Forests, Volume 8, Issue 7 (July 2017) – 40 articles

Increasing forest vegetation is important for carbon dynamics and to maintain the ecological and environmental balance in China. However, there is little understanding of how socioeconomic factors affect forest biomass carbon storage (FBCS). Here, we used continuous functions for biomass expansion factors and China’s seven completed forest inventories to estimate the changes in FBCS for 31 provinces in mainland China between 1977 and 2013. We developed a model that decomposes the contribution of the different socioeconomic factors driving FBCS. We found China’s FBCS increased from 4972 TgC (1 Tg = 10¹²g) in 1977–1981 to 7435 TgC in 2009–2013, with a mean growth of 77 TgC/a, and the average forest carbon density increased from 36.0 to 38.9Mg/ha (1 Mg = 10⁶g), mainly due to the arbor forest contribution. Among the seven regions in China, the southwestern region currently accounts for the highest proportion (37.3%) of national FBCS, followed by northeastern (19.7%), northern (12.5%) and eastern region (10.8%). The main socio-economic factors affecting FBCS were forest land dependence, industrial structure and economic development level. Optimizing forest type and age structure, improving forest productivity, and strengthening forest management are feasible options to further increase China’s FBCS. Full article

Timber management directly influences the population dynamics of tree species, like Copaifera spp. (copaíba), which provide oil-resin with ecological and economic importance. The aim of this study was to evaluate the structure and population dynamics of Copaifera in unmanaged and managed stands by reduced-impact logging (RIL) in eastern Amazon in Pará state, Brazil. Based on a stem map of the study area, 40 Copaifera trees were randomly selected, where an equal number of trees were selected in managed and unmanaged stands. A transect of 10 × 100 m was centered at each tree (50 m each side) to assess Copaifera regeneration. Transects were subdivided into ten plots, of which six were systematically chosen to assess the height, diameter and number of Copaifera seedlings and saplings. The field assessment occurred in 2011 and 2013. To estimate the amount of sunlight transmitted to the forest floor, we computed canopy cover from airborne LiDAR data. According to the results, the abundance of Copaifera seedlings/saplings was higher in managed than unmanaged stands. About 5% of Copaifera regeneration was found between 45–50 m from the Copaifera tree while ~73% of regeneration was concentrated within a 10 m radius of the Copaifera tree. We verified that the diameter distribution of Copaifera regeneration was not a negative exponential distribution, as is typical of most tree species in natural forest. Rather, the Copaifera regeneration had a spatially aggregated distribution. In this short-term analysis, the impact of timber management is not negatively affecting the population structure or dynamics of Copaifera regeneration. Full article

Co-management has been introduced into Special Use Forests (SUFs) of Vietnam for more than 10 years. However, the extent to which Vietnamese laws and policies support co-management remains unclear. This paper reviews existing policies and laws from the national to commune levels and assesses their facilitation of co-management in SUFs. The review demonstrates there is support for co-management, albeit scattered and uncoordinated across a range of policies and laws. Modifications to policy on ownership and use rights would support the development of SUF co-management. Additionally, clearer legislative underpinning for benefit sharing in SUFs could better incentivize the participation of local people and private sector actors to engage in more effective co-management arrangements. Full article

Climate-smart agriculture (CSA) is proposed as a necessity, as the agricultural sector will need to adapt to resist future climatic change, to which high emissions from the sector contribute significantly. This study, which is an exploratory case study based on qualitative interviews and field observations, investigates the barriers to making a CSA-adjustment in maize production among Maya communities in southern Belize. The adjustment is alley cropping, which is a low-input adjustment that has the potential to result in both adaptation and mitigation benefits, and furthermore, to enhance food security. The findings show that a CSA-adjustment in small-scale maize production in Maya villages in southern Belize is possible in principle, though several barriers can make the overall climate-smart objective difficult to implement in practice. The barriers are of a proximate and indirect nature, exist at different spatial scales, and involve various levels of governance. The barriers are shown to be land tenure, market access, and changes in the traditional culture, however, these barriers are not homogenous across the villages in the region. To break down the barriers an overall district-level strategy is possible, but the toolbox should contain a wide variety of approaches. These could happen, for instance, through alterations to land tenure and the land taxation system nationally, enhancement of the agricultural extension system to ease access to knowledge and input at the district level, and support to a less complex governance structure at the village level. Full article

Tropical forest management increasingly is challenged by multiple, complex, intersecting, and in many cases unprecedented changes in the environment that are triggered by human activity. Many of these changes are associated with the Anthropocene—a new geologic epoch in which humans have become a dominating factor in shaping the biosphere. Ultimately, as human activity increasingly influences systems and processes at multiple scales, we are likely to see more extraordinary and surprising events, making it difficult to predict the future with the level of precision and accuracy needed for broad-scale management prescriptions. In this context of increasing surprise and uncertainty, learning, flexibility, and adaptiveness are essential to securing ecosystem resilience and sustainability, particularly in complex systems such as tropical forests. This article examines the experience to date with and potential for collaborative, adaptive land and resource management in the El Yunque National Forest (EYNF)—the only tropical forest in the U.S. National Forest System. The trajectory of EYNF policy and practice over time and its capacity for learning, flexibility, and adaptiveness to change and surprise are analyzed through an historical institutionalism approach. EYNF policies and practices have shifted from an early custodial approach that focused mostly on protection and prevention to a top-down, technical approach that eventually gave way to an ecosystem approach that has slowly incorporated more flexible, adaptive, and active learning elements. These shifts in EYNF management mostly have been reactive and incremental, with some rarer, rapid changes primarily in response to significant changes in national-level policies, but also to local level conditions and changes in them. Looking to the future, it seems the EYNF may be better positioned than ever before to address increasing uncertainty and surprise at multiple scales. However, it must be able to count on the resources necessary for implementing adaptive, collaborative forest management in a tropical setting and on the institutional and organizational space and flexibility to make swift adjustments or course corrections in response to system changes and surprises. Full article

The aim of this work has been the development of a methodology for the evaluation of residual forest biomass in Biscay, a province in northern Spain. The study area is located in the Oka river basin, an area of great ecological value qualified by UNESCO (United Nations Educational Scientific and Cultural Organization) in 1984 as a Biosphere Reserve. The project tries to determine the potential, available and usable as energy resource, residual forests biomass, after the treatments of forest species in the area. Soil erosion was modeled using the USLE (Universal Soil Loss Equation) and MUSLE (Modified USLE) methods by estimating rainfall erosivity factor (R), the soil erodibility factor (K), the topographic factors (L and S), cropping factor (C), and the conservation practice factor (P). By means of these models, it will be possible to determine the current soil erosion rate and its potential evolution due to different forest treatments. Soil erodibility, slope of the terrain and the loss of SOC (Soil Organic Carbon) were the restrictive indicators for the bioenergy use of forest biomass, taking into account principles of sustainability. The amount of residual forestry biomass useable for energy purposes has been estimated at 4858.23 Mg year⁻¹. Full article

Improvements in the management of pine plantations result in multiple industrial and environmental benefits. Remote sensing techniques can dramatically increase the efficiency of plantation management by reducing or replacing time-consuming field sampling. We tested the utility and accuracy of combining field and airborne lidar data with Random Forest, a supervised machine learning algorithm, to estimate stem total and assortment (commercial and pulpwood) volumes in an industrial Pinus taeda L. forest plantation in southern Brazil. Random Forest was populated using field and lidar-derived forest metrics from 50 sample plots with trees ranging from three to nine years old. We found that a model defined as a function of only two metrics (height of the top of the canopy and the skewness of the vertical distribution of lidar points) has a very strong and unbiased predictive power. We found that predictions of total, commercial, and pulp volume, respectively, showed an adjusted R² equal to 0.98, 0.98 and 0.96, with unbiased predictions of −0.17%, −0.12% and −0.23%, and Root Mean Square Error (RMSE) values of 7.83%, 7.71% and 8.63%. Our methodology makes use of commercially available airborne lidar and widely used mathematical tools to provide solutions for increasing the industry efficiency in monitoring and managing wood volume. Full article

Recent increases in forest diseases have produced significant mortality in boreal forests. These disturbances influence merchantable volume predictions as they affect the distribution of live and dead trees. In this study, we assessed the use of lidar, alone or combined with multispectral imagery, to classify trees and predict the merchantable volumes of 61 balsam fir plots in a boreal forest in eastern Canada. We delineated single trees on a canopy height model. The number of detected trees represented 92% of field trees. Using lidar intensity and image pixel metrics, trees were classified as live or dead with an overall accuracy of 89% and a kappa coefficient of 0.78. Plots were classified according to their class of mortality (low/high) using a 10.5% threshold. Lidar returns associated with dead trees were clipped. Before clipping, the root mean square errors were of 22.7 m³ ha⁻¹ in the low mortality plots and of 39 m³ ha⁻¹ in the high mortality plots. After clipping, they decreased to 20.9 m³ ha⁻¹ and 32.3 m³ ha⁻¹ respectively. Our study suggests that lidar and multispectral imagery can be used to accurately filter dead balsam fir trees and decrease the merchantable volume prediction error by 17.2% in high mortality plots and by 7.9% in low mortality plots. Full article

Post-fire salvage logging (SL) is a common management action that involves the harvesting of burnt trees. As a consequence, a large amount of biological legacies in the form of logs and other coarse woody debris are removed from the post-fire habitat, creating a more simplified landscape. Therefore, SL could act as an additional disturbance over that produced by fire. In this study, we seek to determine the effect of SL on the regeneration of the bryophyte community of a laurel forest from the Canary Islands (Spain). We hypothesized that SL will act as an additional disturbance and, consequently, salvaged areas will have a higher difference in community composition with respect to a reference ecosystem (RE). Mosses and liverworts were sampled 22 months after the salvage operations in salvaged plots, non-salvaged, and in an RE represented by areas of the original forest. Species richness did not differ between salvage and non-salvaged treatments. However, multivariate analysis and species-indicator analysis showed that non-salvaged plots had a composition closer to that of the RE, with a higher proportion of closed-canopy, perennial, and long-lived species, as well as some epiphytes. By contrast, salvaged plots were dominated by early-successional terrestrial species and species preferring open habitats. We conclude that post-fire SL represents an additional disturbance that further delays succession, a result that is consistent with previous studies using other taxonomic groups. SL should therefore be avoided or, if implemented, the possibility of leaving part of the post-fire biological legacies in situ should be considered. Full article

The attribution of forest disturbances to disturbance agents is a critical challenge for remote sensing-based forest monitoring, promising important insights into drivers and impacts of forest disturbances. Previous studies have used spectral-temporal metrics derived from annual Landsat time series to identify disturbance agents. Here, we extend this approach to new predictors derived from intra-annual time series and test it at three sites in Central Europe, including managed and protected forests. The two newly tested predictors are: (1) intra-annual timing of disturbance events and (2) temporal proximity to windstorms based on prior knowledge. We estimated the intra-annual timing of disturbances using a breakpoint detection algorithm and all available Landsat observations between 1984 and 2016. Using spectral, temporal, and topography-related metrics, we then mapped four disturbance classes: windthrow, cleared windthrow, bark beetles, and other harvest. Disturbance agents were identified with overall accuracies of 76–86%. Temporal proximity to storm events was among the most important predictors, while intra-annual timing itself was less important. Moreover, elevation information was very effective for discriminating disturbance agents. Our results demonstrate the potential of incorporating dense, intra-annual Landsat time series information and prior knowledge of disturbance events for monitoring forest ecosystem change at the disturbance agent level. Full article

With the aim of improving poplar timber production, a successive 8-year irrigation and fertilization factorial experiment with three blocks was designed to measure the response of Populus tomentosa stands to water and nitrogen in Huabei Plain, China. Specifically, we examined the responses of four P. tomentosa clones (P. tomentosa BT17, S86, B331, and 1316) to three irrigation levels (45%, 60%, and 75% above field capacity), as irrigation thresholds, and four N levels (0, 80, 160, and 240 g per plant). The results showed that both irrigation and nitrogen had significant effects in terms of improving clone stand volume. Further, we demonstrated positive interactions between irrigation and nitrogen. The stand volume increment of the four hybrid clones varied from 104.53 ± 19.84 to 191.35 ± 30.56 m³/ha in the descending order S86 > B331 > BT17 > 1316. With increasing irrigation level, the average stand volume of the four clones increased significantly from 120.46 ± 5.23 to 158.53 ± 21.72 m³/ha. When nitrogen level was increased from 0 to 240 g/plant, the average stand volume increment of the four clones increased from 126.04 ± 8.75 to 156.16 ± 26.01 m³/ha, respectively. Our results suggest that a comprehensive and specific management program is needed to improve poplar timber production. Full article

Fine roots are a major pathway of C input into soils. The aim of this study was to quantify fine root stocks, production and turnover in natural forest and land use systems converted from forests in Ethiopia. The study was conducted in a remnant Afromontane forest, eucalyptus plantation and grass and cropland in NW Ethiopia. Fine root dynamics were investigated using three different methods: sequential coring, in-growth cores and in-growth nets. Soil cores for sequential analyses were taken in quarterly intervals, while in-growth cores and nets were harvested corresponding to 1-, 2-, 3-, 4-, 5-, 8- and 12-month interval. Fine root stocks averaged 564, 425, 56 and 46 g·m⁻² in the forest, eucalyptus, grazing land and cropland ecosystems, respectively. The values decreased exponentially with increasing soil depth. In forest and eucalyptus, fine root biomass and necromass were highest in the dry season. Estimates of fine root production differed according to the method used. Fine root production based on in-growth coring averaged 468, 293, 70 and 52 g m⁻²·year⁻¹. In general, land use conversion from forest to open lands reduced fine root production by 85–91%. The turnover rate of fine roots was 1.5 for forest and 2.1 for eucalyptus plantation. Full article

Soil respiration is a major carbon pathway sensitive to environmental changes. Using prescribed burnings to reduce fuel accumulation and lower risks of large-scale wildfires has recently become more important. Prescribed burning can significantly alter the soil environment, but its effect in practice on soil respiration is not sufficiently understood. We evaluated the effects of prescribed burning on soil respiration before and after burning (May–July 2016). Prescribed burning was conducted in two natural pine areas by comparing a mixed stand of Pinus nigra Arn. ssp. salzmannii with Pinus pinaster Ait. to a pure stand of Pinus nigra Arn. ssp. salzmannii in the central Iberian Peninsula. Soil respiration was measured by an EGM-4 (Environmental Gas Monitor) infrared gas analyser in both burned and unburned (control) plots. Burnings were low-intensity, and slightly more energetic in the pure stand given its larger litter volume. Post-burning soil respiration followed a similar evolution to that in the control plots, but was greater in the pure stand burned zone and slightly lower in the burned plots in the mixed stand. No significant differences were found in any stand. Soil respiration significantly changed in temporal evolution due to increasing temperatures when summer began. We conclude that prescribed fire induces no changes in SR immediately after fire. This study helps understand how prescribed burnings can affect soil respiration in pure and mixed Spanish black pine forest stands. Full article

Post-fire hillslope stabilization treatments aim to reduce runoff-erosion risks following forest fires by counteracting the impact of fire on key soil and hillslope properties. Here we evaluate the effectiveness of wood shred mulch, long-leaved pine needle mulch, and polyacrylamide (PAM) in reducing post-fire runoff and erosion in two volcanic soil types of contrasting wettability using rainfall simulations (55 mm h⁻¹ for 30 min) at the microplot (0.25 m²) scale. The cover provided by the wood shreds and pine needles led to a reduction of runoff and erosion in both the wettable—(62% and 92%, respectively, for wood shreds, and 55% and 87%, respectively, for needle mulch) and the extremely water-repellent soils (44% and 61%, respectively, for wood shreds). In contrast to what might be expected, PAM did not reduce runoff or erosion when applied to the extremely water-repellent soils, suggesting that PAM should not be applied in this terrain type. Although more research is needed to determine whether the high effectiveness of pine needle mulch and wood shred mulch fully translates to coarser scales, the results are encouraging in terms of these materials’ ability to provide effective and relatively economic mitigation treatments for fire-induced runoff-erosion risks in volcanic soils. Full article

The U.S. Forest Service has found itself in an era of intense human activity, a changing climate; development and loss of open space; resource consumption; and problematic introduced species; and diversity in core beliefs and values. These challenges test our task-relevant maturity and the ability and willingness to meet the growing demands for services. The Forest Service is now on a transformative campaign to improve abilities and meet these challenges. The “All-Lands Approach to Conservation” brings agencies, organizations, landowners and stakeholders together across boundaries to decide on common goals for the landscapes they share. This approach is part of a larger transformation occurring in the American Conservation Movement where large-scale conservation partnerships possibly define the fourth or contemporary era. The intent of this communication is to present one perspective of what large-scale conservation partnerships should include, namely an emphasis on rethinking what leadership looks like in a collaborative context, relational governance, cooperative teamwork procedures, and communications. Full article

Many forest ecosystems with a large pine component in the western United States have experienced environmental stress associated with climate change and increased competition with forest densification in the absence of fire. Information on how changes in climate and competition affect carbon allocation to tree growth and defense is needed to anticipate changes to tree vigor and, ultimately, stand structure. This study retrospectively examined the influence of annual climate and competition measures on the growth and defense of 113 large sugar pines (Pinus lambertiana) in a mixed-conifer forest of the central Sierra Nevada of California. We found that growth in large sugar pine was positively associated with higher January temperatures and lower intraspecific competition. Resin duct size was negatively associated with climatic water deficit and total competition, while resin duct area contrastingly showed a positive relationship with total competition. From 1979 to 2012, the rates of growth increased, while resin duct size decreased. Our results suggest that tree vigor measures can respond differently to climate and competition factors that may lead to separate growth and defense trends over time. Stress associated with warmer temperatures and higher competition may distinctly influence individual tree and stand-level vigor with potential implications for future forest dynamics. Full article

Wildfires play a significant role in many different elements of Mediterranean forest ecosystems. In recent years, prescribed fires have started being used more often as a fuel reduction tool, and also as silvicultural treatment to help the regeneration and health improvement of stands. Apart from the fact that fire may alter microsite conditions, very little is known about the impact of prescribed burning on natural regeneration or plant species renewal in Mediterranean pine forests. Likewise, knowledge about the influence of seedling predators on post-fire regeneration is still scarce. In this study, we aimed to compare the effects of seedling predation on recruitment in earlier stages after prescribed burnings in three pine stands in Central Spain: a pure stand of Pinus nigra; a mixed stand of Pinus halepensis and Pinus pinaster and a mixed stand P. nigra with P. pinaster. In situ we superficially sowed seeds from two different species. In the sowing experiment, we tested two different seed provenances (drier and more humid spanish regions) for each species. In all, 60 plots (30 burned, 30 unburned) per site, with 10 seeding units per plot and more than 20,000 seeds, were used in the whole study. Seedling predation was evaluated by replicating the seeding units inside and outside a wire cage as protection for rodents and birds. Our results showed that prescribed fires alter initial seedling predation intensity: predation was significantly higher in the seedlings grown in the plots affected by prescribed fire. The individuals sown before the fire passed showed slightly more predation than those sown after fire passage. Provenances did not appear as an important predation drive. Understanding the role of the predation associated with these treatments can help improve Mediterranean pine forest management. Full article

Global food security concerns emphasize the need for sustainable agriculture and local food production. In Puerto Rico, over 80 percent of food is imported, and local production levels have reached historical lows. Efforts to increase local food production are driven by government agencies, non-government organizations, farmers, and consumers. Integration of geographic information helps plan and balance the reinvention and invigoration of the agriculture sector while maintaining ecological services. We used simple criteria that included currently protected lands and the importance of slope and forest cover in protection from erosion to identify land well-suited for conservation, agriculture and forestry in Puerto Rico. Within these categories we assessed U.S. Department of Agriculture (USDA) farmland soils classification data, lands currently in agricultural production, current land cover, and current land use planning designations. We found that developed lands occupy 13 percent of Puerto Rico; lands well-suited for conservation that include protected areas, riparian buffers, lands surrounding reservoirs, wetlands, beaches, and salt flats, occupy 45 percent of Puerto Rico; potential working lands encompass 42 percent of Puerto Rico. These include lands well-suited for mechanized and non-mechanized agriculture, such as row and specialty crops, livestock, dairy, hay, pasture, and fruits, which occupy 23 percent of Puerto Rico; and areas suitable for forestry production, such as timber and non-timber products, agroforestry, and shade coffee, which occupy 19 percent of Puerto Rico. Full article

Water availability, together with temperature, represents the most limiting abiotic factor regulating soil CO₂ efflux (SR). Besides the direct effect of water limitation, drought also influences plant activity, determining changes in the quality and quantity of root exudates, thus indirectly affecting soil microbial activity. To determine how the seasonal changes of plant activity and soil microbial metabolism and structure affect SR response to drought, we investigated the correlation between leaf gas exchange, soil carbon pools and soil respiration sources and the role of soil carbon pools on microbial populations and soil respiration, in a summer deciduous Mediterranean (SDS) and a winter deciduous temperate (WDS) shrublands, experiencing a dry summer period. In both sites, drought reduced photosynthesis, but affected SR differently: in SDS, SR decreased, although microbial heterotrophic respiration (SR_h) remained unchanged; in WDS, SR did not vary but SR_h was reduced. While in SDS the microbial community was able to respire more complex substrates, in WDS it was strongly dependent on easily decomposable molecules, thus on plant activity. Therefore, the response of soil CO₂ efflux to water limitation is not exclusively influenced by climate as it is modulated by the degree of adaptation of the microbial community to drought. Full article

Forests are the most important land ecosystems that can mitigate the earth’s ongoing climate change through their ability to sequester CO₂ as C stock in forest biomass and soil. Short-rotation deciduous hardwoods or N₂-fixing species are ideal candidates for afforestation and reforestation, given that most of the carbon accumulates in the first 30 years. Alders match both of the above-mentioned features, and Italian alder, which is less dependent on riparian habitats and more drought tolerant, is an ideal candidate. Despite this, few studies exist of this tree species and its effect on soil organic matter. In this study, we focused on litter input and leaf litter decomposition dynamics, forest floor leaf litter and topsoil (0–5 cm) organic matter, and patterns of covariation from litter to topsoil. The leaf litter was rich in nitrogen and decomposed quickly (k = 0.002 day⁻¹). There was a large organic carbon stock, which varied in the leaf litter (from 1.7 ± 0.3 Mg/ha in January to 0.4 ± 0.1 Mg/ha in July) and was stable in the topsoil (on average 28.6 ± 1.5 Mg/ha). Stocks for total nitrogen, cellulose, lignin, water and ethanol extractables, and total phenols were also evaluated. In order to investigate patterns of covariation in these stocks from litter to soil, we used two-block partial least squares. The first axis showed that from January to July there was a reduction of total nitrogen, lignin and cellulose in the forest floor leaf litter, while in the topsoil there was a decrease in water extractables and total organic carbon. The second axis showed minor phenomena involving phenols, water and ethanol extractables, and total N. The fast turnover of dissolved organic matter fractions (water and ethanol extractables), linked with cellulose and lignin dynamics, might suggest that within the Italian alder ecosystem there is a reasonably fast formation of stable C compounds in the soil. Thus, Italian alder is an ideal species for afforestation and reforestation, which could be particularly interesting for land-use policies. Full article

Integration of remote sensing (RS) data in forest inventories for enhancing plot-based forest variable prediction is a widely researched topic. Geometric consistency between forest inventory plots and areas for extraction of RS-based predictive metrics is considered a crucial factor for accurate modelling of forest variables. Achieving geometric consistency is particularly difficult with regard to angle-count sampling (ACS) plots, which have neither distinct shape nor distinct extent. This initial study considers a new approach for integrating ACS and RS data, where the concept of ACS is transferred to RS-based metrics extraction. By using the relationship between tree height and diameter at breast height (DBH), pixels of a RS-based canopy height model are extracted if their value suggests a DBH that would lead to inclusion in an angle-count sample at the given distance to the plot centre. Different variations of this approach are tested by modelling timber volume in national forest inventory plots in Germany. The results are compared to those achieved using fixed-radius plots. A root mean square error of approximately 42% is achieved by both the new and fixed-radius approaches. Therefore, the new approach is not yet considered sufficient for overcoming all difficulties concerning the integration of ACS plot and RS data. However, possibilities for improvement are discussed and will be the subject of further research. Full article

Landsat time series data were used to characterize forest degradation in Lam Dong Province, Vietnam. We conducted three types of image change analyses using Landsat time series data to characterize the land cover changes. Our analyses concentrated on the timeframe of 1973–2014, with much emphasis on the latter part of that range. We conducted a field trip through Lam Dong Province to develop a better understanding of the ground conditions of the region, during which we obtained many photographs of representative forest sites with Global Positioning System locations to assist us in our image interpretations. High-resolution Google Earth imagery and Landsat data of the region were used to validate results. In general, our analyses indicated that many land-use changes have occurred throughout Lam Dong Province, including gradual forest to non-forest transitions. Recent changes are most marked along the relatively narrow interfaces between agricultural and forest areas that occur towards the boundaries of the province. One important observation is that the most highly protected national reserves in the region have not changed much over the entire Landsat timeframe (1972–present). Spectral changes within these regions have not occurred at the same levels as those areas adjacent to the reserves. Full article

Forest tree hybrid zones provide a wealth of novel genetic variation that can be harnessed to safeguard populations in changing climates. In the past 30 years, natural and artificial forest hybrid zones have facilitated significant contributions to selective breeding programs, conservation, and our understanding of the evolutionary processes and mechanisms that influence the maintenance of species and community interactions. This review highlights advances in these areas using forest hybrid zones. Taking examples from well-known genera, including eucalypt, poplar, oak and spruce, this review details the important role hybrid zones play in managing conservation of genetic variation, the environmental and non-environmental factors that influence barriers to reproduction, and the impact that genetic ancestry may have on community biodiversity. Given increasing concern surrounding species adaptability under rapidly changing conditions, we describe how the study of forest hybrid zones, using quantitative and genomic approaches, can facilitate conservation of genetic diversity and long-term species management. Full article

Armillaria root disease is a significant forest health concern in the Atlantic forest ecosystems in Spain. The damage occurs in conifers and hardwoods, causing especially high mortality in young trees in both native forests and plantations. In the present study, the distribution of Armillaria root disease in the forests and plantations of the Basque Country is reported. Armillaria spp. were more frequently isolated from stands with slopes of 20–30% and west orientation, acid soils with high permeability, deciduous hosts, and a rainfall average above 1800 mm. In a large-scale survey, 35% of the stands presented Armillaria structures and showed disease symptoms. Of the isolated Armillaria samples, 60% were identified using molecular methods as A. ostoyae, 24% as A. mellea, 14% as A. gallica, 1% as A. tabescens, and 1% as A. cepistipes. In a small scale sampling, population diversity was defined by somatic compatibility tests and Universally Primed-PCR technique. Finally, the pathogenicity of A. mellea, the species with the broadest host range, was determined on different tree species present in the Atlantic area of Spain in order to determine their resistance levels to Armillaria disease. A significant difference in disease severity was observed among tree species (p < 0.001), with Pinus radiata being the most susceptible tree species and Cryptomeria japonica the most resistant to A. mellea. Full article

In this study, we demonstrate the potential of using high spatial resolution airborne imagery to characterize the structural development stages of forest canopies. Four forest succession stages were adopted: stand initiation, young multistory, understory reinitiation, and old growth. Remote sensing metrics describing the spatial patterns of forest structures were derived and a Random Forest learning algorithm was used to classify forest succession stages. These metrics included texture variables from Gray Level Co-occurrence Measures (GLCM), range and sill from the semi-variogram, and the fraction of shadow and its spatial distribution. Among all the derived variables, shadow fractions and the GLCM variables of contrast, mean, and dissimilarity were the most important for characterizing the forest succession stages (classification accuracy of 89%). In addition, a LiDAR (Light Detection and Ranging) derived forest structural index (predicted Lorey’s height) was employed to validate the classification result. The classification using imagery spatial variables was shown to be consistent with the LiDAR derived variable (R² = 0.68 and Root Mean Square Error (RMSE) = 2.39). This study demonstrates that high spatial resolution imagery was able to characterize forest succession stages with promising accuracy and may be considered an alternative to LiDAR data for this kind of application. Also, the results of stand development stages build a framework for future wildlife habitat mapping. Full article

In Boreal North America, management approaches inspired by the variability in natural disturbances are expected to produce more resilient forests. Wind storms are recurrent within Boreal Ontario. The objective of this study was to simulate wind damage for common Boreal forest types for regular as well as extreme wind speeds. The ForestGALES_BC windthrow prediction model was used for these simulations. Input tree-level data were derived from permanent sample plot (PSP) data provided by the Ontario Ministry of Natural Resources. PSPs were assigned to one of nine stand types: Balsam fir-, Jack pine-, Black spruce-, and hardwood-dominated stands, and, Jack pine-, spruce-, conifer-, hardwood-, and Red and White pine-mixed species stands. Morphological and biomechanical parameters for the major tree species were obtained from the literature. At 5 m/s, predicted windthrow ranged from 0 to 20%, with damage increasing to 2 to 90% for winds of 20 m/s and to 10 to 100% for winds of 40 m/s. Windthrow varied by forest stand type, with lower vulnerability within hardwoods. This is the first study to provide such broad simulations of windthrow vulnerability data for Boreal North America, and we believe this will benefit policy decisions regarding risk management and forest planning. Full article

Polylepis woodlands, the dominant high-elevation woodland species of the Andes of South America, are an increasingly important focus of conservation and restoration efforts as a buffer to the regional effects of climate change. However, the natural extent of these woodlands before the arrival of human populations is still debated. One significant approach to this question is an assessment of the change in woodland extent from a hypothetical peak at the time of the Last Glacial Maximum (LGM) to the present where distributions have been altered by both Holocene climate oscillations and anthropogenic pressures of pre-Colombian and modern communities. LGM and present distributions for 21 Polylepis species were modeled using Maxent with environmental data obtained from the WorldClim database. Overall, potential woodland extent is 36% smaller today than at LGM, however a few species have experienced a projected increase in potential range of 180%. This has occurred at the interface of the southern Amazonian Basin with the Altiplano where Polylepis species richness is highest. Bioclimatically stable areas for each species averaged 20 ± 4% of the modeled range and mostly occurred in disjunct pockets from central Peru to northern Argentina and Chile. Full article

Tree height growth measurements at monthly and annual time scales are important for calibrating and validating forest growth models, forest management and studies of forest ecology and biophysical processes. Previous studies measured the terminal growth of individual trees or forest stands at annual or decadal time scales. Short-term, within-season measurements, however, are largely unavailable due to technical and practical limitations. Here, we describe a novel approach for measuring within-season tree height growth using a time series of co-registered digital surface models obtained with a low-cost unmanned aerial vehicle in combination with ground control plates and Structure from Motion data processing. The test site was a 2-hectare temperate mixed forest stand of varying age and successional stage in central Europe. Our results show median growth rates between 27 May and 19 August of 68 cm for Norway spruce, 93 cm for Scots pine, 106 cm for Silver birch and 26 cm for European beech. The results agree well with published field observations for these species. This study demonstrates the capability of inexpensive, increasingly user-friendly and versatile UAV systems for measuring tree height growth at short time scales, which was not previously possible, opening up new avenues for investigation and practical applications in forestry and research. Full article