| 51. |
- Fedrowitz, Katja, et al.
(författare)
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Can retention forestry help conserve biodiversity? A meta-analysis
- 2014
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 51, s. 1669–1679-
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Forskningsöversikt (refereegranskat)abstract
- Industrial forestry typically leads to a simplified forest structure and altered species composition. Retention of trees at harvest was introduced about 25years ago to mitigate negative impacts on biodiversity, mainly from clearcutting, and is now widely practiced in boreal and temperate regions. Despite numerous studies on response of flora and fauna to retention, no comprehensive review has summarized its effects on biodiversity in comparison to clearcuts as well as un-harvested forests. Using a systematic review protocol, we completed a meta-analysis of 78 studies including 944 comparisons of biodiversity between retention cuts and either clearcuts or un-harvested forests, with the main objective of assessing whether retention forestry helps, at least in the short term, to moderate the negative effects of clearcutting on flora and fauna. Retention cuts supported higher richness and a greater abundance of forest species than clearcuts as well as higher richness and abundance of open-habitat species than un-harvested forests. For all species taken together (i.e. forest species, open-habitat species, generalist species and unclassified species), richness was higher in retention cuts than in clearcuts. Retention cuts had negative impacts on some species compared to un-harvested forest, indicating that certain forest-interior species may not survive in retention cuts. Similarly, retention cuts were less suitable for some open-habitat species compared with clearcuts. Positive effects of retention cuts on richness of forest species increased with proportion of retained trees and time since harvest, but there were not enough data to analyse possible threshold effects, that is, levels at which effects on biodiversity diminish. Spatial arrangement of the trees (aggregated vs. dispersed) had no effect on either forest species or open-habitat species, although limited data may have hindered our capacity to identify responses. Results for different comparisons were largely consistent among taxonomic groups for forest and open-habitat species, respectively.Synthesis and applications. Our meta-analysis provides support for wider use of retention forestry since it moderates negative harvesting impacts on biodiversity. Hence, it is a promising approach for integrating biodiversity conservation and production forestry, although identifying optimal solutions between these two goals may need further attention. Nevertheless, retention forestry will not substitute for conservation actions targeting certain highly specialized species associated with forest-interior or open-habitat conditions.Our meta-analysis provides support for wider use of retention forestry since it moderates negative harvesting impacts on biodiversity. Hence, it is a promising approach for integrating biodiversity conservation and production forestry, although identifying optimal solutions between these two goals may need further attention. Nevertheless, retention forestry will not substitute for conservation actions targeting certain highly specialized species associated with forest-interior or open-habitat conditions.
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| 52. |
- Filbee-Dexter, Karen, et al.
(författare)
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Quantifying ecological and social drivers of ecological surprise
- 2018
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 55:5, s. 2135-2146
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Tidskriftsartikel (refereegranskat)abstract
- 1. A key challenge facing ecologists and ecosystem managers is understanding what drives unexpected shifts in ecosystems and limits the effectiveness of human interventions. Research that integrates and analyses data from natural and social systems can provide important insight for unravelling the complexity of these dynamics. It is, therefore, a critical step towards the development of evidence-based, whole-system management approaches.2. To examine our ability to influence ecosystems that are behaving in unexpected ways, we explore three prominent cases of ecological surprise. We captured the social-ecological systems (SES) using key variables and interactions from Ostrom's SES framework, which integrates broader ecosystem processes (e.g. climate, connectivity), management variables (e.g. quotas, restrictions, monitoring), resource use behaviours (e.g. harvesting) and the resource unit (e.g. trees, fish, clean water) being managed.3. Structural equation modelling revealed that management interventions often influenced resource use behaviours (e.g. rules and limits strongly affected harvest or pollution), but they did not have a significant effect on the abundance of the managed resource. Instead, most resource variability was related to ecological processes and feedbacks operating at broader spatial or temporal scales than management interventions, which locked the resource system into the degraded state.4. Synthesis and applications. Mismatch between the influence of management systems and ecosystem processes can limit the effectiveness of human interventions during periods of ecological surprise. Management strategies should shift from a conventional focus on removal or addition of a single resource towards solutions that influence the broader ecosystem. Operationalizing Ostrom’s framework to quantitatively analyse social‐ecological systems using structural equation models shows promise for testing solutions to navigate these events.
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| 53. |
- Fournier, Auriel M. V., et al.
(författare)
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Combining citizen science species distribution models and stable isotopes reveals migratory connectivity in the secretive Virginia rail
- 2017
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Ingår i: Journal of Applied Ecology. - : WILEY. - 0021-8901 .- 1365-2664. ; 54:2, s. 618-627
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Tidskriftsartikel (refereegranskat)abstract
- 1. Stable hydrogen isotope (delta D) methods for tracking animal movement are widely used yet often produce low resolution assignments. Incorporating prior knowledge of abundance, distribution or movement patterns can ameliorate this limitation, but data are lacking for most species. We demonstrate how observations reported by citizen scientists can be used to develop robust estimates of species distributions and to constrain dD assignments. 2. We developed a Bayesian framework to refine isotopic estimates of migrant animal origins conditional on species distribution models constructed from citizen scientist observations. To illustrate this approach, we analysed the migratory connectivity of the Virginia rail Rallus limicola, a secretive and declining migratory game bird in North America. 3. Citizen science observations enabled both estimation of sampling bias and construction of bias-corrected species distribution models. Conditioning dD assignments on these species distribution models yielded comparably high-resolution assignments. 4. Most Virginia rails wintering across five Gulf Coast sites spent the previous summer near the Great Lakes, although a considerable minority originated from the Chesapeake Bay watershed or Prairie Pothole region of North Dakota. Conversely, the majority of migrating Virginia rails from a site in the Great Lakes most likely spent the previous winter on the Gulf Coast between Texas and Louisiana. 5. Synthesis and applications. In this analysis, Virginia rail migratory connectivity does not fully correspond to the administrative flyways used to manage migratory birds. This example demonstrates that with the increasing availability of citizen science data to create species distribution models, our framework can produce high-resolution estimates of migratory connectivity for many animals, including cryptic species. Empirical evidence of links between seasonal habitats will help enable effective habitat management, hunting quotas and population monitoring and also highlight critical knowledge gaps.
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| 54. |
- Frainer, André, et al.
(författare)
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Enhanced ecosystem functioning following stream restoration : The roles of habitat heterogeneity and invertebrate species traits
- 2018
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Ingår i: Journal of Applied Ecology. - : Wiley-Blackwell Publishing Inc.. - 0021-8901 .- 1365-2664. ; 55:1, s. 377-385
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Tidskriftsartikel (refereegranskat)abstract
- 1. Habitat restoration is increasingly undertaken in degraded streams and rivers to help improve biodiversity and ecosystem functioning. Follow-up assessments focused on outcomes for biodiversity have often found scant evidence for recovery, raising concerns about the efficacy of habitat restoration for improving ecological integrity. However, responses of other ecological variables, such as ecosystem process rates and the functional trait composition of biological assemblages, have been little evaluated.2. We assessed how the restoration of habitat heterogeneity affected multiple functional parameters in 20 boreal stream reaches encompassing both more and less extensively restored sites, as well as channelised and natural reference sites. We further assessed relationships between our functional parameters and a fluvial geomorphic measure of habitat heterogeneity.3. Leaf decomposition was positively related to habitat heterogeneity. This was associated with shifts in the functional composition of detritivore assemblages, with the most obligate litter consumers more prominent in reaches showing higher habitat heterogeneity. The deposition of fine particulate organic matter was consistently higher in restored than channelised sites, and was positively related to the heterogeneity gradient. Algal biomass accrual per unit area did not vary either with restoration or the heterogeneity gradient.4. Synthesis and applications. Our findings demonstrate that restoration of river habitat heterogeneity can enhance retention and decomposition of organic matter, key ecosystem properties underpinning ecosystem functioning and service delivery. Significantly, enhanced litter decomposition was linked with a change in the functional composition rather than diversity of detritivore assemblages. Future evaluation of the success of habitat restorations should incorporate quantification of ecosystem processes and the functional traits of biota, in addition to measures of fluvial geomorphology and more traditional biotic metrics, to facilitate a more comprehensive and mechanistic assessment of ecological responses.
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| 55. |
- Frankow-Lindberg, Bodil, et al.
(författare)
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Ecosystem function enhanced by combining four functional types of plant species in intensively managed grassland mixtures: a 3-year continental-scale field experiment
- 2013
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 50, s. 365-375
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Tidskriftsartikel (refereegranskat)abstract
- A coordinated continental-scale field experiment across 31 sites was used to compare the biomass yield of monocultures and four species mixtures associated with intensively managed agricultural grassland systems. To increase complementarity in resource use, each of the four species in the experimental design represented a distinct functional type derived from two levels of each of two functional traits, nitrogen acquisition (N2-fixing legume or nonfixing grass) crossed with temporal development (fast-establishing or temporally persistent). Relative abundances of the four functional types in mixtures were systematically varied at sowing to vary the evenness of the same four species in mixture communities at each site and sown at two levels of seed density. Across multiple years, the total yield (including weed biomass) of the mixtures exceeded that of the average monoculture in >97% of comparisons. It also exceeded that of the best monoculture (transgressive overyielding) in about 60% of sites, with a mean yield ratio of mixture to best-performing monoculture of 1 center dot 07 across all sites. Analyses based on yield of sown species only (excluding weed biomass) demonstrated considerably greater transgressive overyielding (significant at about 70% of sites, ratio of mixture to best-performing monoculture=1 center dot 18). Mixtures maintained a resistance to weed invasion over at least 3years. In mixtures, median values indicate <4% of weed biomass in total yield, whereas the median percentage of weeds in monocultures increased from 15% in year 1 to 32% in year 3. Within each year, there was a highly significant relationship (P<0 center dot 0001) between sward evenness and the diversity effect (excess of mixture performance over that predicted from the monoculture performances of component species). At lower evenness values, increases in community evenness resulted in an increased diversity effect, but the diversity effect was not significantly different from the maximum diversity effect across a wide range of higher evenness values. The latter indicates the robustness of the diversity effect to changes in species' relative abundances. Across sites with three complete years of data (24 of the 31 sites), the effect of interactions between the fast-establishing and temporal persistent trait levels of temporal development was highly significant and comparable in magnitude to effects of interactions between N2-fixing and nonfixing trait levels of nitrogen acquisition. Synthesis and applications. The design of grassland mixtures is relevant to farm-level strategies to achieve sustainable intensification. Experimental evidence indicated significant yield benefits of four species agronomic mixtures which yielded more than the highest-yielding monoculture at most sites. The results are relevant for agricultural practice and show how grassland mixtures can be designed to improve resource complementarity, increase yields and reduce weed invasion. The yield benefits were robust to considerable changes in the relative proportions of the four species, which is extremely useful for practical management of grassland swards.
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| 56. |
- Gustafsson, Lena
(författare)
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Landscape properties affect biodiversity response to retention approaches in forestry
- 2017
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 54, s. 1627-1637
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Tidskriftsartikel (refereegranskat)abstract
- 1. Retention forestry, in which trees and tree patches are set aside at harvest to promote biodiversity, has been proven to have positive effects on biodiversity at the stand-level across different taxa. However, the effectiveness of retention approaches with regard to landscape composition remains unexplored.2. We linked the effect sizes from two meta-analyses (31 case studies and 1050 comparisons from boreal and temperate regions), which quantified the effectiveness of biodiversity conservation as a result of retention practices, with the stand property of retention level (the percentage of trees retained after logging) and with Landsat-retrieved landscape data on forest cover and spatial configurations at three spatial scales (1, 3, and 5 km radii).3. We found that, in addition to the fundamental importance of tree retention as a local-scale implementation for conservation, landscape properties were important in models to predict biodiversity responses. The effect sizes for species richness decreased with increasing patch contiguity within the landscapes at all spatial scales. Similar results were observed for abundance responses at the largest spatial scale. These results suggest that biodiversity responses to tree retention may be weaker in less fragmented landscapes, which is in agreement with theoretical and empirical findings from agricultural landscapes (the intermediate landscape-complexity hypothesis').4. The benefits of retention levels within a stand (percentage of trees retained) varied amongst species with different habitat requirements (forest-dependent, open habitat, and generalist species). Whilst this stand-level property was often an important determinant of biodiversity responses, models that included landscape properties as explanatory variables always performed better than those that were only based on the retention levels for all species groups. Thus, within-stand habitat conditions and landscape configurations likely have synergetic influences on biodiversity responses.5. Synthesis and applications. In addition to the importance of stand-level properties, such as the action of retention harvesting itself and the number of trees retained, conditions in the surrounding landscape can simultaneously affect biodiversity in stands that are managed under retention forestry. Our study suggests that retention patches are particularly important in moderately fragmented landscapes. Retention practices could be less important in previously unlogged and less fragmented landscapes, where setting aside large reserves is a conservation priority. For highly fragmented landscapes, different actions of forest restoration, which are not limited to set-aside actions during logging, would be important. Our study emphasizes that carefully planned conservation schemes with a large-scale perspective, as well as local-scale actions, such as retention forestry, are critical for effective forest management and conservation planning.
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| 57. |
- Gustavsson, Anne-Maj
(författare)
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Weed suppression greatly increased by plant diversity in intensively managed grasslands: A continental-scale experiment
- 2018
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 55, s. 852-862
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Tidskriftsartikel (refereegranskat)abstract
- 1. Grassland diversity can support sustainable intensification of grassland production through increased yields, reduced inputs and limited weed invasion. We report the effects of diversity on weed suppression from 3 years of a 31-site continental-scale field experiment.2. At each site, 15 grassland communities comprising four monocultures and 11 four-species mixtures based on a wide range of species' proportions were sown at two densities and managed by cutting. Forage species were selected according to two crossed functional traits, "method of nitrogen acquisition" and "pattern of temporal development".3. Across sites, years and sown densities, annual weed biomass in mixtures and monocultures was 0.5 and 2.0 t DM ha(-1) (7% and 33% of total biomass respectively). Over 95% of mixtures had weed biomass lower than the average of monocultures, and in two-thirds of cases, lower than in the most suppressive monoculture (transgressive suppression). Suppression was significantly transgressive for 58% of site-years. Transgressive suppression by mixtures was maintained across years, independent of site productivity.4. Based on models, average weed biomass in mixture over the whole experiment was 52% less (95% confidence interval: 30%-75%) than in the most suppressive monoculture. Transgressive suppression of weed biomass was significant at each year across all mixtures and for each mixture.5. Weed biomass was consistently low across all mixtures and years and was in some cases significantly but not largely different from that in the equiproportional mixture. The average variability (standard deviation) of annual weed biomass within a site was much lower for mixtures (0.42) than for monocultures (1.77).6. Synthesis and applications. Weed invasion can be diminished through a combination of forage species selected for complementarity and persistence traits in systems designed to reduce reliance on fertiliser nitrogen. In this study, effects of diversity on weed suppression were consistently strong across mixtures varying widely in species' proportions and over time. The level of weed biomass did not vary greatly across mixtures varying widely in proportions of sown species. These diversity benefits in intensively managed grasslands are relevant for the sustainable intensification of -agriculture and, importantly, are achievable through practical farm-scale actions.
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| 58. |
- Hämäläinen, Aino, et al.
(författare)
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Low-productivity boreal forests have high conservation value for lichens
- 2020
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 57, s. 43-54
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Tidskriftsartikel (refereegranskat)abstract
- 1. Land set aside for preservation of biodiversity often has low productivity. As biodiversity generally increases with productivity, due to higher or more diverse availability of resources, this implies that some of the biodiversity may be left unprotected. Due to a lack of knowledge on the species diversity and conservation value of low-productivity habitats, the consequences of the biased allocation of low-productivity land for set-asides are unknown.2. We examined the conservation value of boreal low-productivity forests (potential tree growth <1 m(3) ha(-1) year(-1)) by comparing assemblages of tree- and deadwood-dwelling lichens and forest stand structure between productive and low-productivity forest stands. We surveyed 84 Scots pine-dominated stands in three regions in Sweden, each including four stand types: two productive (managed and unman-aged) and two low-productivity stands (on mires and on thin, rocky soils).3. Lichen species richness was the highest in low-productivity stands on thin soil, which had similar amounts and diversity of resources (living trees and dead wood) to productive unmanaged stands. Stands in low-productivity mires, which had low abundance of living trees and dead wood, hosted the lowest lichen richness. Lichen species composition differed among stand types, but none of them hosted unique species. The differences in both species richness and composition were more pronounced in northern than in southern Sweden, likely due to shorter history of intensive forestry.4. Synthesis and applications. Boreal low-productivity forests can have as high conservation value as productive forests, which should be reflected in conservation strategies. However, their value is far from uniform, and conservation planning should acknowledge this variation and not treat all low-productivity forests as a uniform group. Some types of low-productivity forest (e.g. on rocky soil) are more valuable than others (e.g. on mires), and should thus be prioritized in conservation. It is also important to consider the landscape context: low-productivity forests may have higher value in landscapes where high-productivity forests are highly influenced by forestry. Finally, although low-productivity forests can be valuable for some taxa, productive forests may still be important for other taxa.
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| 59. |
- Jakobsson, Simon, et al.
(författare)
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The importance of trees for woody pasture bird diversity and effects of the European Union's tree density policy
- 2017
-
Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 54:6, s. 1638-1647
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Tidskriftsartikel (refereegranskat)abstract
- 1. Recent reforms in the Common Agricultural Policy aim for a greening of the subsidy system with potential improvements for biodiversity conservation. As part of that process, the tree density limit for pastures to qualify for European Union subsidies has been increased from 50 to 100 trees per hectare. However, recent studies show that the high biodiversity values of these habitats may be threatened by these limits, highlighting the need for policy improvements. Still, little is known about the direct effects of tree density limitations on bird communities in woody pastures. 2. We investigated how bird diversity and species composition are affected by tree density in 49 Swedish woody pastures along a gradient of 4-214 trees per hectare. We recorded bird communities, tree density and stand structure estimates in the field and estimated forest cover in the surrounding landscape from aerial photos. Using generalised additive models and redundancy analysis, we analysed how bird territorial species richness, bird abundance and species composition are affected by tree density, taking into account other local and landscape scale explanatory variables. 3. Tree density had a significant positive effect on bird species richness at low tree densities and species richness saturated at approximately 50 trees per hectare. Shrub density had a significant positive linear effect on both bird species richness and abundance. Tree and shrub density were also the major drivers of bird community composition, with secondary effects of tree species diversity and landscape forest cover. 4. Policy implications. Our results show that tree density is not the limiting factor, but rather a driver of bird diversity and species composition in woody pastures and that tree density limits may fail to capture the whole range of biological values. To improve policy recommendations, we therefore stress the importance of considering additional social-ecological drivers associated to management quality, e.g. taking into account moral and cultural motivations among farmers, to preserve biodiversity in woody pastures.
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| 60. |
- Johansson, Maria, et al.
(författare)
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Fuel, fire and cattle in African highlands: traditional management maintains a mosaic heathland landscape
- 2014
-
Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 51, s. 1396-1405
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Tidskriftsartikel (refereegranskat)abstract
- 1. Shrubland ecosystems are often inherently flammable due to a canopy structure favourable for fire propagation. At the same time, the fuel bed is not spatially uniform, but a complex mix of shrubs and herbaceous vegetation that will change with time since fire. These patterns are further influenced by megaherbivores capable of consuming large quantities of biomass that otherwise would enter the fuel bed, but the net effects for temporal thresholds of flammability are poorly known.2. We quantified post-fire fuel succession and effects of free-ranging cattle in high-elevation Erica shrublands in Ethiopia where traditional fire management is still practised above the treeline at 3500 m, despite being challenged by authorities.3. We found a near-linear accumulation of canopy fuel at 2 . 6 Mg ha(-1) year(-1), but stands <5 years old did not burn due to spatial separation of individual Erica shrubs before canopy closure and lack of fine dead fuels.4. Inside cattle exclosures, Erica height growth was nearly three times faster and reached the assumed flammability threshold c. 3 years earlier than in browsed/grazed stands, where cattle also kept herbaceous vegetation between shrubs short, thus eliminating litter that could otherwise bridge the discontinuous fuel bed in early succession.5. Modelling of fire behaviour indicated progressively higher fire intensity and rate of spread for stands >5 years. But if stands escape fire for several decades, flammability again decreases as canopy fuels become increasingly separated from the ground. This may be the ultimate reason for sharp treelines on many tropical mountains where fire is confined mainly to higher elevations.6. Synthesis and applications. In shrublands where dominant plants can outgrow consumption by large herbivores, provision of good cattle habitat typically requires fire. We found that fire and cattle interact to maintain a relatively stable system, where fuel limitation in early succession creates fire breaks that prevent landscape-wide wildfires. The same negative feedback protects the Erica from degradation by too frequent fires. As shrublands can have widely different compositions, the response to variation in fire frequency and herbivore pressure is likely to differ, but for sustainable management fire and grazing have to be treated in consort.
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