Urban forest management in Addis Ababa,Ethiopia. A policy policy Arrangement Approach

Recently in Ethiopia, forest decline has been observed in every part of the country and identified as an important problem. However, studies on policy approaches are scarce, and thus policy change analysis is imperative for understanding urban forest management. This study aims at analyzing Ethiopian forest policies using a Policy Arrangement Approach (PAA) with four dimensions: discourse, actors, power and resources, and rules of the game. Policy changes during three regimes (Imperial, 1936–1974; Derg, 1974–1991; and the present government, 1991 to present) are analyzed. A qualitative research design was employed to obtain and analyze data. Our analysis has revealed that policy changes from government to governance with the government. This major turn reflects a fundamental shift in the dominant discourse about the management of forests. It is found that PAA is a useful analytical tool to understand and explain policy changes. Insights from this analysis can contribute to the design of an integrated urban forest policy and critically reflect the challenges and interventions needed to positively influence forest management.     

Effects of landscape structure and forest reserve location on old-growth forest bird species in Northern Finland

Old-growth forest birds in Fennoscandia have sharply declined in numbers during the last decades apparently due to commercial forest harvesting and fragmentation of old-growth forests. Conservation measures have led to the establishment of a forest reserve network to assure the persistence of forest birds at a regional scale. However, little is known about the effects of landscape structure within and around the reserves on the distribution of old-growth forest birds. We used a hierarchical approach to address the questions of how landscape structure and composition within forest reserves, landscape composition of surrounding areas and reserve location affect the abundance of resident, old-growth forest birds in the Northern Finnish forest reserve network. The positive role of particular landscape features on bird distribution indicates that both the proportion of old-growth forests and the structure of boreal landscape mosaic has an important role in determining the distribution of these birds. The landscape composition surrounding the reserves proved to be only a weak predictor in species distribution models, which argues against the primary role of the surrounding matrix in determining species distribution within forest reserves. Reserves located near the Russian border showed a higher abundance of old-growth birds than more western ones. Once east-west gradients in overall landscape composition had been accounted for, however, reserves did not differ significantly in the number of species present. These results suggest that landscape gradients, rather than ecological processes such as the presence of source areas located along the border with Russia, are the main determinant of the distribution of old-growth forest birds in the Finnish reserve network. We propose that to enhance regional persistence of old-growth forest birds, conservation efforts should be primarily directed towards the protection and enhancement of forest habitat quality and natural heterogeneity of landscapes within targeted areas. This revised version was published online in July 2006 with corrections to the Cover Date.     

试析靖边县林木病虫害的防治

森林病虫害防治是国家减灾工程的重要组成部分,森林病虫害防治的成败关系到森林资源安全,生态环境安全和人居环境安全,进而影响到社会稳定和谐的可持续发展。我县是油、气、煤资源大县,在森林病虫害防治方面有许多成功的经验和不足,现在加以总结。     

The effect of Appalachian mountaintop mining on interior forest

Southern Appalachian forests are predominantly interior because they are spatially extensive with little disturbance imposed by other uses of the land. Appalachian mountaintop mining increased substantially during the 1990s, posing a threat to the interior character of the forest. We used spatial convolution to identify interior forest at multiple scales on circa 1992 and 2001 land-cover maps of the Southern Appalachians. Our analyses show that interior forest loss was 1.75–5.0 times greater than the direct forest loss attributable to mountaintop mining. Mountaintop mining in the southern Appalachians has reduced forest interior area more extensively than the reduction that would be expected based on changes in overall forest area alone. The loss of Southern Appalachian interior forest is of global significance because of the worldwide rarity of large expanses of temperate deciduous forest.     

Landscapes as continuous entities: forest disturbance and recovery in the Albertine Rift landscape

Kibale National Park, within the Albertine Rift, is known for its rich biodiversity. High human population density and agricultural conversion in the surrounding landscape have created enormous resource pressure on forest fragments outside the park. Kibale presents a complex protected forest landscape comprising intact forest inside the park, logged areas inside the park, a game corridor with degraded forest, and forest fragments in the landscape surrounding the park. To explore the effect of these different levels of forest management and protection over time, we assessed forest change over the previous three decades, using both discrete and continuous data analyses of satellite imagery. Park boundaries have remained fairly intact and forest cover has been maintained or increased inside the park, while there has been a high level of deforestation in the landscape surrounding the park. While absolute changes in land cover are important changes in vegetation productivity, within land cover classes are often more telling of longer term changes and future directions of change. The park has lower Normalized Difference Vegetation Index (NDVI) values than the forest fragments outside the park and the formerly logged area—probably due to forest regeneration and early succession stage. The corridor region has lower productivity, which is surprising given this is also a newer regrowth region and so should be similar to the logged and forest fragments. Overall, concern can be raised for the future trajectory of this park. Although forest cover has been maintained, forest health may be an issue, which for future management, climate change, biodiversity, and increased human pressure may signify troubling signs.     

Balancing landscape-level forest management between recreation and wood production

Although many forested landscapes are used for both wood production and outdoor recreation, intensive forest management can negatively impact the recreational value of forests, including in Sweden, a country with rich forest resources and a strong forest industry. In Sweden, urbanization has increased the importance of, and demand for, urban and peri-urban recreational green areas such as forests. It is the responsibility of the local government – i.e., the municipalities – to provide a good living environment for its inhabitants, including recreational areas. However, most of the forest areas in Sweden are owned by private individuals and companies, which have a large degree of freedom in their forest management decisions. Municipalities can make formal agreements with forest owners to protect forests with high recreational values, but this requires financial resources, which are often scarce. Thus, tools are needed to identify the forest areas that should be prioritized for the use of forest management strategies that maintain or increase the recreational value of forests. In this study, we elaborate an approach that balances economic and recreational forest values within a forest decision support system (DSS) and test the approach for a case study area in southern Sweden. The recreation model included in the forest DSS links locational aspects, such as population density and proximity to water, with forest structure aspects, which are simulated over time under different management strategies. Our results suggest that the model could be useful for more efficient planning of the recreational potential of forests at the landscape level. The results from the case study indicate that substantial increases in the recreational value of a forest landscape can be achieved with relatively small overall economic losses, for example, by extending rotation periods in forests close to densely populated areas.     

Effects of varying forest edge permeability on seed dispersal in a neotropical montane forest

Hard (high-contrast with pastures) and soft (low-contrast with old-fields) forest edges created by slash-and-burn agriculture have become common landscape features in regions dominated by neotropical montane forest. However, little is know about the impacts of such edge types on forest regeneration dynamics. The consequences of varying forest edge permeability for oak acorn dispersal were investigated in a forest mosaic in the Highlands of Chiapas, Mexico. Rates of acorn production and removal, as well as the abundance and composition of small mammal seed consumers, were monitored along these different edge types (hard vs. soft) at specific distances from forest edges into forest patches and adjacent grasslands during two consecutive years. Results show that acorn removal declined significantly only in grasslands of sites characterised by hard edges (Logistic regression, P < 0.05). Movements of metal-tagged acorns support the hypothesis that soft edges are more permeable to small mammals, with rodents moving acorns up to 15 m into grasslands of sites with soft edges. In sites with hard edges, higher rates of acorn dispersal were recorded from the forest edge towards the forest interior. Peromyscus spp. were the main acorn predators and/or dispersers of acorns present in our study sites. Rates of acorn removal during a non-masting year were greater than the subsequent mast-seeding year (85% removal within 138 days vs. 75% within 213 days), demonstrating that mast seeding may allow some seeds to escape predation. The implications of these results for oak dispersal and regeneration along edges in fragmented tropical forest landscapes are discussed.     

Mapping large-scale forest dynamics: a geospatial approach

Digital map of forest dynamics is emerging as a useful research and management tool. As a key issue to address in developing digital maps of forest dynamics, spatial autocorrelation has been distinguished into ??true?? and ??false?? gradients. Previous ecological models are mostly focused on either ??true?? or ??false?? gradient, and little has been studied to simultaneously account for both gradients in a single model. The main objective of this study was to incorporate both gradients of spatial autocorrelation in a deterministic geospatial model to provide improved accuracy and reliability in future digital maps of forest dynamics. The mapping was based on two underlying assumptions??unit homogeneity and intrinsic stationarity. This study shows that when the factors causing the spatial non-stationarity have been accounted for, forest states could become a stationary process. A prototype geospatial model was developed for the Alaska boreal forest to study current and future stockings across the region. With areas of the highest basal area increment rate projected to cluster along the major rivers and the lowest near the four major urban developments in Alaska, it was hypothesized that moisture limitation and inappropriate human interference were the main factors affecting the stocking rates. These results could be of unprecedented value, especially for the majority of Alaska boreal region where little information is available.     

浅谈林木病害防治做法

凤岗县是重点的天然林深护区,森林覆盖率达57%,因此在保护利用森林方面取得了较好的社会效益和经济效益,随着经济林木的日益扩大和发展,特别是林木病虫害防治是抓好林业产业化发展的关键所在,所以,凤岗县林业发展及病虫害预防工作,主要围绕认真贯彻执行《植物检疫条例》和《森林病虫害防治条例》,严格执行苗木"两证一签"制度,全面开展检疫、监测和防治工作,并产生了良好的社会和经济效应,本人以从事林木防治工作多年的实践谈谈以下几点:     

Expectations towards forestry: The influence of personal networks with forest owners

Forest and wood enjoy a high prestige in urban societies, however, forestry in general is held at a lower level of esteem. This hypothesis has been supported by several national and regional surveys throughout Europe and is often presented as an obligatory concomitant phenomenon of urbanisation processes.

Nevertheless, psychological studies indicate the importance of the social context for the evolution of peoples' preferences. Hence, personal communication with members of the forestry community may also influence the expectations of individuals towards forest management. Approximately 1.5 million people in Germany own forests, therefore, the chance of knowing one or more forest owners is relatively high, even in urban areas. The role of forest owners as propagators of forestry core beliefs may be important.

Within this context, the role of forest owners in interpersonal networks has been analysed in its importance in the evolution of preferences and expectations. The data was taken from a nation-wide survey based on telephone interviews with 2800 people. Important questions that can be answered with this study are 1) How many people know a forest owner? 2) What kind of relationship do they have with the forest owner? 3) Do they talk about forest management and, if so, how often? 4) What do people learn about forest owners' practices? 5) Do people address expectations to forest owners? 6) Do the networks influence the expectations people have towards forest management?

The results of this study are compared to results gained by network analyses in other fields and studies of small scale forest owner research.     

Old-growth forest landscape transitions from pre-European settlement to present

We conducted a multi-temporal spatial analysis of forest cover for a 9600 ha landscape in northern Wisconsin, U.S.A., using data from pre-European settlement (1860s), post-settlement (1931), and current (1989) periods. Using GIS we have shown forest landscape changes and trajectories that have been generally described in aggregate for the norther Great Lake States region. We created the pre-European settlement map from the witness tree data of the original federal General Land Office survey notes. The 1931 cover was produced from the Wisconsin Land Economic Inventory, and the 1989 cover map was based on color infrared photography. We used GIS to analyze 1) land area occupied by different forest types at different dates, 2) temporal transitions between dates and their driving proceses, and 3) successional trajectories with landforms and spatial associations of forest types. Over the 120 year period, forest cover has changed from a landscape dominated by old-growth hemlock (Tsuga canadensis) and hardwood forests (Acer saccharum, Betula alleghaniensis) to largely second-growth hardwoods and conifers. The former dominant hemlock is largely eliminated from the landscape. From 1860 to 1931, large-scale disturbances associated with logging were the dominant processes on the landscape. Early successional forest types covered much of the landscape by the 1930s. From 1931 to 1989, succession was the dominant process driving forest transitions as forest types succeeded to a diverse group of upland hardwood and conifer forest types. If successional trajectories continue, a more homogeneous landscape may develop comprised of both a northern hardwood type dominated by sugar maple, and a boreal conifer/hardwood forest.     

Modeling and mapping forest diversity in the boreal forest of interior Alaska

Context

Patterns of forest diversity are less well known in the boreal forest of interior Alaska than in most ecosystems of North America. Proactive forest planning requires spatially accurate information about forest diversity. Modeling is a cost-efficient way of predicting key forest diversity measures as a function of human and environmental factors.

Objectives

Investigate and predict the patterns and processes in tree species and tree size-class diversity within the boreal forest of Alaska for a first mapped quantitative baseline.

Methods

For the boreal forest of Alaska, USA, we employed Random Forest Analysis (machine learning) and the Boruta algorithm in R to predict tree species and tree size-class diversity for the entire region using a combination of forest inventory data and a suite of 30 predictors from public open-access data archives that included climatic, distance, and topographic variables. We developed prediction maps in a GIS for the current levels (Year 2012) of tree size-class and species diversity.

Results

The method employed here yielded good accuracy for the huge Alaskan landscape despite the exclusion of spectral reflectance data. It’s the first quantified GIS prediction baseline. The results indicate that the geographic pattern of tree species diversity differs from the pattern of tree size-class diversity across this forest type.

Conclusions

The results suggest that human factors combined with topographical factors had a large impact on predicting the patterns of diversity in the boreal forest of interior Alaska.

     

Landscape effects of forest loss in a pollination system

Forest loss has been invoked as a cause for changes in the reproductive success of animal-pollinated woodland plants, associated with changes in their pollinators. To analyze such effects, it is important to include all of the three key players: landscapes, pollinators and a plant. We investigated effects of forest loss on an insect-pollinated plant through landscapes in forested ecosystems to pollinator communities and plant populations. Then we questioned if abundance and species richness in pollinator communities decrease as forest loss increases, and this in turn leads to a decrease in reproductive output of an insect-pollinated plant. We made a study with 12 populations of the bee pollinated herb, Erythronium americanum, in a landscape characterized by scattered fragments of deciduous forest within intensively managed agricultural fields. We also sampled bees as the potential pollinators by pan traps. We quantified the study landscapes using the amount of forest cover and the length of forest edge within each of the six radii (250, 500, 750, 1,000, 1,250 and 1,500 m). Regression analyses showed that the abundance and species richness of all collected bees were positively related to only the forest cover at the radius of 750 m. We also found the positive relationships for the seed set of E. americanum when the forest cover at the same radius and abundance of all collected bees were used as the predictor variables. These results indicate that forest loss causes negative impacts on potential pollinator communities and seed sets of some woodland herbs.     

Temporal change in forest fragmentation at multiple scales

Previous studies of temporal changes in fragmentation have focused almost exclusively on patch and edge statistics, which might not detect changes in the spatial scale at which forest occurs in or dominates the landscape. We used temporal land-cover data for the Chesapeake Bay region and the state of New Jersey to compare patch-based and area–density scaling measures of fragmentation for detecting changes in the spatial scale of forest that may result from forest loss. For the patch-based analysis, we examined changes in the cumulative distribution of patch sizes. For area–density scaling, we used moving windows to examine changes in dominant forest. We defined dominant forest as a forest parcel (pixel) surrounded by a neighborhood in which forest occupied the majority of pixels. We used >50% and ≥60% as thresholds to define majority. Moving window sizes ranged from 2.25 to 5,314.41 hectares (ha). Patch size cumulative distributions changed very little over time, providing no indication that forest loss was changing the spatial scale of forest. Area–density scaling showed that dominant forest was sensitive to forest loss, and the sensitivity increased nonlinearly as the spatial scale increased. The ratio of dominant forest loss to forest loss increased nonlinearly from 1.4 to 1.8 at the smallest spatial scale to 8.3 to 11.5 at the largest spatial scale. The nonlinear relationship between dominant forest loss and forest loss in these regions suggests that continued forest loss will cause abrupt transitions in the scale at which forest dominates the landscape. In comparison to the Chesapeake Bay region, dominant forest loss in New Jersey was less sensitive to forest loss, which may be attributable the protected status of the New Jersey Pine Barrens.     

Modeling configuration dynamics of harvested forest landscapes in the Canadian boreal plains

Habitat configuration has important implications for the persistence of faunal and floral populations at a variety of spatial scales. Forest harvesting alters habitat configurations. However, measuring and predicting such alterations remains challenging, in part because previously developed metrics of habitat configuration are often not statistically independent of habitat amount. Thus, their ability to measure independent effects of habitat configurations and habitat amount on ecosystem components such as wildlife populations has been limited. Here, we evaluate habitat configuration based on newly developed metrics that are independent of habitat amount but do not depend on regression residuals of abundance and configuration relationships on any population of landscapes. We use these new metrics to measure and predict changes in habitat configuration following forest harvesting in the boreal forest of Alberta, Canada. Our findings clearly demonstrate changes in habitat configuration resulting from forest harvesting can be predicted precisely with information about initial habitat patch structure and harvesting patterns. Because forest harvesting has significant implications for habitat configuration, accurately predicting these changes is critical for determining if forest harvesting strategies are sustainable for ecosystem components and processes. This study provides a set of novel, robust metrics for tracking landscape-scale changes in habitat configuration in harvested boreal forests.     

Deciduous forest and resident birds: the problem of fragmentation within a coniferous forest landscape

Six species of resident birds were censused in patches of deciduous forest within a coniferous forest landscape in south central Sweden. Here, the forests have been subjected to active forestry for a long time, but with recently increased intensity. Although the forest cover is more or less continuous in this landscape, mature deciduous forest is now a rare element compared with the untouched forest.All censused patches were similar with regards to size, proportion and amount of deciduous trees, but were either isolated in the coniferous forest (isolated patches) or near to other deciduous patches (aggregated patches). We concentrated on six species of resident birds, with moderate area requirements, that are tied to deciduous forest and whose ecology is well-known. The Nuthatch and the Marsh tit, which both show strict year-round territoriality and have a restricted dispersal phase, were significantly more likely to be found in aggregated than in isolated patches. No effect was found for the Great tit and the Blue tit, which are less territorial outside the breeding season and have a longer dispersal phase. Moreover, the Great tit is less specialized on deciduous forest than the other species. Also, the Long-tailed tit was negatively affected by isolation, which may be due to restricted dispersal and to larger area requirements of this flock-territorial species. The Hazel grouse, finally, was not affected, but this larger bird probably uses the forest in a different way from the smaller species.Our study clearly shows that fragmentation of one type of forest (deciduous) within another can have serious detrimental effects on forest-living species and raises important issues for forest management practices and conservation within a forest landscape.     

Evaluating restoration success of a 40-year-old urban forest in reference to mature natural forest

We assessed whether forest restoration was successful in Expo ’70 Commemorative Park in Osaka Prefecture, Japan, which was planted in the 1970s with native late-successional tree species. Detailed survey and analysis of species composition, stand vertical stratification, and forest dynamics, including comparison with a reference, natural late-successional forest, were conducted. The restoration plots had grown to larger basal area compared with the reference plots, however, this was a consequence of very high densities of the overstory trees due to low self-thinning rate. Stand vertical structure of the restoration plots was biased toward overstory layers, causing high mortality of understory trees and shrubs. Because there are no mature forests near the restoration site that could act as a seed source, abundance and diversity of understory trees are likely to continue decreasing in the restoration plots, resulting in single-layered forest structure similar to those of monocultures and even-aged forests. Many seedlings of exotic species emerged in the restoration plots and this could lead to a plagiosere where exotic species dominate the vegetation inhibiting regeneration and growth of native species. Ordination analysis using different measures, basal area and abundance, showed apparently contradicting results, suggesting that multiple criteria are needed to evaluate forest restoration success. Our results indicate restoration of mature, late-successional forest cannot be achieved by simultaneous planting of native species. To sustain urban forests into the future, we must conduct long-term monitoring and management referencing natural forest structure and dynamics.     

Influence of high-resolution data on the assessment of forest fragmentation

Context

Remote sensing has been a foundation of landscape ecology. The spatial resolution (pixel size) of remotely sensed land cover products has improved since the introduction of landscape ecology in the United States. Because patterns depend on spatial resolution, emerging improvements in the spatial resolution of land cover may lead to new insights about the scaling of landscape patterns.

Objective

We compared forest fragmentation measures derived from very high resolution (1 m²) data with the same measures derived from the commonly used (30 m?×??30 m; 900 m²) Landsat-based data.

Methods

We applied area-density scaling to binary (forest; non-forest) maps for both sources to derive source-specific estimates of dominant (density ≥?60%), interior (≥?90%), and intact (100%) forest.

Results

Switching from low- to high-resolution data produced statistical and geographic shifts in forest spatial patterns. Forest and non-forest features that were “invisible” at low resolution but identifiable at high resolution resulted in higher estimates of dominant and interior forest but lower estimates of intact forest from the high-resolution source. Overall, the high-resolution data detected more forest that was more contagiously distributed even at larger spatial scales.

Conclusion

We anticipate that improvements in the spatial resolution of remotely sensed land cover products will advance landscape ecology through re-interpretations of patterns and scaling, by fostering new landscape pattern measurements, and by testing new spatial pattern-ecological process hypotheses.

     

林木植原体病害传播及PCR检测研究进展

林木植原体病害危害日趋严重,对林业经济和生态造成了巨大损失,但国内林业工作者及相关研究者对其关注较少。为了对林木植原体病害致病机理的深入研究和其快速检测提供理论依据,在对相关文献研究进行总结分析的基础上,综述了主要林木植原体病害传播特性和PCR及高通量测序技术检测的研究进展,同时展望了林木植原体病害PCR检测的研究前景。     

Simulating the cumulative effects of multiple forest management strategies on landscape measures of forest sustainability

While the cumulative effects of the actions of multiple owners have long been recognized as critically relevant to efforts to maintain sustainable forests at the landscape scale, few studies have addressed these effects. We used the HARVEST timber harvest simulator to predict the cumulative effects of four owner groups (two paper companies, a state forest and non-industrial private owners) with different management objectives on landscape pattern in an upper Michigan landscape managed primarily for timber production. We quantified trends in landscape pattern metrics that were linked to Montreal Process indicators of forest sustainability, and used a simple wildlife habitat model to project habitat trends. Our results showed that most trends were considered favorable for forest sustainability, but that some were not. The proportion of all age classes and some forest types moved closer to presettlement conditions. The trend for the size of uneven-aged patches was essentially flat while the average size of patches of the oldest and youngest age classes increased and the size of patches of the remaining age classes decreased. Forest fragmentation generally declined, but edge density of age classes increased. Late seral forest habitat increased while early successional habitat declined. The owners use different management systems that cumulatively produce a diversity of habitats. Our approach provides a tool to evaluate such cumulative effects on other landscapes owned by multiple owners. The approach holds promise for helping landowner groups develop and evaluate cooperative strategies to improve landscape patterns for forest sustainability.