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Forests, Volume 5, Issue 6 (June 2014), Pages 1122-1507

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Research

Open AccessArticle Sensitivity Analysis of 3D Individual Tree Detection from LiDAR Point Clouds of Temperate Forests
Forests 2014, 5(6), 1122-1142; doi:10.3390/f5061122
Received: 4 March 2014 / Revised: 8 April 2014 / Accepted: 14 May 2014 / Published: 28 May 2014
Cited by 5 | PDF Full-text (2606 KB) | HTML Full-text | XML Full-text
Abstract
Light detection and ranging (LiDAR) sampling or full-area coverage is deemed as favorable means to achieve timely and robust characterizations of forests. Recently, a 3D segmentation approach was developed for extracting single trees from LiDAR data. However, key parameters for modules used in
[...] Read more.
Light detection and ranging (LiDAR) sampling or full-area coverage is deemed as favorable means to achieve timely and robust characterizations of forests. Recently, a 3D segmentation approach was developed for extracting single trees from LiDAR data. However, key parameters for modules used in the strategy had to be empirically determined. This paper highlights a comprehensive study for the sensitivity analysis of 3D single tree detection from airborne LiDAR data. By varying key parameters, their influences on results are to be quantified. The aim of the study is to enlighten the optimal combination of parameter values towards new applications. For the experiment, a number of sample plots from two temperate forest sites in Europe were selected. LiDAR data with a point density of 25 pts/m2 over the first site in the Bavarian forest national park were captured with under both leaf-on and leaf-off conditions. Moreover, a Riegl scanner was used to acquire data over the Austrian Alps forest with four-fold point densities of 5 pts/m2, 10 pts/m2, 15 pts/m2 and 20 pts/m2, respectively, under leaf-off conditions. The study results proved the robustness and efficiency of the 3D segmentation approach. Point densities larger than 10 pts/m2 did not seem to significantly contribute to the improvement in the performance of 3D tree detection. The performance of the approach can be further examined and improved by optimizing the parameter settings with respect to different data properties and forest structures. Full article
Open AccessArticle Governing Forest Landscape Restoration: Cases from Indonesia
Forests 2014, 5(6), 1143-1162; doi:10.3390/f5061143
Received: 20 January 2014 / Revised: 16 May 2014 / Accepted: 20 May 2014 / Published: 28 May 2014
Cited by 6 | PDF Full-text (662 KB) | HTML Full-text | XML Full-text
Abstract
Forest landscape restoration includes both the planning and implementation of measures to restore degraded forests within the perspective of the wider landscape. Governing forest landscape restoration requires fundamental considerations about the conceptualisation of forested landscapes and the types of restoration measures to be
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Forest landscape restoration includes both the planning and implementation of measures to restore degraded forests within the perspective of the wider landscape. Governing forest landscape restoration requires fundamental considerations about the conceptualisation of forested landscapes and the types of restoration measures to be taken, and about who should be engaged in the governance process. A variety of governance approaches to forest landscape restoration exist, differing in both the nature of the object to be governed and the mode of governance. This paper analyses the nature and governance of restoration in three cases of forest landscape restoration in Indonesia. In each of these cases, both the original aim for restoration and the initiators of the process differ. The cases also differ in how deeply embedded they are in formal spatial planning mechanisms at the various political scales. Nonetheless, the cases show similar trends. All cases show a dynamic process of mobilising the landscape’s stakeholders, plus a flexible process of crafting institutional space for conflict management, negotiation and decision making at the landscape level. As a result, the landscape focus changed over time from reserved forests to forested mosaic lands. The cases illustrate that the governance of forest landscape restoration should not be based on strict design criteria, but rather on a flexible governance approach that stimulates the creation of novel public-private institutional arrangements at the landscape level. Full article
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Open AccessArticle Wood Density-Climate Relationships Are Mediated by Dominance Class in Black Spruce (Picea mariana (Mill.) B.S.P.)
Forests 2014, 5(6), 1163-1184; doi:10.3390/f5061163
Received: 28 February 2014 / Revised: 8 May 2014 / Accepted: 20 May 2014 / Published: 28 May 2014
Cited by 1 | PDF Full-text (1045 KB) | HTML Full-text | XML Full-text
Abstract
The relationships between climate and wood density components, i.e., minimum ring density, maximum ring density and mean ring density have been studied mainly in dominant trees. However, the applicability of the findings to trees of other dominance classes is unclear. The aim
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The relationships between climate and wood density components, i.e., minimum ring density, maximum ring density and mean ring density have been studied mainly in dominant trees. However, the applicability of the findings to trees of other dominance classes is unclear. The aim of this study was to address whether climate differentially influences wood density components among dominance classes. X-ray densitometry data was obtained from 72 black spruce (Picea mariana (Mill.) B.S.P.) trees harvested in Northwestern Ontario, Canada. Dominant, co-dominant and intermediate trees were sampled and the data analysed using mixed-effect modelling techniques. For each density component, models were first fitted to the pooled data using ring width and cambial age as predictors, before monthly climatic variables were integrated into the models. Then, separate models were fitted to the data from each dominance class. In general, the addition of climatic factors led to a small but significant improvement in model performance. The predicted historical trends were well synchronized with the observed data. Our results indicate that trees from all dominance classes in a stand should be sampled in order to fully characterize wood density-climate relationships. Full article
Open AccessCommunication Discovery of Walnut Twig Beetle, Pityophthorus juglandis, Associated with Forested Black Walnut, Juglans nigra, in the Eastern U.S.
Forests 2014, 5(6), 1185-1193; doi:10.3390/f5061185
Received: 18 March 2014 / Revised: 9 May 2014 / Accepted: 21 May 2014 / Published: 28 May 2014
Cited by 3 | PDF Full-text (768 KB) | HTML Full-text | XML Full-text
Abstract
Thousand cankers disease (TCD) is an insect-mediated disease of walnut trees (Juglans spp.) involving walnut twig beetle (Pityophthorus juglandis) and a fungal pathogen (Geosmithia morbida). Although first documented on walnut species in the western U.S., TCD is now
[...] Read more.
Thousand cankers disease (TCD) is an insect-mediated disease of walnut trees (Juglans spp.) involving walnut twig beetle (Pityophthorus juglandis) and a fungal pathogen (Geosmithia morbida). Although first documented on walnut species in the western U.S., TCD is now found on black walnut (J. nigra) in five states in the eastern U.S. Most collections of P. juglandis or G. morbida are from trees in agriculturally- or residentially-developed landscapes. In 2013, 16 pheromone-baited funnel traps were deployed in or near black walnuts in forested conditions to assess the risk of infestation of forested trees by P. juglandis. Four of the 16 funnel traps collected adult P. juglandis from three forested areas (one in North Carolina and two in Tennessee). These collections, while in forested settings, may still be strongly influenced by human activities. The greatest number of P. juglandis (n = 338) was collected from a forested location in an urbanized area near a known TCD-positive tree. The other two forested locations where P. juglandis (n = 3) was collected were in areas where camping is common, and infested firewood may have introduced P. juglandis unintentionally into the area. Future studies to assess P. juglandis on more isolated forested walnuts are planned. Full article
Open AccessArticle Growth Response of Northern White-Cedar (Thuja occidentalis) to Natural Disturbances and Partial Cuts in Mixedwood Stands of Quebec, Canada
Forests 2014, 5(6), 1194-1211; doi:10.3390/f5061194
Received: 15 April 2014 / Revised: 20 May 2014 / Accepted: 21 May 2014 / Published: 28 May 2014
Cited by 3 | PDF Full-text (1439 KB) | HTML Full-text | XML Full-text
Abstract
Northern white-cedar (Thuja occidentalis) is a species of high commercial and ecological value, the abundance of which has been declining since the middle of the 19th century. Very little information regarding its silviculture in mixedwood stands is currently available, even though
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Northern white-cedar (Thuja occidentalis) is a species of high commercial and ecological value, the abundance of which has been declining since the middle of the 19th century. Very little information regarding its silviculture in mixedwood stands is currently available, even though a significant portion of wood resources comes from these stands. The present study is a retrospective analysis of white-cedar growth in partially harvested mixedwood stands of western Quebec, Canada. Eight stands distributed across two regions were analyzed. Dendrochronological approaches examined long-term diameter growth for sample white-cedar trees and stems of associated species. These approaches were used to reconstruct stand characteristics at the time of harvesting, together with local harvesting intensity. The study demonstrated white-cedar’s capacity to maintain good growth for long periods of time and at large tree sizes. Accession to the upper canopy positions occurs through repeated episodes of suppression/release, most of which seem to be associated with spruce budworm (Choristoneura fumiferana) outbreaks. White-cedar response to partial harvesting varies with tree size, residual basal area and species composition. Growth response was generally stronger for small trees, even though large trees still maintained the best diameter growth. Growth of white-cedar was negatively affected by an increase in softwood proportion in basal area. Growth responses to harvesting could be sustained for a period of 20 years. Full article
Open AccessArticle Estimating Soil Displacement from Timber Extraction Trails in Steep Terrain: Application of an Unmanned Aircraft for 3D Modelling
Forests 2014, 5(6), 1212-1223; doi:10.3390/f5061212
Received: 22 April 2014 / Revised: 20 May 2014 / Accepted: 27 May 2014 / Published: 10 June 2014
Cited by 4 | PDF Full-text (5789 KB) | HTML Full-text | XML Full-text
Abstract
Skid trails constructed for timber extraction in steep terrain constitute a serious environmental concern if not well planned, executed and ameliorated. Carrying out post-harvest surveys in monitoring constructed trails in such terrain is an onerous task for forest administrators, as hundreds of meters
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Skid trails constructed for timber extraction in steep terrain constitute a serious environmental concern if not well planned, executed and ameliorated. Carrying out post-harvest surveys in monitoring constructed trails in such terrain is an onerous task for forest administrators, as hundreds of meters need to be surveyed per site, and the quantification of parameters and volumes is largely based on assumptions of trail symmetry and terrain uniformity. In this study, aerial imagery captured from a multi-rotor Unmanned Aerial Vehicle was used in generating a detailed post-harvest terrain model which included all skid trails. This was then compared with an Airborne Laser Scanning derived pre-harvest terrain model and the dimensions, slopes and cut-and-fill volumes associated with the skid trails were determined. The overall skid trail length was 954 m, or 381 m·ha−1 with segments varying from 40–60 m, inclinations from 3.9% to 9.6%, and cut volumes, from 1.7 to 3.7 m3 per running meter. The methods used in this work can be used in rapidly assessing the extent of disturbance and erosion risk on a wide range of sites. The multi-rotor Unmanned Aerial Vehicle (UAV) was found to be highly suited to the task, given the relatively small size of harvested stands, their shape and their location in the mountainous terrain. Full article
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Open AccessArticle Vulnerability of Plantation Carbon Stocks to Defoliation under Current and Future Climates
Forests 2014, 5(6), 1224-1242; doi:10.3390/f5061224
Received: 16 April 2014 / Revised: 22 May 2014 / Accepted: 26 May 2014 / Published: 10 June 2014
Cited by 2 | PDF Full-text (497 KB) | HTML Full-text | XML Full-text
Abstract
Plantation species globally are susceptible to a range of defoliating pests, but pest damage is rarely considered when estimating biomass C sequestered by these forests. We examined the impacts of defoliation on Eucalyptus globulus plantation C stocks under current and future climates using
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Plantation species globally are susceptible to a range of defoliating pests, but pest damage is rarely considered when estimating biomass C sequestered by these forests. We examined the impacts of defoliation on Eucalyptus globulus plantation C stocks under current and future climates using Mycospharella Leaf Disease (MLD) as a case study, hypothesising that biomass C sequestered in plantations would decrease with a warming and drying climate, and that impacts of defoliation would be strongly site dependent. Six E. globulus plantation sites with varying productivity were selected for the study. Current (1961–2005) and future (2030 and 2070) severity and frequency of MLD were estimated for each site using the bioclimatic niche model CLIMEX, and used as inputs to the process-based forest productivity model CABALA. CABALA was used to develop annual estimates of total living and dead biomass for current, 2030 and 2070 climate scenarios. Averaged annual biomass outputs were used to initialise the carbon accounting model FullCAM for calculation of C sequestered in living and dead biomass over a growing cycle. E. globulus plantations were predicted to sequester between 4.8 and 13.4 Mg C·ha−1·year−1 over 10 years under current climatic conditions. While our estimates suggest that overall this is likely to increase slightly under future climates (up to a maximum of 17.2 Mg C·ha−1·year−1 in 2030, and a shift in minimum and maximum values to 7.6 and 17.6 respectively in 2070), we predict considerable between-site variation. Our results suggest that biomass C sequestration will not necessarily be enhanced by future climatic conditions in all locations. We predict that biomass C sequestration may be reduced considerably by defoliation meaning that any gains in C sequestration associated with changing climate may be substantially offset by defoliation. While defoliation has a generally small impact under current climatic conditions in these plantations, the impact is likely to increase in the future, with reductions of up to 40% predicted for some sites under future climates. We conclude that the combined impacts of climate change on pest frequency and severity, and on host responses to defoliation, may reduce biomass C sequestration in E. globulus plantations in the future. Full article
(This article belongs to the Special Issue Forest and Wood Vegetation Carbon Stores and Sequestration)
Open AccessArticle Comparative Structural Dynamics of the Janj Mixed Old-Growth Mountain Forest in Bosnia and Herzegovina: Are Conifers in a Long-Term Decline?
Forests 2014, 5(6), 1243-1266; doi:10.3390/f5061243
Received: 16 April 2014 / Revised: 12 May 2014 / Accepted: 20 May 2014 / Published: 10 June 2014
Cited by 7 | PDF Full-text (1611 KB) | HTML Full-text | XML Full-text
Abstract
Regression of conifers in European mixed old-growth mountain forests has been observed for a long period and studied from different aspects. Old-growth (OG) forests in Bosnia and Herzegovina (BiH) have not experienced heavy air pollution and chronic overbrowsing that have affected many other
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Regression of conifers in European mixed old-growth mountain forests has been observed for a long period and studied from different aspects. Old-growth (OG) forests in Bosnia and Herzegovina (BiH) have not experienced heavy air pollution and chronic overbrowsing that have affected many other European OG forests, while climatic and anthropogenic disturbances have been well documented. We analysed stand structure in the Janj OG forest, compared it with inventories of Lom and Perucica OG forests (BiH) and with earlier inventories of the same reserves. At present, OG forest Janj is characterized by a high growing stock (1215 m3∙ha−1). This is due to good site quality, prevalence of conifers (84%) and dominant endogenous processes in recent decades. In all three OG forests, indicators of structural change exhibited progression of European beech over time. Historical evidence revealed the occurrence of warm summers and droughts followed by bark beetle outbreaks in the 1920s, 1940s and early 1950s, which in turn influenced a marked conifer decline. It seems likely that repeated canopy opening released waves of European beech regeneration. These stand structural changes have delayed the rejuvenation of conifers and can help explain the early observations of conifer decline. Full article
Open AccessArticle Mapping Forest Biomass Using Remote Sensing and National Forest Inventory in China
Forests 2014, 5(6), 1267-1283; doi:10.3390/f5061267
Received: 21 January 2014 / Revised: 19 April 2014 / Accepted: 29 May 2014 / Published: 11 June 2014
Cited by 9 | PDF Full-text (2068 KB) | HTML Full-text | XML Full-text
Abstract
Quantifying the spatial pattern of large-scale forest biomass can provide a general picture of the carbon stocks within a region and is of great scientific and political importance. The combination of the advantages of remote sensing data and field survey data can reduce
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Quantifying the spatial pattern of large-scale forest biomass can provide a general picture of the carbon stocks within a region and is of great scientific and political importance. The combination of the advantages of remote sensing data and field survey data can reduce uncertainty as well as demonstrate the spatial distribution of forest biomass. In this study, the seventh national forest inventory statistics (for the period 2004–2008) and the spatially explicit MODIS Land Cover Type product (MCD12C1) were used together to quantitatively estimate the spatially-explicit distribution of forest biomass in China (with a resolution of 0.05°, ~5600 m). Our study demonstrated that the calibrated forest cover proportion maps allow proportionate downscaling of regional forest biomass statistics to forest cover pixels to produce a relatively fine-resolution biomass map. The total stock of forest biomass in China was 11.9 Pg with an average of 76.3 Mg ha−1 during the study period; the high values were located in mountain ranges in northeast, southwest and southeast China and were strongly correlated with forest age and forest density. Full article
(This article belongs to the Special Issue Applications of Remote Sensing to Forestry)
Open AccessArticle Forest Cover Database Updates Using Multi-Seasonal RapidEye Data—Storm Event Assessment in the Bavarian Forest National Park
Forests 2014, 5(6), 1284-1303; doi:10.3390/f5061284
Received: 26 February 2014 / Revised: 19 May 2014 / Accepted: 29 May 2014 / Published: 11 June 2014
Cited by 4 | PDF Full-text (3525 KB) | HTML Full-text | XML Full-text
Abstract
This study is a part of a research program that investigates the potential of RapidEye (RE) satellite data for timely updates of forest cover databases to reflect both regular management activities and sudden changes due to bark beetle and storms. Applied here in
[...] Read more.
This study is a part of a research program that investigates the potential of RapidEye (RE) satellite data for timely updates of forest cover databases to reflect both regular management activities and sudden changes due to bark beetle and storms. Applied here in the Bavarian Forest National Park (BFNP) in southeastern Germany, this approach detected even small changes between two data takes, thus, facilitating documentation of regular management activities. In the case of a sudden event, forest cover databases also serve as a baseline for damage assessment. A storm event, which occurred on 13 July, 2011, provided the opportunity to assess the effectiveness of multi-seasonal RE data for rapid damage assessment. Images of sufficient quality (<20% cloud cover) acquired one day before the storm event were used as a baseline. Persistent cloud cover meant that the first “after event” image of sufficient quality was acquired six weeks later, on 22 August, 2011. Aerial images (AI) for the official damage assessment done by the BFNP administration were acquired on that same day. The RE analysis for damage assessment was completed two weeks after the post-event data take with an overall accuracy of 96% and a kappa coefficient of 0.86. In contrast, the official aerial image survey from the BFNP was first released in late November, eleven weeks later. Comparison of the results from the two analyses showed a difference in the detected amount of forest cover loss of only 3%. The estimated cost of the RE approach was four times less than that of the standard digital AI procedure employed by the BFNP. Full article
(This article belongs to the Special Issue Applications of Remote Sensing to Forestry)
Open AccessArticle Evaluation and Comparison of QuickBird and ADS40-SH52 Multispectral Imagery for Mapping Iberian Wild Pear Trees (Pyrus bourgaeana, Decne) in a Mediterranean Mixed Forest
Forests 2014, 5(6), 1304-1330; doi:10.3390/f5061304
Received: 9 January 2014 / Revised: 15 April 2014 / Accepted: 29 May 2014 / Published: 11 June 2014
Cited by 3 | PDF Full-text (2182 KB) | HTML Full-text | XML Full-text
Abstract
The availability of images with very high spatial and spectral resolution from airborne sensors or those aboard satellites is opening new possibilities for the analysis of fine-scale vegetation, such as the identification and classification of individual tree species. To evaluate the potential of
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The availability of images with very high spatial and spectral resolution from airborne sensors or those aboard satellites is opening new possibilities for the analysis of fine-scale vegetation, such as the identification and classification of individual tree species. To evaluate the potential of these images, a study was carried out to compare the spatial, spectral and temporal resolution between QuickBird and ADS40-SH52 imagery, in order to discriminate and identify, within the mixed Mediterranean forest, individuals of the Iberian wild pear (Pyrus bourgaeana). This is a typical species of the Mediterranean forest, but its biology and ecology are still poorly known. The images were subjected to different correction processes and data were homogenized. Vegetation classes and individual trees were identified on the images, which were classified from two types of supervised classification (Maximum Likelihood and Support Vector Machines) on a pixel-by-pixel basis. The classification values were satisfactory. The classifiers were compared, and Support Vector Machines was the algorithm that provided the best results in terms of overall accuracy. The QuickBird image showed higher overall accuracy (86.16%) when the Support Vector Machines algorithm was applied. In addition, individuals of Iberian wild pear were discriminated with probability of over 55%, when the Maximum Likelihood algorithm was applied. From the perspective of improving the sampling effort, these results are a starting point for facilitating research on the abundance, distribution and spatial structure of P. bourgaeana at different scales, in order to quantify the conservation status of this species. Full article
(This article belongs to the Special Issue Applications of Remote Sensing to Forestry)
Open AccessArticle Performance of Oak Seedlings Grown under Different Oust® XP Regimes
Forests 2014, 5(6), 1331-1340; doi:10.3390/f5061331
Received: 24 March 2014 / Revised: 31 May 2014 / Accepted: 5 June 2014 / Published: 11 June 2014
PDF Full-text (186 KB) | HTML Full-text | XML Full-text
Abstract
Herbaceous weed control (HWC) is prescribed for growing season control of vegetative competition in hardwood afforestation attempts on former agricultural areas. Without HWC, planted seedlings often exhibit poor growth and survival. While currently employed HWC methods are proven, there is a substantial void
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Herbaceous weed control (HWC) is prescribed for growing season control of vegetative competition in hardwood afforestation attempts on former agricultural areas. Without HWC, planted seedlings often exhibit poor growth and survival. While currently employed HWC methods are proven, there is a substantial void in research comparing HWC treatments spanning multiple years. A total of 4,320 bare-root seedlings of three oak species were planted on three Mississippi sites. All sites were of comparable soils and received above average precipitation for the majority of the three-year study. Eight combinations of HWC and mechanical site preparation were utilized at each site, with 480 seedlings planted in each of the nine blocks, and a total of 1,440 seedlings per species planted across all sites. Treatments were installed on 3.1 m centers, with mechanical treatments as follows: control, subsoiling, bedding, and combination plowing. HWC treatments included one and two-year applications of Oust® XP. Treatments were applied over seedlings post-planting in 1.5 m bands, at a rate of 140.1 g product/hectare. Excepting one species, HWC dependent height or groundline diameter differences were not detected among mechanical treatments, species, HWC regime, or combinations thereof. No survival differences were observed among site preparation treatments or species. However, analysis detected a growing season/HWC treatment interaction for seedling survival. Full article
Open AccessArticle Innovation Insights from North American Forest Sector Research: A Literature Review
Forests 2014, 5(6), 1341-1355; doi:10.3390/f5061341
Received: 11 April 2014 / Revised: 24 May 2014 / Accepted: 5 June 2014 / Published: 12 June 2014
Cited by 7 | PDF Full-text (205 KB) | HTML Full-text | XML Full-text
Abstract
The promise of increased industry competitiveness through innovation has driven interest in innovation by industry managers, policy makers and academicians. Forest sector researchers have produced a strong body of work in recent years. This article provides a review of work originating in North
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The promise of increased industry competitiveness through innovation has driven interest in innovation by industry managers, policy makers and academicians. Forest sector researchers have produced a strong body of work in recent years. This article provides a review of work originating in North America during the period 2000–2013. The review includes 28 journal articles focused on the forest sector in the U.S. and Canada. Seven important themes from the literature are identified and discussed: defining innovation and innovativeness; measuring innovativeness; factors influencing innovativeness; new product development; climate/culture; innovation systems; and innovativeness and firm performance. The positive culture and climate within a company has a clear connection to improved innovativeness and firm performance. Generally, findings describing the culture of the forest sector show a conservative group that fails to sufficiently invest in innovativeness and innovation. Culture change presents a significant opportunity within the industry to strive toward the improved development of new products, processes and business systems to reap the rewards of improved performance. The implications for managers and researchers are outlined. Full article
Open AccessArticle Mapping Above- and Below-Ground Biomass Components in Subtropical Forests Using Small-Footprint LiDAR
Forests 2014, 5(6), 1356-1373; doi:10.3390/f5061356
Received: 4 April 2014 / Revised: 8 May 2014 / Accepted: 10 June 2014 / Published: 16 June 2014
Cited by 5 | PDF Full-text (1033 KB) | HTML Full-text | XML Full-text
Abstract
In order to better assess the spatial variability in subtropical forest biomass, the goal of our study was to use small-footprint, discrete-return Light Detection and Ranging (LiDAR) data to accurately estimate and map above- and below-ground biomass components of subtropical forests. Foliage, branch,
[...] Read more.
In order to better assess the spatial variability in subtropical forest biomass, the goal of our study was to use small-footprint, discrete-return Light Detection and Ranging (LiDAR) data to accurately estimate and map above- and below-ground biomass components of subtropical forests. Foliage, branch, trunk, root, above-ground and total biomass of 53 plots (30 × 30 m) were modeled using a range of LiDAR-derived metrics, with individual models built for each of the three dominant forest types using stepwise multi-regression analysis. A regular grid covered the entire study site with cell size 30 × 30 m corresponding to the same size of the plots; it was generated for mapping each biomass component. Overall, results indicate that biomass estimation was more accurate in coniferous forests, compared with the mixed and broadleaved plots. The coefficient of determination (R2) for individual models was significantly enhanced compared with an overall generic, or common, model. Using independent stand-level data from ground inventory, our results indicated that overall the model fit was significant for most of the biomass components, with relationships close to a 1:1 line, thereby indicating no significant bias. This research illustrates the potential for LiDAR as a technology to assess subtropical forest carbon accurately and to provide a better understanding of how forest ecosystems function in this region. Full article
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Open AccessArticle LiDAR Remote Sensing of Forest Structure and GPS Telemetry Data Provide Insights on Winter Habitat Selection of European Roe Deer
Forests 2014, 5(6), 1374-1390; doi:10.3390/f5061374
Received: 10 March 2014 / Revised: 10 May 2014 / Accepted: 10 June 2014 / Published: 16 June 2014
Cited by 8 | PDF Full-text (1166 KB) | HTML Full-text | XML Full-text
Abstract
The combination of GPS-Telemetry and resource selection functions is widely used to analyze animal habitat selection. Rapid large-scale assessment of vegetation structure allows bridging the requirements of habitat selection studies on grain size and extent, particularly in forest habitats. For roe deer, the
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The combination of GPS-Telemetry and resource selection functions is widely used to analyze animal habitat selection. Rapid large-scale assessment of vegetation structure allows bridging the requirements of habitat selection studies on grain size and extent, particularly in forest habitats. For roe deer, the cold period in winter forces individuals to optimize their trade off in searching for food and shelter. We analyzed the winter habitat selection of roe deer (Capreolus capreolus) in a montane forest landscape combining estimates of vegetation cover in three different height strata, derived from high resolution airborne Laser-scanning (LiDAR, Light detection and ranging), and activity data from GPS telemetry. Specifically, we tested the influence of temperature, snow height, and wind speed on site selection, differentiating between active and resting animals using mixed-effects conditional logistic regression models in a case-control design. Site selection was best explained by temperature deviations from hourly means, snow height, and activity status of the animals. Roe deer tended to use forests of high canopy cover more frequently with decreasing temperature, and when snow height exceeded 0.6 m. Active animals preferred lower canopy cover, but higher understory cover. Our approach demonstrates the potential of LiDAR measures for studying fine scale habitat selection in complex three-dimensional habitats, such as forests. Full article
Open AccessArticle Soil Organic Carbon in Particle Size and Density Fractionations under Four Forest Vegetation-Land Use Types in Subtropical China
Forests 2014, 5(6), 1391-1408; doi:10.3390/f5061391
Received: 21 January 2014 / Revised: 19 April 2014 / Accepted: 29 May 2014 / Published: 17 June 2014
PDF Full-text (649 KB) | HTML Full-text | XML Full-text
Abstract
Data on the effect of vegetation and land use type on soil organic carbon (SOC) distribution in particle-size and density fractions in the subtropical forest region in China will improve our understanding of the C sequestration potential of those different vegetation-land use types.
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Data on the effect of vegetation and land use type on soil organic carbon (SOC) distribution in particle-size and density fractions in the subtropical forest region in China will improve our understanding of the C sequestration potential of those different vegetation-land use types. We quantified SOC in particle size (coarse, medium and fine) and density fractions (light and heavy) under four types of common forest vegetation-land uses: an evergreen broad-leaf forest, a pine forest, a managed chestnut forest and an intensively managed bamboo forest in subtropical China. The SOC in the 0–20 and 20–40 cm soil layers was the highest in the bamboo forest (31.6–34.8 g·C·kg−1), followed by the evergreen broad-leaf forest (10.2–19.9 g·C·kg−1), the pine forest (8.5–13.6 g·C·kg−1) and the chestnut forest (6.3–12.2 g·C·kg−1). The SOC was largely in the coarse fraction under the evergreen broad-leaf, pine and bamboo forests, while it was largely in the fine fraction in the chestnut forest, suggesting that SOC in the chestnut forest was likely more stable than that in the other forest vegetation-land use types. The SOC in the light fraction under the four forest vegetation-land use types ranged from 1.4 to 13.1 g·C·kg−1 soil, representing 21%–37% of the total organic C; this suggests that the majority of the SOC was in the better protected, heavy fraction. We conclude that forest vegetation-land use type (and the associated management practices) influenced SOC distribution in particle size and density fractions in the studied subtropical forests in southeastern China. Full article
Open AccessArticle Analyzing Trade-Offs, Synergies, and Drivers among Timber Production, Carbon Sequestration, and Water Yield in Pinus elliotii Forests in Southeastern USA
Forests 2014, 5(6), 1409-1431; doi:10.3390/f5061409
Received: 13 February 2014 / Revised: 24 May 2014 / Accepted: 9 June 2014 / Published: 20 June 2014
Cited by 10 | PDF Full-text (900 KB) | HTML Full-text | XML Full-text
Abstract
Managing Pinus elliotii forests for timber production and/or carbon sequestration is a common management objective, but can negatively affect water yield due to high losses from evapotranspiration. Thus, understanding the trade-offs and potential synergies among multiple ecosystem goods services, as well as the
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Managing Pinus elliotii forests for timber production and/or carbon sequestration is a common management objective, but can negatively affect water yield due to high losses from evapotranspiration. Thus, understanding the trade-offs and potential synergies among multiple ecosystem goods services, as well as the drivers influencing these interactions, can help identify effective forest management practices. We used available data from 377 permanent plots from the USDA Forest Service Forest Inventory and Analysis Program for 2002–2011, and a forest water yield model to quantify provision levels and spatial distribution and patterns of carbon sequestration, timber volume and water yield for Pinus elliotii ecosystems in North Florida, USA. A ranking-classification framework and statistical analyses were used to better understand the interactions among ecosystem services and the effect of biophysical drivers on ecosystem service bundles. Results indicate that increased biomass reduced water yield but this trade-off varied across space. Specific synergies, or acceptable provision levels, among carbon sequestration, timber volume and water yield were identified and mapped. Additionally, stand age, silvicultural treatment, and site quality significantly affected the provision level of, and interactions among, the three ecosystem goods and services. The framework developed in this study can be used to assess, map, and manage subtropical forests for optimal provision of ecosystem services. Full article
Open AccessArticle Quantifying Ladder Fuels: A New Approach Using LiDAR
Forests 2014, 5(6), 1432-1453; doi:10.3390/f5061432
Received: 28 February 2014 / Revised: 3 June 2014 / Accepted: 10 June 2014 / Published: 20 June 2014
Cited by 4 | PDF Full-text (4449 KB) | HTML Full-text | XML Full-text
Abstract
We investigated the relationship between LiDAR and ladder fuels in the northern Sierra Nevada, California USA. Ladder fuels are often targeted in hazardous fuel reduction treatments due to their role in propagating fire from the forest floor to tree crowns. Despite their importance,
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We investigated the relationship between LiDAR and ladder fuels in the northern Sierra Nevada, California USA. Ladder fuels are often targeted in hazardous fuel reduction treatments due to their role in propagating fire from the forest floor to tree crowns. Despite their importance, ladder fuels are difficult to quantify. One common approach is to calculate canopy base height, but this has many potential sources of error. LiDAR may be a way forward to better characterize ladder fuels, but has only been used to address this question peripherally and in only a few instances. After establishing that landscape fuel treatments reduced canopy and ladder fuels at our site, we tested which LiDAR-derived metrics best differentiated treated from untreated areas. The percent cover between 2 and 4 m had the most explanatory power to distinguish treated from untreated pixels across a range of spatial scales. When compared to independent plot-based measures of ladder fuel classes, this metric differentiated between high and low levels of ladder fuels. These findings point to several immediate applications for land managers and suggest new avenues of study that could lead to possible improvements in the way that we model wildfire behavior across forested landscapes in the US. Full article
Open AccessArticle Interest of a Full-Waveform Flown UV Lidar to Derive Forest Vertical Structures and Aboveground Carbon
Forests 2014, 5(6), 1454-1480; doi:10.3390/f5061454
Received: 12 December 2013 / Revised: 22 April 2014 / Accepted: 10 June 2014 / Published: 20 June 2014
Cited by 5 | PDF Full-text (2004 KB) | HTML Full-text | XML Full-text
Abstract
Amongst all the methodologies readily available to estimate forest canopy and aboveground carbon (AGC), in-situ plot surveys and airborne laser scanning systems appear to be powerful assets. However, they are limited to relatively local scales. In this work, we have developed a full-waveform
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Amongst all the methodologies readily available to estimate forest canopy and aboveground carbon (AGC), in-situ plot surveys and airborne laser scanning systems appear to be powerful assets. However, they are limited to relatively local scales. In this work, we have developed a full-waveform UV lidar, named ULICE (Ultraviolet LIdar for Canopy Experiment), as an airborne demonstrator for future space missions, with an eventual aim to retrieve forest properties at the global scale. The advantage of using the UV wavelength for a demonstrator is its low multiple scattering in the canopy. Based on realistic airborne lidar data from the well-documented Fontainebleau forest site (south-east of Paris, France), which is representative of managed deciduous forests in temperate climate zones, we estimate the uncertainties in the retrieval of forest vertical structures and AGC. A complete uncertainty study using Monte Carlo approaches is performed for both the lidar-derived tree top height (TTH) and AGC. Our results show a maximum error of 1.2 m (16 tC ha‑1) for the TTH (AGC) assessment. Furthermore, the study of leaf effect on AGC estimate for mid-latitude deciduous forests highlights the possibility for using calibration obtained during only one season to retrieve the AGC during the other, by applying winter and summer airborne measurements. Full article
Open AccessArticle Small Drones for Community-Based Forest Monitoring: An Assessment of Their Feasibility and Potential in Tropical Areas
Forests 2014, 5(6), 1481-1507; doi:10.3390/f5061481
Received: 11 February 2014 / Revised: 6 June 2014 / Accepted: 16 June 2014 / Published: 24 June 2014
Cited by 19 | PDF Full-text (639 KB) | HTML Full-text | XML Full-text
Abstract
Data gathered through community-based forest monitoring (CBFM) programs may be as accurate as those gathered by professional scientists, but acquired at a much lower cost and capable of providing more detailed data about the occurrence, extent and drivers of forest loss, degradation and
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Data gathered through community-based forest monitoring (CBFM) programs may be as accurate as those gathered by professional scientists, but acquired at a much lower cost and capable of providing more detailed data about the occurrence, extent and drivers of forest loss, degradation and regrowth at the community scale. In addition, CBFM enables greater survey repeatability. Therefore, CBFM should be a fundamental component of national forest monitoring systems and programs to measure, report and verify (MRV) REDD+ activities. To contribute to the development of more effective approaches to CBFM, in this paper we assess: (1) the feasibility of using small, low-cost drones (i.e., remotely piloted aerial vehicles) in CBFM programs; (2) their potential advantages and disadvantages for communities, partner organizations and forest data end-users; and (3) to what extent their utilization, coupled with ground surveys and local ecological knowledge, would improve tropical forest monitoring. To do so, we reviewed the existing literature regarding environmental applications of drones, including forest monitoring, and drew on our own firsthand experience flying small drones to map and monitor tropical forests and training people to operate them. We believe that the utilization of small drones can enhance CBFM and that this approach is feasible in many locations throughout the tropics if some degree of external assistance and funding is provided to communities. We suggest that the use of small drones can help tropical communities to better manage and conserve their forests whilst benefiting partner organizations, governments and forest data end-users, particularly those engaged in forestry, biodiversity conservation and climate change mitigation projects such as REDD+. Full article

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