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Volume 8
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Forests, Volume 8, Issue 2 (February 2017) – 22 articles

Cover Story (view full-size image): The rapid spread of laurel wilt in the United States is due to an efficient vector, X. glabratus, and the movement of wood infested with the insect and pathogen. These factors, the absence of fully resistant genotypes, and the paucity of effective control measures severely constrain the disease’s management in forest ecosystems and avocado production areas. View this paper.
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4734 KiB  
Article
Soil Erosion Risk Assessment in Uganda
by Fidele Karamage, Chi Zhang, Tong Liu, Andrew Maganda and Alain Isabwe
Forests 2017, 8(2), 52; https://doi.org/10.3390/f8020052 - 22 Feb 2017
Cited by 60 | Viewed by 12096
Abstract
Land use without adequate soil erosion control measures is continuously increasing the risk of soil erosion by water mainly in developing tropical countries. These countries are prone to environmental disturbance due to high population growth and high rainfall intensity. The aim of this [...] Read more.
Land use without adequate soil erosion control measures is continuously increasing the risk of soil erosion by water mainly in developing tropical countries. These countries are prone to environmental disturbance due to high population growth and high rainfall intensity. The aim of this study is to assess the state of soil erosion by water in Uganda at national and district levels, for various land cover and land use (LCLU) types, in protected areas as well to predict the impact of support practices on soil loss reduction. Predictions obtained using the Revised Universal Soil Loss Equation (RUSLE) model indicated that the mean rate of soil loss risk in Uganda’s erosion‐prone lands was 3.2 t∙ha−1∙y−1, resulting in a total annual soil loss of about 62 million tons in 2014. About 39% of the country’s erosion‐prone lands were comprised of unsustainable mean soil loss rates >1 t∙ha−1∙y−1. Out of 112 districts in Uganda, 66 districts were found to have unsustainable estimated soil loss rates >1 t∙ha−1∙y−1. Six districts in Uganda were found to have mean annual soil loss rates of >10 t∙ha−1∙y−1: Bududa (46.3 t∙ha−1∙y−1), Kasese (37.5 t∙ha−1∙y−1), Bundibugyo (28.9 t∙ha−1∙y−1), Bulambuli (20.9 t∙ha−1∙y−1), Sironko (14.6 t∙ha−1∙y−1) and Kotido (12.5 t∙ha−1∙y−1). Among the LCLU types, the highest soil loss rates of 11 t∙ha−1∙y−1 and 10.6 t∙ha−1∙y−1 were found in moderate natural forest and dense natural forest, respectively, mainly due to their locations in highland areas characterized by steep slopes ranging between 16% to 21% and their high rainfall intensity, ranging from 1255 mm∙y−1 to 1292 mm∙y−1. Only five protected areas in Uganda were found to have high mean estimated mean soil loss rates >10 t∙ha−1∙y−1: Rwenzori Mountains (142.94 t∙ha−1∙y−1), Mount Elgon (33.81 t∙ha−1∙y−1), Bokora corridor (12.13 t∙ha−1∙y−1), Matheniko (10.39 t∙ha−1∙y−1), and Nangolibwel (10.33 t∙ha−1∙y−1). To manage soil erosion in Uganda’s protected areas, there is an urgent need to control wildfires and human‐induced disturbances such as timber harvesting and soil compaction from domestic animals. Our study analysis revealed that well‐established terraces and strip‐cropping could significantly reduce soil loss rates in Uganda’s croplands by 80% (from 1.5 t∙ha−1∙y−1 to 0.3 t∙ha−1∙y−1) and by 47% (from 1.5 t∙ha−1∙y−1 to 0.8 t∙ha−1∙y−1), respectively, well below the sustainable soil erosion tolerance rate (1 t∙ha−1∙y−1) for land and water conservation. Full article
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Article
Resources and Rules of the Game: Participation of Civil Society in REDD+ and FLEGT‐VPA Processes in Lao PDR
by Irmeli Mustalahti, Mathias Cramm, Sabaheta Ramcilovic‐Suominen and Yitagesu T. Tegegne
Forests 2017, 8(2), 50; https://doi.org/10.3390/f8020050 - 21 Feb 2017
Cited by 29 | Viewed by 10019
Abstract
Reducing Emissions from Deforestation and Forest Degradation (REDD+) aims to achieve its purpose by working across multiple sectors and involving multilevel actors in reducing deforestation and forest degradation in tropical countries. By contrast, the European Union (EU) Action Plan on Forest Law Enforcement, [...] Read more.
Reducing Emissions from Deforestation and Forest Degradation (REDD+) aims to achieve its purpose by working across multiple sectors and involving multilevel actors in reducing deforestation and forest degradation in tropical countries. By contrast, the European Union (EU) Action Plan on Forest Law Enforcement, Governance and Trade (FLEGT) and its Voluntary Partnership Agreements (VPAs) focus on forestry and functions at a bilateral state level. The FLEGT Action Plan specifically aims to tackle illegal logging and improve forest governance in countries exporting tropical timber to the EU. Since illegal logging is just one driver of forest degradation, and legalisation of logging does not necessarily reduce deforestation and forest degradation, the two instruments differ in scope. However, by addressing the causes of forest degradation and their underlying governance issues, the FLEGT VPAs and REDD+ share many functional linkages at higher levels of forest policy and forest governance. The contribution and participation of civil society organisations (CSOs) and other actors are imperative to both processes. Our study is based on a survey of key actors (national and international) in REDD+ and FLEGT VPA processes in the Lao People’s Democratic Republic (Lao PDR). Our analysis was guided by the theoretical perspectives of the policy arrangement approach and examination of two specific dimensions of this approach, namely resources and rules of the game. This paper argues that participation of CSOs in both processes is crucial because it facilitates and nurtures much needed cooperation between other national and international actors. The paper concludes that participation of CSOs could bring valuable information and knowledge into REDD+ and FLEGT VPA processes, thus contributing to increased legitimacy, justice and transparency. Full article
(This article belongs to the Special Issue REDD+ Crossroads Post Paris: Politics, Lessons and Interplays)
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4144 KiB  
Article
Simulating Changes in Fires and Ecology of the 21st Century Eurasian Boreal Forests of Siberia
by Ksenia Brazhnik, Charles Hanley and Herman H. Shugart
Forests 2017, 8(2), 49; https://doi.org/10.3390/f8020049 - 21 Feb 2017
Cited by 12 | Viewed by 8042
Abstract
Wildfires release the greatest amount of carbon into the atmosphere compared to other forest disturbances. To understand how current and potential future fire regimes may affect the role of the Eurasian boreal forest in the global carbon cycle, we employed a new, spatially-explicit [...] Read more.
Wildfires release the greatest amount of carbon into the atmosphere compared to other forest disturbances. To understand how current and potential future fire regimes may affect the role of the Eurasian boreal forest in the global carbon cycle, we employed a new, spatially-explicit fire module DISTURB-F (DISTURBance-Fire) in tandem with a spatially-explicit, individually-based gap dynamics model SIBBORK (SIBerian BOReal forest simulator calibrated to Krasnoyarsk Region). DISTURB-F simulates the effect of forest fire on the boreal ecosystem, namely the mortality of all or only the susceptible trees (loss of biomass, i.e., carbon) within the forested landscape. The fire module captures some important feedbacks between climate, fire and vegetation structure. We investigated the potential climate-driven changes in the fire regime and vegetation in middle and south taiga in central Siberia, a region with extensive boreal forest and rapidly changing climate. The output from this coupled simulation can be used to estimate carbon losses from the ecosystem as a result of fires of different sizes and intensities over the course of secondary succession (decades to centuries). Furthermore, it may be used to assess the post-fire carbon storage capacity of potential future forests, the structure and composition of which may differ significantly from current Eurasian boreal forests due to regeneration under a different climate. Full article
(This article belongs to the Special Issue Dynamics and Management of Boreal Forests)
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Article
Laurel Wilt in Natural and Agricultural Ecosystems: Understanding the Drivers and Scales of Complex Pathosystems
by Randy C. Ploetz, Paul E. Kendra, Robin Alan Choudhury, Jeffrey A. Rollins, Alina Campbell, Karen Garrett, Marc Hughes and Tyler Dreaden
Forests 2017, 8(2), 48; https://doi.org/10.3390/f8020048 - 18 Feb 2017
Cited by 51 | Viewed by 12176
Abstract
Laurel wilt kills members of the Lauraceae plant family in the southeastern United States. It is caused by Raffaelea lauricola T.C. Harr., Fraedrich and Aghayeva, a nutritional fungal symbiont of an invasive Asian ambrosia beetle, Xyleborus glabratus Eichhoff, which was detected in Port [...] Read more.
Laurel wilt kills members of the Lauraceae plant family in the southeastern United States. It is caused by Raffaelea lauricola T.C. Harr., Fraedrich and Aghayeva, a nutritional fungal symbiont of an invasive Asian ambrosia beetle, Xyleborus glabratus Eichhoff, which was detected in Port Wentworth, Georgia, in 2002. The beetle is the primary vector of R. lauricola in forests along the southeastern coastal plain of the United States, but other ambrosia beetle species that obtained the pathogen after the initial introduction may play a role in the avocado (Persea americana Miller) pathosystem. Susceptible taxa are naïve (new-encounter) hosts that originated outside Asia. In the southeastern United States, over 300 million trees of redbay (P. borbonia (L.) Spreng.) have been lost, and other North American endemics, non-Asian ornamentals and avocado—an important crop that originated in MesoAmerica—are also affected. However, there are no reports of laurel wilt on the significant number of lauraceous endemics that occur in the Asian homeland of R. lauricola and X. glabratus; coevolved resistance to the disease in the region has been hypothesized. The rapid spread of laurel wilt in the United States is due to an efficient vector, X. glabratus, and the movement of wood infested with the insect and pathogen. These factors, the absence of fully resistant genotypes, and the paucity of effective control measures severely constrain the disease’s management in forest ecosystems and avocado production areas. Full article
(This article belongs to the Special Issue Forest Pathology and Plant Health)
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Article
Forest Islands and Castaway Communities: REDD+ and Forest Restoration in Prey Lang Forest
by Courtney Work
Forests 2017, 8(2), 47; https://doi.org/10.3390/f8020047 - 17 Feb 2017
Cited by 11 | Viewed by 7977
Abstract
Climate Change policies are playing an ever-increasing role in global development strategies and their implementation gives rise to often-unforeseen social conflicts and environmental degradations. A landscape approach to analyzing forest-based Climate Change Mitigation policies (CCM) and land grabs in the Prey Lang Forest [...] Read more.
Climate Change policies are playing an ever-increasing role in global development strategies and their implementation gives rise to often-unforeseen social conflicts and environmental degradations. A landscape approach to analyzing forest-based Climate Change Mitigation policies (CCM) and land grabs in the Prey Lang Forest landscape, Cambodia revealed two Korea-Cambodia partnership projects designed to increase forest cover that are juxtaposed in this paper. Case study data revealed a REDD+ project with little negative impact or social conflict in the project area and an Afforestation/Reforestation (A/R) project that created both social and ecological conflicts. The study concludes that forest-based CCM policies can reduce conflict through efforts at minimal transformation of local livelihoods, maximal attention to the tenure rights, responsibilities, and authority of citizens, and by improving, not degrading, the project landscapes. The paper presents the circumstances under which these guidelines are sidestepped by the A/R project, and importantly reveals that dramatic forest and livelihood transformation had already affected the community and environment in the REDD+ project site. There are deep contradictions at the heart of climate change policies toward which attention must be given, lest we leave our future generations with nothing but forest islands and castaway communities. Full article
(This article belongs to the Special Issue REDD+ Crossroads Post Paris: Politics, Lessons and Interplays)
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Article
A Demographic Approach to Evaluating Tree Population Sustainability
by Corey R. Halpin and Craig G. Lorimer
Forests 2017, 8(2), 46; https://doi.org/10.3390/f8020046 - 16 Feb 2017
Cited by 13 | Viewed by 6174
Abstract
Quantitative criteria for assessing demographic sustainability of tree populations would be useful in forest conservation, as climate change and a growing complex of invasive pests are likely to drive forests outside their historic range of variability. In this paper, we used CANOPY, a [...] Read more.
Quantitative criteria for assessing demographic sustainability of tree populations would be useful in forest conservation, as climate change and a growing complex of invasive pests are likely to drive forests outside their historic range of variability. In this paper, we used CANOPY, a spatially explicit, individual‐tree model, to examine the effects of initial size distributions on sustainability of tree populations for 70 northern hardwood stands under current environmental conditions. A demographic sustainability index was calculated as the ratio of future simulated basal area to current basal area, given current demographic structure and density‐dependent demographic equations. Only steeply descending size distributions were indicated to be moderately or highly sustainable (final basal area/initial basal area ≥0.7 over several tree generations). Five of the six principal species had demographic sustainability index values of <0.6 in 40%–84% of the stands. However, at a small landscape scale, nearly all species had mean index values >1. Simulation experiments suggested that a minimum sapling density of 300 per hectare was required to sustain the initial basal area, but further increases in sapling density did not increase basal area because of coincident increases in mortality. A variable slope with high q‐ratios in small size classes was needed to maintain the existing overstory of mature and old‐growth stands. This analytical approach may be useful in identifying stands needing restoration treatments to maintain existing species composition in situations where forests are likely to have future recruitment limitations. Full article
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2073 KiB  
Article
Regeneration Responses to Management for Old-Growth Characteristics in Northern Hardwood-Conifer Forests
by Aviva J. Gottesman and William S. Keeton
Forests 2017, 8(2), 45; https://doi.org/10.3390/f8020045 - 16 Feb 2017
Cited by 12 | Viewed by 6013
Abstract
Successful tree regeneration is essential for sustainable forest management, yet it can be limited by the interaction of harvesting effects and multiple ecological drivers. In northern hardwood forests, for example, there is uncertainty whether low-intensity selection harvesting techniques will result in adequate and [...] Read more.
Successful tree regeneration is essential for sustainable forest management, yet it can be limited by the interaction of harvesting effects and multiple ecological drivers. In northern hardwood forests, for example, there is uncertainty whether low-intensity selection harvesting techniques will result in adequate and desirable regeneration. Our research is part of a long-term study that tests the hypothesis that a silvicultural approach called “structural complexity enhancement” (SCE) can accelerate the development of late-successional forest structure and functions. Our objective is to understand the regeneration dynamics following three uneven-aged forestry treatments with high levels of retention: single-tree selection, group selection, and SCE. Regeneration density and diversity can be limited by differing treatment effects on or interactions among light availability, competitive environment, substrate, and herbivory. To explore these relationships, manipulations and controls were replicated across 2 ha treatment units at two Vermont sites. Forest inventory data were collected pre-harvest and periodically over 13 years post-harvest. We used mixed effects models with repeated measures to evaluate the effect of treatment on seedling and sapling density and diversity (Shannon–Weiner H’). The treatments were all successful in recruiting a sapling class with significantly greater sapling densities compared to the controls. However, undesirable and prolific beech (Fagus americana) sprouting dominates some patches in the understory of all the treatments, creating a high degree of spatial variability in the competitive environment for regeneration. Multivariate analyses suggest that while treatment had a dominant effect, other factors were influential in driving regeneration responses. These results indicate variants of uneven-aged systems that retain or enhance elements of stand structural complexity—including old-growth characteristics—can generally foster abundant regeneration of important late successional tree species depending on site conditions, but they may require beech control where beech sprouting inhibits desired regeneration. Full article
(This article belongs to the Special Issue Stand Dynamics of Forests Managed Using Variable Retention Harvesting Systems)
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3306 KiB  
Article
Use of Real‐Time GNSS‐RF Data to Characterize the Swing Movements of Forestry Equipment
by Ryer M. Becker, Robert F. Keefe and Nathaniel M. Anderson
Forests 2017, 8(2), 44; https://doi.org/10.3390/f8020044 - 15 Feb 2017
Cited by 22 | Viewed by 6204
Abstract
The western United States faces significant forest management challenges after severe bark beetle infestations have led to substantial mortality. Minimizing costs is vital for increasing the feasibility of management operations in affected forests. Multi‐transmitter Global Navigation Satellite System (GNSS)‐radio frequencies (RF) technology has [...] Read more.
The western United States faces significant forest management challenges after severe bark beetle infestations have led to substantial mortality. Minimizing costs is vital for increasing the feasibility of management operations in affected forests. Multi‐transmitter Global Navigation Satellite System (GNSS)‐radio frequencies (RF) technology has applications in the quantification and analysis of harvest system production efficiency and provision of real‐time operational machine position, navigation, and timing. The aim of this study was to determine the accuracy with which multi‐transmitter GNSS‐RF captures the swinging and forwarding motions of ground based harvesting machines at varying transmission intervals. Assessing the accuracy of GNSS in capturing intricate machine movements is a first step toward development of a real‐time production model to assist timber harvesting of beetle‐killed lodgepole pine stands. In a complete randomized block experiment with four replicates, a log loader rotated to 18 predetermined angles with GNSS‐RF transponders collecting and sending data at two points along the machine boom (grapple and heel rack) and at three transmission intervals (2.5, 5.0, and 10.0 s). The 2.5 and 5.0 s intervals correctly identified 94% and 92% of cycles at the grapple and 92% and 89% of cycles at the heel, respectively. The 2.5 s interval successfully classified over 90% of individual cycle elements, while the 5.0 s interval returned statistically similar results. Predicted swing angles obtained the highest level of similarity to observed angles at the 2.5 s interval. Our results show that GNSS‐RF is useful for realtime, model‐based analysis of forest operations, including woody biomass production logistics. Full article
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1780 KiB  
Article
Evaluating the Effects of Carbon Prices on Trade-Offs between Carbon and Timber Management Objectives in Forest Spatial Harvest Scheduling Problems: A Case Study from Northeast China
by Huiyan Qin, Lingbo Dong and Yingli Huang
Forests 2017, 8(2), 43; https://doi.org/10.3390/f8020043 - 14 Feb 2017
Cited by 24 | Viewed by 4393
Abstract
To mitigate global climatic changes, long-term carbon trading and carbon taxes have been implemented in many countries. However, carbon prices have varied in many of these regions. Therefore, the goal of this paper was to evaluate the effects of carbon prices on trade-offs [...] Read more.
To mitigate global climatic changes, long-term carbon trading and carbon taxes have been implemented in many countries. However, carbon prices have varied in many of these regions. Therefore, the goal of this paper was to evaluate the effects of carbon prices on trade-offs between forest carbon and timber management objectives in spatial harvest scheduling problems. The objective function of the planning problem was designed to maximize the discounted net present value of harvested timber and the differences of carbon stocks in living tree biomass between the beginning and end of the planning horizon (DoC) within a 30-year time frame for a large forest region in northeast China. The constraints primarily related to maintaining an even flow of harvested timber and guaranteeing the maximum opening size. Forest developments were simulated using a set of standard stand-level growth and yield models, and the solutions of the planning problem were generated using the standard version of a simulated annealing algorithm. The effects of a wide range of carbon prices on the harvested timber and DoC levels were examined. The results showed that the trade-offs between forest harvested timber and the DoC displayed a typical nonlinear tendency as carbon prices increased. The current carbon prices (i.e., 25, 50 and 75 ¥/ton) in China had no significant effects on the optimal forest management plans compared with a scenario that used a carbon price of zero. The minimum carbon price that can provide the financial incentive for the forests to function as a significant carbon sink was estimated to be somewhat over 800 ¥/ton. This result could be useful in determining the appropriate carbon offset standard in this region. Full article
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Article
Prediction of Dominant Forest Tree Species Using QuickBird and Environmental Data
by Azadeh Abdollahnejad, Dimitrios Panagiotidis, Shaban Shataee Joybari and Peter Surový
Forests 2017, 8(2), 42; https://doi.org/10.3390/f8020042 - 14 Feb 2017
Cited by 30 | Viewed by 5946
Abstract
Modelling the spatial distribution of plants is one of the indirect methods for predicting the properties of plants and can be defined based on the relationship between the spatial distribution of vegetation and environmental variables. In this article, we introduce a new method [...] Read more.
Modelling the spatial distribution of plants is one of the indirect methods for predicting the properties of plants and can be defined based on the relationship between the spatial distribution of vegetation and environmental variables. In this article, we introduce a new method for the spatial prediction of the dominant trees and species, through a combination of environmental and satellite data. Based on the basal area factor (BAF) frequency for each tree species in a total of 518 sample plots, the dominant tree species were determined for each plot. Also, topographical maps of primary and secondary properties were prepared using the digital elevation model (DEM). Categories of soil and the climate maps database of the Doctor Bahramnia Forestry Plan were extracted as well. After pre-processing and processing of spectral data, the pixel values at the sample locations in all the independent factors such as spectral and non-spectral data, were extracted. The modelling rates of tree and shrub species diversity using data mining algorithms of 80% of the sampling plots were taken. Assessment of model accuracy was conducted using 20% of samples and evaluation criteria. Random forest (RF), support vector machine (SVM) and k-nearest neighbor (k-NN) algorithms were used for spatial distribution modelling of dominant species groups using environmental and spectral variables from 80% of the sample plots. Results showed physiographic factors, especially altitude in combination with soil and climate factors as the most important variables in the distribution of species, while the best model was created by the integration of physiographic factors (in combination with soil and climate) with an overall accuracy of 63.85%. In addition, the results of the comparison between the algorithms, showed that the RF algorithm was the most accurate in modelling the diversity. Full article
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Article
Using Macronutrient Distributions within Trees to Define a Branch Diameter Threshold for Biomass Harvest in Sugar Maple-Dominated Stands
by Samuel Royer-Tardif, Sylvain Delagrange, Philippe Nolet and David Rivest
Forests 2017, 8(2), 41; https://doi.org/10.3390/f8020041 - 11 Feb 2017
Cited by 3 | Viewed by 4778
Abstract
As the use of forest harvesting residues for energy production gains popularity, debate continues regarding the long-term sustainability of whole tree harvesting (WTH). This practice removes nutrient-rich twigs that only account for a small fraction of harvest residues, emphasising the need to develop [...] Read more.
As the use of forest harvesting residues for energy production gains popularity, debate continues regarding the long-term sustainability of whole tree harvesting (WTH). This practice removes nutrient-rich twigs that only account for a small fraction of harvest residues, emphasising the need to develop nutrient-efficient alternatives to WTH. This study assessed N, P, K, Ca, and Mg distributions within sugar maple (Acer saccharum Marshall) and yellow birch (Betula alleghaniensis Britton) branches of various sizes in order to determine the branch diameter threshold that would represent the best compromise between the quantity of harvested biomass and nutrient losses that were generated. Quantities of nutrients that were exported with harvesting were then modelled at the stand level using different biomass harvest scenarios to explore what factors ultimately drove total quantities of nutrients exported with harvest. We found that the branch diameter threshold for biomass harvesting should be set at 2 cm for most nutrients in both tree species. An exception was Mg in yellow birch, for which the harvesting of branches larger than 10 cm would always generate larger nutrient export than gains in terms of biomass. At the stand scale, we provide evidence that the intensity of biomass harvest (i.e., the number of branch compartments harvested) is the principal factor responsible for the quantity of nutrient that is exported with harvesting. Full article
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Article
Temporal Variability of Soil Respiration in Experimental Tree Plantations in Lowland Costa Rica
by James W. Raich
Forests 2017, 8(2), 40; https://doi.org/10.3390/f8020040 - 8 Feb 2017
Cited by 17 | Viewed by 6016
Abstract
The principal objective of this study was to determine if there is consistent temporal variability in soil respiration from different forest plantations in a lowland tropical rainforest environment. Soil respiration was measured regularly over 2004 to 2010 in replicated plantations of 15- to [...] Read more.
The principal objective of this study was to determine if there is consistent temporal variability in soil respiration from different forest plantations in a lowland tropical rainforest environment. Soil respiration was measured regularly over 2004 to 2010 in replicated plantations of 15- to 20-year-old evergreen tropical trees in lowland Costa Rica. Statistically significant but small differences in soil respiration were observed among hours of the day; daytime measurements were suitable for determining mean fluxes in this study. Fluxes varied more substantially among months, with the highest average emissions (5.9 μmol·m−2·s−1) occurring in September and low emissions (3.7 μmol·m−2·s−1) occurring in January. Three of the six tree species had significantly increasing rates of soil respiration across 2004–2010, with fluxes increasing at an average of 0.09 μmol·m−2·s−1 per year: the three other species had no long-term trends. It was hypothesized that there would be a tradeoff between carbon allocation aboveground, to produce new leaves, and belowground, to sustain roots and mycorrhizae, but the relationship between canopy leaf fall—a surrogate for canopy leaf flushing—and soil respiration was significantly positive. The similarities observed among temporal trends across plantation types, and significant relationships between soil respiration, soil water content and soil temperature, suggest that the physical environment largely controlled the temporal variability of soil respiration, but differences in flux magnitude among tree species were substantial and consistent across years. Full article
(This article belongs to the Special Issue Forest Soil Respiration under Climate Changing)
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1533 KiB  
Article
Livelihoods and Land Uses in Environmental Policy Approaches: The Case of PES and REDD+ in the Lam Dong Province of Vietnam
by Leif Tore Trædal and Pål Olav Vedeld
Forests 2017, 8(2), 39; https://doi.org/10.3390/f8020039 - 8 Feb 2017
Cited by 18 | Viewed by 10770
Abstract
This paper explores assumptions about the drivers of forest cover change in a Payments for Environmental Services (PES) and Reduced Emissions from Deforestation and Degradation (REDD+) context in the Lam Dong Province in Vietnam. In policy discourses, deforestation is often linked to ‘poor’ [...] Read more.
This paper explores assumptions about the drivers of forest cover change in a Payments for Environmental Services (PES) and Reduced Emissions from Deforestation and Degradation (REDD+) context in the Lam Dong Province in Vietnam. In policy discourses, deforestation is often linked to ‘poor’ and ‘ethnic minority’ households and their unsustainable practices such as the expansion of coffee production (and other agricultural activities) into forest areas. This paper applies a livelihood framework to discuss the links between livelihoods and land use amongst small-scale farmers in two communities. The findings of the livelihood survey demonstrate no clear linkages between poverty levels and unsustainable practices. In fact, the poorest segments were found to deforest the least. The ways in which current PES and REDD+ approaches are designed, do not provide appropriate solutions to address the underlying dimensions of issues at stake. The paper criticizes one-dimensional perspectives of the drivers behind deforestation and forest degradation often found in public policies and discourses. We suggest more comprehensive analyses of underlying factors encompassing the entire coffee production and land use system in this region. Addressing issues of land tenure and the scarcity of productive lands, and generating viable off-farm income alternatives seem to be crucial. Sustainable approaches for reducing deforestation and degradation could be possible through engaging with multiple stakeholders, including the business-oriented households in control of the coffee trade and of land transactions. Full article
(This article belongs to the Special Issue REDD+ Crossroads Post Paris: Politics, Lessons and Interplays)
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2524 KiB  
Communication
Assessing Precision in Conventional Field Measurements of Individual Tree Attributes
by Ville Luoma, Ninni Saarinen, Michael A. Wulder, Joanne C. White, Mikko Vastaranta, Markus Holopainen and Juha Hyyppä
Forests 2017, 8(2), 38; https://doi.org/10.3390/f8020038 - 8 Feb 2017
Cited by 88 | Viewed by 9936
Abstract
Forest resource information has a hierarchical structure: individual tree attributes are summed at the plot level and then in turn, plot-level estimates are used to derive stand or large-area estimates of forest resources. Due to this hierarchy, it is imperative that individual tree [...] Read more.
Forest resource information has a hierarchical structure: individual tree attributes are summed at the plot level and then in turn, plot-level estimates are used to derive stand or large-area estimates of forest resources. Due to this hierarchy, it is imperative that individual tree attributes are measured with accuracy and precision. With the widespread use of different measurement tools, it is also important to understand the expected degree of precision associated with these measurements. The most prevalent tree attributes measured in the field are tree species, stem diameter-at-breast-height (dbh), and tree height. For dbh and height, the most commonly used measuring devices are calipers and clinometers, respectively. The aim of our study was to characterize the precision of individual tree dbh and height measurements in boreal forest conditions when using calipers and clinometers. The data consisted of 319 sample trees at a study area in Evo, southern Finland. The sample trees were measured independently by four trained mensurationists. The standard deviation in tree dbh and height measurements was 0.3 cm (1.5%) and 0.5 m (2.9%), respectively. Precision was also assessed by tree species and tree size classes; however, there were no statistically significant differences between the mensurationists for dbh or height measurements. Our study offers insights into the expected precision of tree dbh and height as measured with the most commonly used devices. These results are important when using sample plot data in forest inventory applications, especially now, at a time when new tree attribute measurement techniques based on remote sensing are being developed and compared to the conventional caliper and clinometer measurements. Full article
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548 KiB  
Communication
Potentials and Unknowns in Managing Coarse Woody Debris for Soil Functioning
by Kenton P. Stutz and Friederike Lang
Forests 2017, 8(2), 37; https://doi.org/10.3390/f8020037 - 4 Feb 2017
Cited by 20 | Viewed by 6120
Abstract
More intensive removal of woody biomass for the bio-economy will disrupt litter and succession cycles. Especially at risk is the retention of fine and coarse woody debris (FWD and CWD), crucial factors in forest biodiversity and nutrient cycling. However, to what extent CWD [...] Read more.
More intensive removal of woody biomass for the bio-economy will disrupt litter and succession cycles. Especially at risk is the retention of fine and coarse woody debris (FWD and CWD), crucial factors in forest biodiversity and nutrient cycling. However, to what extent CWD affects soil functioning remains unknown, and is seldom considered. From 32 paired test–reference points in eight Fagus sylvatica (L.) stands throughout Southwest Germany, CWD significantly increased soil C/N ratios, base saturation, and possibly pH. CWD-induced changes in soil porosity, available water capacity, and total organic carbon depended on site and CWD characteristics. As such, CWD can be viewed as a “pedogenic hot-spot” of concentrated biogeochemical and -physical processes with outsized effects on soil functioning and development. CWD management for soil functioning should consider site and tree species specific volume thresholds, timed rotations, and spatial densities, but appropriate implementation requires further research to define best management practices. If successful, overall forest resilience as well as soil functioning and productivity can be improved. Full article
(This article belongs to the Special Issue The Role of Bio-Economy for Forestry—Selected Papers from FowiTa German Forest Sciences Conference (Sessions 15–19))
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4580 KiB  
Article
Spatial Upscaling of Soil Respiration under a Complex Canopy Structure in an Old‐Growth Deciduous Forest, Central Japan
by Vilanee Suchewaboripont, Masaki Ando, Shinpei Yoshitake, Yasuo Iimura, Mitsuru Hirota and Toshiyuki Ohtsuka
Forests 2017, 8(2), 36; https://doi.org/10.3390/f8020036 - 30 Jan 2017
Cited by 6 | Viewed by 5524
Abstract
The structural complexity, especially canopy and gap structure, of old‐growth forests affects the spatial variation of soil respiration (Rs). Without considering this variation, the upscaling of Rs from field measurements to the forest site will be biased. The present study examined [...] Read more.
The structural complexity, especially canopy and gap structure, of old‐growth forests affects the spatial variation of soil respiration (Rs). Without considering this variation, the upscaling of Rs from field measurements to the forest site will be biased. The present study examined responses of Rs to soil temperature (Ts) and water content (W) in canopy and gap areas, developed the best fit modelof Rs and used the unique spatial patterns of Rs and crown closure to upscale chamber measurements to the site scale in an old‐growth beech‐oak forest. Rs increased with an increase in Ts in both gap and canopy areas, but the effect of W on Rs was different between the two areas. The generalized linear model (GLM) analysis identified that an empirical model of Rs with thecoupling of Ts and W was better than an exponential model of Rs with only Ts. Moreover, because of different responses of Rs to W between canopy and gap areas, it was necessary to estimate Rs in these areas separately. Consequently, combining the spatial patterns of Rs and the crown closure could allow upscaling of Rs from chamber‐based measurements to the whole site in the present study. Full article
(This article belongs to the Special Issue Forest Soil Respiration under Climate Changing)
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8264 KiB  
Article
Phenology-Based Method for Mapping Tropical Evergreen Forests by Integrating of MODIS and Landsat Imagery
by Weili Kou, Changxian Liang, Lili Wei, Alexander J. Hernandez and Xuejing Yang
Forests 2017, 8(2), 34; https://doi.org/10.3390/f8020034 - 29 Jan 2017
Cited by 29 | Viewed by 8001
Abstract
Updated extent, area, and spatial distribution of tropical evergreen forests from inventory data provides valuable knowledge for research of the carbon cycle, biodiversity, and ecosystem services in tropical regions. However, acquiring these data in mountainous regions requires labor-intensive, often cost-prohibitive field protocols. Here, [...] Read more.
Updated extent, area, and spatial distribution of tropical evergreen forests from inventory data provides valuable knowledge for research of the carbon cycle, biodiversity, and ecosystem services in tropical regions. However, acquiring these data in mountainous regions requires labor-intensive, often cost-prohibitive field protocols. Here, we report about validated methods to rapidly identify the spatial distribution of tropical forests, and obtain accurate extent estimates using phenology-based procedures that integrate the Moderate Resolution Imaging Spectroradiometer (MODIS) and Landsat imagery. Firstly, an analysis of temporal profiles of annual time-series MODIS Normalized Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), and Land Surface Water Index (LSWI) was developed to identify the key phenology phase for extraction of tropical evergreen forests in five typical lands cover types. Secondly, identification signatures of tropical evergreen forests were selected and their related thresholds were calculated based on Landsat NDVI, EVI, and LSWI extracted from ground true samples of different land cover types during the key phenology phase. Finally, a map of tropical evergreen forests was created by a pixel-based thresholding. The developed methods were tested in Xishuangbanna, China, and the results show: (1) Integration of Landsat and MODIS images performs well in extracting evergreen forests in tropical complex mountainous regions. The overall accuracy of the resulting map of the case study was 92%; (2) Annual time series of high-temporal-resolution remote sensing images (MODIS) can effectively be used for identification of the key phenology phase (between Julian Date 20 and 120) to extract tropical evergreen forested areas through analysis of NDVI, EVI, and LSWI of different land cover types; (3) NDVI and LSWI are two effective metrics (NDVI ≥ 0.670 and 0.447 ≥ LSWI ≥ 0.222) to depict evergreen forests from other land cover types during the key phenology phase in tropical complex mountainous regions. This method can make full use of the Landsat and MODIS archives as well as their advantages for tropical evergreen forests geospatial inventories, and is simple and easy to use. This method is suggested for use with other similar regions. Full article
(This article belongs to the Special Issue Optimizing Forest Inventories with Remote Sensing Techniques)
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858 KiB  
Article
Natural Regeneration in a Multi-Layered Pinus sylvestris-Picea abies Forest after Target Diameter Harvest and Soil Scarification
by Lars Drössler, Nils Fahlvik, Natalia K. Wysocka, Karin Hjelm and Christian Kuehne
Forests 2017, 8(2), 35; https://doi.org/10.3390/f8020035 - 28 Jan 2017
Cited by 14 | Viewed by 5824
Abstract
Forest management in Sweden can be characterized by even-aged silviculture heavily relying on three established harvest regimes: clearcutting, the seed-tree method, and the shelterwood system. Less intense, small-scale retention harvest systems such as single tree and group selection harvest are rarely used. In [...] Read more.
Forest management in Sweden can be characterized by even-aged silviculture heavily relying on three established harvest regimes: clearcutting, the seed-tree method, and the shelterwood system. Less intense, small-scale retention harvest systems such as single tree and group selection harvest are rarely used. In addition, natural regeneration dynamics without enrichment planting have barely been studied. Consequently, this study examined natural regeneration establishment in a multi-layered Pinus sylvestris-Picea abies forest stand in southwest Sweden after target diameter harvesting and soil scarification. The creation of forest canopy gaps had a positive effect on total seedling density five years after harvest, mainly due to a significantly higher number of Betula pendula individuals. Seedling density of more desirable tree species suitable for continuous cover forestry such as Fagus sylvatica, Quercus petraea and Picea abies also increased substantially in gaps when compared to pre-harvest conditions or the unharvested plots. In contrast, soil scarification did not increase the number of seedlings of desired tree species due to a significant decrease in Picea abies abundance. Soil moisture and gap size significantly improved Betula pendula seedling establishment while a larger number of Quercus petraea seedlings were observed in Vaccinium myrtillus patches. We conclude that canopy gaps are beneficial under the encountered stand conditions to initiate forest regeneration, and that soil scarification without the timely occurrence of a mast year of desired tree species is not effective in the type of forest studied. Full article
(This article belongs to the Special Issue Stand Dynamics of Forests Managed Using Variable Retention Harvesting Systems)
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1140 KiB  
Article
Soil Microbial Communities in Natural and Managed Cloud Montane Forests
by Ed-Haun Chang, Guanglong Tian and Chih-Yu Chiu
Forests 2017, 8(2), 33; https://doi.org/10.3390/f8010033 - 26 Jan 2017
Cited by 21 | Viewed by 5687
Abstract
Forest management often results in changes in soil microbial communities. To understand how forest management can change microbial communities, we studied soil microbial abundance and community structure in a natural Chamaecyparis (NCP) forest, a disturbed Chamaecyparis (DCP) forest, a secondary (regenerated) Chamaecyparis (SCP) [...] Read more.
Forest management often results in changes in soil microbial communities. To understand how forest management can change microbial communities, we studied soil microbial abundance and community structure in a natural Chamaecyparis (NCP) forest, a disturbed Chamaecyparis (DCP) forest, a secondary (regenerated) Chamaecyparis (SCP) forest and a secondary (reforested) Cryptomeria (SCD) forest. We analyzed soil microbial abundance by measuring phospholipid fatty acids (PLFAs) and microbial community structure by denaturing gradient gel electrophoresis (DGGE) in the studied forest soils. The content of the soil PLFA fungal biomarker decreased from NCP to SCP, DCP and SCD forest soils, associated with the degree of disturbance of forest management. The ratio of soil Gram positive–to-negative bacteria and the stress index (16:1ω7t to 16:1ω7c) increased from NCP to SCP and DCP soils; thus, disturbed forests except for SCD showed increased soil microbial stress. Principal component analysis of soil microbial groups by PLFAs separated the four forest soils into three clusters: NCP, DCP and SCP, and SCD soil. The DGGE analysis showed no difference in the microbial community structure for NCP, DCP and SCP soils, but the community structure differed between SCD and the three other forest soils. In cloud montane forests, disturbance due to forest management had only a slight influence on the soil microbial community, whereas reforestation with different species largely changed the soil microbial community structure. Full article
(This article belongs to the Special Issue Forest Soil Microbe and Biogeochemical Cycling: Biogeochemical Processes in Forest Soils)
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1320 KiB  
Article
Biocontrol of Fusarium circinatum Infection of Young Pinus radiata Trees
by Eugenia Iturritxa, Tyler Trask, Nebai Mesanza, Rosa Raposo, Margarita Elvira-Recuenco and Cheryl L. Patten
Forests 2017, 8(2), 32; https://doi.org/10.3390/f8020032 - 26 Jan 2017
Cited by 18 | Viewed by 7747
Abstract
Pitch canker, caused by the fungus Fusarium circinatum, is a major disease of Pinus radiata currently controlled to some extent in nurseries by good hygiene and application of synthetic fungicides. The aim of this study was to evaluate alternative strategies to control [...] Read more.
Pitch canker, caused by the fungus Fusarium circinatum, is a major disease of Pinus radiata currently controlled to some extent in nurseries by good hygiene and application of synthetic fungicides. The aim of this study was to evaluate alternative strategies to control fungal infections in nurseries and young pine plantations. The antagonistic effects of biocontrol bacteria and essential oils against F. circinatum in vitro and in young P. radiata trees were assessed. Pseudomonas fluorescens, Erwinia billingiae, and Bacillus simplex reduced the growth of the fungus in vitro by 17%–29%, and decreased the density of the mycelial mat. In young P. radiata trees, the length of F. circinatum lesions was reduced by 22%–25% by the same bacterial strains. Direct application of cinnamon and/or clove essential oils to wounds in stems of two-year-old P. radiata trees also limited the damage caused by F. circinatum. Lesion length was reduced by 51% following treatment with cinnamon oil (10% v/v), and by 45% following treatment with clove oil (15% v/v) or a combination of both oils. However, the oils were toxic to younger trees. The biocontrol bacteria and essential oils show promise as prophylactic treatments to reduce the devastating effects of F. circinatum on P. radiata. Full article
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1894 KiB  
Article
Influence of Mature Overstory Trees on Adjacent 12-Year Regeneration and the Woody Understory: Aggregated Retention versus Intact Forest
by Miranda T. Curzon, Susan C. Baker, Christel C. Kern, Brian J. Palik and Anthony W. D’Amato
Forests 2017, 8(2), 31; https://doi.org/10.3390/f8020031 - 25 Jan 2017
Cited by 11 | Viewed by 5639
Abstract
Retention harvesting, an approach that intentionally retains legacy features such as mature overstory trees, provides options for achieving ecological objectives. At the same time, retained overstory trees may compete with the nearby recovering understory for resources, and much remains to be learned about [...] Read more.
Retention harvesting, an approach that intentionally retains legacy features such as mature overstory trees, provides options for achieving ecological objectives. At the same time, retained overstory trees may compete with the nearby recovering understory for resources, and much remains to be learned about potential trade-offs with regeneration objectives, particularly over extended time periods. We assessed the influence of aggregated retention (reserved mature overstory and understory patches) versus intact forest on structure and productivity (standing biomass) of the adjacent woody understory and regeneration 12 years after harvest in northern Minnesota, USA. Each site was dominated by Populus tremuloides Michx., a species that regenerates prolifically via root sprouts following disturbance. Overall, fewer differences than expected occurred between the effects of intact forest and aggregated retention on regeneration, despite the small size (0.1 ha) of aggregates. Instead, harvest status and distance from harvest edge had a greater influence on structure and standing woody biomass. Proximity to aggregates reduced large sapling biomass (all species, combined) relative to open conditions, but only up to 5 m into harvested areas. This suggests the trade-off for achieving productivity objectives might be minimal if managers use retention aggregates in this region to achieve ecological objectives and meet management guidelines. Full article
(This article belongs to the Special Issue Stand Dynamics of Forests Managed Using Variable Retention Harvesting Systems)
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5696 KiB  
Article
Assessing Wildland Fire Risk Transmission to Communities in Northern Spain
by Fermín J. Alcasena, Michele Salis, Alan A. Ager, Rafael Castell and Cristina Vega-García
Forests 2017, 8(2), 30; https://doi.org/10.3390/f8020030 - 24 Jan 2017
Cited by 58 | Viewed by 8959
Abstract
We assessed potential economic losses and transmission to residential houses from wildland fires in a rural area of central Navarra (Spain). Expected losses were quantified at the individual structure level (n = 306) in 14 rural communities by combining fire model predictions [...] Read more.
We assessed potential economic losses and transmission to residential houses from wildland fires in a rural area of central Navarra (Spain). Expected losses were quantified at the individual structure level (n = 306) in 14 rural communities by combining fire model predictions of burn probability and fire intensity with susceptibility functions derived from expert judgement. Fire exposure was estimated by simulating 50,000 fire events that replicated extreme (97th percentile) historical fire weather conditions. Spatial ignition probabilities were used in the simulations to account for non-random ignitions, and were estimated from a fire occurrence model generated with an artificial neural network. The results showed that ignition probability explained most of spatial variation in risk, with economic value of structures having only a minor effect. Average expected loss to residential houses from a single wildfire event in the study area was 7955€, and ranged from a low of 740 to the high of 28,725€. Major fire flow-paths were analyzed to understand fire transmission from surrounding municipalities and showed that incoming fires from the north exhibited strong pathways into the core of the study area, and fires spreading from the south had the highest likelihood of reaching target residential structures from the longest distances (>5 km). Community firesheds revealed the scale of risk to communities and extended well beyond administrative boundaries. The results provided a quantitative risk assessment that can be used by insurance companies and local landscape managers to prioritize and allocate investments to treat wildland fuels and identify clusters of high expected loss within communities. The methodological framework can be extended to other fire-prone southern European Union countries where communities are threatened by large wildland fires. Full article
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