Challenge For Forest Managers Research Articles

Sustainable forest management for nut and fuelwood production in the Jalalabad region, Kyrgyzstan: insights from local communities

Jalalabad region in the Kyrgyz Republic is home to the world’s largest natural walnut (Juglans regia L.) forests and pistachio (Pistacia vera L.) forests. These nut-fruit forests serve as the primary source of income for local people; however, deforestation has led to a decline in the availability of these resources. Wood from the forest is also used as a crucial energy source for cooking and heating in this region, despite state protection of the walnut forest due to a lack of alternative energy sources. This study aimed to explore solutions to restore nut-fruit forests while providing a fuelwood source and improving the income of local people. Qualitative research methods were employed, including semi-structured interviews and survey questionnaires with farmers and central and local government officials. The study investigated the main environmental problem of forest degradation and the challenges of forest management, such as livestock and complicated lease arrangements, and determined possible government support and incentives for local communities to participate in forest rehabilitation, such as planting instead of paying lease fees. The findings indicated that a tree-based farming approach can be a promising alternative land-use solution. Seventy-four percent of local farmers expressed their readiness to plant fruit trees and fast-growing tree species to meet their demand for fuelwood and improve their livelihoods if the government can provide temporary fencing support. The study also highlighted the need for capacity building for farmers to learn proper planting, managing, and harvesting for more sustainable practices. Policymakers need to modify legislation through simplified and incentive-based forest lease arrangements.

Shrub interaction with oak seedlings under high herbivory pressure: The role of ontogeny, drought, and plant competition

Land use changes occurring during the last decades have caused new challenges in forest management of Mediterranean ecosystems, such as overpopulation of wild ungulates. This is causing serious impacts on forest regeneration, particularly increased seedling mortality of dominant tree species. This study aims to unravel whether oak seedlings could be facilitated by non-palatable shrubs under herbivory and drought stress to improve assisted oak regeneration. For this purpose, we planted one- and two-year-old seedlings of an evergreen oak (Quercus ilex L.) in a Mediterranean open shrubland, considering three factors: herbivore exposure (with or without herbivores), seedling age (one- vs. two-year-old seedlings), and shrub cover (seedlings planted under non-palatable shrubs Cistus ladanifer or in open microsites). We evaluated seedling survival and performance monthly along the growing season (February-September), and measured physiological traits in May, just prior to the drought season. Our results revealed that herbivores, mostly wild boar (Sus scrofa), were the main cause of mortality from February to late May, while drought was responsible of mortality from early June to September. Almost all seedlings died within the first year of plantation after a severe long summer. Leaf predawn water potential and leaf stomatal conductance of one-year-old seedlings were lower under shrubs than in open microsites, a negative effect of shrubs that was not evident in the two-year-old seedlings. Plant photosynthetic performance of two-year old seedlings was higher under shrubs than in open microsites. Interestingly, the net effect of shrubs as facilitators (measured monthly through chlorophyll content) was greater in areas with no herbivores, probably due to the strong difference in herbaceous plant cover between open areas and under shrubs. Our results suggest that facilitation of Q. ilex seedlings by C. ladanifer shrub is weak under herbivory pressure and strongly depends on seedling age as shrubs seem to mostly compete for water with one-year-old seedlings and alleviate photoinhibition in two-year-old seedlings. This study reveals the possible use of two-year-old seedlings under very specific conditions, but some important inconveniences may arise as they are more stressed in the open microsites (ungulate induced mortality was similar for one and two-year old oak seedlings) and require more resources (e.g., time, energy and water) before plantation than one-year-old seedlings. We conclude that the age of plant material must be taken into account when planning oak restoration practices that can potentially benefit from the facilitative effects of shrubs under moderate biotic and abiotic stress.

Limited influence of air temperature and precipitation on six-year survival and growth of non-native tree species in a Central European multi-site field trial

The biggest challenge for forest management in the near future will be the silvicultural adaptation of forests on sites where climate change will increase the risk for drought induced tree mortality and for a decrease of the growth performance. One management option is the diversification by promoting climate change adapted non-native tree species. Currently, we have in depth experience with only a few non-native tree species in Central Europe. Other tree species that may complement the species pool in Central Europe need to be carefully selected by a range of criteria. Before establishing larger silvicultural experiments at stand-level, the suitability of species to grow well with a low risk of failure under expected future climatic conditions as well as a good performance already today should be tested, amongst other aspects. We present results of a multi-site common garden experiment where growth and survival of five non-native tree species (Abies bornmuelleriana, Cedrus libani, Fagus orientalis, Tilia tomentosa, and Tsuga heterophylla) and one climate adapted local native species per site are tested in five field trials in Austria, Germany and Switzerland along a temperature (7.9–10.4 °C mean annual Temperature) and precipitation (490–1147 mm annual precipitation) gradient. Each species was replicated on three plots per site using a block-wise design. Lower survival and growth of the non-native species as the native reference on most sites indicate that the studied non-native species are today not as well adapted to current climatic conditions as native species. However, the performance of the non-native species was sufficiently high to justify further trials. Survival and growth rates were mostly equally high on the two sites at the opposing ends of the temperature and humidity gradient and lower on all other sites. Height growth and survival were only marginally affected by the strong summer drought in 2018 in all except one site, presumably due to the low water storage capacity of the sandy soils on this site. This indicates that the tested non-native tree species grow well in the wide range of climatically changing weather conditions from our transnational study sites across Central Europe. So far, the tested tree species did not reach their climatic growth limitation. However, edaphic site conditions may have influenced the performance of the tested non-native species as well and must be considered when discussing the suitability of these tree species.

Grouping tree species to estimate basal area increment in temperate multispecies forests in Durango, Mexico

Multispecies forests have received increased scientific attention, driven by the hypothesis that biodiversity improves ecological resilience. However, a greater species diversity presents challenges for forest management and research. Our study aims to develop basal area growth models for tree species cohorts. The analysis is based on a dataset of 423 permanent plots (2,500 ​m2) located in temperate forests in Durango, Mexico. First, we define tree species cohorts based on individual and neighborhood-based variables using a combination of principal component and cluster analyses. Then, we estimate the basal area increment of each cohort through the generalized additive model to describe the effect of tree size, competition, stand density and site quality. The principal component and cluster analyses assign a total of 37 tree species to eight cohorts that differed primarily with regard to the distribution of tree size and vertical position within the community. The generalized additive models provide satisfactory estimates of tree growth for the species cohorts, explaining between 19 and 53 percent of the total variation of basal area increment, and highlight the following results: i) most cohorts show a “rise-and-fall” effect of tree size on tree growth; ii) surprisingly, the competition index “basal area of larger trees” had showed a positive effect in four of the eight cohorts; iii) stand density had a negative effect on basal area increment, though the effect was minor in medium- and high-density stands, and iv) basal area growth was positively correlated with site quality except for an oak cohort. The developed species cohorts and growth models provide insight into their particular ecological features and growth patterns that may support the development of sustainable management strategies for temperate multispecies forests.

An efficient approach to monitoring pine wilt disease severity based on random sampling plots and UAV imagery

The mapping of forest pests and diseases using remote sensing presents a critical challenge in forest management and conservation. Forestry professionals have shown particular concern about the rapid decline of pine trees caused by pine wilt disease, conducting annual inspections to monitor its impact. However, achieving a balance between large-scale monitoring areas and the identification of individual trees poses a challenging issue. To tackle this issue, we employed a random sampling plan and utilized an unmanned aerial vehicle (UAV) to capture high-resolution images on two separate occasions. This methodology facilitated the comparison of temporal variations in tree health. We applied three object detection algorithms (YOLOv5, Faster-RCNN, CenterNet) to identify diseased trees in the images and introduced an enhanced vision of YOLOv5 for better performance. The improved YOLOv5 demonstrated higher precision of average precision (AP) (0.8806, 0.9004) compared to the other algorithms across two datasets. The improved YOLOv5 generated predictions that identified the topographic regions most severely affected by pine wilt nematode infestation. Geographically, the highest disease incidence was observed at altitudes between 200 and 299 m, slopes ranging from 10 to 15 degrees, and locations facing a sunny slope direction. The primary source of infection is pre-existing diseased trees that are not properly controlled. Additionally, the density of infected trees contributes to the spread, with the most severe outbreaks occurring in densely clustered over large areas. By aggregating the cumulative sampling data, we derived an estimation of the total tree mortality in the two towns. This study introduces an effective monitoring approach for pine wilt disease at the district level by integrating a random sampling protocol, unmanned aerial vehicle (UAV) strategies, and a deep learning algorithm. Our approach can assist forest managers in timely and cost-effective detection and control of pine wilt disease.

Systematic review: Climate and non-climate factors influencing wood density in the boreal zone

Wood density is a crucial factor in determining the quality of wood in boreal ecosystems within the Northern Hemisphere. Climate variables play a significant role in shaping wood density, posing challenges for forest managers and stakeholders in the wood industry to adapt amidst climate change. However, our current understanding of these effects remains incomplete. This systematic literature review explores the multifaceted influences on wood density in the boreal zone, encompassing both climate-related and non-climatic factors. The findings demonstrate that warmer temperatures can cause both increases and decreases in wood density, primarily due to their impact on tracheid lignification and cell wall thickening. Nonetheless, the outcome depends on various factors, including species type, age, soil conditions, presence of pests and diseases, fire, windstorms, and silviculture practices. The quantification of complex relationships between these factors and wood density has been insufficient in existing literature. Understanding the impacts of both climate and non-climate factors on wood density is essential for fostering a sustainable wood industry, while effectively mitigating adverse effects and maximizing benefits. Forest managers can leverage this knowledge to optimize wood production strategies, ensuring long-term ecological resilience amidst the increasingly variable climate challenges.

Effects of drought hardening on the carbohydrate dynamics of Quercus acutissima seedlings under successional drought.

As precipitation patterns are predicted to become increasingly erratic, the functional maintenance of warm-temperate forests constitutes a key challenge for forest managers. In this study, 2-year-old Quercus acutissima seedlings were selected to elucidate the mechanisms whereby they respond to soil water fluctuations and the drought hardening effects on plant carbohydrate dynamics. Seedlings were trained under different soil water conditions for 2 months: drought (D), well-watered (W), 1-month drought and then 1-month well-watered (D-W), and 1-month well-watered and then 1-month drought (W-D). The functional traits involved in water- and carbon-use strategies were explored at the end of the hardening period. Compared with seedlings in group W, seedlings in groups D, D-W, and W-D had increased potential for carbon uptake (i.e., light saturated point, maximum ribulose-1,5-bisphosphate (RuBP) saturated rate, and electron transport rate) and water uptake (i.e., fine root-to-coarse root ratio) and downregulated growth and mitochondrial respiration to decrease carbon consumption. After water fluctuation hardening, we performed a successional dry-down experiment for 1 month to detect carbohydrate dynamics and explore the acclimation caused by prior hardening. Our results revealed that there were more soluble sugars allocated in the leaves and more starch allocated in the stems and roots of seedlings hardened in the D, W-D, and D-W treatments than that of seedlings hardened in the W treatment. No significant changes in total non-structural carbohydrates were found. In addition, we found near-zero (seedlings trained by D and D-W treatments) or negative (seedlings trained by W-D treatment) growth of structural biomass at the end of the dry-down experiment, which was significantly lower than that of W-hardened seedlings. This suggests that there was a shift in allocation patterns between carbon storage and growth under recurrent soil drought, which can be strengthened by drought memory. We conclude that Q. acutissima seedlings adjusted water- and carbon-use strategies in response to water fluctuations, whereas stress memory can enhance their overall performance in reoccurring drought. Therefore, taking advantage of stress memory is a promising management strategy in forest nurseries, and drought-trained seedlings might be more suitable for afforestation practices in sites characterized by fluctuating soil water content, considering the ongoing global climatic changes.

Close-to-nature forestry and intensive forestry – Two response patterns of forestry professionals towards climate change adaptation

Climate change poses a major challenge for forest management in Europe. Understanding how forestry professionals perceive climate change is critical to inform decision-making on climate change adaptation. The aim of this study was to explore the perceptions of forestry professionals regarding climate change and its effects on forests, as well as the importance of different forest management strategies for climate change adaptation. Using a survey, to which we received 565 [retained] responses, we determined regional differences in climate change perceptions across nine European countries and six professional groups. We found a North-South gradient in the perceptions of climate change effects for early 2019 – at the time of the survey – and when looking ahead to 2050. Perceptions of climate change effects and views on the possibility to adapt to climate change were particularly negative in Germany. According to respondents, the most important forest management strategies to adapt to climate change are diversification of tree species, artificial regeneration with improved forest reproductive material, and enrichment of natural regeneration with forest reproductive material better adapted to future climate changes. Two distinct clusters emerged from our analysis on how to adapt forests to climate change: a close-to-nature forestry cluster and an intensive forestry cluster. It appeared that the perception of public forestry regarding climate change effects and the possibility to adapt to climate change was significantly more pessimistic than those of private forestry and the forest industry. Recent extreme summer droughts and exceedances of ecological thresholds have manifested itself in profound changes in the perceptions of climate change by forestry professionals compared to findings of previous surveys in European regions.

Forest stressors and roadside vegetation management in an exurban landscape

As part of the forest landscape, roadside trees are susceptible to multiple stressors that increase potential for tree damage during storm events and contribute to power outages. In exurban areas, decision-making related to the roadside forest is divided among many land ownerships and management entities with diverse objectives. Our objectives were to (1) identify general forest and roadside vegetation management objectives and challenges, (2) identify forest stressors and assess perceived severity and level of concern for forest stressor impacts to the roadside forest, and (3) evaluate manager interrelationships based on management objectives and challenges. We conducted semi-structured interviews with thirty-nine members of the forest management community who manage non-residential and non-industrial tracts of forest land in Connecticut, USA. Improving overall forest health and resilience, wildlife habitat, and forest products were the three most common general forest objectives. The two most frequently identified roadside objectives were public safety and mitigating hazardous conditions. The most common general forest management challenges included workforce limitations, financial constraints, and public perceptions. Support and satisfaction among the public and other stakeholders was the most frequently mentioned roadside forest management challenge. Although participants recognized the importance of roadside vegetation management, many avoided active management along roadsides. Immediate roadside vegetation issues such as public safety were prioritized rather than long-term planning. Stakeholders are constantly orchestrating a balance of numerous objectives as they integrate roadside vegetation considerations into broader forest management.

Forest management system based on carbon sequestration

It is a new challenge for forest managers to balance the relationship between the forest and its derivatives to maximize the overall benefits of the forest. Based on the growth pattern of trees and statistical theory, we developed a carbon sequestration model with a normal distribution at different ages of the forest and derived the amount of carbon sequestered by the forest and its products in a certain period of time. In order to balance the ecological and social values of the forest, we firstly selected 12 indicators from three aspects: climate benefit, ecological benefit and social benefit to build a forest decision model. Secondly, the original indicators were downscaled to three principal components by cluster analysis and principal component analysis and the benefit scores were obtained for each year. Finally, a linear fitting method was used to derive the relationship between the forest area and the composite score.

An economic assessment of options for operating within plantation forestry water entitlements and tightening cap and trade policy

AbstractThe Green Triangle (GT) region of southern Australia is one of only two jurisdictions globally to licence plantation forestry's groundwater use. In response to declines in groundwater resources caused by historical plantation expansion, reductions in forest water allocations (~50%) are likely for some parts of the region, presenting novel challenges for forest managers in maintaining revenues and timber flows. This article presents a mathematical programming model evaluation of water trade opportunities for plantation forest owners to adapt to reduced water entitlements and explores how tightening groundwater policy could affect forestry returns and land use mix for the region. Results suggest that even absent opportunity to sell water, relatively limited 11% reduction in return could be expected for a large (−50%) water entitlement and (−48%) land‐use change out of forestry. Results suggest that opportunities for forestry companies to sell water entitlements may allow them to maintain or even increase combined returns from forestry and water sales. Whilst the results highlight the adaptive capacity of the plantation forestry sector to operate within reduced water entitlement, a significant sectoral and regional economy adjustment would be likely. The discussion focusses on the potential to realise optimisation model‐identified adaptation opportunities accounting for real‐world thin markets, transaction costs and market friction.

Alternative states in the structure of mountain forests across the Alps and the role of disturbance and recovery

ContextStructure is a central dimension of forest ecosystems that is closely linked to their capacity to provide ecosystem services. Drivers such as changing disturbance regimes are increasingly altering forest structure, but large-scale characterizations of forest structure and disturbance-mediated structural dynamics remain rare.ObjectivesHere, we characterize large-scale patterns in the horizontal and vertical structure of mountain forests and test for the presence of alternative structural states. We investigate factors determining the occurrence of structural states and the role of disturbance and recovery in transitions between states.MethodsWe used spaceborne lidar (GEDI) to characterize forest structure across the European Alps. We combined GEDI-derived structural metrics with Landsat-based disturbance maps and related structure to topography, climate, landscape configuration, and past disturbances.ResultsWe found two alternative states of forest structure that emerged consistently across all forest types of the Alps: short, open-canopy forests (24%) and tall, closed-canopy forests (76%). In the absence of disturbance, open-canopy forests occurred at high elevations, forest edges, and warm, dry sites. Disturbances caused a transition to open-canopy conditions in approximately 50% of cases. Within 35 years after disturbance, 72% of forests recovered to a closed-canopy state, except in submediterranean forests, where recovery is slow and long-lasting transitions to open-canopy conditions are more likely.ConclusionsAs climate warming increases disturbances and causes thermophilization of vegetation, transitions to open-canopy conditions could become more likely in the future. Such restructuring could pose a challenge for forest management, as open-canopy forests have lower capacities for providing important ecosystem services.

One park, two owners—Inconsistencies in forest stewardship

AbstractAppropriate management of European spruce forests in this time of climate change is a significant challenge. Uniform principles of quality forest practice must be applied, essentially in forests that are valuable from a conservation point of view. However, this may be problematic in protected areas with mixed ownership and disparate priorities. Managerial decision‐making is often based on personal knowledge, previous experience, priorities other than conservation, or political influence. Clear management guidelines at the European and national levels are lacking in many protected areas. In this article, we use data from the Šumava NP to elucidate varied management approaches applied by state and private municipal owners in forests of high conservation value. We used high‐resolution aerial photographs to evaluate the effects of forest management practices applied, and compared the status of spruce habitats before and after a major windstorm and large‐scale bark beetle outbreak. We found that follow‐up forest management measures have significantly affected forests in the Šumava NP negatively. However, changes are not equally spread across the area of study, with forest ownership important for the type and intensity of changes. Kašperské Hory Municipality, managed their forests more as a productive commercial forest as contrasted to the state owned forest. We compare our findings with experiences from other Central European national parks with similar forest management challenges. Options for improving and unifying the management of conservation‐valuable forests held in state and private ownership are discussed in the conclusion. Wide political consensus and stability together with long‐term mutual trust and a willingness to collaborate among conservationists, forest managers and forest owners were recognized to be essential for the successful achievement of conservation goals.

Comparison of the approach to determination of the rotation period of forest stands in the Czech Republic and in the Slovak Republic

The exact determination of the rotation period is still a current and important essential issue of forestry. It attracts the attention of forest economists, managers and owners worldwide, not only of forest economists but also of forest managers. The rotation period is defined by physical, technical or financial parameters of forest management. Therefore, it is necessary to distinguish between the biological and the economic optimal rotation period. A fundamental challenge in forest management is the need for appropriate determination of the rotation period. The primary interest of our research was to compare the effective legislation for the determination of the rotation period in the Czech Republic and in the Slovak Republic. Scientific methods such as document analysis and questionnaire survey were applied. The results of the legislation analysis and other related documents were compared with the expert opinions of the relevant stakeholders. Those who affect the decision process related to the problem and those where are “affected” by the problem were involved in the study. Results show that respondents do not agree with the regulation of rotation period according to effective law. Moreover, they consider it as not usable as the conditions in forest ecosystems have changed recently, which is not considered in the legislation.

Soil Environment and Fauna Communities in Europe after Afforestation of Post-Agricultural Lands—A Review

Afforestation can make an important contribution mitigating the effects of changing climate and provide structural and functional benefits. Afforestation also provides challenges for forest managers connected with past land-use history; therefore, there is an urgent need to summarize knowledge about such habitats and point out the gaps in knowledge for planning future studies. Although post-agricultural forests cover a large forest area in Europe, our understanding of the mechanisms governing the below-ground environment is still poor, especially when soil fauna is considered. In this study, we revised knowledge about the soil environment and the response of soil fauna to afforestation on former agricultural lands located in Europe based on research articles from the ISI Web of Science database. Data came from various but distinct locations, compared forests with different types of agricultural lands, and presented previous knowledge about soil chemistry and accompanying soil fauna communities. Finally, we selected 15 studies, investigating soil fauna communities on post-agricultural lands. The meta-analysis was based on response ratio (R) for available data, although in many cases the data were incomplete. Results indicated that post-agricultural forests differ from arable lands in reference to soil pH, but not for soil organic matter and carbon content. Different soil animal groups were represented by a similar number of studies: microfauna (seven studies) and mesofauna (nine), whereas macrofauna were represented by five studies. Meta-analysis revealed that the response of soil fauna to afforestation differed between soil fauna size classes. Additionally, in total, 18 tree species, 12 soil types, and 20 soil parameters were provided in the literature but only a few of them were presented in a single study. Future studies should include the impact of microclimate, detailed stand characteristics and soil conditions, which could help to clearly describe the impact of certain tree species growing on certain soil types. In future soil fauna ecological studies, the data should include mean values, standard deviation (SD) and/or standard effort of means (SE) for abundance, species richness, diversity indices and number of collected samples. Providing the above mentioned information will give the broad audience the opportunity to include data in future comparative analyses.

Trembling Aspen Stand Response 15 Years after Windthrow, Salvage Harvesting, and Forest Renewal

Windthrow is a common occurrence in boreal forests, affecting wood supply and presenting regeneration challenges for forest managers. Salvage harvesting is often conducted afterwards to extract valuable wood and improve access for forest renewal activities. Research efforts, however, are generally limited to the effects of windthrow and salvage harvesting in the first few years following disturbance. In 2006, a catastrophic wind event occurred in a trembling aspen (Populus tremuloides Michx.) forest in northeastern Ontario. A field study was established with a range of silvicultural treatments from leaving after windthrow (W) to forest renewal treatments including windrow site preparation, planting, and herbicide release (WSPR). While the results of first 5-year assessment have been reported, the objective of the current study was to reassess treatment effects at 15 years post-disturbance, a stage of stand development that is more indicative of future forest conditions. Compared to the results of the earlier assessment, the 15-year assessment indicated that standing dead wood (snags) declined, whereas coarse downed wood did not change substantially over time. Post-disturbance salvage harvesting improved aspen regeneration in terms of density, stocking, and growth, but substantially reduced the proportion of conifers relative to windthrow only. Thus, salvage harvesting helped to sustain aspen composition, compared to other treatment options that increased proportions of pine and spruce trees from W to windthrow and salvage harvesting combined with windrow site preparation and planting (WSP), and from WSP to WSPR.

Motives for Sustainability Certification—Private Certified Forest Owners’ Perspectives

Traditional forest-management practices are currently being scrutinised. Forest certification may verify sustainable development practices in primary forest production. However, certification of privately owned forest lands cannot be taken for granted, as it is associated with the demands and challenges of forest management. Despite these challenges, some private owners of forest lands chose to certify their operations. The aim of this study is to explain these motives for certification. A qualitative approach, based on thematic interviews with selected forest owners, offers a context-bound and contemporary understanding. The implications of this research are seen in market development for certified forest resources and policy adaptations to support voluntary certification schemes.

Climate change may cause distribution area loss for tree species in southern China

Climate change will cause a range shift in tree species, which will create challenges for forest management, utilization and preservation in the future; hence, it is worthy of more attention, especially at the regional scale. Here, we selected 56 common cultured tree species in southern China and employed a comprehensive habitat suitability model to analyse the changes in the potential planting areas of these species at baseline and in different future climate change scenarios. The results indicated that climatic variable changes, especially a change in the mean diurnal temperature range greater than ±0.25 °C, will cause a decrease in the distribution area of most tree species in southern China. With the projected temperature rise, the number of species with habitat loss and the rate of distribution area loss will increase significantly. In the most intense warming scenarios, 22 tree species will lose more than 50% of their potential distribution area compared with that in the baseline condition. Additionally, increasing temperatures are expected to cause species diversity loss in the study area. This phenomenon will generate an increase in wood gaps, environmental degradation and the risk of alien species invasion. Mountainous areas in southern China may provide a refuge for tree species in the context of global warming. In future planting initiatives and forest management strategies, the range shifts and distribution area loss for tree species should be fully considered.

Spatial patterns and species composition of new forest areas present challenges for forest management in Latvia

Forest area increase has been characteristic to the Eastern Baltic region since the early twentieth century. The emergence of new forest areas in significant amounts changes the visual and ecological character of landscapes and affects forest management decisions. The aim of this study was to investigate how emerging spatial patterns and stand characteristics of new forest areas impact forests in Latvia. Four study areas were selected in Latvia – Skrunda, Bauska, Skujene and Kaunata to analyze new and stable forest areas. Inside these four areas, 27,205 forest compartments were analyzed from new forests and 93,902 compartments in stable forests for reference. New and stable forest areas were mapped for the period of 1967–2017. Latvian State Forest register database provided compartment-level characteristics for new and stable forests. Descriptive statistics was used to analyze differences in tree species composition, ownership structure and management restrictions; and GIS methods – to assess compartment accessibility by roads. Spatial pattern metrics were calculated using Morphological Spatial Pattern Analysis in Guidos Toolbox 2.6. Results show that the majority of new forest areas have emerged from spontaneous afforestation, this was especially pronounced in Kaunata area (only 5% of new forest areas were planted). Scots pine, Norway spruce and two birch species comprised the majority in stable forest areas compared to new forest areas, where the proportions of dominant tree species were more evenly distributed. Spatial pattern analysis showed that the emergence of new forest areas has contributed to the homogenization of forest pattern with increasing Core area, reducing Edge and Islet (isolated patch) proportion. 93–99% of new forest areas identified in this study were not state-owned. Compartment accessibility was very good for all four study areas in Latvia, with 60–80% of stands being located closer than 500 m from roads. This study demonstrated that management of such small, spatially scattered and young forest compartments can be problematic. Since the majority or Latvia’s private forest owners’ holdings are smaller than 50 ha, the lack of resources and education as well physical factors impede successful involvement of these numerous small owners in sustainable management efforts.

Tracking the temporal dynamics of insect defoliation by high‐resolution radar satellite data

Abstract Quantifying tree defoliation by insects over large areas is a major challenge in forest management, but it is essential in ecosystem assessments of disturbance and resistance against herbivory. However, the trajectory from leaf‐flush to insect defoliation to refoliation in broadleaf trees is highly variable. Its tracking requires high temporal‐ and spatial‐resolution data, particularly in fragmented forests. In a unique replicated field experiment manipulating gypsy moth Lymantria dispar densities in mixed‐oak forests, we examined the utility of publicly accessible satellite‐borne radar (Sentinel‐1) to track the fine‐scale temporal trajectory of defoliation. The ratio of backscatter intensity between two polarizations from radar data of the growing season constituted a canopy development index (CDI) and a normalized CDI (NCDI), which were validated by optical (Sentinel‐2) and terrestrial laser scanning (TLS) data as well by intensive caterpillar sampling from canopy fogging. The CDI and NCDI strongly correlated with optical and TLS data (Spearman's ρ = 0.79 and 0.84, respectively). The significantly explained caterpillar abundance (R2 = 0.52). The NCDI at critical timesteps and ΔNCDI related to defoliation and refoliation well discriminated between heavily and lightly defoliated forests. We demonstrate that the high spatial and temporal resolution and the cloud independence of Sentinel‐1 radar potentially enable spatially unrestricted measurements of the highly dynamic canopy herbivory. This can help monitor insect pests, improve the prediction of outbreaks and facilitate the monitoring of forest disturbance, one of the high priority Essential Biodiversity Variables, in the near future.