CH4 and N2O dynamics of a Larix gmelinii forest in a continuous permafrost region of central Siberia during the growing season

Forest soils are generally sinks of CH₄ and sources of N₂O. To characterize the dynamics of these major greenhouse gases in central Siberia during the growing season, we measured fluxes from forest soil and assessed the relationships between CH₄ and N₂O fluxes and forest floor vegetation types, soil temperature, and moisture conditions. At the soil surface, both CH₄ uptake and emission (−6.6 to 3.1 μg CH₄–C m⁻² h⁻¹) were observed, and CH₄ fluxes did not differ among vegetation types. CH₄ flux was positively correlated with soil moisture, but not with soil temperature. The small CH₄ uptake compared with previous reports was due to CH₄ production in response to high precipitation. N₂O was also emitted and taken up by soil (−0.2 to 0.4 μg N₂O–N m⁻² h⁻¹), and N₂O fluxes did not differ among vegetation types. N₂O flux was negatively correlated with soil moisture and not correlated with soil temperature. Our findings suggest that high soil moisture and low availability of mineral nitrogen resulted in N₂O uptake due to denitrification. Furthermore, both CH₄ and N₂O were emitted from a river at the site; these were produced in the basin of the riverbank rather than deep in the soil.     

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Is Certification Associated with Better Forest Management and Socioeconomic Benefits? A Comparative Analysis of Three Certification Schemes Applied to Brazil Nuts in Western Amazonia

Nontimber forest product (NTFP) certification has potential to promote sustainable harvest and to bolster rural livelihoods. This research compares environmental and socioeconomic benefits of Brazil nut certification for 231 producers in 17 communities in the trinational border region of Bolivia, Brazil, and Peru during the 2006–2007 harvest. Specific objectives were: (1) to analyze differences in “best management practices” between certified and noncertified producers; (2) to identify socioeconomic benefits associated with certified nuts; and (3) to explore producer perceptions of nut certification. Organic and Fairtrade certification were associated with better postharvest practices and higher prices, while Forest Stewardship Council (FSC) certification was related to preharvest planning. Certification was viewed most positively in Bolivia, where producers gleaned financial and social benefits, moderately in Peru, and least positively in Brazil, where benefits were lower or nonexistent. Partnerships with cooperatives, donors, government, and nongovernmental organizations were essential to maximize conservation and development objectives.     

The Community Economic Impacts of Large Wildfires: A Case Study from Trinity County,California

Wildfires are increasing in severity and frequency in the American West, but there is limited understanding of their economic effects at the community level. We conducted a case study of the impacts of large wildfires in 2008 in Trinity County, California, by examining labor market, suppression spending, and qualitative interview data. We found that the 2008 fires had interrelated effects on several economic sectors in the county. Labor market data indicated a decrease in total private-sector employment and wages and an increase in public-sector employment and wages during the summer of 2008 compared to the previous year, while interviews captured more nuanced impacts for individual businesses.     

Upgrading Bay Leaf Farmers in Value Chains—Strategies for Improving Livelihoods and Poverty Reduction from Udayapur District of Nepal

This article highlights the results of an action research to upgrade mountain farmers of bay leaf (Cinnamomum tamala Nees and Eberm) in Udayapur district of Nepal. Farmers received low prices, lacked market information, capacities, and institutional mechanisms, and were exploited by traders. To address these constraints, three independent but interlinked pro-poor value chain (VC) upgrading strategies comprising VC coordination upgrading and horizontal and vertical contractualization were implemented. Information was collected from focus-group discussions with collectors, traders, and facilitators, and a questionnaire was used to collect pre- and postintervention data (n = 120). VC upgrading strategies improved harvesting practices, increased farmers’ bargaining power, and led to a threefold increase in price, which increased household incomes. Results demonstrated improved terms of participation of farmers and a general increase in market price of bay leaf in Udayapur. The study approach can be up scaled to reduce poverty from high value products.     

A forestry GIS-based study on evaluating the potential of imaging spectroscopy in mapping forest land fertility

Fertility, or the availability of nutrients and water, controls forest productivity. It affects its carbon sequestration, and thus the forest's effect on climate, as well as its commercial value. Although the availability of nutrients cannot be measured directly using remote sensing methods, fertility alters several vegetation traits detectable from the reflectance spectra of the forest stand, including its pigment content and water stress. However, forest reflectance is also influenced by other factors, such as species composition and stand age. Here, we present a case study demonstrating how data obtained using imaging spectroscopy is correlated with site fertility. The study was carried out in Hyytiälä, Finland, in the southern boreal forest zone. We used a database of state-owned forest stands including basic forestry variables and a site fertility index. To test the suitability of imaging spectroscopy with different spatial and spectral resolutions for site fertility mapping, we performed two airborne acquisitions using different sensor configurations. First, the sensor was flown at a high altitude with high spectral resolution resulting in a pixel size in the order of a tree crown. Next, the same area was flown to provide reflectance data with sub-meter spatial resolution. However, to maintain usable signal-to-noise ratios, several spectral channels inside the sensor were combined, thus reducing spectral resolution. We correlated a number of narrowband vegetation indices (describing canopy biochemical composition, structure, and photosynthetic activity) on site fertility. Overall, site fertility had a significant influence on the vegetation indices but the strength of the correlation depended on dominant species. We found that high spatial resolution data calculated from the spectra of sunlit parts of tree crowns had the strongest correlation with site fertility.     

Markov-random-field-based super-resolution mapping for identification of urban trees in VHR images

Identification of tree crowns from remote sensing requires detailed spectral information and submeter spatial resolution imagery. Traditional pixel-based classification techniques do not fully exploit the spatial and spectral characteristics of remote sensing datasets. We propose a contextual and probabilistic method for detection of tree crowns in urban areas using a Markov random field based super resolution mapping (SRM) approach in very high resolution images. Our method defines an objective energy function in terms of the conditional probabilities of panchromatic and multispectral images and it locally optimizes the labeling of tree crown pixels. Energy and model parameter values are estimated from multiple implementations of SRM in tuning areas and the method is applied in QuickBird images to produce a 0.6 m tree crown map in a city of The Netherlands. The SRM output shows an identification rate of 66% and commission and omission errors in small trees and shrub areas. The method outperforms tree crown identification results obtained with maximum likelihood, support vector machines and SRM at nominal resolution (2.4 m) approaches.     

Use of ALS, Airborne CIR and ALOS AVNIR-2 data for estimating tropical forest attributes in Lao PDR

In this study, the potential of remote sensing in tropical forests is examined in relation to the diversification of sensors. We report here on the comparison of alternative methods that use multisource data from Airborne Laser Scanning (ALS), Airborne CIR and ALOS AVNIR-2 to estimate stem volume and basal area, in Laos. Multivariate linear regression analyses with stepwise selection of predictors were implemented for modelling. The predictors of ALS metrics were calculated by means of the canopy height distribution approach, while predictors from both spectral and textual features were respectively generated for Airborne CIR and ALOS AVNIR-2 data. With respect to the estimation capacity from individual data sources after leave-one-out cross-validation, the ALS data proved superior, with the lowest RMSE of 36.92% for stem volume and 47.35% for basal area, whereas Airborne CIR and ALOS AVNIR-2 remained at similar accuracy levels, but fell well behind the ALS data. By integrating ALS metrics with other predictors from Airborne CIR or ALOS AVNIR-2, hybrid modelling was further tested respectively. The results showed that only the hybrid model for stem volume involving ALS and Airborne CIR improved the accuracy of 1.9% in terms of relative RMSE than that of using ALS alone.     

森林地上生物量的极化相干层析估计方法

基于微波的后向散射系数估计森林地上生物量(AGB)易受后向散射系数饱和的影响,而利用森林高度,根据生长方程估计AGB,却没有考虑和AGB密切相关的林分密度、树种组成、林层垂直分布等空间结构特征的作用,针对这些问题,提出一种基于极化相干层析(Polarization Coherence Tomography,PCT)技术的AGB估计方法。基于德国宇航局(DLR)机载SAR系统(ESAR)获取的特劳斯坦(Traunstein)试验区L-波段极化干涉SAR(PolInSAR)数据,通过对具有不同AGB水平的典型林分的相对反射率函数曲线的分析,定义了9个与AGB具有相关性的特征参数。然后基于20个林分的实测AGB数据,以林分尺度上这9个特征参数的平均值为自变量,以实测林分平均AGB为因变量,采用逐步回归分析法构建了AGB估测模型,并对该模型进行评价,对影响模型估计精度的因素进行分析,结果表明,由PCT提取的相对反射率函数特征参数对AGB很敏感,充分利用相对反射率函数信息可提高AGB估计精度。     

利用组件GIS和构件技术建立林业GIS系统

随着计算机技术的进步,以林业GIS系统为代表的林业信息化进程得到前所未有的发展,但也存在着工程重复建设的问题,没有按统一的标准、规范和要求进行,特别是林业专业模型的实现一直进展缓慢.本文将软件复用的思想引入到林业GIS系统专业模型的构件设计与开发上,通过组件GIS技术与构件技术相结合的方法实现林业GIS系统功能的复用,...