Scaling Issues in Forest Succession Modelling

This paper reviews scaling issues in forest succession modelling, focusing on forest gap models. Two modes of scaling are distinguished: (1) implicit scaling, i.e. taking scale-dependent features into account while developing model equations, and (2) explicit scaling, i.e. using procedures that typically involve numerical simulation to scale up the response of a local model in space and/or time. Special attention is paid to spatial upscaling methods, and downscaling is covered with respect to deriving scenarios of climatic change to drive gap models in impact assessments. When examining the equations used to represent ecological processes in forest gap models, it becomes evident that implicit scaling is relevant, but has not always been fully taken into consideration. A categorization from the literature is used to distinguish four methods for explicit upscaling of ecological models in space: (1) Lumping, (2) Direct extrapolation, (3) Extrapolation by expected value, and (4) Explicit integration. Examples from gap model studies are used to elaborate the potential and limitations of these methods, showing that upscaling to areas as large as 3000 km² is possible, given that there are no significant disturbances such as fires or insect outbreaks at the landscape scale. Regarding temporal upscaling, we find that it is important to consider migrational lags, i.e. limited availability of propagules, if one wants to assess the transient behaviour of forests in a changing climate, specifically with respect to carbon storage and the associated feedbacks to the atmospheric CO₂ content. Regarding downscaling, the ecological effects of different climate scenarios for the year 2100 were compared at a range of sites in central Europe. The derivation of the scenarios is based on (1) imposing GCM grid-cell average changes of temperature and precipitation on the local weather records; (2) a qualitative downscaling technique applied by the IPCC for central and southern Europe; and (3) statistical downscaling relating large-scale circulation patterns to local weather records. Widely different forest compositions may be obtained depending on the local climate scenario, suggesting that the downscaling issue is quite important for assessments of the ecological impacts of climatic change on forests.     

Temporal patterns of deforestation and fragmentation in lowland Bolivia: implications for climate change

The lowlands of eastern and northeastern Bolivia are characterized by a transition between the humid evergreen forests of the Amazon Basin and the deciduous thorn-scrub vegetation of the Gran Chaco. Within this landscape lies one of the world’s best preserved areas: the ecoregion known as the Chiquitano dry forest, where deforestation patterns over a 30 year period were analyzed. Results indicate that the area of the natural cover was reduced from 97.21 % before 1976 to 82.10 % in 2008, causing significant change in the landscape, especially in the spatial configuration of forest cover. The density of forest fragments increased from 0.073 patches per 100 ha before 1976 to 0.509 in 2008, with a mean distance between patches of 151 and 210 m over the same period, leading to a considerable reduction in the fragment sizes, from 1,204 ha before 1976 to a mere 54 in 2008. This pattern, observed in forests, does not occur in the savannas because, on one hand the savanna area is much lower compared to that of forests, and on the other because the deforestation process tended to be concentrated within forested areas. Based on the observed patterns, it is possible that in the future the natural landscapes will be substituted principally by anthropic landscapes, if there is no change in the economic and land distribution policies. If this process continues, it will stimulate the expansion of mechanized agriculture and the colonization of new areas, which will lead to further deforestation and landscape fragmentation.     

Data and processes linking vulnerability assessment to adaptation decision-making on climate change in Norway

The article focuses on the use of climate change vulnerability assessments in a local decision-making context, with particular reference to recent studies in Norway. We focus on two aspects of vulnerability assessments that we see as key to local decision-making: first, the information generated through the assessments themselves, and second, the institutional linkages to local level decision-making processes. Different research approaches generate different types of data. This is rarely made explicit, yet it has important implications for decision-making. In addressing these challenges we propose a dialectic approach based on exchange, rather than integration of data from different approaches. The focus is on process over product, and on the need for anchoring vulnerability assessments in local decision-making processes. In conclusion, we argue that there is unlikely to be one single ‘correct’ assessment tool or indicator model to make vulnerability assessments matter at a local level.     

Reform or reversal: the impact of REDD+ readiness on forest governance in Indonesia

Indonesia has turned its alleged role as global leader of land-based carbon emissions into a role as a global trailblazer exploring modalities for Reducing Emissions from Deforestation and Forest Degradation (REDD+). REDD+ readiness is largely about improving forest governance, but this itself is a multilayered concept. This article analyses how the processes and practices of REDD+ readiness are leading to various forest governance reforms in Indonesia. We analysed six dimensions of REDD+ readiness progress over the past six years and the way these interact with land tenure reform and land-use planning. We found evidence that (1) tenure issues are taken more seriously, as evidenced by the development of social safeguard mechanisms and efforts to accelerate the gazettement of forest boundaries, although a constitutional court recognition in 2013 for customary forest management is, however, yet to be operationalized; (2) spatial planning relates forests more clearly to other parts of the landscape in terms of compliance with Nationally Appropriate Mitigation Actions (NAMAs) commitments; and (3) the forest and peatland conversion moratorium initiative led to a revamping of forest management. Despite progress, there are still major obstacles to full REDD+ implementation in Indonesia. The discussion focuses on the weaker part of readiness and possible ways forward.     

Exploring some of the myths of land use change: Can rural to urban migration drive declines in biodiversity?

Forest transition theory describes a reversal in land-use trends for a given area, from a period of net forest area loss, to a period of net forest area gain. Some assume that such forest gain necessarily equates with biodiversity conservation. We question this assumption, based on research conducted in Oaxaca, Mexico. In Oaxaca's northern highlands, low intensity forest use and rotational (milpa) agriculture have led to pronounced spatial heterogeneity in forest structure and composition, and created a high-biodiversity forest-agriculture mosaic. In the Zapotec community of San Juan Evangelista Analco and the Chinantec community of Santiago Comaltepec, as across much of Oaxaca, fewer people are farming; farmers are cultivating less land, working closer to settlements, and growing fewer crop varieties. Widespread agricultural abandonment has initiated unprecedented changes in ecological succession, patch size, and edge effects, which we speculate will be having an impact on the biodiversity of the landscape mosaic. Our work suggests that the decline of land use activity may result in a gradual loss of the forest-agriculture mosaic, leading to localised declines in biodiversity, despite (or because of) extensive forest resurgence. These findings support the view that indigenous cultures in Oaxaca and Mexico should not be seen as an environmental constraint but rather as an agent of landscape renewal that allows for both cultural and biological diversity to flourish, a reality that national and international conservation bodies need to more fully recognise and incorporate into policy.     

Precipitation projections under GCMs perspective and Turkish Water Foundation (TWF) statistical downscaling model procedures

Insect outbreaks are major disturbances that affect a land area similar to that of forest fires across North America. The recent mountain pine bark beetle (D endroctonus ponderosae) outbreak and its associated blue stain fungi (Grosmannia clavigera) are impacting water partitioning processes of forests in the Rocky Mountain region as the spatially heterogeneous disturbance spreads across the landscape. Water cycling may dramatically change due to increasing spatial heterogeneity from uneven mortality. Water and energy storage within trees and soils may also decrease, due to hydraulic failure and mortality caused by blue stain fungi followed by shifts in the water budget. This forest disturbance was unique in comparison to fire or timber harvesting because water fluxes were altered before significant structural change occurred to the canopy. We investigated the impacts of bark beetles on lodgepole pine (Pinus contorta) stand and ecosystem level hydrologic processes and the resulting vertical and horizontal spatial variability in energy storage. Bark beetle-impacted stands had on average 57 % higher soil moisture, 1.5 °C higher soil temperature, and 0.8 °C higher tree bole temperature over four growing seasons compared to unimpacted stands. Seasonal latent heat flux was highly correlated with soil moisture. Thus, high mortality levels led to an increase in ecosystem level Bowen ratio as sensible heat fluxes increased yearly and latent heat fluxes varied with soil moisture levels. Decline in canopy biomass (leaf, stem, and branch) was not seen, but ground-to-atmosphere longwave radiation flux increased, as the ground surface was a larger component of the longwave radiation. Variability in soil, latent, and sensible heat flux and radiation measurements increased during the disturbance. Accounting for stand level variability in water and energy fluxes will provide a method to quantify potential drivers of ecosystem processes and services as well as lead to greater confidence in measurements for all dynamic disturbances.     

青藏高原土壤湿度的变化特征及其对中国东部降水影响的研究进展

青藏高原土壤湿度受积雪与冻土的共同影响,能够记忆长时间的陆面干湿过程,是气候变化的重要因子,对随后的中国东部降水有预测意义。由于高原观测站点稀少,土壤湿度观测资料匮乏,致使现有相关研究大多是基于再分析资料、模式资料和卫星遥感资料(统称替代资料)进行的,且所得结论既有差异,也存在不确定性。因此本文首先综述了各种土壤湿度替代资料的适用性对比研究,进而讨论了青藏高原地区土壤湿度的变化特征及其对我国东部气候的影响。现有研究表明:1)资料对比研究指出,现有的各种替代资料对高原土壤湿度存在明显的高估或低估现象,且评估结论受评估指标和插值方法不同的影响。相对而言,SSM/I和风云3B的土壤湿度产品与实际观测资料相关性较好。2)高原土壤湿度具有多时间尺度变化特征和空间非均匀性,在年变化上具有显著的融冻特征,年代际变化趋势和年际特征呈现显著的区域性差异。SSM/I资料表明春季高原主体土壤湿度的年代际变化趋势呈现为增加的特征,与高原的增暖相一致;年际变率存在东、西两个高值区,与其相关的潜热、感热通量能共同激发遥相关波列影响我国长江流域降水;同时高原土壤湿度在垂直方向上具有一致性,在空间分布上具有南部边缘最大、由东南向西北递减的特征。3)前人对高原土壤湿度影响中国东部降水的结论各有不同,其可能原因之一是采用的替代资料及其适用性不同,其二是模式试验中忽略土壤湿度的空间差异性而带来的误差等。相关问题需要进一步深入研究。     

气象探测环境等级评估方法及应用

利用1990,1994,2000,2005,2011,2013年夏季北京地区Landsat卫星资料、2009年数字高程资料计算气象站周边景观指标参数,结果表明:土地利用类型、气象站周边景观指数、建筑物高度及天空可视因子等参数能对气象探测环境的结构配置信息以数字化方式呈现。此外,景观指标参数和气象要素相关分析表明:对气温变化影响较大的景观指标参数主要有城镇面积、水体面积、最大斑块指数、最大斑块占城镇面积比例、蔓延度指数、平均分维数和天空可视因子。对绝对湿度影响较大的景观指标参数为城镇面积、水体面积、最大斑块指数、最大斑块占城镇面积比例、蔓延度指数、聚集度指数和天空可视因子。对小风占比影响较大的景观指标参数仅为水体面积、最大斑块指数和最大斑块占城镇面积比例。基于以上统计结果,提出了一套对探测环境进行评估的方法——景观指标评估法。利用该方法对北京市15个国家级地面气象观测站进行评估,结果表明:周围环境对观测资料影响程度最小的站为怀柔站;环境影响最大的站为丰台站、朝阳站。     

Historical footprints in contemporary land use systems: forest cover changes in savannah woodlands in the Sudano-Sahelian zone

The paper analyses land use trajectories in savannah woodlands in the Central-West Region, Burkina Faso and the Upper East Region in northern Ghana by use of satellite images and historical archives. Observed trends differ in terms of spatial location and correlation with population pressure from normally accepted characterizations. Colonial forestry policies are proposed as key determinants of present-day land use patterns. However, these reinforced pre-colonial land use patterns inasmuch as land gazetted as forest reserves were tracts affected by vectors of human and livestock disease. It is suggested that the transformation of wooded agricultural landscapes in the Sudano-Sahelian region is the outcome of historically and culturally embedded interactions between complex social, economic and ecological processes which operate at widely varying scales and which change over time; the implications hereof for modelling of global environmental issues is discussed.     

Circumglobal teleconnection and early summer rainfall in the US Intermountain West

Physical processes responsible for the abnormally wet condition in the Central Intermountain West (CIW) of the United States in June 2009 were investigated. It was illustrated that persistent rainy conditions over the CIW during June 2009 were associated with a pronounced circumglobal teleconnection pattern, which is characterized as a short Rossby wave train along the jet stream waveguide with a wave number 5 structure. The ascending motion and moisture flux convergence over the CIW associated with the cyclonic action center over the US West Coast in the teleconnection wave train could be essential for the persistent local rainfall during June 2009. Further analysis suggested that the June 2009 circulation pattern is consistent with a prevailing mode of the summer circumglobal teleconnection pattern. The findings in this study provide information for improved understanding of the early summer rainfall regime in the CIW.     

Carbon forestry in West Africa: The politics of models,measures and verification processes

In a context of neo-liberal environmental governance, imperatives for global climate change mitigation are motivating a new round of policy initiatives and projects aimed at carbon forestry: conserving and enhancing forest carbon stocks, and trading these values in emerging carbon markets. In this context modelling and measurement, always significant in framing and justifying forest policy initiatives, are of renewed importance, with a growing array of protocols focused on counting and accounting for forest carbon as a commodity. This article draws on perspectives from science and technology studies and environmental discourse analysis to explore how these modelling and measurement processes are being co-constructed with forest carbon policies and political economies, and applied in project design in local settings. Document analysis and key informant interviews are used to track and illustrate these processes in a pair of case studies of forest carbon projects in Sierra Leone and Ghana. These are chosen to highlight different project types – focused respectively on forest reserve and farm-forestry – in settings with multi-layered histories of people-forest relations, landscape change and prior project intervention. The analysis shows how longer established framings and assessments of deforestation are being re-invoked and re-worked amidst current carbon concerns. We demonstrate that measurement processes are not just technical but social and political, carrying and thus cementing particular views of landscape and social relations that in turn make likely particular kinds of intervention pathway, with fortress style conservation or plantations becoming the dominant approach. In the process, other possibilities – including alternative pathways that might treat and value carbon as part of complex, lived-in landscapes, or respond more adaptively to less equilibrial people–forest relations, are occluded.     

The discursive politics of ‘fracking’: Frames,storylines, and the anticipatory contestation of shale gas development in the United Kingdom

How contested sources of energy such as shale gas are perceived in frontier countries considering their development is incredibly important to national and international climate policies. The UK shale development case is of particular interest currently as the Government attempts to position the UK as a pioneer of European, safe, sustainable shale gas development. We conduct a mixed-methods analysis of the UK policy debate on shale gas development involving 30 stakeholder interviews and 1557 political documents. This empirical focus extends the existing literature by identifying the use of frames in and through the institutions and practices of formal UK politics. We identify nine key frames and their associated storylines, analyse their use over time, and compare these findings with other national case studies. Perhaps unsurprisingly, given most UK Governments within our timeframe have supported shale development, pro-shale development frames dominate in the policy debate; however, we also find a high level of anti-shale development frame use, suggesting a deep and ongoing framing contest in national formal political sites. We find in particular a more prominent focus on land-use issues and impacts on the landscape than other UK studies or other national contexts. Conceptually, the study puts forward an integrative approach to the related concepts of frames and storylines, as well as arguments concerning the impotence of storylines in anticipatory political debate and the polyvalence of framing strategies. Questions about governance are raised by the general lack of consensus over the framing of shale development within formal political sites, let alone amongst the broader public; and by the lack of a coherent response from the Government to criticisms of its approach. Finally, we reflect on the apparent lack of evidence for Hajer’s ‘communicative miracle’ in our case, and speculate as to whether the lack of broad-based resonance of the ‘bridge’ storyline signals trouble for the positive-sum thinking of ecological modernisation.     

Potential impacts of global climate change on the hydrology and ecology of ephemeral freshwater systems of the forests of the northeastern United States

Global, national, and regional assessments of the potential effects of Global Climate Change (GCC) have been recently released, but not one of these assessments has specifically addressed the critical issue of the potential impacts of GCC on ephemeral freshwater systems (EFS). I suggest that this is a major oversight as EFS occur in various forms across the globe. In the northeastern United States, these systems, whether ephemeral (“vernal”) pools or ephemeral or intermittent headwater streams are abundant and provide unique habitats critical to the maintenance of forest biodiversity. Since the hydrology of these waterbodies is strongly affected by weather patterns (in the short-term) or climate (long-term), they are especially sensitive to climate change. In this essay, I review the literature on relationships between climate and hydrology of EFS and on relationships between hydrology and ecology of these systems. I then conclude with my assessment of potential impacts of GCC on the hydrology of EFS and implications for their ecology. The focus of this essay will be on EFS of the forests of the northeastern United States, but will include literature from other regions as they relate to the general relationships between GCC and EFS.     

The Impact of Landscape Fragmentation on Atmospheric Flow: A Wind-Tunnel Study

Landscape discontinuities such as forest edges play an important role in determining the characteristics of the atmospheric flow by generating increased turbulence and triggering the formation of coherent tree-scale structures. In a fragmented landscape, consisting of surfaces of different heights and roughness, the multiplicity of edges may lead to complex patterns of flow and turbulence that are potentially difficult to predict. Here, we investigate the effects of different levels of forest fragmentation on the airflow. Five gap spacings (of length approximately 5h, 10h, 15h, 20h, 30h, where h is the canopy height) between forest blocks of length 8.7h, as well as a reference case consisting of a continuous forest after a single edge, were investigated in a wind tunnel. The results reveal a consistent pattern downstream from the first edge of each simulated case, with the streamwise velocity component at tree top increasing and turbulent kinetic energy decreasing as gap size increases, but with overshoots in shear stress and turbulent kinetic energy observed at the forest edges. As the gap spacing increases, the flow appears to change monotonically from a flow over a single edge to a flow over isolated forest blocks. The apparent roughness of the different fragmented configurations also decreases with increasing gap size. No overall enhancement of turbulence is observed at any particular level of fragmentation.     

Collective action for changing forests: A spatial,social-ecological approach to assessing participation in invasive plant management

Environmental governance research has discovered much about what drives collective action to address human-environment issues, including factors such as risk perceptions and self-efficacy. Yet the design of many studies limits our ability to draw conclusions about collective action under conditions of environmental change, especially across spatial or temporal scales. In this study, we integrate social and biophysical data—assessing data over time and examining the influence of space—to analyze efforts by community members to manage rapid environmental change in the form of an invasive plant (Mikania micrantha) in community forests in Chitwan, Nepal. Invasive species are an increasingly complex ethical, cultural, and ecological issue that is becoming more pressing with global environmental and social changes. We combine household surveys, ecological surveys, and spatial data in Bayesian hierarchical linear models to explore changes in the drivers of collective action since initial household surveys in 2014. We find that risk perceptions, reliance on forest resources, perceptions of forest safety, and M. micrantha abundance were the most influential factors in our models. Additionally, our findings suggest that the influence of M. micrantha abundance on collective action varies across spatial scales, indicating important interactions between social and biophysical drivers of collective action. Ultimately, our results highlight the importance of considering social and biophysical factors across space and time to inform the design of institutions that will be effective in addressing collection action problems tied to environmental change.     

Simulation of Turbulent Flow in An Urban Forested Park Damaged by a Windstorm

The damage caused by windstorms to forest ecosystems is often very heterogeneous. In order to improve the stability of forested landscapes, it is of great importance to identify the factors responsible for this spatial variability. The structure of the landscape itself may play a role, through possible influences of canopy heterogeneities on the development of turbulence. For the purpose of investigating the role of landscape fragmentation on turbulence development, we used a numerical flow model with a k–ε turbulence scheme model, previously validated in simple cases with well-defined surface changes (roughness change and forest edge flow). A series of two- and three-dimensional simulations were performed over a heterogeneous urban forested park in Europe, which was severely damaged in various places by the Lothar windstorm in December 1999. The model shows the development of a region of strong turbulence, resulting from the generation of large wind shear at the top of the canopy. A sensitivity study shows how the location, extension and intensity of the region depend on canopy characteristics such as the leaf density, the nature of the edge or the presence of gaps and clearings. Simulations performed in conditions representative of the windstorm show that the location of the damaged areas corresponds very closely to the regions where the turbulent kinetic energy was above a certain threshold.     

A social-ecological network approach for understanding wildfire risk governance

Large wildfire events (e.g. >100 square km) highlight the importance of governance systems that address wildfire risk at landscape scales and among multiple land owners and institutions. A growing body of empirical work demonstrates that environmental governance outcomes depend upon how well patterns of interaction among actors align with patterns of ecological connectivity, such as wildfire transmission. However, the factors that facilitate or inhibit this alignment remain poorly understood. It is crucial to improve understanding of the conditions under which actors establish or maintain linkages with other actors with whom they are interdependent because of ecological linkages. To this end, we introduce the concept of “risk interdependence archetypes” based on the spatial configurations by which one actor (i.e. a particular organization) is exposed to risk via the actions of another actor. We then develop a set of hypotheses to explore how different sets of conditions associated with each spatial configurations of risk interdependence may shape the likelihood that an actor coordinates with another actor in ways that promote social-ecological alignment. We test these hypotheses using network analysis of a wildfire transmission network developed through simulation of wildfires over several thousand fire seasons and a governance network created from interviews with 154 representatives of 87 organizations involved in efforts to mitigate wildfire risk in the Eastern Cascades Ecoregion, USA. Results indicate that social-ecological alignment is more likely when actors have opportunities to influence forest management practices on ignition-prone lands that they do not manage themselves, and when actors bear greater responsibility for averting losses from wildfires that spread to lands they manage independently. Importantly, not all forms of risk interdependence increase the likelihood of alignment, implying that organizations have limited capacity for interaction and may prioritize certain risk mitigation partnerships over others. While the performance of risk governance systems may hinge on the alignment of social and ecological networks, our results suggest that alignment in turn may depend on actor-level strategies for interaction with other actors.     

城市景观格局与热岛效应研究进展

概述了城市景观格局和城市热岛效应及城市景观格局对城市热岛效应影响等领域的研究现状,探讨了城市景观格局对城市热岛效应的影响作用,并结合城市景观格局研究中的新领域——景观格局优化,提出了解决城市热岛问题的新思路,即通过优化景观格局来达到缓解甚至消除热岛效应。展望了城市景观格局和城市热岛效应研究领域存在的问题和面临的任务。     

双季稻主要气象灾害研究进展

热害、洪涝、干旱和冷害是影响我国双季稻安全生产的主要气象灾害。气候变化背景下,双季稻遭受的极端气候事件增加,应对气象灾害的任务更加紧迫。我国双季稻主要气象灾害的时空分布特征不同:热害、洪涝和干旱发生频率整体呈增加趋势,西部南部较高;冷害弱减轻,北高南低,不同生育期存在差异。文中对双季稻生产的影响、监测预警技术（站点监测、遥感监测、指标预警、数理统计和动态机理模型）以及防御气象灾害的减灾保产技术进行了阐述。针对当前气候资源的时空分布特点以及关于双季稻气象灾害研究存在的不足,提出了双季稻气象灾害在未来研究中需要重点关注的科学问题,即双季稻气象灾变过程及其动态监测指标体系、气候变暖背景下双季稻气象灾害遥感监测技术及其气象灾损动态评估技术、星-地耦合的双季稻气象灾变过程数值模式研发、双季稻种植制度对气候变化的适应性及其抗灾减灾新技术与示范研究,为双季稻有效防御气象灾害和稳产高产提供依据和技术支撑。