Linking herbivory and ecosystem services in urban forests

Urban forests provide important benefits for humans. Species interactions, in particular herbivory, can alter their function and ultimately threaten their ecosystem service provisioning. We call for research that identifies herbivory drivers in urban forests and tests for links between herbivory and forest services. Knowledge gained can inform management of urban ecosystems.     

基于GIS的广州市中心城区城市森林可达性分析

城市森林是城市中主要的生态功能景观,已经成为城市生态环境建设的主体。基于居民方便获取城市森林服务的要求,根据大型城市森林斑块、道路网和街区单元数据,利用ArcGIS9.2的Network Analyst工具,分析了广州市中心城区在2km步行距离内街区单元到达城市森林斑块的可达性以及城市森林斑块的承载力,并结合航片解译的树冠覆盖数据对具有不同可达性的街区单元进行了分析。分析结果表明：广州中心城区的外环高速以内的区域范围,分别有73%、46%和18%的的街区单元在步行2km、1km和0.5km距离内能够到达大型城市森林绿地斑块。从街区单元的行政归属看,以越秀区的街区可达性最好,而海珠区和原芳村区的街区可达性较差。研究范围内,0.5km内不能到达大型城市森林斑块且树冠覆盖超过30%的街区类型中,以公共管理单位类型为主,单位绿化对于树冠覆盖的贡献率大;而绝大多数以住宅类型为主的街区单元的树冠覆盖率低于10%,其中64%的街区树冠覆盖率低于5%。以街区单元为基本对象进行可达性度量,分析城市森林斑块现状分布和服务状况,并结合其树冠覆盖特征,可以明确需要重点关注区域的空间分布,可为广州市在较小尺度上的城市森林空间布局优化提供参考。     

Integrating ecological and cultural values toward conservation and utilization of shrine/temple forests as urban green space in Japanese cities

In Japan, forests associated with shrines and temples are recognized as important components of urban green space, which can potentially function as centers for ecosystem conservation in rapidly urbanizing Japanese cities. In addition to their ecological value, shrine/temple forests have social value, providing recreational and aesthetic needs to residents of urban areas. We review the historical development of shrine/temple forests in Japan and discuss current conservation issues from both ecological and sociological perspectives. Generally, shrine forests are minimally managed and public access is discouraged, whereas temple forests are intensively managed for public display. Shrines tend to be spatially scattered across the landscape but associated with specific geographical features, whereas temples tend to be clustered. Their wide and random distribution in urban areas suggests that shrine forests can potentially be used as stepping stones in the urban green space network, whereas spatially clustered temple forests can be integrated to form large areas of green space. Species diversity of shrine/temple forests declines with decreasing area. The distribution pattern of species is not completely nested, indicating that although conservation of large forest fragments may be effective for maintaining landscape-level biodiversity, smaller forest fragments and adjacent precincts are sometimes significant because rare species occasionally inhabit them. Active management and ecological restoration, such as removal of invasive species, are also important to maintain the desirable near-natural forest conditions. A working group including the owner, community, regional government, and ecologists should be involved in creating an effective, long-term management plan. Because social and cultural values are diverse, basic ecological studies of shrine/temple forests would contribute a scientific basis that fosters public confidence in the process.     

上海环城林带保健功能评价及其机制

选取上海环城林带典型的植物群落,分别在夏季和冬季对群落的温湿度调节、负离子提升、抑菌、降噪和大气净化等保健功能进行测定和评价;同时结合群落结构因子,分析群落结构与保健功能之间的关系,并探讨了群落物种组成和结构特征对保健功能的影响,以期揭示群落保健功能发挥的机制.结果表明:夏季,落叶针叶林池杉群落除抑菌功能以外,在其他保健功能上均具有较好的效果,而落叶阔叶林全缘叶栾树群落和悬铃木群落效果较差,其他类型的群落居中;冬季,常绿阔叶林女贞群落在各种保健功能方面均具有较好的效果,其次为常绿落叶阔叶混交林的全缘叶栾树+香樟群落和杂交杨+香樟群落,其他类型的群落效果较差.群落各种保健功能与群落结构特征的相关性分析表明,叶面积指数和郁闭度在夏冬两季均与多种保健功能呈显著正相关,是指示群落保健功能优劣的重要结构因子.研究结果表明人工森林群落的保健功能可通过调整群落结构来提升,为城市森林的群落建构与管理提供了科学依据.     

城市林木树冠覆盖研究进展

随着城市化进程的加快以及人们对由此产生的大量环境问题认识的不断加深,城市森林受到了越来越多的关注,它被越来越多的普通市民和科学家看做是有效解决城市环境与生态问题的最根本途径.在城市森林的维护、规划与建设过程中,城市林木树冠覆盖被认为是城市森林最重要的结构与功能衡量指标.针对我国城市森林研究与实践起步较晚的现实需求,从城市林木树冠覆盖的概念、分类与评价、城市林木树冠覆盖与城市森林服务功能、城市林木树冠覆盖的研究方法和城市林木树冠覆盖率与城市森林规划等4个方面,对国内外城市林木树冠覆盖研究的现状进行了评述.指出了该方面研究的未来趋势包括4个方面,首先,城市林木树冠覆盖研究,已经与城市的生态建设和日常生态、生产管理紧密结合.其次,高分辨率(米级以下)卫星影像在城市森林树冠调查与制图过程中的应用越来越普遍.第三,像面向对象的影像解译方法与激光雷达(LIDAR)等新技术将会得到更广泛的使用.第四,为了最终实现城市森林建设规划能够落地的目标,在城市森林建设的规划实施决策过程中,计算机辅助人工智能的应用将会普及.     

Nontimber Forest Product Use in Two Human Populations from Northwest Patagonia: A Quantitative Approach

The ancestral tradition of gathering nontimber products in the Andean forests of Patagonia seems to be on the verge of disappearing. Edible wild plant knowledge and differential patterns of use have been compared in two populations of different economic and cultural backgrounds—a small rural Mapuche community (Rams), and an outlying population (El Frutillar). The first is located in an herbaceous steppe far from the nearest Andean forest while the second is located outside the town of Bariloche, near the forests of Nahuel Huapi National Park. Semistructured interviews and related ecological variables were compared in both communities. In the past, both communities utilized nontimber forest products from the Andean Temperate forests. However, today, cost and benefit trade-offs appear to affect when and what edible resources are collected. The people from El Frutillar gather fewer wild plants in spite of the high plant abundance and the notorious food scarcity they suffer. The Mapuche people use more nutritious resources, more native species, spend longer traveling to the gathering site, and longer handling time preparing edible plants.     

北京西山典型城市森林内PM_(2.5)动态变化规律

城市森林内PM2.5浓度的状况可以直接反映城市森林对PM2.5的净化效果,也是居民休闲游憩关心的森林环境问题。选择北京西山3种典型的游憩型城市森林,通过对林内PM2.5浓度一年四季昼夜24h内变化的同步观测,分析了不同类型城市森林内PM2.5浓度的季节变化、日变化以及影响因素,结果表明:(1)北京西山3种游憩林内PM2.5浓度多数时候远低于城区对照值,在春、夏、秋三季都达到了国家城市化地区的标准,甚至在春季、秋季还达到了国家一类地区的标准。(2)城市森林在不同季节对PM2.5的净化效果存在差异,林内PM2.5浓度总体上呈现冬季夏季秋季春季的规律。(3)林内PM2.5浓度在一天24h内有很大变化波动,夜间浓度总体上高于白天,日变化曲线近似呈"双峰双谷"型,两个高峰出现在夜晚和早上,两个低谷出现在凌晨和中午前后。一年四季白天低谷出现时间有所不同,春季15:00左右、夏季13:00—17:00、秋季13:00—15:00、冬季9:00—11:00。(4)PM2.5在不同类型游憩林内的变化趋势和浓度值存在一定差异。郁闭度较大的侧柏林夜间PM2.5浓度总体上高于其它两种林型,其高峰和低谷出现时间延迟,高峰值大,高峰期持续时间长,且这种规律在秋季表现得更明显。(5)基于上述研究认为,北京西山城市森林为居民在PM2.5污染比较突出的都市背景下提供了一个相对清洁、健康的森林游憩环境,春季、夏季、秋季全天以及冬季9:00—11:00均是森林中PM2.5状况健康而适宜外出游憩的时段。     

The effects of soil fertility on the abundance of rowan (<Emphasis Type="Italic">Sorbus aucuparia</Emphasis> L.) in urban forests

The amount of rowan saplings has increased considerably in urban forests in Finland. In this study, we investigated the effects of soil fertility on rowan abundance. Urban forests studied were more fertile than rural forests, and consequently included more rowans than reference areas. The abundance of rowan increased with increasing soil fertility in urban areas, being the highest at forest edges. Furthermore, rowan did not suffer from trampling, and the presence of other trees and saplings did not restrict its growth in relatively open urban forests. We conclude that the effects of urbanization, e.g., edge effects, and factors related to trampling (e.g., dog excrement), may increase forest soil fertility creating favorable conditions for rowan. To control the spread of rowan in urban forests, we recommend that open forest edges with a large number of broad-leaved trees should be avoided, and recreational use of forests should be guided to the maintained path network.     

Urban trees: bridge-heads for forest pest invasions and sentinels for early detection

Urban trees have been increasingly appreciated for the many benefits they provide. As concentrated hubs of human-mediated movement, the urban landscape is, however, often the first point of contact for exotic pests including insects and plant pathogens. Consequently, urban trees can be important for accidentally introduced forest pests to become established and potentially invasive. Reductions in biodiversity and the potential for stressful conditions arising from anthropogenic disturbances can predispose these trees to pest attack, further increasing the likelihood of exotic forest pests becoming established and increasing in density. Once established in urban environments, dispersal of introduced pests can proceed to natural forest landscapes or planted forests. In addition to permanent long-term damage to natural ecosystems, the consequences of these invasions include costly attempts at eradication and post establishment management strategies. We discuss a range of ecological, economic and social impacts arising from these incursions and the importance of global biosecurity is highlighted as a crucially important barrier to pest invasions. Finally, we suggest that urban trees may be viewed as ‘sentinel plantings’. In particular, botanical gardens and arboreta frequently house large collections of exotic plantings, providing a unique opportunity to help predict and prevent the invasion of new pests, and where introduced pests with the capacity to cause serious impacts in forest environments could potentially be detected during the initial stages of establishment. Such early detection offers the only realistic prospect of eradication, thereby reducing damaging ecological impacts and long term management costs.     

The socioeconomic conditions determining the development, persistence, and decline of forest garden systems

There is a range of forest management systems between pure extraction and plantation systems. Such “intermediate systems” range from wild forests modified for increased production of selected products to anthropogenic forests with a high-density of valuable species growing within a relatively diverse and complex structure. These systems, classed here as “Forest Garden Systems” (FGS), have important socioeconomic and ecological benefits, and yet they have been largely overlooked by researchers, development practitioners, and policy makers. Based on case examples and the authors’ experience, this paper analyzes the socioeconomic and institutional factors that explain the development, persistence, and decline of FGS. These systems combine productivity and biodiversity values and are important components in the diverse economic systems of their managers. As such, the model warrants increased attention to protect existing values, to support the adaptation of existing systems to changing circumstances, and to inform the development of new models of integrated forest management     

The ecological basis of hunter-gatherer subsistence in African Rain Forests: The Mbuti of Eastern Zaire

The Mbuti pygmies, hunter-gatherers of the Ituri Forest of Zaire, trade forest products and labor for agricultural foods. It has been assumed that the Mbuti lived independently in the equatorial forest prior to its penetration by shifting cultivators. We assessed forest food resources (plant and animal) to determine their adequacy to support a hunting and gathering economy. For five months of the year, essentially none of the calorically important forest fruits and seeds are available. Honey is not abundant during this season of scarcity. Wild game meat is available year round, but the main animals caught have low fat content. This makes them a poor substitute for starch-dense agricultural foods, now staples in Mbuti diet. In general, in the closed evergreen forest zone, edible wild plant species are more abundant in agriculturally derived secondary forest than in primary forest. Similarly, they are more common at the savanna ecotone and in gallery forests. We suggest that it is unlikely that hunter-gatherers would have lived independently in the forest interior with its precarious resource base, when many of the food species they exploit are more abundant toward the savanna border.     

Nonnative plant invasion increases urban vegetation structure and influences arthropod communities

Aim

Ecological theory and empirical evidence indicate that greater structural complexity and diversity in plant communities increases arthropod abundance and diversity. Nonnative plants are typically associated with low arthropod abundance and diversity due to lack of evolutionary history. However, nonnative plants increase the structural complexity of forests, as is common in urban forests. Therefore, urban forests are ideal ecosystems to determine whether structural complexity associated with nonnative plants will increase abundance and diversity of arthropods, as predicted by complexity literature, or whether structural complexity associated with nonnative plants will be depauperate of arthropods, as predicted by nonnative plant literature.

Location

We sampled 24 urban temperate deciduous and mixed forests in two cites, Raleigh, North Carolina and Newark, Delaware, in the eastern United States.

Methods

We quantified ground cover vegetation and shrub layer vegetation in each forest and created structural complexity metrics to represent total, nonnative and native understory vegetation structural complexity. We vacuum sampled arthropods from vegetation and quantified the abundance, biomass, richness and diversity of spiders and non-spider arthropods.

Results

Nonnative plants increase understory vegetation complexity in urban forests. In Raleigh and Newark, we found support for the hypotheses that dense vegetation will increase arthropod abundance and biomass, and against the hypothesis that nonnative vegetation will decrease arthropods. Urban forest arthropod abundance and biomass, but not diversity, increased with greater nonnative and native structural complexity.

Main Conclusions

Invaded urban forests may provide adequate food in the form of arthropod biomass to transfer energy to the next trophic level, but likely fail to provide ecological services and functions offered by diverse species, like forest specialists. Urban land managers should survey urban forests for nonnative and native plant communities and prioritize replacing dense nonnative plants with native species when allocating vegetation maintenance resources.     

Social Perceptions of Biodiversity and Ecosystem Services in the Ecuadorian Amazon

The Amazon basin is widely recognized for its high biological and cultural diversity, enabling the provision of many ecosystem services. This study explores social perceptions of some of the features of biodiversity and ecosystem services in a tropical forest in Sangay Parish, Ecuador. Following a survey of residents, we identified three groups whose perceptions vary in relation to socioeconomic characteristics, cultural backgrounds, lifestyles, and the benefits obtained from the Sangay forest. Mestizo professionals, with a better socioeconomic situation, identify more regulation and cultural services; Shuar farmers have a comprehensive knowledge of biodiversity features and rely on provisioning services; and Shuar gatherers consume more forest products but are the least likely to formally recognize ecosystem services. We emphasize the importance of identifying social groups within a population and understanding their particular characteristics and perspectives before developing conservation and land use planning policies.     

Succession Influences Wild Bees in a Temperate Forest Landscape: The Value of Early Successional Stages in Naturally Regenerated and Planted Forests

In many temperate terrestrial forest ecosystems, both natural human disturbances drive the reestablishment of forests. Succession in plant communities, in addition to reforestation following the creation of open sites through harvesting or natural disturbances, can affect forest faunal assemblages. Wild bees perform an important ecosystem function in human-altered and natural or seminatural ecosystems, as they are essential pollinators for both crops and wild flowering plants. To maintain high abundance and species richness for pollination services, it is important to conserve and create seminatural and natural land cover with optimal successional stages for wild bees. We examined the effects of forest succession on wild bees. In particular, we evaluated the importance of early successional stages for bees, which has been suspected but not previously demonstrated. A range of successional stages, between 1 and 178 years old, were examined in naturally regenerated and planted forests. In total 4465 wild bee individuals, representing 113 species, were captured. Results for total bees, solitary bees, and cleptoparasitic bees in both naturally regenerated and planted conifer forests indicated a higher abundance and species richness in the early successional stages. However, higher abundance and species richness of social bees in naturally regenerated forest were observed as the successional stages progressed, whereas the abundance of social bees in conifer planted forest showed a concave-shaped relationship when plotted. The results suggest that early successional stages of both naturally regenerated and conifer planted forest maintain a high abundance and species richness of solitary bees and their cleptoparasitic bees, although social bees respond differently in the early successional stages. This may imply that, in some cases, active forest stand management policies, such as the clear-cutting of planted forests for timber production, would create early successional habitats, leading to significant positive effects for bees in general.     

Comparison of wild edible plant diversity and foraging strategies in two aboriginal communities of northwestern Patagonia

We have compared edible plant richness, diversity and differential patterns of use in two Mapuche communities of Argentina. The populations of Rams and Cayulef are located in a herbaceous steppe, far from the temperate forests of northwestern Patagonia where their ancestors lived in the past. Ecological concepts and methods, such as diversity indices, niche breadth and optimal foraging theory have been used in this comparative study. Our results indicate that the diversity of wild plants used in Rams and Cayulef is associated with the variety of gathering environments they visit. When comparing diversity indices among the three environments within each community, in Cayulef we found the highest diversity indices for steppe species and the lowest for forest plants. In contrast, in Rams the niche breadth is similar in all environments, indicating an ample exploration and use of edible wild plants. Cost and benefit trade-offs seem to be considered in both communities when edible plants are collected. Nevertheless, we found that the people from Rams not only utilize a greater richness of wild plants than the Cayulef people, but also use more nutritious resources, spend more time traveling to the gathering sites and a longer handling time in preparing these edible plants. This study has quantitatively shown that the restricted access to Pehuen forest (Araucaria araucana) is the main factor which seems to limit wild plant diversity used in these Mapuche communities.     

Quantifying tree carbon stock in historically conserved Seminary Hills urban forest of Nagpur,India

Urban forests help regulating flow of ecosystem services and are efficient to sequester atmospheric carbon. Tree carbon stock in urban forests and green spaces can help improving human well-being. Nagpur being one of the fastest growing urban agglomerate in India that has faced rapid loss of green spaces in last three decades. Present study assessed tree biomass carbon storage potential of a historically conserved large (67.41 ha) Seminary Hills Reserve forest of Nagpur. A total of 150 quadrats of 100 m² were laid to understand the vegetation structure and tree biomass storage. Overall structure and composition of the forest was assessed while, non-destructive biomass estimation was carried out using tree volume eqs. A total of 27 tree species belonging to 12 plant families were observed from the forest with only 6 tree species being dominant and remaining 21 being rare in occurrence. The maximum tree carbon storage was observed in dominant tree species of Hardwickia binata (76.30 t C ha^?1) followed by 17.04 t C ha^?1 in Tectona grandis and 1.19 t C ha^?1 in Boswellia serrata. Carbon stock in other co-dominant species was reported in Terminalia bellirica (76.57 kg C ha^?1), Gardenia resinifera (1118.6 g C ha^?1) and Terminalia arjuna (84.8 g C ha^?1). Total carbon stock of dominant tree species present in Seminary Hills urban forest was 94.53 ± 39.6 t C ha^?1. The study intends to bring focus ecosystem benefits from Urban Forests in growing urban sprawls of India and the need to include their vital role in urban planning.     

城市森林研究进展与发展战略

城市是一个以人类活动为中心的社会．经济．自然复合生态系统,城市森林是城市生态系统重要的组成部分,是城市生态系统健康和城市可持续发展的基础和保障,具有重要的生态服务功能。本文阐述了城市森林产生的背景、概念、范围和国内外的研究现状,以及当前城市森林研究的热点问题,最后提出了城市森林的发展战略。     

Growing trees: risks and rewards for society

Forests provide 1.75 billion cubic meters of timber each year and a similar amount of fuel wood. Our understanding of forest ecosystems is far from complete. Biotechnology can provide means to speed up adaptation by forest species in response to pathogen introduction, climate change, or other perturbations. Consensus building on forest issues is always likely to be difficult, as diversity in the nature of forests and their cultural and historical significance must be recognized. The potential risks and possible benefits of deploying or choosing not to deploy forest biotechnology products must be considered on a case-by-case, product- rather than process-driven basis for rational, evidence-based decisions to be reached. Aspects of ecologically neutral field trials, ecological and social perceptions of risk, and steady state and dynamic paradigms of nature are discussed alongside challenges facing biotechnology in adequately avoiding or limiting risks to allow deployment in forests. Communicated by Ronald Sederoff     

Discerning Fragmentation Dynamics of Tropical Forest and Wetland during Reforestation,Urban Sprawl,and Policy Shifts

Despite the overall trend of worldwide deforestation over recent decades, reforestation has also been found and is expected in developing countries undergoing fast urbanization and agriculture abandonment. The consequences of reforestation on landscape patterns are seldom addressed in the literature, despite their importance in evaluating biodiversity and ecosystem functions. By analyzing long-term land cover changes in Puerto Rico, a rapidly reforested (6 to 42% during 1940–2000) and urbanized tropical island, we detected significantly different patterns of fragmentation and underlying mechanisms among forests, urban areas, and wetlands. Forest fragmentation is often associated with deforestation. However, we also found significant fragmentation during reforestation. Urban sprawl and suburb development have a dominant impact on forest fragmentation. Reforestation mostly occurs along forest edges, while significant deforestation occurs in forest interiors. The deforestation process has a much stronger impact on forest fragmentation than the reforestation process due to their different spatial configurations. In contrast, despite the strong interference of coastal urbanization, wetland aggregation has occurred due to the effective implementation of laws/regulations for wetland protection. The peak forest fragmentation shifted toward rural areas, indicating progressively more fragmentation in forest interiors. This shift is synchronous with the accelerated urban sprawl as indicated by the accelerated shift of the peak fragmentation index of urban cover toward rural areas, i.e., 1.37% yr⁻¹ in 1977–1991 versus 2.17% yr⁻¹ in 1991–2000. Based on the expected global urbanization and the regional forest transition from deforested to reforested, the fragmented forests and aggregated wetlands in this study highlight possible forest fragmentation processes during reforestation in an assessment of biodiversity and functions and suggest effective laws/regulations in land planning to reduce future fragmentation.     

Ethnobiology, socio-economics and management of mangrove forests: A review

There is growing research interest in the ethnobiology, socio-economics and management of mangrove forests. Coastal residents who use mangroves and their resources may have considerable botanical and ecological knowledgeable about these forests. A wide variety of forest products are harvested in mangroves, especially wood for fuel and construction, tannins and medicines. Although there are exceptions, mangrove forest products are typically harvested in a small-scale and selective manner, with harvesting efforts and impacts concentrated in stands that are closer to settlements and easiest to access (by land or by sea). Mangroves support diverse, local fisheries, and also provide critical nursery habitat and marine productivity which support wider commercial fisheries. These forests also provide valuable ecosystem services that benefit coastal communities, including coastal land stabilization and storm protection. The overlapping of marine and terrestrial resources in mangroves creates tenure ambiguities that complicate management and may induce conflict between competing interests. Mangroves have been cut and cleared extensively to make way for brackish water aquaculture and infrastructure development. More attention is now given to managing remaining forests sustainably and to restoring those degraded from past use. Recent advances in remotely sensed, geo-spatial monitoring provide opportunities for researchers and planners to better understand and improve the management of these unique forested wetlands.