Growing the urban forest: tree performance in response to biotic and abiotic land management

Forests are vital components of the urban landscape because they provide ecosystem services such as carbon sequestration, storm‐water mitigation, and air‐quality improvement. To enhance these services, cities are investing in programs to create urban forests. A major unknown, however, is whether planted trees will grow into the mature, closed‐canopied forest on which ecosystem service provision depends. We assessed the influence of biotic and abiotic land management on planted tree performance as part of urban forest restoration in New York City, U.S.A. Biotic treatments were designed to improve tree growth, with the expectation that higher tree species composition (six vs. two) and greater stand complexity (with shrubs vs. without) would facilitate tree performance. Similarly, the abiotic treatment (compost amendment vs. without) was expected to increase tree performance by improving soil conditions. Growth and survival was measured for approximately 1,300 native saplings across three growing seasons. The biotic and abiotic treatments significantly improved tree performance, where shrub presence increased tree height for five of the six tree species, and compost increased basal area and stem volume of all species. Species‐specific responses, however, highlighted the difficulty of achieving rapid growth with limited mortality. Pioneer species had the highest growth in stem volume over 3 years (up to 3,500%), but also the highest mortality (up to 40%). Mid‐successional species had lower mortality (<16%), but also the slowest growth in volume (approximately 500% in volume). Our results suggest that there will be trade‐offs between optimizing tree growth versus survival when implementing urban tree planting initiatives.     

城市生态系统修复研究进展

城市生态系统是社会-经济-自然复合生态系统。城市生态系统修复的实质是协调好城市复合生态系统的自然过程、经济过程和社会过程之间的关系,促进复合生态系统的各方面协调高效可持续发展。以城市绿地、城市湿地、城市废弃地三类主要的城市生态空间为对象,论述了城市生态系统修复的研究进展,提出当前城市生态系统修复存在以人工修复技术为主、自然修复不足、机理和量化研究缺乏、理论和应用脱节、管理机制不健全、复合生态系统理论体现不足等问题。梳理了当前城市生态系统修复的研究热点,包括城市生态系统修复机理、城市生态资产与生态系统服务、城市生态系统质量和健康、问题导向的生态修复、面向人类福祉的生态修复、生态修复多学科融贯,以及新方法和新技术的应用等几个方面。提出了城市生态修复与管理的相关对策和建议,可为我国城市生态系统修复的研究和实践提供参考。     

Towards more effective integration of tropical forest restoration and conservation

Conservation and restoration interventions can be mutually reinforcing and are converging through an increased focus on social dimensions. This paper examines how to more effectively integrate the complementary goals of conservation and restoration of tropical forests. Forest conservation and restoration interventions are integral components of a broad approach to forest ecosystem and landscape management that aims to maintain and restore key ecological processes and enhance human well‐being, while minimizing biodiversity loss. The forest transition model provides a useful framework for understanding the relative importance of forest conservation and restoration interventions in different regions. Harmonizing conservation and restoration presents serious challenges for forest policy in tropical countries, particularly regarding the use and management of secondary forests, fallow vegetation, and forests degraded by logging and fire. Research to implement restoration more effectively in tropical regions can be stimulated by transforming questions that initially focused on conservation issues. Examination of papers published in Biotropica from 2000–2018 shows that most studies relevant to tropical forest conservation do not address forest restoration issues. Forest restoration studies, on the other hand, show a consistent association with conservation issues. There is much scope for further integration of conservation and restoration in research, practice, and policy. Securing a sustainable future for tropical forests requires developing and applying integrated approaches to landscape management that effectively combine knowledge and tools from multiple disciplines with practical experience and engagement of local stakeholders. Abstract in Portuguese is available with online material.     

Ecological indicators for assessing ecological success of forest restoration: a world review

Restoration is increasingly being used to reverse degradation and destruction of forest ecosystems. With increasing investment in restoration, there is an urgent need to develop effective programs to assess treatment efficacy and effects. We conducted a global review of forest restoration assessments, in order to identify geographic trends in the locations where assessments have been implemented and the specific ecological attributes (ecosystem composition, structure, and function) and indicators being used to measure effects. We found that the number of forest restoration assessments varied by region and was not related to degree of degradation or restoration need. Some regions, like Africa, which have experienced high rates of forest loss and degradation, had few assessments. The majority (43%) of assessments included indicators for only two of three key ecological attributes (composition‐structure or composition‐function) and assessments on average used fewer than three indicators per attribute. The most commonly employed indicators for composition were richness and abundance of plant species and for structure were height and diameter of trees, variables that are generally relatively easy to measure. The use of functional indicators has been increasing over time and they are now more commonly used than structural indicators. The most common functional indicators were soil functions. Most investigators evaluated treatment effects for 6–10 years after implementation. Our findings related to gaps in analysis of ecological indicators can serve as a guide for developing monitoring and assessment protocols for current global forest restoration initiatives by 2020–2030.     

林火迹地森林恢复研究进展

火灾对森林造成不同程度的破坏,火后如何恢复森林是人们面临的关键问题,为了掌握火灾后迹地的变化及演替规律,使森林生态系统向良性发展,国内外专家对此作了大量的研究。本文就国内外的研究进行综述与比较,为完善该领域的研究提出相应的对策,对未来的发展趋势加以展望。     

A diagnostic for collaborative monitoring in forest landscape restoration

Monitoring is crucial to meet the goals of the major global forest landscape restoration (FLR) initiatives that are underway. If members of the global FLR community are going to learn from one another, a multi‐scalar, multi‐site monitoring approach is needed to generate information that can provide the basis for social learning and adaptive management, both of which are essential processes for FLR. This requires reframing and expanding the perspective of monitoring so that compliance monitoring is just one component of a multidimensional approach where collaborative monitoring and compliance‐oriented monitoring are complementary. However, FLR planners and implementers often lack experience in applying collaborative approaches in multi‐stakeholder settings, and there are few tools that show how to implement FLR or to engage in collaborative monitoring in FLR. Through a literature review, we identified the factors that contribute to successful collaborative monitoring in FLR and synthesized them into a diagnostic that was vetted by 20 global experts. The result is a checklist of 42 core success factors to be assessed at local, subnational, and national levels at different stages in the planning and implementation of FLR. The tool has practical application by providing guidance on best practices: specifically, how to start collaborative monitoring, and more generally, how to plan, prepare for, and evaluate FLR activities. This diagnostic complements other diagnostics, such as those used to identify FLR sites, as it can identify preexisting strengths and weaknesses in new initiatives, or pinpoint problems with ongoing implementation. The diagnostic explicitly addresses issues of scale, including multiple sites, governance levels, and changes over time.     

退化森林生态系统恢复评价研究综述

森林退化是一个世界性的问题,对退化的森林进行恢复评价是合理地进行森林生态系统管理的基础。介绍了森林退化的概念,综述了退化森林生态系统恢复评价的一般程序,主要包括恢复目标的确定、参照系的选择、评价指标体系的构建及定量评价等几个方面。目前,大多数退化森林恢复评价主要包括物种多样性、植被结构和生态学过程3个方面。其中,物种多样性包括物种丰富度和多度等;植被结构包括植被盖度、乔木密度、高度、胸高断面积、生物量和凋落物结构等;生态学过程包括养分库、土壤有机质以及生物间的相互关系等。不同的研究者或管理者由于对恢复其生态系统服务功能的需求存在差异,评价退化生态系统恢复的角度也不一样。恢复评价可以从特殊种群到整个生态系统的不同层次进行。在深刻理解森林退化定义的基础上,建立现实的目标和正确地选择参照系是恢复评价的前提。     

海草场生态系统及其修复研究进展

海草场能够提供重要的生态系统服务。自20世纪末以来,由于人类活动和自然灾害的影响,全球范围内的海草场出现了急剧衰退,由此也促进了海草场生态系统的研究以及海草场人工修复技术的发展。近年来,针对海草场生境流失的现状,中国也开始开展海草场修复工作。从以下方面进行论述:(1)海草的种类、分布,海草场生态系统功能及其生态系统服务:与陆地系统相比,全球海草物种多样性较低,了解海草的分布特征有助于通过了解海草如何适应当地环境压力,以揭示海草适应环境的能力;海草场提供重要而广泛的自然生态系统服务,特别是在维护近岸生态系统健康和满足人类需求过程中起到重要的作用;(2)海草场的衰退及其原因:认识并缓解人类压力对海草场的危害是促进海草场生态系统可持续发展的重要一环;(3)国内外海草场修复现状:以此阐明海草场修复原理,为海草场修复提供科学的方法;(4)总结与讨论:基于科学研究背景,为中国海草场生态系统保护和修复提出建议。海草场的修复和保护应当相辅相成,并与我国海岸长远规划相结合,以此推动我国海草场生态系统服务的可持续发展。     

Time,space, place,and the Bonn Challenge global forest restoration target

The Bonn Challenge, a global effort to begin restoring 350 million hectares of degraded forest landscapes by 2030, was launched in 2011. To date countries have committed to restore more than 60 million hectares as part of the Bonn Challenge. As global decision‐makers, governments, and communities join the effort to restore degraded land, new questions about the economics of restoration have emerged. Critics argue that restoration takes too long, costs too much, and produces too few benefits to justify public or private expenditures. This paper addresses these concerns by presenting a methodology for valuing the net benefits of large‐scale ecosystem restoration initiatives by estimating the net benefit of achieving the Bonn Challenge. This paper also estimates the net benefit of achieving the Bonn Challenge restoration target under different social discounting regimes, different valuations of public goods, and different time horizons to see how they affect the argument for investing society's scarce resources in restoration. The results suggest that achieving the Bonn Challenge would generate a net benefit of between U.S.$0.7 and U.S.$9 trillion. The results show that restoration can create benefits that exceed its costs and that the value of these benefits might differ depending on the discount rate. The results show that lower social discount rates correspond to higher restoration rates. This suggests that the Bonn Challenge target is more likely to be met when a low social discount rate is used to discount the benefits and costs of restoration.     

Undertaking large‐scale forest restoration to generate ecosystem services

The global community is seeking to substantially restore the world's forest cover to improve the supply of ecosystem services. However, it is not clear what type of reforestation must be used and there is a risk that the techniques used in industrial timber plantations will become the default methodology. This is unlikely to be sufficient because of the well‐known relationship between biodiversity and ecological functioning. Restoration may be achieved through natural regeneration but this may not always occur at critical locations. Ecological restoration involving species‐rich plantings might also be used but can be difficult to implement at landscape scales. I review here the consequence of planting more limited numbers of species and the effects of this on the delivery of ecosystem services. Evidence suggests many commonly sought ecosystem services—though not all—may be generated by the modest levels of species richness provided these species have appropriate traits. The literature also shows that the alpha diversity of restored forests is not the only driver of functionality and that the location and extent of any reforestation are significant as well; beta and gamma diversity may also affect functionality but these relationships remain unclear. Encouraging the adoption of even moderately diverse plantings at landscape scales and at key locations will require policies and institutions to balance the type, location, and scale of restoration and make the necessary trade‐offs between national and local aspirations. New approaches and metrics will have to be developed to monitor and assess restoration success at these larger scales.     

Underplanting degraded exotic Pinus with indigenous conifers assists forest restoration

We propose that nonharvest plantations could provide important opportunities for restoration of indigenous forest cover and related ecosystem services. We assessed the relative performance of three Podocarpaceae (podocarps) species planted into a degraded Ponderosa Pine (Pinus ponderosa) plantation, central North Island, New Zealand. We hypothesised that the degraded pine plantation overstorey could provide suitable conditions for the development of a podocarp‐dominated forest structure within ca. 50 years of underplanting and that podocarp growth would differ depending on the species suitability to the site. Rimu (Dacrydium cupressinum) significantly outperformed both Totara (Podocarpus totara) and Kahikatea (Dacrycarpus dacrydioides) in height and diameter growth. Rimu was now the structurally dominant tree where it occurred rather than pine. Per annum scaled carbon storage within Rimu stands was significantly greater than the Totara, Kahikatea or Pine stands. All podocarp species had attained a greater stand density compared to the pine overstorey. Possible reasons for the differing podocarp growth performance include different light requirements, response to soil nutrients, elevational distributions and frost susceptibility. There were significant differences in understorey species richness among the different stands of podocarp species. Underplanting accelerated successional development by incorporating late‐successional indigenous canopy dominants within the forest succession and overcame limitations imposed on forest succession at the site from its isolation from indigenous forest tree seed sources.     

Multiple successional pathways in human‐modified tropical landscapes: new insights from forest succession,forest fragmentation and landscape ecology research

Old‐growth tropical forests are being extensively deforested and fragmented worldwide. Yet forest recovery through succession has led to an expansion of secondary forests in human‐modified tropical landscapes (HMTLs). Secondary forests thus emerge as a potential repository for tropical biodiversity, and also as a source of essential ecosystem functions and services in HMTLs. Such critical roles are controversial, however, as they depend on successional, landscape and socio‐economic dynamics, which can vary widely within and across landscapes and regions. Understanding the main drivers of successional pathways of disturbed tropical forests is critically needed for improving management, conservation, and restoration strategies. Here, we combine emerging knowledge from tropical forest succession, forest fragmentation and landscape ecology research to identify the main driving forces shaping successional pathways at different spatial scales. We also explore causal connections between land‐use dynamics and the level of predictability of successional pathways, and examine potential implications of such connections to determine the importance of secondary forests for biodiversity conservation in HMTLs. We show that secondary succession (SS) in tropical landscapes is a multifactorial phenomenon affected by a myriad of forces operating at multiple spatio‐temporal scales. SS is relatively fast and more predictable in recently modified landscapes and where well‐preserved biodiversity‐rich native forests are still present in the landscape. Yet the increasing variation in landscape spatial configuration and matrix heterogeneity in landscapes with intermediate levels of disturbance increases the uncertainty of successional pathways. In landscapes that have suffered extensive and intensive human disturbances, however, succession can be slow or arrested, with impoverished assemblages and reduced potential to deliver ecosystem functions and services. We conclude that: (i) succession must be examined using more comprehensive explanatory models, providing information about the forces affecting not only the presence but also the persistence of species and ecological groups, particularly of those taxa expected to be extirpated from HMTLs; (ii) SS research should integrate new aspects from forest fragmentation and landscape ecology research to address accurately the potential of secondary forests to serve as biodiversity repositories; and (iii) secondary forest stands, as a dynamic component of HMTLs, must be incorporated as key elements of conservation planning; i.e. secondary forest stands must be actively managed (e.g. using assisted forest restoration) according to conservation goals at broad spatial scales.     

国土综合整治与生态修复对区域生态系统服务价值的影响评估

国土整治与生态修复对保障区域生态质量、优化生态安全格局和提升生态系统服务价值有积极的促进作用。定量化测算国土综合整治与生态修复对区域生态质量的影响是领域的研究热点和难点。以广西壮族自治区贺州市为例,提出了国土综合整治与生态修复对区域生态系统服务价值的影响评估方法,主要结论如下:(1)不同地类由于其质量不同,单位面积生态系统服务价值差距较大,研究提出了基于地类质量的单位面积生态系统服务价值确定方法,并据此测算了各地类通过整治修复质量的提升潜力;(2)贺州市整治修复前生态系统服务总价值为411.80亿元,经过评估,整治修复后生态系统服务总价值可以增加到458.06亿元,增加比例为11.23%。贺州市林地生态系统服务价值增加潜力最大,其次是草地、耕地。生态系统服务价值增加潜力在空间上呈现了东西两翼高于中部、南部地区高于东部地区的趋势;(3)贺州市各区县整治修复潜力差距较大,潜力最大的为八步区和昭平县,潜力提升比例最高的是富川县,不同区县可以根据结果确定整治修复的工程布局。研究结果对于区域国土空间整治与生态修复工程安排及整治修复绩效评估有重要的指导意义。     

Beyond hectares: four principles to guide reforestation in the context of tropical forest and landscape restoration

New climate change agreements emerging from the 21st Conference of the Parties and ambitious international commitments to implement forest and landscape restoration (FLR) are generating unprecedented political awareness and financial mobilization to restore forests at large scales on deforested or degraded land. Restoration interventions aim to increase functionality and resilience of landscapes, conserve biodiversity, store carbon, and mitigate effects of global climate change. We propose four principles to guide tree planting schemes focused on carbon storage and commercial forestry in the tropics in the context of FLR. These principles support activities and land uses that increase tree cover in human‐modified landscapes, while also achieving positive socioecological outcomes at local scales, in an appropriate contextualization: (1) restoration interventions should enhance and diversify local livelihoods; (2) afforestation should not replace native tropical grasslands or savanna ecosystems; (3) reforestation approaches should promote landscape heterogeneity and biological diversity; and (4) residual carbon stocks should be quantitatively and qualitatively distinguished from newly established carbon stocks. The emerging global restoration movement and its growing international support provide strong momentum for increasing tree and forest cover in mosaic landscapes. The proposed principles help to establish a platform for FLR implementation and monitoring based on a broad set of socioenvironmental benefits including, but not solely restricted, to carbon mitigation and wood production.     

The relevance of international restoration principles for ecosystem restoration practice in Rwanda

The restoration of degraded ecosystems is considered a key strategy to contribute to ecological integrity and human well-being. To support restoration practice, 10 “Principles to guide the UN Decade on Ecosystem Restoration 2021–2030” were conceived through a consultative process and put forward by a group of leading international restoration actors. The extent to which these principles can inform successful restoration activities on the ground, however, remains largely unknown. Using a combination of qualitative and quantitative data collection methods, we probed 32 stakeholders who plan, manage, and implement restoration in Rwanda to elicit which factors they perceive as most important for successful restoration based on the UN Decade principles. Using the Q-methodology, we discovered that participants overall agreed that the UN Decade principles are relevant to inform successful ecosystem restoration in the study area. Further, the Q-study revealed three distinct groups of stakeholders with different priorities in terms of opinions on restoration aims, stakeholder involvement, and relevant spatial scales. Based on semi-structured interviews, we identified four considerations for successful restoration that require special attention in future restoration interventions in the study area: (1) restoring historical conditions, (2) collecting baseline data, (3) increasing local communities' sense of ownership, and (4) pursuing a long-term vision for restoration activities. To address these considerations and thereby harvest the potential of ecosystem restoration to benefit both people and nature in the long run, diverse stakeholders with different priorities for restoration need to come together to discuss possible differences in their perceived priorities, perspectives, and approaches.     

森林景观恢复过程中景观要素斑块规模的动态分析

以１９５９年以来的４期航片为基础资料,通过对研究地区各类景观要素的斑块平均规模和粒级结构及其动态变化过程进行分析,揭示了研究地区森林景观恢复演替过程中景观要素斑块动态特点,阐明了植被演替和干扰格局控制下森林景观要素斑块恢复演替的过程和规律。研究地区森林景观自５０年代以来在整体上始终属于细景观,但景观要素斑志规模和粒级结构发生了显著变化,在三个不同时期表现出不同的变化特点,而且不同景观要素的斑块规模     

An overview of the progress and challenges of peatland restoration in Western Europe

Peatlands are the most efficient terrestrial carbon store on Earth, and deliver multiple other ecosystem services including climate regulation, water purification, preservation of ecological and archaeological records, etc. Disturbed and degraded peatlands do not provide the same ecological services and thus bear a significant cost to society. Because this cost may be alleviated by appropriate restoration measures, money is being invested in peatland restoration projects around the world. Here, we review over 25 years of restoration in Western Europe. First, we provide an overview of techniques used in different contexts and evaluate the status of the evidence base for restoration outcomes. Between 1993 and 2015, the EU‐LIFE nature programme alone invested 167.6M € in 80 projects, which aim to restore over 913 km² of peatland habitats in Western European countries, mostly in protected sites part of the Natura 2000 EU network. This represents less than 2% of the total remaining area of peatlands in these countries, most of which have been impacted to some degree by anthropogenic disturbances. Potential for restoration should be considered in nondesignated sites. We reviewed a number of case studies covering a range of restoration approaches used in different parts of Western Europe. We found that published evidence of restoration progress was limited to specific sites/areas, and in many cases lacked baseline measurements and clear goals, that is, measurable target or contemporary reference(s). We discuss barriers and opportunities to turn the tide for peatland restoration in Western Europe and promote the establishment of robust, standardized monitoring schemes.     

IPBES土地退化和恢复专题评估报告及其潜在影响

随着国际社会对生物多样性保护和人类福祉关注度的提升, 土地退化作为全球面临的重要问题逐渐成为国际公约和进程关注的热点问题。生物多样性和生态系统服务政府间科学政策平台(Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, IPBES)将“土地退化和恢复”列入2014-2018年工作方案, 开展评估。2018年3月, 该评估报告在IPBES第六次全体会议上获得通过。本文概述了评估报告的主要内容和结论, 探讨了对其他国际进程的可能影响。评估报告在IPBES概念框架的基础上, 厘清了土地退化的概念与内涵, 全面梳理了土地退化对人类生活质量的影响, 阐明了土地退化的现状和进程, 分析了直接和间接驱动因素与土地退化的作用, 揭示了土地退化与人类福祉的关系, 提出了土地退化和恢复的对策建议。该项评估将为各国决策者制定政策工具提供最有效的技术支撑, 为相关国际进程谈判提供重要的科学参考。中国作为生物多样性大国, 应重视IPBES的评估机制并积极参与, 加强促进生物多样性和生态系统服务领域的科学成果转化, 适时针对国内关键问题启动相关评估, 促进我国生态文明建设和山水林田湖草系统治理, 实现美丽中国的建设目标。     

茂兰退化喀斯特森林植被自然恢复中生态系统碳吸存特征

为了了解退化喀斯特森林自然恢复中生态系统碳吸存趋势, 采用空间代替时间的方法, 研究了茂兰退化喀斯特森林自然恢复中生态系统碳吸存特征。结果表明: 总体上植被生物量随恢复进程递增, 其中乔木层与其变化一致, 草本层、灌木层则相反; 喀斯特植被的地上与地下生物量之比较低, 尤其灌木层的地上与地下生物量之比最低; 加权平均含碳率随恢复进展递增; 随恢复进程, 植被乔木层碳密度递增, 草本层、灌木层碳密度递减; 总体上生态系统及其植被、土壤的碳密度由恢复早期(草本阶段、草灌阶段)经中期(灌木阶段、灌乔阶段)至后期(乔木阶段、顶极阶段)呈增加趋势, 而凋落物的相反。在贵州茂兰国家级自然保护区喀斯特森林的恢复进程中, 植被对生态系统碳库的影响最大, 尤其是木本植被, 而土壤的影响较小, 因此, 加强植被恢复对喀斯特地区生态系统碳汇具有极重要的意义。     

南方红壤区3种典型森林恢复方式对植物群落多样性的影响

合理的森林恢复方式能提高植物多样性,进而提高生态系统服务功能.在我国南方红壤区研究了3种典型森林恢复方式(引进种恢复的湿地松(Pinus elliottii)人工林本地种恢复的马尾松(Pinus massoniana)人工林和自然恢复的天然次生林)的植物区系构成和植物群落多样性.结果表明:(1)湿地松人工林有155种植物,隶属66科118属,马尾松人工林有137种植物,隶属59科97属;天然次生林有226种植物,隶属86科160属,3种森林恢复方式的乔木层、灌木层和草本层的优势科属明显不同,马尾松人工林的优势物种和天然次生林更相似;(2)天然次生林的植物区系基本构成、植物区系类型种类高于马尾松人工林和湿地松人工林,并且天然次生林的温带成分比例高于湿地松人工林;(3)恢复方式对植物群落的多样性指数有显著影响,天然次生林的物种丰富度、辛普森指数明显高于马尾松人工林和湿地松人工林,两种人工林之间差异不显著;(4)3种森林恢复方式的植物群落结构存在显著差异,相比湿地松人工林,马尾松人工林的植物群落组成与天然次生林更相似.总之,自然恢复的天然次生林植物群落多样性高于人工恢复的马尾松人工林和湿地松人工林,本地种马尾松人工林在维持区域植物群落结构功能上优于引进种湿地松人工林.