Municipal Forest Research Articles

Land ownership affects diversity and abundance of tree microhabitats in deciduous temperate forests

Tree microhabitats – e.g. cavities, bark pockets or crown dead wood – have been described as key habitat elements, which are particularly important for birds, bats and xylobiont insects. They are therefore vital for promoting biodiversity in forest ecosystems. The occurrence of such tree microhabitats in forest stands is closely related to forest management. In Central European cultural landscapes, forest areas are subdivided into a mosaic of stands under different ownership types and owners vary in their forest management strategies and practices. However, little is known about the influence of forest ownership on the density and diversity of tree microhabitats in forest stands. In this study, we investigate tree microhabitats – categorised into 31 different tree microhabitat types – within forest stands in clusters of different ownership types. We compare small-scale private forests, municipal forests and state-owned forests in deciduous temperate forest ecosystems in south-western Germany. Our results reveal that the density of tree microhabitats per hectare is more than twice as high in small-scale private forests than in municipal or state-owned forests. Similarly, the diversity of tree microhabitats related to area is highest in small-scale private forests. Moreover, we found differences in tree microhabitat occurrences under the three ownership types at the single tree level. Besides ownership type, relevant indicators for tree microhabitats are basal area of forest stands as well as tree vitality and diameter. Within the study region, the share of tree microhabitats provided by small-scale private forests plays a substantive role for overall forest biodiversity. Management of publicly owned forests should promote a higher density and diversity of tree microhabitats to comply with goals of close-to-nature forest management approaches. In conclusion, we regard the type of forest ownership as a relevant driver of tree microhabitat occurrence. Ownership should therefore be considered in the design of policy frameworks and instruments which address the promotion of forest biodiversity.

The influence of attitudes and perception of tree benefits on park management priorities

Urban parks are important public resources for outdoor recreation in cities. While the previous studies have concluded that people in general value parks and trees, it is still unclear how public attitudes towards trees and tree-centered management of parks relate to their support for park management priorities, and whether such attitude vary among parks within a city. This study surveyed visitors’ opinion in three parks within the City of Oak Ridge, Tennessee and focused primarily on aspects of park trees to determine what visitors believed should be a future priority for park management. Exploratory factor analysis and multiple regression analysis were employed to data collected from 263 visitors intercepted on site (response rate of 78.5%). Results showed that visitors placed relatively higher preference on planting more trees, increasing species richness and density of trees, than on planting trees in straight rows or pruning or caring. Similarly, visitors placed comparatively higher preference on trees that are native, less hazardous, resistant to pests and diseases, have longer life span, provide shade, wildlife habitat, than those having ability to block out the view of city’s developed landscape. Results also showed that visitors’ personal preference of tree aspects and attitude towards trees significantly affected their support for future tree planting and tree care efforts in city parks. Findings will be useful to city planners, municipal foresters, and landscape designers in understanding public preference for trees and tree-oriented management, and incorporating such information in designing new parks, and enhancing amenity value of existing parks.

The role of native species in urban forest planning and practice: A case study of Carolinian Canada

In recent years, many North American municipalities have adopted urban forest management plans. These plans typically include ambitious tree planting goals, with a focus on increasing native species’ presence. Having a high percentage of native species can increase ecological integrity, but there are also benefits associated with planting non-native trees in urban forests. The possibility of using assisted migration as a way for cities to respond to climate change raises additional questions about the importance of managing for native species. This study explores the ways native tree species are treated in urban forestry planning and practice in light of on-going debates around ecological integrity, non-native benefits, and assisted migration through a case study of municipalities in Carolinian Canada (Ontario, Canada). In particular, we (1) examine the role of native species in urban forest management plans, (2) explore municipal foresters’ attitudes and actions related to native tree species, and (3) determine if municipalities with and without formal management plans are making different decisions regarding native tree species planting. The objectives are addressed by examining management plans and interviewing urban foresters from municipalities with and without formal plans. We found all of the municipalities with management plans emphasize native species, and many justify their planting as a way to increase ecological integrity. These municipalities are also considering more of the managerial aspects associated with native species than municipalities without a plan. However, only a fraction of species native to the region are available through nursery stock, meaning many native species are not planted by municipalities. Most municipalities are also passively practicing assisted migration without considering the ways it can be used as a climate change adaptation tool. The gaps between municipal plans and practice are discussed, as well as future research needed to help guide treatment of native species in urban forests.

Resources of dead wood in the municipal forests in Warsaw

Abstract Dead wood plays an important role for the biodiversity of forest ecosystems and influences their proper development. This study assessed the amount of coarse woody debris in municipal forests in Warsaw (central Poland). Based on the forest site type, dominant tree species and age class, we stratified all complexes of the Warsaw urban forests in order to allocate 55 sample plots. For these plots, we determined the volume of dead wood including standing dead trees, coarse woody debris and broken branches as well as uprooted trees. We calculated the amount of dead wood in the distinguished site-species-age layers and for individual complexes. The volume of dead matter in municipal forests in Warsaw amounted to 38,761 m3, i.e. 13.7 m3/ha. The obtained results correspond to the current regulations concerning the amount of dead organic matter to be left in forests. Only in the Las Bielański complex (northern Warsaw) volume of dead wood is comparable to the level observed in Polish national parks or nature reserves, which is still far lower than the values found for natural forests. In general, municipal forests in Warsaw stand out positively in terms of dead wood quantity and a high degree of variation in the forms and dimensions of dead wood.

Challenges of municipal greening and multifunctional forest management: The case of Finland

The structure of the Finnish forest sector is in transition due to institutional, social and market-driven factors. While non-industrial private forest owners have been researched extensively, the pressures faced by public forest owners have been left relatively unexplored. Our study is a part of a broader research programme attempting to form new understanding concerning the municipal forest owners in Finland. Our research questions were: (1) how are municipal forests divided into different usage categories, (2) how is their current usage expected to change in the future, (3) what various preferences exist among municipal decision-makers concerning the use of municipal forests, (4) what various aims might the different decision-making preferences represent (both conflicting and complementing), (5) do municipal decision-makers representing different types of municipal backgrounds elicit differences in the way they orientate themselves towards forest usage? Survey data were collected during 2011–2012 using a web-based questionnaire sent to all continental municipalities in Finland. Responses were received from 139 municipalities (a response rate of 43%). Based on the survey, there is need for multifunctional municipal forest management. However, service markets seem to mostly support commercial forest usage. Besides timber production, a four-dimensional structure describing decision-making in municipal forest management was linked with (a) nonwood economic values of forests, (b) health effects of forests, (c) image of the municipality and (d) carbon neutrality goals.

Hniloba pevníku krvavějícího (Stereum sanguinolentum) a její šíření kmenem smrku na LHC Obrova noha

In the LHC Obrova noha management-plan area (Municipal Forests Prostějov), peeling and browsing damage to spruce (Picea abies) caused by red deer was monitored. In total, 20 plots of an area of 25 × 25 m were monitored in stands aged 26–65 years. On the whole, 56% of 1561 trees were damaged by peeling and browsing, 82% of the damaged trees were attacked by Stereum sanguinolentum (Alb. et Schw.: Fr.) Fr. Trees in the 3rd age class affected by rot show the highest proportion, viz 92% trees damaged by peeling. In the plots, in total 90 sample trees with the presence of rot were cut down. Peeling damage happened 6 to 41 years ago. The rot affected 10 to 94% of the sample tree stem volume (on average 39%). The volume of devalued wood is in positive correlation with a time elapsed after peeling damage (r = 0.683). The rot spread vertically through the tree stem by an average speed of 10.5 cm.year– 1 (from 1.3 to 28.1 cm.year–1). The progress rate negatively correlated with a period elapsed after the stem damage (r = –0.723).

The implications of stand composition, age and spatial patterns of forest regions with different ownership type for management optimisation in northern Latvia

Forests with different ownership type often form complex mosaics of stands, thus adding new challenges to the spatial planning of sustainable management in forested landscapes. This study attempted to analyse the spatial patterns and age structures of forest regions with different ownership type and to formulate suggestions for the optimisation of tactical planning of forest management planning by addressing ecological functionality at the landscape level. We hypothesised that structure of forests of various ownership groups differs significantly. National forest inventory data from 2011 was used in this study to compare spatial patterns of forest stands and clearcuts, as well as forest age structures. In total three areas with forest matrix in northern Latvia were selected for this study – owned by state, municipality and multiple private owners. Stand structure and current management regimen were characterised through the analysis of thematic landscape pattern maps and age structures of the canopy layer. Results showed significant differences between state and private patch configuration metrics. State forest stands were dominated by three tree species and a stable harvesting level. Municipal forest had largest stand patch size and the most even size of age classes in age structures. Lower road density, more complex canopy vertical structure and higher tree species richness characterised the private forest tract. We see landscape ecological planning of functionality as a way to optimise existing forest patterns. The incorporation of the modelling of future patterns under different management regimen in state, municipal and private forests could give valuable insights for more sustainable forest management.

Problems of Forest Management in Municipal Forests of the City of Poznań

The article presents some selected management problems in municipal forests occurring as a result of the increasing pressure on recreation and urbanization. The object of investigation was municipal forests of the city of Poznań. A thesis was formed that the consequences of the recreational pressure can be reduced through reasonable equipment of forest areas in appropriate recreational infrastructure. The second thesis put forward an assumption that an uncontrolled urban pressure posed a threat to the stability of ecosystems of municipal forests.

Impact of the invasive plant Syzigium jambos (Myrtaceae) on patterns of understory seedling abundance in a Tropical Premontane Forest, Costa Rica

Habitat fragmentation, along with other human-induced disturbances, increase the vulnerability of native habitats to be invaded by aggressive, ecologically released, exotic species. Syzigium jambos (L.) Alston (Myrtaceae, Rose Apple) is an important invader still spreading throughout Hawaii, the Antilles, Central and South America. This study examines the effects of S. jambos on plant understory diversity in a 25 ha Tropical Premontane Moist Forest in Atenas, Alajuela, Costa Rica, a protected watershed that supplies drinking water for several human communities. Our final objective is to develop a management strategy combining water protection with the preservation of a representative sample of the original plant diversity in the area. Thirty 2 x 2 m plots were distributed throughout the Municipal Forest maintaining a minimum of 10 m between plots, and 2 m from trails, to sample all understory seedlings and saplings of S. jambos, Coffea arabica (coffee) and tree seedlings. We found a clear dominance of S. jambos over all other understory plants. Of the total 1,285 sampled plants, S. jambos comprised 51%, coffee seedlings represented 14.78%, being the rest tree seedlings. Syzigium jambos had the highest density (5.46 plants/m2, S.D. = 6.44) compared to tree (3.67 plants/m2, S.D. = 3.44) and coffee seedlings (1.58 plants/m2, S.D. = 2.13). There was a highly significant negative relationship between the relative abundance of S. jambos and tree (r2 = 0.52, p < 0.00001) and coffee seedlings (r2 = 0.28, p < 0.002). The abundance of coffee seedlings did not affect the abundance of tree seedlings (r2 = 0.01, p < 0.58). Since the canopy of the Municipal Forest is relatively closed and composed of a monolayer of trees with almost no overlapping crowns, we found no relationship between canopy cover and the abundance of S. jambos. The height distribution indicated that the majority of S. jambos individuals were seedlings and saplings (height < or = 1.5 m), with only 4.6% classified as adults, (height > or = 2 m). The results show a clear role of S. jambos as an aggressive, invasive species within the Municipal Forest. This invasion is enhanced by both the ecological characteristics of the species and the fragmentation of the forest by coffee farming around the site. Among a variety of management possibilities, an ecosystem-level approach of manually removing S. jambos over time while replanting native species appears to be the preferred strategy, given the intended continued use of the Municipal Forest as a source of drinking water and as a representative sample of the original vegetation of the area.

Financially optimized management planning under risk aversion results in even-flow sustained timber yield

The effect of explicit integration of uncertainty – determined through financial, non-linear optimization – on the distribution of timber harvests and net revenues over time was examined. A management plan for a 30year period was developed for (1) a Bavarian municipal forest rich in standing timber, and (2) a hypothetical forest enterprise with even-aged stands which were based on actual growth data from the municipal forest. Maximization of net present value (NPV) – which implicitly accounts for uncertainty by discounting future returns – was contrasted with two alternative objective functions which explicitly account for uncertainty: maximization of the certainty equivalent (CE) and of the value-at-risk (VAR). The sources of risk considered were hazard probabilities of trees, and price volatility. Periodic harvest volumes and resulting net revenues were smoothest and increasingly more consistent when VAR was maximized, while NPV maximization encouraged sudden, unbalanced outputs. The enterprise value – measured by NPV – was reduced by 16%. The impact of risk aversion was slightly less pronounced when initial age-class structure more closely resembled a fully regulated forest. Yet, the coefficients of variation for harvests and net revenues were reduced to 14% and 21%. However, risk aversion offered a more effective hedge than age-class structure.

Soil Compaction and Changes in CO&lt;sub&gt;2&lt;/sub&gt; Content in Forest Stand Soil Caused by Passage of Skidding Technology

The paper was aimed on reforming on damage to soil caused by passage of universal wheeled tractors and forest wheeled tractors. We focused mainly on determining the changes in CO2 content in soil after its compaction in comparison with unimpaired soil from the stand. We carried out the measurements in municipal forests of Stará Turá, in four stands, where a regeneration felling was done. We acquired data on the depth of ruts through the method of transversal profiles took samples of soil from the ruts and unimpaired stand to determine the bulk density and moisture content. We determined the content of CO2 in stand and ruts with a Vaisala MI70 device. We selected the stands so that they would be uniform in age, terrain incline, terrain, and soil type. All of the stands had a low bearing sub – soils – flysch sandstone. This affected the rut depth after both machines passage. Rut depth indicated severe damage to the stand soil. We also observed severe differences in CO2 content of the compacted soil. Measurements in all of the stands showed a significant increase in CO2 content after its compression. Unimpaired soil reaches volume of 0.3% and rut soil reaches 1.8%. The compressed soils contained 6x the CO2 of uncompressed soils. The results of statistical analysis show, that moisture content affects the CO2 content more than bulk density. Coeficients of correlation between CO2 and moisture content were r = 0.68 and 0.52 and between CO2 and balk density were r = 0.26 and 0.36. Increase in moisture content causes CO2 accumulation. Combined effects of these two characteristics are significant and show very strong correlation. There was for example r = 0.83 and independent characteristics influenced dependent on 69%.From the outcomes the measurements we can state, that the passage of mechanisms causes significant changes in the stand soil.

Unexpected connections between residential urban forest diversity and vulnerability to two invasive beetles

Invasive pests pose a threat to the key environmental and social benefits provided by urban forests, and diverse tree planting is a primary management strategy for reducing pest vulnerability. For example, past urban forest losses to Dutch elm disease (DED) prompted municipal foresters to emphasize diversification, but it is unclear whether residential properties developed after the peak DED outbreak are actually more diverse than older properties. To address this issue, we inventoried all public and private trees on 150 residential properties in the Twin Cities Metropolitan Area, Minnesota, USA, and compared genus diversity on pre- and post-Dutch elm properties. We then quantified vulnerability to two current invasive pest threats, emerald ash borer (EAB) (Agrilus planipennis) and Asian longhorned beetle (ALB) (Anoplophora glabripennis), to evaluate whether higher diversity corresponds with lower pest vulnerability. We assessed vulnerability based on two fundamental urban forest metrics–frequency and size of vulnerable trees. Surprisingly, properties developed after the peak DED outbreak were less diverse than older properties. At the same time, less diverse post-Dutch elm properties exhibited low ALB vulnerability and modest EAB vulnerability, while more diverse older sites were highly susceptible to ALB. The importance of pest host specificity in characterizing urban forest vulnerability was underscored by low EAB vulnerability and high ALB vulnerability on our oldest study sites. This research highlights an apparent disconnect between the theoretical notion that higher diversity should reduce invasive pest vulnerability, and our empirical data indicating that genus diversity does not necessarily correspond with pest vulnerability.

Evaluation of three spatial interpolation methods to estimate forest volume in the municipal forest of the Greek island Skyros

Forest volume is of great interest to forest managers. Plot observations of forest volume are available from planning reports. For managers, however, what is relevant are forest volume surfaces. In this study, three interpolation methods were employed to construct continuous surfaces for the evaluation of forest volume at positions for which no measurements are available. For the Municipal Forest of Skyros Island, we compared spatial predictions derived from Inverse Distance Weighting (IDW), Block Kriging (BK), and Block Co-Kriging (BCK) interpolation methods, as applied to data from 120 sample plots. The existence of spatial autocorrelation in the data was identified using correlograms of Moran’s I index. Spatial outliers were identified and excluded from the analysis using the local Moran’s I index. Only slope, of the examined environmental factors, showed an acceptable correlation with forest volume and was used as an auxiliary variable for BCK. The performance of the three methods was evaluated, using an independent validation set and comparing these indices: mean error (ME) and root mean square error. Additionally, for BK and BCK, the indices, standardized ME, average standard error, and the standardized root-mean-square error were used. For the three interpolation methods, the BK method gave the more accurate results; BCK is the next more accurate method and IDW the third.

Comparison of stem volume of Eastern white pine (Pinus strobus L.) and Scotch pine (Pinus sylvestris L.)

This study deals with mensurational and volumetric characteristics of introduced Eastern white pine (Pinus strobus) in comparison with native Scotch pine (Pinus sylvestris) of the similar age and habitat. Municipal forests of Hradec Králové city (an area with the natural occurrence of Scotch pine and introduced Eastern white pine; east part of Bohemia, altitude from 250 to 280 m a.s.l.) belong to typological unit – nutrient-very poor, and acidic sites. There comparative analysis of basic stem variables (stem diameter at the breast-height – DBH, total tree height – H and stem volume – V) of dominant trees (10 individuals with the highest DBH of both species) in four suitable forest stands of age from 42 to 102 years was done. Statistical analysis showed similar trends in all forests stands. Eastern white pine compared to Scotch pine reached larger mean DBH (up to 16%). H – values do not have a clear trend across the forest stands and did not show large differences in all cases. Eastern white pine compared to Scotch pine showed also larger mean stem volume (up to 47%). Therefore, introduced Eastern white pine reached higher stem size parameters and wood production compared to native Scotch pine in studied forest district.

A municipal forest report card: Results for California, USA

This study integrates two existing computer programs, the Pest Vulnerability Matrix and i-Tree Streets, into a decision-support tool for assessing municipal forest stability and recommending strategies to mitigate risk of loss. A report card concept was developed to communicate levels of performance in terms that managers and the public easily understand. Grades were assigned to four aspects of a stable and resilient municipal forest: Species Dominance, Age Structure, Pest Threat and Potential Asset Loss. The data pool of 29 California municipal forest inventories contained information on 836,943 trees. Letter grades (A–F) were assigned to the four criteria and each city received customized recommendations for improving its grades. Three inventories received final grades of As, 18 received Bs, 6 Cs and 2 Ds. Twelve inventories received their highest grade for Species Dominance. Thirteen inventories received their lowest grade for Age Structure, largely because juvenile trees were underrepresented. Pest Threat received the lowest grade in 11 inventories and reduce Pest Threat was the top priority recommendation in 18 inventories. Four multi-host pests posed the greatest risk: Granulate ambrosia beetle, Asian longhorned beetle, Armillaria root rot and red palm weevil. Sycamore/plane was the most vulnerable taxon, followed by oaks, ash and eucalyptus. Eliminating or limiting the use of highly vulnerable tree species was recommended in nearly every city to reduce Pest Threat and improve Species Dominance. Increased planting of vacant sites with species not vulnerable to the most abundant and severe pests was a frequent recommendation for improving Age Structure. Another common recommendation to improve Age Structure was planned removal and replacement of overabundant mature and senescent taxa such as pear, eucalyptus, jacaranda and carrotwood.

Analysis of adaptation of selected forest recreational facilities to requirements of potential users

Both linear and aerial elements of forest recreational management should be equipped with recreational facilities which are called “small architecture”. Small architecture is very diverse and serves many different functions, thus it is very important in recreation space. Recreation facilities have to be safe for potential users and offer comfort and relaxation. These conditions can be fulfilled if the construction of facilities is based on anthropometric features of the users. In this paper, there are presented the results of analyses carried out with regard to adaptating technical parameters of selected forest facilities to potential user anthropometry. The study was conducted in Warsaw municipal forests. The analyses were based on analytical formulas, which give appropriate information about the parameters of perfectly designed facilities. Examination of technical condition of the recreation facilities analyzed was also included in the study.

Assessing the Degradation Effects of Local Residents on Urban Forests in Ontario, Canada

Urban forests provide essential social, ecological, and economic functions in support of their communities; however, surveys indicate adjacent residents conduct activities within their yards and the adjacent public forest edge that degrade these systems. Local governments rely on boundary-focused passive management and/or active management to limit impacts. Encroachment results from various boundary treatments; however, it is not known whether encroachment represents a substantial source of degradation within Ontario, Canada, municipal forests. To evaluate this, percentage cover of encroachment impacts adjacent to 186 homes within 40 forests of six Southern Ontario municipalities was surveyed. The results indicated degradation resulting from encroachment was substantial. Encroachment occurred in highly valued and sensitive ecosystems, and during sensitive time periods. This was highly prevalent and covered a substantial proportion of the forest edge. Some encroachment behaviors were particularly harmful, resulting in the loss of significant forest area to residential land uses. Furthermore, encroachments remained over long periods. The small sizes and convoluted shapes of urban forests leave them vulnerable to these impacts. Prevailing municipal strategies are insufficient to protect these systems from encroachment. To ensure their long term protection, municipalities and their communities need to substantially increase their commitment and resources for addressing encroachment.

Maintaining the Diversity of California’s Municipal Forests

Policies to promote urban forest diversity were assessed in 49 California, U.S. municipalities through a short questionnaire, followed by evaluation of street tree inventories and approved planting lists. While the majority of respondents (82%) indicated maintaining species diversity was an objective in managing their municipal forest, fewer than half of those responding positively (48%) had codified the objective in an actual urban forest management plan. Protecting against invasive species was an objective for a minority of communities (24%). Street tree inventories, provided by 18 respondents, indicated a high existing diversity within the communities of the state of California (avg. 185 species per community; range 95–408). In communities where both inventories and approved planting lists could be compared directly, the number of approved species for future planting was 29% of the number of species in the existing inventory. This suggests that the future diversity of California’s urban forests may be at risk. In order to improve diversity of their municipal forests, it is suggested communities retain an experimental approach to evaluating new species, build productive collaborations with all stakeholders as well as other communities, and develop outreach opportunities to enhance public awareness of the multiple values of a diverse urban forest.

Managing municipal green space for ecosystem services

Cities are the dominant form of human settlement. As centers of economic growth and population they are focal points of both ecological disturbance (through resource consumption and land conversion) and the provision of public goods. Ecosystem services provided by municipal forests and green space are positioned to address both these arenas. While technical means to mainstreaming this approach have grown, the importance municipal foresters’ departments place on pursuing this objective and their department's engagement in actions necessary for its realization is under-researched. I surveyed the membership of the Society for Municipal Arborists to address this gap. I found that municipal foresters perceived the management of municipal green space to enhance ecosystem services to be increasingly significant to the goals and actions of their departments. Survey respondents expected this role to grow in importance, matching or exceeding some traditional objectives of their profession. While most perceived traditional services such as tree planting and maintenance, and social outputs like beautification and enhancing public health to remain high departmental priorities; respondents rated managing municipal green space to produce ecosystem services such as enhanced energy and climate management, water quality and habitat and biodiversity as more important to their department than traditional objectives such as maintenance of property values and protection of power lines. As responsibility for the management of urban green space resides predominantly at the municipal level, the importance municipal foresters’ departments place on managing for ecosystem services is fundamental to advancing this strategy for the delivery of public goods in urban centers.

Spatial prediction of forest stand variables

This study aims at the development of a model to predict forest stand variables in management units (stands) from sample plot inventory data. For this purpose we apply a non-parametric most similar neighbour (MSN) approach. The study area is the municipal forest of Waldkirch, 13 km north-east of Freiburg, Germany, which comprises 328 forest stands and 834 sample plots. Low-resolution laser scanning data, classification variables as well rough estimations from the forest management planning serve as auxiliary variables. In order to avoid common problems of k-NN-approaches caused by asymmetry at the boundaries of the regression spaces and distorted distributions, forest stands are tessellated into subunits with an area approximately equivalent to an inventory sample plot. For each subunit only the one nearest neighbour is consulted. Predictions for target variables in stands are obtained by averaging the predictions for all subunits. After formulating a random parameter model with variance components, we calibrate the prior predictions by means of sample plot data within the forest stands via BLUPs (best linear unbiased predictors). Based on bootstrap simulations, prediction errors for most management units finally prove to be smaller than the design-based sampling error of the mean. The calibration approach shows superiority compared with pure non-parametric MSN predictions.