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1.
The carbon market offers a unique opportunity to achieve large‐scale ecological restoration of degraded agricultural landscapes. Here, we outline some of the benefits of planting mixes of native species rather than monocultures in carbon plantings as a step towards creating biodiverse carbon‐rich forests and woodlands in Australia. We highlight the gaps in our knowledge and emphasise the importance of setting benchmarks for carbon projects to maximise their potential to deliver co‐benefits such as habitat provision for wildlife. On the whole, we are optimistic that ongoing refinement of joined biodiversity conservation and carbon credit initiatives will help to develop a carbon market that can drive ecological restoration of Australian agricultural landscapes.  相似文献   

2.
Summary   Conservation planning aims to ensure the protection and continuation of biodiversity. In rural landscapes in Victoria, this will require the restoration of habitat and biophysical processes to levels that can sustain the majority of species. Planning is required at scales large enough to have ecological relevance. In this study, a land-use change scenario that plans for the conservation of native biodiversity within the Goulburn Broken Catchment was developed using simple ecological principles. A set of indicative rules for restoring remnant native vegetation was modelled within a geographical information system. The modelling of the rules resulted in a change in rural landscapes from highly fragmented (with few large remnants) to highly connected. Future applications of this approach include incorporating the biodiversity rules into a biophysical model to assess the effect of planning landscapes for the conservation of biodiversity on hydrological and economic outcomes for the region. In addition, the rules are to be refined so that the priority landscapes for biodiversity planning can be identified.  相似文献   

3.
Bounded by ocean and desert, the isolated, predominately Mediterranean‐climate region of south‐western Australia (SWA) includes nine bioregions (circa 44 million hectares). The ecological integrity of the landscapes in this global biodiversity hotspot has been compromised by deforestation, fragmentation, exploitation, and introduced biota. Nature and degree of transformation varies between four interconnected landscapes (Swan Coastal Plain; South‐west Forests; Wandoo Woodlands; and Great Western Woodlands). A Gondwanan perspective emphasizes a venerable biota and a cultural component to deep time. The particular importance of remnants and protected areas is recognized in restoring ecological integrity to Gondwanan landscapes. The nature and magnitude of the restoration task in these ancient, and neighboring, landscapes require higher levels of investment and more time than do recent landscapes. The protection, conservation, restoration, and rehabilitation of ecological integrity require multiple approaches in each landscape as well as consideration of the whole. Active conservation of biota and minimizing the impact of industrial‐ and agricultural‐use are priorities. Integrating a climate focus and rethinking fire are critical restoration considerations to future trajectories under anthropogenic climate change. A legislative mandate to coordinate industrial‐scale restoration and active conservation to build from protected areas must become a societal priority to restore ecological integrity.  相似文献   

4.
Long‐term ecological success of large‐scale restoration programs planned for the next decades will rely on genetic diversity (GD) of reintroduced or colonizing species, a limiting factor in highly fragmented landscapes. In small and isolated natural remnants or restoration areas, substantial reduction in population's size or connectivity may lead to local extinctions due to the accumulation of deleterious recessive alleles and ongoing reduction of fecundity, plant vigor, recruitment success, and adaptive potential. Despite the paramount role of GD for species persistence, its levels in restoration programs are poorly known. We assessed the GD of four model tree species (different succession stages, dispersal, and pollination syndromes) from the Brazilian Atlantic Forest, comparing two high‐diversity restoration plantations, one forest fragment and one conserved remnant. Contrary to the expectation that the plantation strategies adopted in the restoration programs could result in genetic composition homogenization, we found that restoration areas established heterogeneous genetic groups with similar levels of neutral GD and inbreeding to those observed in natural forest remnants. This pattern was consistent across the four functionally different tree species, despite some species idiosyncrasies. For instance, we observed lower allelic richness in early successional species in restoration sites, suggesting that some species may be more prone to reintroduction with lower GD. Thus, we advocate the use of high GD levels in restoration to support biodiversity conservation in human‐modified landscapes, thus reinforcing the role of ecological restoration for recovering the diversity of genes—the basic constituent of biodiversity.  相似文献   

5.
“再野化”:山水林田湖草生态保护修复的新思路   总被引:2,自引:0,他引:2  
杨锐  曹越 《生态学报》2019,39(23):8763-8770
作为一种新兴的生态保护修复方法,“再野化”(rewilding)是指特定区域中荒野程度的提升过程,尤其强调提升生态系统韧性和维持生物多样性。再野化实践的核心要素包括保护核心荒野地、增加荒野地的连通性、保护和重引入关键种(包括大型食肉动物)、适度允许自然干扰的发生、降低人类干扰和管理程度、拆除部分人工基础设施等。评述了北美洲和欧洲的再野化实践。通过比较研究,提出基于再野化的我国山水林田湖草生态保护修复的新思路,包括战略层面的5项转变和行动层面的5项建议。5项战略转变,包括从还原论思维转向整体思维、从工程性修复转向保护优先和自然恢复为主、从项目尺度转向景观尺度、从短期试点转向长期实践、从政府主导转向多方参与;5项行动建议,包括开展荒野和再野化基础调查、保护仅存的高价值荒野地、探索“城-乡-野”系统性再野化途径、以荒野保护区和再野化区域为核心建立大尺度景观保护网络、开展基于再野化的生态体验和自然教育。  相似文献   

6.
A major global effort to enable cost‐effective natural regeneration is needed to achieve ambitious forest and landscape restoration goals. Natural forest regeneration can potentially play a major role in large‐scale landscape restoration in tropical regions. Here, we focus on the conditions that favor natural regeneration within tropical forest landscapes. We illustrate cases where large‐scale natural regeneration followed forest clearing and non‐forest land use, and describe the social and ecological factors that drove these local forest transitions. The self‐organizing processes that create naturally regenerating forests and natural regeneration in planted forests promote local genetic adaptation, foster native species with known traditional uses, create spatial and temporal heterogeneity, and sustain local biodiversity and biotic interactions. These features confer greater ecosystem resilience in the face of future shocks and disturbances. We discuss economic, social, and legal issues that challenge natural regeneration in tropical landscapes. We conclude by suggesting ways to enable natural regeneration to become an effective tool for implementing large‐scale forest and landscape restoration. Major research and policy priorities include: identifying and modeling the ecological and economic conditions where natural regeneration is a viable and favorable land‐use option, developing monitoring protocols for natural regeneration that can be carried out by local communities, and developing enabling incentives, governance structures, and regulatory conditions that promote the stewardship of naturally regenerating forests. Aligning restoration goals and practices with natural regeneration can achieve the best possible outcome for achieving multiple social and environmental benefits at minimal cost.  相似文献   

7.
Natural experiments have been proposed as a way of complementing manipulative experiments to improve ecological understanding and guide management. There is a pressing need for evidence from such studies to inform a shift to landscape‐scale conservation, including the design of ecological networks. Although this shift has been widely embraced by conservation communities worldwide, the empirical evidence is limited and equivocal, and may be limiting effective conservation. We present principles for well‐designed natural experiments to inform landscape‐scale conservation and outline how they are being applied in the WrEN project, which is studying the effects of 160 years of woodland creation on biodiversity in UK landscapes. We describe the study areas and outline the systematic process used to select suitable historical woodland creation sites based on key site‐ and landscape‐scale variables – including size, age, and proximity to other woodland. We present the results of an analysis to explore variation in these variables across sites to test their suitability as a basis for a natural experiment. Our results confirm that this landscape satisfies the principles we have identified and provides an ideal study system for a long‐term, large‐scale natural experiment to explore how woodland biodiversity is affected by different site and landscape attributes. The WrEN sites are now being surveyed for a wide selection of species that are likely to respond differently to site‐ and landscape‐scale attributes and at different spatial and temporal scales. The results from WrEN will help develop detailed recommendations to guide landscape‐scale conservation, including the design of ecological networks. We also believe that the approach presented demonstrates the wider utility of well‐designed natural experiments to improve our understanding of ecological systems and inform policy and practice.  相似文献   

8.
Aim Restoration of habitats may be used as a conservation tool when ecosystems have lost their natural structure, dynamics or functioning over large areas. Controlled and planned use of fire could be an effective way to restore habitats of many threatened species in boreal forests where fire suppression has been effective. We asked whether the large‐scale landscape context affects the occurrence of rare and threatened species in forest habitats that have been burned to restore their fire‐related structures. Location Boreal forests in southern Finland. Methods We designed a large‐scale field experiment that included nine Pinus sylvestris forests (5–10 ha each) in southern Finland. Sites were located in two regions: (1) in eastern region with shorter management history and (2) in western region where intensive forestry has continued longer. We evaluated whether restoration of dead/burned wood is beneficial for rare and conservation‐dependent species and measured the recovery of pyrophilous and red‐listed insects (beetles and flatbugs) in burned forests, using standardized sampling effort. Altogether, 956 individuals of 29 red‐listed and pyrophilous species were sampled. Results Rare species colonized areas quickly, but there was a clear difference in species richness between the regions. The eastern forests harboured higher species richness after restoration. In these sites, the average species richness was 13.7 species per site, whereas in western forests it was 5.0 species per site. Similar pattern was also observed in subgroups: the corresponding numbers for pyrophilous species were 9.7 vs. 3.8, for red‐listed 8.7 vs. 2.3 and for red‐listed pyrophiles 4.7 vs. 1.2. Main conclusions Introducing fire back to boreal forests can aid in the recovery of rare species, but the landscape context considerably affects the success of restoring species. If restored habitats are located in landscapes that have lost their natural properties long ago, the success of restoration seems to be more challenging than in landscapes where habitats have been modified more recently.  相似文献   

9.
Summary A common approach to nature conservation is to identify and protect natural ‘assets’ such as ecosystems and threatened species. While such actions are essential, protection of assets will not be effective unless the ecological processes that sustain them are maintained. Here, we consider the role of ecological processes and the complementary perspective for conservation arising from an emphasis on process. Many kinds of ecological processes sustain biodiversity: including climatic processes, primary productivity, hydrological processes, formation of biophysical habitats, interactions between species, movements of organisms and natural disturbance regimes. Anthropogenic threats to conservation exert their influence by modifying or disrupting these processes. Such threats extend across tenures, they frequently occur offsite, they commonly induce non‐linear responses, changes may be irreversible and the full consequences may not be experienced for lengthy periods. While many managers acknowledge these considerations in principle, there is much scope for greater recognition of ecological processes in nature conservation and greater emphasis on long time‐frames and large spatial scales in conservation planning. Practical measures that promote ecological processes include: monitoring to determine the trajectory and rate of processes; incorporating surrogates for processes in conservation and restoration projects; specific interventions to manipulate and restore processes; and planning for the ecological future before options are foreclosed. The long‐term conservation of biodiversity and the well‐being of human society depend upon both the protection of natural assets and maintaining the integrity of the ecological processes that sustain them.  相似文献   

10.
Regrowing forests on cleared land is a key strategy to achieve both biodiversity conservation and climate change mitigation globally. Maximizing these co‐benefits, however, remains theoretically and technically challenging because of the complex relationship between carbon sequestration and biodiversity in forests, the strong influence of climate variability and landscape position on forest development, the large number of restoration strategies possible, and long time‐frames needed to declare success. Through the synthesis of three decades of knowledge on forest dynamics and plant functional traits combined with decision science, we demonstrate that we cannot always maximize carbon sequestration by simply increasing the functional trait diversity of trees planted. The relationships between plant functional diversity, carbon sequestration rates above ground and in the soil are dependent on climate and landscape positions. We show how to manage ‘identities’ and ‘complementarities’ between plant functional traits to achieve systematically maximal cobenefits in various climate and landscape contexts. We provide examples of optimal planting and thinning rules that satisfy this ecological strategy and guide the restoration of forests that are rich in both carbon and plant functional diversity. Our framework provides the first mechanistic approach for generating decision‐makingrules that can be used to manage forests for multiple objectives, and supports joined carbon credit and biodiversity conservation initiatives, such as Reducing Emissions from Deforestation and forest Degradation REDD+. The decision framework can also be linked to species distribution models and socio‐economic models to find restoration solutions that maximize simultaneously biodiversity, carbon stocks, and other ecosystem services across landscapes. Our study provides the foundation for developing and testing cost‐effective and adaptable forest management rules to achieve biodiversity, carbon sequestration, and other socio‐economic co‐benefits under global change.  相似文献   

11.
Aim Most approaches to conservation prioritization are focused on biodiversity features that are already threatened. While this is necessary in the face of accelerating anthropogenic threats, there have been calls to conserve large intact landscapes, often termed ‘wilderness’, to ensure the long‐term persistence of biodiversity. In this study, we examine the consequences of directing conservation expenditure using a threat‐based framework for wilderness conservation. Location The Australian continent. Methods We measured the degree of congruence between the extent of wilderness and the Australian protected area network in 2000 and 2006, which was established using a threat‐based systematic planning framework. We also assessed priority areas for future reserve acquisitions identified by the Australian government under the current framework. Results In 2000, 14% of Australia’s wilderness was under formal protection, while the protected area network covered only 8.5% of the continent, suggesting a historical bias towards wilderness protection. However, the expansion of the reserve system from 2000 to 2006 was biased towards non‐wilderness areas. Moreover, 90% of the wilderness that was protected over this period comprised areas not primarily designated for biodiversity conservation. We found a significant (P < 0.05) negative relationship between bioregions considered to be a priority for future reserve prioritization and the amount of wilderness they contain. Main conclusions While there is an urgent need to overcome past biases in reserve network design so as to better protect poorly represented species and habitats, prioritization approaches should not become so reactive as to ignore the role that large, intact landscapes play in conserving biodiversity, especially in a time of human‐induced climate change. This can be achieved by using current or future threats rather than past threats to prioritize areas, and by incorporating key ecological processes and costs of acquisition and management within the planning framework.  相似文献   

12.
The loss and degradation of woody vegetation in the agricultural matrix represents a key threat to biodiversity. Strategies for habitat restoration in these landscapes should maximize the biodiversity benefit for each dollar spent in order to achieve the greatest conservation outcomes with scarce funding. To be effective at scale, such strategies also need to account for the opportunity cost of restoration to the farmer. Here, we critique the Whole‐of‐Paddock Rehabilitation program, a novel agri‐environment scheme which seeks to provide a cost‐effective strategy for balancing habitat restoration and livestock grazing. The scheme involves the revegetation of large (minimum 10 ha) fields, designed to maximize biodiversity benefits and minimize costs while allowing for continued agricultural production. The objectives and design of the scheme are outlined, biodiversity and production benefits are discussed, and we contrast its cost‐effectiveness with alternative habitat restoration strategies. Our analysis indicates that this scheme achieves greater restoration outcomes at approximately half the cost of windbreak‐style plantings, the prevailing planting configuration in southeastern Australia, largely due to a focus on larger fields, and the avoidance of fencing costs through the use of existing farm configuration and infrastructure. This emphasis on cost‐effectiveness, the offsetting of opportunity costs through incentive payments, and the use of a planting design that seeks to maximize biodiversity benefits while achieving production benefits to the farmer, has the potential to achieve conservation in productive parts of the agricultural landscape that have traditionally been “off limits” to conservation.  相似文献   

13.
Restoring native habitats in heavily cleared and fragmented areas such as agricultural landscapes is important to maintain and increase remaining native floral and faunal communities. Identifying priority vegetation types for restoration – as well as the parcels of land where this restoration could take place at a landscape scale – may assist in strategically protecting these biodiversity assets. To prioritise the restoration of terrestrial habitats around an ecologically and culturally significant Ramsar‐listed wetland in South Australia, we used the spatial prioritisation tool Marxan. Originally designed for prioritising the protection of reserve areas, Marxan can also be used to identify parcels of land for restoration purposes. We tested how Marxan prioritised the restoration of four distinct vegetation types around the Coorong and Lower Lakes region of South Australia using the inverse of habitat remnancy as a cost and soil type and distance to ecologically significant bird species as a conservation feature. By prioritising restoration activities around certain landscape features, such as remnant areas, our results indicate that we would be able to strategically restore parcels of native habitat that would maximise biodiversity outcomes. This study highlights the need for robust input data, such as priority vegetation types and bird species associated with these habitats, to ensure informative modelling outputs. It also suggests that other measures, such as the cost of different land types, should be included in future restoration planning. Finally, we illustrate how prioritisation tools such as Marxan can be used by natural resource managers to restore areas within fragmented agricultural landscapes.  相似文献   

14.
汶川地震重灾区生态保护重要性评价与对策   总被引:9,自引:0,他引:9  
开展生态保护重要性评价,鉴定生态保护重要地区是地震灾区恢复与重建的前提与基础。选取水土流失敏感性、生物多样性保护重要性以及水源涵养重要性这3个指标,评价了地震重灾区51个县(市区)的生态保护重要性。研究表明,生态保护极重要地区面积约为3.5&#215;10^4km^2,约占整个研究区域面积的26.7%,主要分布于邛崃山系北部的汶川与四姑娘山地区,以及岷山山系的大部分地区;而生态保护重要地区面积约为4.6&#215;10^4km^2,约占整个研究区域的34.5%,主要分布于评价区的西部与东北部;其余地区为生态保护一般地区。建议在灾后重建时对生态极重要地区进行严格保护,禁止开展大型开发建设活动,并控制这些地区的人口规模。另外,生态保护重要地区的开发活动应该受到限制。并通过开展生态补偿,结合正在实施的天然林保护、退耕还林与流域综合治理等生态工程措施,促进灾区生态功能的恢复。  相似文献   

15.
Wildlife-friendly farming benefits rare birds, bees and plants   总被引:1,自引:0,他引:1  
Agricultural intensification is a leading cause of global biodiversity loss, especially for threatened and near-threatened species. One widely implemented response is 'wildlife-friendly farming', involving the close integration of conservation and extensive farming practices within agricultural landscapes. However, the putative benefits from this controversial policy are currently either unknown or thought unlikely to extend to rare and declining species. Here, we show that new, evidence-based approaches to habitat creation on intensively managed farmland in England can achieve large increases in plant, bee and bird species. In particular, we found that habitat enhancement methods designed to provide the requirements of sensitive target biota consistently increased the richness and abundance of both rare and common species, with 10-fold to greater than 100-fold more rare species per sample area than generalized conventional conservation measures. Furthermore, targeting landscapes of high species richness amplified beneficial effects on the least mobile taxa: plants and bees. Our results provide the first unequivocal support for a national wildlife-friendly farming policy and suggest that this approach should be implemented much more extensively to address global biodiversity loss. However, to be effective, these conservation measures must be evidence-based, and developed using sound knowledge of the ecological requirements of key species.  相似文献   

16.
The effectiveness of ecological restoration actions toward biodiversity conservation depends on both local and landscape constraints. Extensive information on local constraints is already available, but few studies consider the landscape context when planning restoration actions. We propose a multiscale framework based on the landscape attributes of habitat amount and connectivity to infer landscape resilience and to set priority areas for restoration. Landscapes with intermediate habitat amount and where connectivity remains sufficiently high to favor recolonization were considered to be intermediately resilient, with high possibilities of restoration effectiveness and thus were designated as priority areas for restoration actions. The proposed method consists of three steps: (1) quantifying habitat amount and connectivity; (2) using landscape ecology theory to identify intermediate resilience landscapes based on habitat amount, percolation theory, and landscape connectivity; and (3) ranking landscapes according to their importance as corridors or bottlenecks for biological flows on a broader scale, based on a graph theory approach. We present a case study for the Brazilian Atlantic Forest (approximately 150 million hectares) in order to demonstrate the proposed method. For the Atlantic Forest, landscapes that present high restoration effectiveness represent only 10% of the region, but contain approximately 15 million hectares that could be targeted for restoration actions (an area similar to today's remaining forest extent). The proposed method represents a practical way to both plan restoration actions and optimize biodiversity conservation efforts by focusing on landscapes that would result in greater conservation benefits .  相似文献   

17.
We currently face both an extinction and a biome crisis embedded in a changing climate. Many biodiverse ecosystems are being lost at far higher rates than they are being protected or ecologically restored. At the same time, natural climate solutions offer opportunities to restore biodiversity while mitigating climate change. The Bonn Challenge is a U.N. programme to restore biodiversity and mitigate climate change through restoration of the world's degraded landscapes. It provides an unprecedented chance for ecological restoration to become a linchpin tool for addressing many environmental issues. Unfortunately, the Forest and Landscape Restoration programme that underpins the Bonn Challenge, as its name suggests, remains focused on trees and forests, despite rising evidence that many non‐forest ecosystems also offer strong restoration potential for biodiversity and climate mitigation. We see a need for restoration to step back to be more inclusive of different ecosystem types and to step up to provide integrated scientific knowledge to inform large‐scale restoration. Stepping back and up will require assessments of where to restore what species, with recognition that in many landscapes multiple habitat types should be restored. In the process, trade‐offs in the delivery of different ecosystem services (e.g. carbon, biodiversity, water, albedo, livestock forage) should be clearly addressed. We recommend that biodiversity safeguards be included in policy and implemented in practice, to avoid undermining the biophysical relationships that provide ecosystem resilience to climate change. For ecological restoration to contribute to international policy goals will require integrated large‐scale science that works across biome boundaries.  相似文献   

18.
The conservation of biodiversity in highly fragmented landscapes often requires large‐scale habitat restoration in addition to traditional biological conservation techniques. The selection of priority restoration sites to support long‐term persistence of biodiversity within landscape‐scale projects however remains a challenge for many restoration practitioners. Techniques developed under the paradigm of systematic conservation planning may provide a template for resolving these challenges. Systematic conservation planning requires the identification of conservation objectives, the establishment of quantitative targets for each objective, and the identification of areas which, if conserved, would contribute to meeting those targets. A metric developed by systematic conservation planners termed “irreplaceability” allows for analysis and prioritization of such conservation options, and allows for the display of analysis results in a way that can engage private landowners and other decision makers. The process of systematic conservation planning was modified to address landscape‐level restoration prioritization in southern Ontario. A series of recent and locally relevant landscape ecology studies allowed the identification of restoration objectives and quantitative targets, and a simple algorithm was developed to identify and prioritize potential restoration projects. The application of an irreplaceability analysis to landscape‐level restoration planning allowed the identification of varying needs throughout the planning region, resulting from underlying differences in topography and settlement patterns, and allowed the effective prioritization of potential restoration projects. Engagement with rural landowners and agricultural commodity groups, as well as the irreplaceability maps developed, ultimately resulted in a substantial increase in the number and total area of habitat restoration projects in the planning region.  相似文献   

19.
Natural regeneration offers a cheaper alternative to active reforestation and has the potential to become the predominant way of restoring degraded tropical landscapes at large‐scale. We conducted a meta‐analysis for tropical regions and quantified the relationships between both ecological and socioeconomic factors and biodiversity responses in naturally regenerating areas. Biogeographic realms, past disturbance, and the human development index (HDI) were used as explanatory variables for biodiversity responses. In addition, we present a case study of large‐scale natural regeneration in the Brazilian Atlantic Forest and identify areas where different forms of restoration would be most suitable. Using our dataset for tropical regions, we showed that natural regeneration was predominantly reported within: the Neotropical realm; areas that were intensively disturbed; and countries with medium HDI. We also found that biodiversity in regenerating forests was more similar to the values found in old growth forests in: countries with either low, high, or very high HDI; less biodiverse realms; and areas of less intensive past disturbance. Our case study from Brazil showed that the level of forest gain resulting from environmental legislation, in particular the Brazilian Forest Code, has been reduced, but remains substantial. Complementary market incentives and financial mechanisms to promote large‐scale natural regeneration in human‐modified agricultural landscapes are also needed. Our analysis provides insights into the factors that promote or limit the recovery of biodiversity in naturally regenerating areas, and aids to identify areas with higher potential for natural regeneration.  相似文献   

20.
Forest structural reference conditions are widely used to understand how ecosystems have been altered and guide restoration and management objectives. We used six stem‐mapped permanent plots established in the early twentieth century to provide precise structural reference conditions for ponderosa pine forests of northern Arizona prior to Euro‐American settlement. Reference conditions for these plots in 1873–1874 included the following historical attributes: tree densities of 45–127 trees/ha, mean tree diameter at breast height (dbh) of 43.8 cm with a corresponding quadratic mean diameter range of 41.5–51.3 cm, and a stand basal area of 9.2–18.0 m2/ha. The reconstructed diameter distributions (for live ponderosa pine trees with dbh ≥9.14 cm) prior to fire exclusion varied in shape but generally displayed an irregular unimodal distribution. We suggest that management objectives for the structural restoration of ponderosa pine forests of northern Arizona emphasize: (1) conservation and retention of all pre‐settlement (>130 years) trees; (2) reduction of tree densities with a restoration objective ranging between 50 and 150 trees/ha having a large‐tree component between 25 and 50% of the total trees per hectare, respectively; (3) manipulation of the diameter distribution to achieve a unimodal or irregular, uneven‐aged shape (possibly targeting a balanced, uneven‐aged shape on cinder soil types) through the use of harvest and thinning practices that mimic gap disturbances (i.e., individual tree selection system); and (4) retention of 3–11 snags and logs per hectare resulting from natural mortality.  相似文献   

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