Forests

3608 KiB

Open AccessArticle

Forest Inventory with Terrestrial LiDAR: A Comparison of Static and Hand-Held Mobile Laser Scanning

by Sébastien Bauwens, Harm Bartholomeus, Kim Calders and Philippe Lejeune

Forests 2016, 7(6), 127; https://doi.org/10.3390/f7060127 - 21 Jun 2016

Cited by 258 | Viewed by 16996

The application of static terrestrial laser scanning (TLS) in forest inventories is becoming more effective. Nevertheless, the occlusion effect is still limiting the processing efficiency to extract forest attributes. The use of a mobile laser scanner (MLS) would reduce this occlusion. In this [...] Read more.

The application of static terrestrial laser scanning (TLS) in forest inventories is becoming more effective. Nevertheless, the occlusion effect is still limiting the processing efficiency to extract forest attributes. The use of a mobile laser scanner (MLS) would reduce this occlusion. In this study, we assessed and compared a hand-held mobile laser scanner (HMLS) with two TLS approaches (single scan: SS, and multi scan: MS) for the estimation of several forest parameters in a wide range of forest types and structures. We found that SS is competitive to extract the ground surface of forest plots, while MS gives the best result to describe the upper part of the canopy. The whole cross-section at 1.3 m height is scanned for 91% of the trees (DBH > 10 cm) with the HMLS leading to the best results for DBH estimates (bias of −0.08 cm and RMSE of 1.11 cm), compared to no fully-scanned trees for SS and 42% fully-scanned trees for MS. Irregularities, such as bark roughness and non-circular cross-section may explain the negative bias encountered for all of the scanning approaches. The success of using MLS in forests will allow for 3D structure acquisition on a larger scale and in a time-efficient manner. Full article

(This article belongs to the Special Issue Forest Ground Observations through Terrestrial Point Clouds)

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1641 KiB

Open AccessArticle

Influence of Starvation on the Structure of Gut-Associated Bacterial Communities in the Chinese White Pine Beetle (Dendroctonus armandi)

by Xia Hu, Ming Li, Feiping Zhang and Hui Chen

Forests 2016, 7(6), 126; https://doi.org/10.3390/f7060126 - 20 Jun 2016

Cited by 6 | Viewed by 4693

Abstract

This study investigated the influence of starvation on the structure of the gut bacterial community in the Chinese white pine beetle (Dendroctonus armandi). A total of 14 operational taxonomic units (OTUs_0.03) clusters belonging to nine genera were identified. Denaturing [...] Read more.

This study investigated the influence of starvation on the structure of the gut bacterial community in the Chinese white pine beetle (Dendroctonus armandi). A total of 14 operational taxonomic units (OTUs_0.03) clusters belonging to nine genera were identified. Denaturing gradient gel electrophoresis (DGGE) profiles of bacterial PCR-amplified 16S rRNA gene fragments from the guts of starved male and female adults revealed that the bacterial community diversity increased after starvation. The dominant genus Citrobacter decreased significantly, whereas the genus Serratia increased in both starved female and starved male adults. The most predominant bacterial genus in D. armandi adults was Citrobacter, except for starved male adults, in which Serratia was the most abundant genus (27%). Our findings reveal that starvation affects gut bacterial dynamics in D. armandi, as has been observed in other insect species. Full article

(This article belongs to the Special Issue Tree Defense Physiology to Bark Beetles)

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Open AccessArticle

Wildfires Dynamics in Siberian Larch Forests

by Evgenii I. Ponomarev, Viacheslav I. Kharuk and Kenneth J. Ranson

Forests 2016, 7(6), 125; https://doi.org/10.3390/f7060125 - 17 Jun 2016

Cited by 127 | Viewed by 11379

Abstract

Wildfire number and burned area temporal dynamics within all of Siberia and along a south-north transect in central Siberia (45°–73° N) were studied based on NOAA/AVHRR (National Oceanic and Atmospheric Administration/ Advanced Very High Resolution Radiometer) and Terra/MODIS (Moderate Resolution Imaging Spectroradiometer) data [...] Read more.

Wildfire number and burned area temporal dynamics within all of Siberia and along a south-north transect in central Siberia (45°–73° N) were studied based on NOAA/AVHRR (National Oceanic and Atmospheric Administration/ Advanced Very High Resolution Radiometer) and Terra/MODIS (Moderate Resolution Imaging Spectroradiometer) data and field measurements for the period 1996–2015. In addition, fire return interval (FRI) along the south-north transect was analyzed. Both the number of forest fires and the size of the burned area increased during recent decades (p < 0.05). Significant correlations were found between forest fires, burned areas and air temperature (r = 0.5) and drought index (The Standardized Precipitation Evapotranspiration Index, SPEI) (r = −0.43). Within larch stands along the transect, wildfire frequency was strongly correlated with incoming solar radiation (r = 0.91). Fire danger period length decreased linearly from south to north along the transect. Fire return interval increased from 80 years at 62° N to 200 years at the Arctic Circle (66°33’ N), and to about 300 years near the northern limit of closed forest stands (about 71°+ N). That increase was negatively correlated with incoming solar radiation (r = −0.95). Full article

(This article belongs to the Special Issue Fire Regimes: Spatial and Temporal Variability and Their Effects on Forests)

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2097 KiB

Open AccessArticle

Enhancing Stand Structure through Snag Creation in Northeastern U.S. Forests: Using Ethanol Injections and Bark Beetle Pheromones to Artificially Stress Red Maple and White Pine

by Kevin J. Dodds, Ryan P. Hanavan and Tom Wansleben

Forests 2016, 7(6), 124; https://doi.org/10.3390/f7060124 - 15 Jun 2016

Cited by 4 | Viewed by 5100

Abstract

We investigated two methods to create white pine and red maple snags in a forested setting. The first involved injecting trees with ethanol at two times (single Ethanol (ETOH) and double ETOH injections) to increase attractiveness to insects and elicit attacks on trees. [...] Read more.

We investigated two methods to create white pine and red maple snags in a forested setting. The first involved injecting trees with ethanol at two times (single Ethanol (ETOH) and double ETOH injections) to increase attractiveness to insects and elicit attacks on trees. The second method was unique to white pines and involved both injection treatments in combination with baiting trees with Ips-specific pheromones. Three of five white pines from the double ETOH treatment died in the second year. Species including Ips pini (Say), Ips grandicollis Eichhoff, Orthotomicus caelatus Eichhoff, Crypturgus borealis Swaine and Monochamus notatus (Drury) responded more strongly to at least one of the treatments over control trees. However, there were no differences found in individual Scolytinae or Cerambycidae species response to treatments in red maple. Fitness (F_V/F_M) and vitality (PI_abs) were both significantly reduced in both ETOH treatments compared to controls in white pine. In red maple, fitness was reduced in the double ETOH treated trees but the final mean F_V/F_M values were within the approximate optimal of health. Ethanol injections, in combination with Ips-specific semiochemicals, show promise for creating standing coarse woody debris (CWD) in white pine. Injecting ethanol was not effective for stressing red maple. Full article

(This article belongs to the Special Issue Tree Defense Physiology to Bark Beetles)

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622 KiB

Open AccessCorrection

Correction: Wang, J.S., et al. Effects of Nitrogen Addition on Leaf Decomposition of Single-Species and Litter Mixture in Pinus tabulaeformis Forests. Forests, 2015, 6, 4462–4476

by Jinsong Wang, Wensheng Bu, Bo Zhao, Xiuhai Zhao, Chunyu Zhang, Juan Fan and Klaus V. Gadow

Forests 2016, 7(6), 123; https://doi.org/10.3390/f7060123 - 14 Jun 2016

Cited by 1 | Viewed by 3627

Abstract

We discovered typographical errors in two sentences and, therefore, changes are needed to our published manuscript [1].[...] Full article

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Open AccessArticle

Object-Based Tree Species Classification in Urban Ecosystems Using LiDAR and Hyperspectral Data

by Zhongya Zhang, Alexandra Kazakova, Ludmila Monika Moskal and Diane M. Styers

Forests 2016, 7(6), 122; https://doi.org/10.3390/f7060122 - 11 Jun 2016

Cited by 70 | Viewed by 10305

Abstract

In precision forestry, tree species identification is key to evaluating the role of forest ecosystems in the provision of ecosystem services, such as carbon sequestration and assessing their effects on climate regulation and climate change. In this study, we investigated the effectiveness of [...] Read more.

In precision forestry, tree species identification is key to evaluating the role of forest ecosystems in the provision of ecosystem services, such as carbon sequestration and assessing their effects on climate regulation and climate change. In this study, we investigated the effectiveness of tree species classification of urban forests using aerial-based HyMap hyperspectral imagery and light detection and ranging (LiDAR) data. First, we conducted an object-based image analysis (OBIA) to segment individual tree crowns present in LiDAR-derived Canopy Height Models (CHMs). Then, hyperspectral values for individual trees were extracted from HyMap data for band reduction through Minimum Noise Fraction (MNF) transformation which allowed us to reduce the data to 20 significant bands out of 118 bands acquired. Finally, we compared several different classifications using Random Forest (RF) and Multi Class Classifier (MCC) methods. Seven tree species were classified using all 118 bands which resulted in 46.3% overall classification accuracy for RF versus 79.6% for MCC. Using only the 20 optimal bands extracted through MNF, both RF and MCC achieved an increase in overall accuracy to 87.0% and 88.9%, respectively. Thus, the MNF band selection process is a preferable approach for tree species classification when using hyperspectral data. Further, our work also suggests that RF is heavily disadvantaged by the high-dimensionality and noise present in hyperspectral data, while MCC is more robust when handling high-dimensional datasets with small sample sizes. Our overall results indicated that individual tree species identification in urban forests can be accomplished with the fusion of object-based LiDAR segmentation of crowns and hyperspectral characterization. Full article

(This article belongs to the Special Issue LiDAR Remote Sensing of Forest Resources)

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3806 KiB

Open AccessArticle

Spatio-Temporal Changes in Structure for a Mediterranean Urban Forest: Santiago, Chile 2002 to 2014

by Francisco J. Escobedo, Sebastian Palmas-Perez, Cynnamon Dobbs, Salvador Gezan and Jaime Hernandez

Forests 2016, 7(6), 121; https://doi.org/10.3390/f7060121 - 11 Jun 2016

Cited by 31 | Viewed by 7515

Abstract

There is little information on how urban forest ecosystems in South America and Mediterranean climates change across both space and time. This study statistically and spatially analyzed the spatio-temporal dynamics of Santiago, Chile’s urban forest using tree and plot-level data from permanent plots [...] Read more.

There is little information on how urban forest ecosystems in South America and Mediterranean climates change across both space and time. This study statistically and spatially analyzed the spatio-temporal dynamics of Santiago, Chile’s urban forest using tree and plot-level data from permanent plots from 2002 to 2014. We found mortality, ingrowth, and tree cover remained stable over the analysis period and similar patterns were observed for basal area (BA) and biomass. However, tree cover increased, and was greater in the highest socioeconomic stratum neighborhoods while it dropped in the medium and low strata. Growth rates for the five most common tree species averaged from 0.12 to 0.36 cm·year⁻¹. Spatially, tree biomass and BA were greater in the affluent, northeastern sections of the city and in southwest peri-urban areas. Conversely, less affluent central, northwest, and southern areas showed temporal losses in BA and biomass. Overall, we found that Santiago’s urban forest follows similar patterns as in other parts of the world; affluent areas tend to have more and better managed urban forests than poorer areas, and changes are primarily influenced by social and ecological drivers. Nonetheless, care is warranted when comparing urban forest structural metrics measured with similar sampling-monitoring approaches across ecologically disparate regions and biomes. Full article

(This article belongs to the Special Issue Urban and Periurban Forest Diversity and Ecosystem Services)

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Open AccessArticle

How Do Urban Forests Compare? Tree Diversity in Urban and Periurban Forests of the Southeastern US

by Amy Blood, Gregory Starr, Francisco Escobedo, Art Chappelka and Christina Staudhammer

Forests 2016, 7(6), 120; https://doi.org/10.3390/f7060120 - 9 Jun 2016

Cited by 45 | Viewed by 9596

Abstract

There is a need to understand how anthropogenic influences affect urban and periurban forest diversity at the regional scale. This study aims to compare urban and periurban tree composition along a geographic gradient, and test hypotheses about species composition and ecological homogeneity. We [...] Read more.

There is a need to understand how anthropogenic influences affect urban and periurban forest diversity at the regional scale. This study aims to compare urban and periurban tree composition along a geographic gradient, and test hypotheses about species composition and ecological homogeneity. We paired urban forest (UF) data from eight cities across the southeastern US with periurban forest (PF) data from the USDA Forest Service Forest Inventory and Analysis program. We found that tree diversity, as well as both observed and estimated species richness values were greater in UF versus PF. Community size structure analysis also indicated a greater proportion of large trees and greater numbers of non-native, invasive, and unclassified tree species in the UF versus the PF, regardless of location. Both forest type and ecological province had a significant effect on community species composition, with forests closer together in space being more similar to each other than those more distant. While land use change and management has been associated with ecological homogenization in human dominated landscapes, we found that species composition was more dissimilar along latitudinal lines than compared to between forest types, refuting this hypothesis, at least in terms of tree diversity. Full article

(This article belongs to the Special Issue Urban and Periurban Forest Diversity and Ecosystem Services)

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Open AccessArticle

Managing Tree Diversity: A Comparison of Suburban Development in Two Canadian Cities

by Sophie A. Nitoslawski and Peter N. Duinker

Forests 2016, 7(6), 119; https://doi.org/10.3390/f7060119 - 31 May 2016

Cited by 21 | Viewed by 7899

Abstract

Is (sub)urban forest diversity shaped by previous land use? This study was designed to quantitatively assess the impacts of subdivision development on urban tree-species composition in two Canadian cities: Halifax, Nova Scotia, and London, Ontario. The main goal was to determine whether cities [...] Read more.

Is (sub)urban forest diversity shaped by previous land use? This study was designed to quantitatively assess the impacts of subdivision development on urban tree-species composition in two Canadian cities: Halifax, Nova Scotia, and London, Ontario. The main goal was to determine whether cities with contrasting pre-urbanized or pre-settlement landscapes—woodlands in Halifax and agricultural fields in London—also revealed differences in urban tree diversity losses and/or gains due to urbanization. In each city, four residential neighbourhoods representing two age categories, older and newer (40–50 years, <15 years), were examined and trees on three land types were sampled: public (street), private (residential), and remnant (woodland). All public street trees within the chosen neighbourhoods were inventoried and approximately 10% of the residential property lots were sampled randomly. Plots were examined in remnant forests in or near each city, representing the original forest habitats prior to agricultural and/or urban landscape transformations. Diameter at breast height, species richness and evenness, and proportions of native and non-native trees were measured. In both cities, streetscapes in newer neighbourhoods exhibit greater species richness and evenness, and are characterized by substantially more native trees. Despite this trend, developers and home owners continue to intensively plant non-native species on newer and smaller property lots. Older neighbourhoods in Halifax containing remnant forest stands hold the greatest number of native trees on private property, alluding to the importance of residual forest buffers and patches in promoting naturalness in the private urban forest. These results suggest that identifying and quantifying flows of species between green spaces during and after development is valuable in order to effectively promote native species establishment and enhance overall urban forest diversity. Full article

(This article belongs to the Special Issue Urban and Periurban Forest Diversity and Ecosystem Services)

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1339 KiB

Open AccessArticle

Innovation Strategy in Slovak Forest Contractor Firms—A SWOT Analysis

by Martina Štěrbová, Erika Loučanová, Hubert Paluš, Ľubomír Ivan and Jaroslav Šálka

Forests 2016, 7(6), 118; https://doi.org/10.3390/f7060118 - 31 May 2016

Cited by 32 | Viewed by 9543

Abstract

The aim of the study is to determine the innovation strategy of contractor firms in the Slovak forestry service sector in the area of further innovation activities development. The strategy identification was based on the analysis of the strengths, weaknesses, opportunities and threats [...] Read more.

The aim of the study is to determine the innovation strategy of contractor firms in the Slovak forestry service sector in the area of further innovation activities development. The strategy identification was based on the analysis of the strengths, weaknesses, opportunities and threats in this sector. The results indicate that weaknesses of contractor firms exceed their strengths and, considering the degree and importance of their impact, opportunities exceed identified threats. Based on these findings revealing the relations in the area of innovation activities of forestry service contractors, the “Strategy of Partnership” was suggested as the most suitable type of strategy. It can be concluded that such a form of grouping cooperation brings many benefits to contractors in the form of information availability, guidance, training, and management of conflicts, risks and uncertainty, which are associated with the innovation process. Full article

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Open AccessArticle

Fertilization Response, Light Use, and Growth Efficiency in Eucalyptus Plantations across Soil and Climate Gradients in Brazil

by Renato Meulman Leite Da Silva, Rodrigo Eiji Hakamada, José Henrique Bazani, Marina Shinkai Gentil Otto and José Luiz Stape

Forests 2016, 7(6), 117; https://doi.org/10.3390/f7060117 - 31 May 2016

Cited by 18 | Viewed by 5062

Abstract

Fertilization increases productivity in Eucalyptus plantations, but losses in productivity associated with soil fertility continue at operational scales. In this study, we evaluated the fertilization response (FR), light use efficiency (LUE) and growth efficiency (GE), i.e., the amount of wood biomass accumulated [...] Read more.

Fertilization increases productivity in Eucalyptus plantations, but losses in productivity associated with soil fertility continue at operational scales. In this study, we evaluated the fertilization response (FR), light use efficiency (LUE) and growth efficiency (GE), i.e., the amount of wood biomass accumulated per unit of light absorbed (LUE) and per unit of leaf area index of Eucalyptus plantations. We used a “twin plot” approach, with 161 blocks representing 52,700 ha of planted forests that spanned a broad range of edaphoclimatic conditions in southeastern Brazil. The normal plots (NP) were part of a permanent inventory network, whereas the twin plots (TP) received extra high levels of fertilization and extra weed control after fertilization. The intensive management (twin plots) led to a large increase of 5.3 Mg·ha⁻¹·year⁻¹ of wood increment. The region without dry periods and with soils with high clay content was most responsive to fertilization, with a 15% increment in the LUE and 10% increase in the GE of the TPs compared with those of the NPs. Our results suggested that water availability was the primary element affecting productivity and potential response to fertilization. With this information, decisions can be made on which regions should receive priority fertilization investments. However, more research is required to determine the most limiting nutrient in each type of environment. Full article

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Open AccessArticle

Public Opinions and Use of Various Types of Recreational Infrastructure in Boreal Forest Settings

by Vegard Gundersen and Odd Inge Vistad

Forests 2016, 7(6), 113; https://doi.org/10.3390/f7060113 - 31 May 2016

Cited by 19 | Viewed by 5112

Abstract

We have investigated public preferences for use intensity and visual quality of forest recreational infrastructure. Forest infrastructure covers five classes, along a continuum from unmarked paths to paved walkways. Altogether, 39 sites were categorized into the five classes and measured with automatic counters. [...] Read more.

We have investigated public preferences for use intensity and visual quality of forest recreational infrastructure. Forest infrastructure covers five classes, along a continuum from unmarked paths to paved walkways. Altogether, 39 sites were categorized into the five classes and measured with automatic counters. A sample of 545 respondents living in southeastern and middle Norway were asked to rate 15 forest scenes and 35 preconceptions of recreational settings. The path scenarios were depicted as digitally calibrated photos that systematically displayed physical path feature in boreal, semi-natural settings. Survey participants showed a clearly greater preference for photos and preconceptions of forests settings containing minor elements of forest infrastructure; unmarked paths received the highest score and forest roads/walkways/bikeways the lowest. We identified a clear mismatch between public preferences for forest infrastructure and the intensity of use; the less appreciated infrastructure was the most used. Planning and management has to consider these different needs for recreational infrastructure, and we propose an area zoning system that meets the different segments of forest visitors. Full article

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Open AccessArticle

Carbon Sequestration and Sedimentation in Mangrove Swamps Influenced by Hydrogeomorphic Conditions and Urbanization in Southwest Florida

by Daniel A. Marchio, Michael Savarese, Brian Bovard and William J. Mitsch

Forests 2016, 7(6), 116; https://doi.org/10.3390/f7060116 - 30 May 2016

Cited by 58 | Viewed by 11722

Abstract

This study compares carbon sequestration rates along two independent tidal mangrove creeks near Naples Bay in Southwest Florida, USA. One tidal creek is hydrologically disturbed due to upstream land use changes; the other is an undisturbed reference creek. Soil cores were collected in [...] Read more.

This study compares carbon sequestration rates along two independent tidal mangrove creeks near Naples Bay in Southwest Florida, USA. One tidal creek is hydrologically disturbed due to upstream land use changes; the other is an undisturbed reference creek. Soil cores were collected in basin, fringe, and riverine hydrogeomorphic settings along each of the two tidal creeks and analyzed for bulk density, total organic carbon profiles, and sediment accretion. Radionuclides ¹³⁷Cs and ²¹⁰Pb were used to estimate recent sediment accretion and carbon sequestration rates. Carbon sequestration rates (mean ± standard error) for seven sites in the two tidal creeks on the Naples Bay (98 ± 12 g-C m⁻²·year⁻¹ (n = 18)) are lower than published global means for mangrove wetlands, but consistent with other estimates from the same region. Mean carbon sequestration rates in the reference riverine setting were highest (162 ± 5 g-C m⁻²·year⁻¹), followed by rates in the reference fringe and disturbed riverine settings (127 ± 6 and 125 ± 5 g-C m⁻²·year⁻¹, respectively). The disturbed fringe sequestered 73 ± 10 g-C m⁻²·year⁻¹, while rates within the basin settings were 50 ± 4 g-C m⁻²·year⁻¹ and 47 ± 4 g-C m⁻²·year⁻¹ for the reference and disturbed creeks, respectively. These data support our hypothesis that mangroves along a hydrologically disturbed tidal creek sequestered less carbon than did mangroves along an adjacent undisturbed reference creek. Full article

(This article belongs to the Collection Forests Carbon Fluxes and Sequestration)

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2106 KiB

Open AccessCommunication

Surface Soil Carbon Storage in Urban Green Spaces in Three Major South Korean Cities

by Tae Kyung Yoon, Kyung Won Seo, Gwan Soo Park, Yeong Mo Son and Yowhan Son

Forests 2016, 7(6), 115; https://doi.org/10.3390/f7060115 - 28 May 2016

Cited by 16 | Viewed by 6853

Abstract

Quantifying and managing carbon (C) storage in urban green space (UGS) soils is associated with the ecosystem services necessary for human well-being and the national C inventory report of the Intergovernmental Panel on Climate Change (IPCC). Here, the soil C stocks at 30-cm [...] Read more.

Quantifying and managing carbon (C) storage in urban green space (UGS) soils is associated with the ecosystem services necessary for human well-being and the national C inventory report of the Intergovernmental Panel on Climate Change (IPCC). Here, the soil C stocks at 30-cm depths in different types of UGS’s (roadside, park, school forest, and riverside) were studied in three major South Korean cities that have experienced recent, rapid development. The total C of 666 soil samples was analyzed, and these results were combined with the available UGS inventory data. Overall, the mean soil bulk density, C concentration, and C density at 30-cm depths were 1.22 g·cm⁻³, 7.31 g·C·kg⁻¹, and 2.13 kg·C·m⁻², respectively. The UGS soil C stock (Gg·C) at 30-cm depths was 105.6 for Seoul, 43.6 for Daegu, and 26.4 for Daejeon. The lower C storage of Korean UGS soils than those of other countries is due to the low soil C concentration and the smaller land area under UGS. Strategic management practices that augment the organic matter supply in soil are expected to enhance C storage in South Korean UGS soils. Full article

(This article belongs to the Special Issue Urban and Periurban Forest Diversity and Ecosystem Services)

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704 KiB

Open AccessArticle

Socioeconomic Predictors of Family Forest Owner Awareness and Use of U.S. Federal Income Tax Provisions

by John E. Hatcher, Thomas J. Straka, Tamara L. Cushing, John L. Greene and William C. Bridges

Forests 2016, 7(6), 114; https://doi.org/10.3390/f7060114 - 28 May 2016

Cited by 2 | Viewed by 3837

Abstract

Family forest owners (FFOs) control a majority of private forestland in the United States and have widely diverse ownership and management objectives. Many FFOs manage their holdings for timber production and, thus, are concerned with issues such as reforestation incentives and tax treatment [...] Read more.

Family forest owners (FFOs) control a majority of private forestland in the United States and have widely diverse ownership and management objectives. Many FFOs manage their holdings for timber production and, thus, are concerned with issues such as reforestation incentives and tax treatment of timber revenues. Their actual knowledge of the tax aspects of timber management varies, with some owners even unaware of the federal income tax provisions that apply to timber. This research used econometric techniques to establish socioeconomic predictors of FFO awareness and use of federal income tax provisions. Socioeconomic factors (such as size of forest holding, ownership objective, education, age, and income) were evaluated in terms of association with awareness and use of income tax provisions. Data were obtained from a survey of 1350 South Carolina FFOs (472 useable responses). A two-step sample selection methodology revealed that membership in a landowner organization and size of forest holding positively influence landowner awareness of the seven tax provisions, while ownership objective and level of education exhibited varying degrees of influence. Overall, the findings suggest that size of forest holding is the key determinant that influences landowner use of the provisions. These tax incentives are one of the foundations of federal policies encouraging active forest management by FFOs and the effectiveness of the various incentives has crucial implications for forest policy analysis. Full article

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Open AccessArticle

Soil Enzyme Activities in Pinus tabuliformis (Carriére) Plantations in Northern China

by Weiwei Wang, Deborah Page-Dumroese, Ruiheng Lv, Chen Xiao, Guolei Li and Yong Liu

Forests 2016, 7(6), 112; https://doi.org/10.3390/f7060112 - 26 May 2016

Cited by 15 | Viewed by 5526

Abstract

Changes in forest stand structure may alter the activity of invertase, urease, catalase and phenol oxidase after thinning Pinus tabuliformis (Carriére) plantations in Yanqing County of Beijing, China. We examined changes in these soil enzymes as influenced by time since thinning (24, 32, [...] Read more.

Changes in forest stand structure may alter the activity of invertase, urease, catalase and phenol oxidase after thinning Pinus tabuliformis (Carriére) plantations in Yanqing County of Beijing, China. We examined changes in these soil enzymes as influenced by time since thinning (24, 32, and 40 years since thinning) for 3 seasons (spring, summer and autumn) following harvesting at two depths in the mineral soil (0–10 cm and 10–20 cm). Invertase and urease increased significantly with time since thinning. Catalase activity was highest in the 24-year-old stand and there were no statistically significant differences between the 32- and 40-year-old stands. In addition, maximum invertase, urease, catalase, and phenol oxidase activities occurred during the summer; minimum activities occurred in autumn. Invertase and urease were positively correlated with each other, as were catalase and phenol oxidase. Most soil enzyme activity was higher in the 0–10 cm layer than at the 10–20 cm depth. As time from thinning increased, differences among soil depth became less significant. These results suggest that seasonal changes of these enzymes have different roles, as the time since thinning and thinning treatments may have both short- and long-term impacts on soil microbial activity. Full article

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Open AccessArticle

Tree Species and Their Space Requirements in Six Urban Environments Worldwide

by Jens Dahlhausen, Peter Biber, Thomas Rötzer, Enno Uhl and Hans Pretzsch

Forests 2016, 7(6), 111; https://doi.org/10.3390/f7060111 - 25 May 2016

Cited by 33 | Viewed by 6914

Abstract

Urban trees have gained in importance during recent decades, but little is known about the temporal dynamic of tree growth in urban areas. The present study investigated the allometric relationships of stem diameter, tree height, and crown radius for six different tree species [...] Read more.

Urban trees have gained in importance during recent decades, but little is known about the temporal dynamic of tree growth in urban areas. The present study investigated the allometric relationships of stem diameter, tree height, and crown radius for six different tree species in six metropolises worldwide. Increment cores of the trees were used for identifying the relationship of basal area and basal area increment and for extrapolating the temporal dynamics for each species in relation to the allometric parameters and growth extensions. Space limitation and its direct influence on growth were quantified, as well as the aboveground woody biomass and the carbon storage capacity. The results show that, among the investigated species, Quercus nigra and Khaya senegalensis have the highest growth rates for stem diameter and crown radius, whereas Tilia cordata and Aesculus hippocastanum remain on a lower level. A significant reduction of tree growth due to restricted non-paved area was found for Aesculus hippocastanum and Khaya senegalensis. Estimations of aboveground biomass were highest for Quercus nigra and lowest for Tilia cordata. These results show the species-specific allometries of urban trees over a projected time period. Thus, the data set is highly relevant for planners and urban green managers. Full article

(This article belongs to the Special Issue Urban and Periurban Forest Diversity and Ecosystem Services)

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Open AccessArticle

Seedling Growth and Physiological Responses of Sixteen Eucalypt Taxa under Controlled Water Regime

by Paulo H. M. Silva, Otavio C. Campoe, Rinaldo C. De Paula and David J. Lee

Forests 2016, 7(6), 110; https://doi.org/10.3390/f7060110 - 24 May 2016

Cited by 25 | Viewed by 5064

Abstract

We assessed growth and physiological responses of Eucalyptus and Corymbia species to water limitation aiming to widen possibilities for plantations in dry climatic conditions. We selected 16 taxa: 4 Corymbia and 12 Eucalyptus species from the Subgenera Symphyomyrtus. Seedlings were evaluated from [...] Read more.

We assessed growth and physiological responses of Eucalyptus and Corymbia species to water limitation aiming to widen possibilities for plantations in dry climatic conditions. We selected 16 taxa: 4 Corymbia and 12 Eucalyptus species from the Subgenera Symphyomyrtus. Seedlings were evaluated from 100 to 170 days after sowing. Growth and physiological traits showed significant differences among taxa and between two levels of water availability. Water limitation significantly impacted biomass production and physiological characteristics, however in different levels. Leaf area and biomass production decreased 15%–48% under water limitation among taxa. Eucalyptus moluccana, CCV 2, and VM1 (drought tolerant clone) showed the largest decrease in leaf area. Transpiration across taxa decreased 30%–57% and photosynthesis 14%–48% under water limited condition. Taxa from cold environments were less responsive in leaf area reduction under water limitation, and taxa from Exsertaria section showed lower reduction in photosynthesis (E. camaldulensis showed the lowest reduction). Responses to water limitation are related to the environment of origin. E. molucana, the only Adnataria species from a high precipitation region (>1500 mm year⁻¹), was one of the most sensitive in reduction of biomass production, different behavior from the other Adnataria species, originated in regions with rainfall <750 mm year⁻¹. Water limitation increased leaf-level water use efficiency by 18% on average, 8% in E. longirostrata, and 28% in E. camaldulensis, E. brassiana, and E. crebra. Growth and physiological responses observed show the potential of different eucalypts taxa to tolerate water limited environments. Full article

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Forests, Volume 7, Issue 6 (June 2016) – 18 articles

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