5 years of monitoring, grasses were still dominant and re-invasion minimal. It is important to note that fire without prior clearing did not have the same effect and was not successful in reducing densities of C. odorata. An integrated control practice targeting the species with mechanical and chemical methods, while simultaneously targeting its habitat through fire, effectively controlled dense C. odorata thickets during the course of the experiment. However, this approach transformed regular surface fires into high-intensity canopy fires that are rare in savannas. We discuss how this altered fire regime may threaten native habitats, including fire-sensitive forest patches and riverine woodlands within the savanna mozaic. This is an important dilemma for managers that should not be overlooked and asks for long-term data on the impact of control programs on the native vegetation.

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“…The accumulation of litter decreases the amount of N available for microbial activity and the increased fire frequency augments N losses by volatilization (Evans et al, 2001). Moreover, an increased fire return period from about once per century to once every four to five years induces positive feedback processes on B. tectorum and ultimately destabilization of shrubland structure by removing shrubs and other native vegetation (Brooks et al, 2004). Similarly, fires damage the crust biota and frequent fires may prevent biocrust reestablishment to pre-disturbance levels (Greene et al, 1989;Johansen, 2003;Hilty et al, 2004).…”

Section: Ecological Considerationsmentioning

confidence: 99%

“…However, disturbance by domestic grazers and invasion of exotic annual plants over the past century have reduced biocrust cover and transformed relatively stable, diverse sagebrush steppe communities into more homogenous grasslands dominated by exotic annuals (Brooks et al, 2004). While various non-native plants are responsible for changes in vegetation composition, perhaps the single most important factor causing replacement of native vegetation has been invasion by the annual grass Bromus tectorum L. (cheatgrass) (Brooks et al, 2004). In the Great Basin alone, more than 20,000 km 2 are now dominated by B. tectorum, which frequently forms extensive monocultures (Bradley and Mustard, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, as B. tectorum plants dry out in early summer, their stems and inflorescences create large amounts of vegetation litter. This litter leads to the formation of a rather continuous and homogeneous layer of fine fuel that can drastically increase wild fire frequency to as often as once every five years and eliminate fire-sensitive vegetation including many biocrust components (Johansen, 2003;Bowker et al, 2004;Brooks et al, 2004). In addition, cover by litter is likely to alter the biocrust microenvironment, particularly in terms of light, temperature, and moisture (Belnap, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Bromus tectorum litter alters photosynthetic characteristics of biological soil crusts from a semiarid shrubland

Serpe

Roberts

Eldridge

et al. 2013

Soil Biology and Biochemistry

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Invasion by the exotic annual grass Bromus tectorum has increased the cover and connectivity of fine litter in the sagebrush steppes of western North America. This litter tends to cover biological soil crusts, which could affect their metabolism and growth. To investigate this possible phenomenon, biological soil crusts dominated by either the moss Bryum argenteum or the lichen Diploschistes muscorum were covered with B. tectorum litter (litter treatment) or left uncovered (control treatment) and exposed to natural field conditions. After periods of five and ten months, we removed the litter and compared the photosynthetic performance of biological soil crusts from the two treatments. Litter induced photosynthetic changes in our samples. In both B. argenteum and D. muscorum, biological soil crusts that had been covered with litter for ten months had lower rates of gross photosynthesis and lower chlorophyll content than control samples. Similarly in both biological soil crust types, litter reduced the rate of dark respiration. For D. muscorum, the reduction in dark respiration fully compensated for the decrease in gross photosynthesis, resulting in similar values of net photosynthesis in the two treatments. In contrast, for B. argenteum, net photosynthesis was four-times greater in the control than the litter treatment. Also under litter cover, D. muscorum showed three common adaptations to shade conditions: a decrease in the light compensation point, in the light intensity needed to achieve 95% of maximal net photosynthesis, and in the chlorophyll a/b ratio. None of these changes was apparent in B. argenteum. Overall, our results indicate that photosynthetic responses to the presence of litter varied among species of the crust biota and that the litter can reduce the photosynthetic capacity of biological soil crusts. These results help to explain field observations of decreases in biological soil crust cover and changes in biological soil crust composition with increases in litter cover, and suggest that the landscape-wide invasion by B. tectorum may have substantial effects on biological soil crust performance and therefore their capacity to function in semiarid shrublands.Keywords: Biological soil crusts, Bromus tectorum, Bryum argenteum, Diploschistes muscorum, lichens, litter, mosses, photosynthesis, semiarid environments, sagebrush steppe Abbreviations: Biological soil crusts (biocrusts), ΔF/F m ', photosystem II operating efficiency, F v /F m , maximum quantum efficiency of photosystem II photochemistry; LCP, light compensation point, NPQ, non-photochemical quenching; PPFR 95% , light intensity necessary to achieve 95% of maximal net photosynthesis 2

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Effects of Invasive Alien Plants on Fire Regimes

Cited by 1,328 publications

References 23 publications

Advancing impact prediction and hypothesis testing in invasion ecology using a comparative functional response approach

Advancing impact prediction and hypothesis testing in invasion ecology using a comparative functional response approach

Managing invasions at the cost of native habitat? An experimental test of the impact of fire on the invasion of Chromolaena odorata in a South African savanna

Bromus tectorum litter alters photosynthetic characteristics of biological soil crusts from a semiarid shrubland

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