How green was my valley: forest canopy density in relation to topography and anthropogenic effects in Manipur valley,India     

Kiran Sharma 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(2):137-150

Forest canopy density (FCD) is a major factor in the evaluation of forest status and is an important indicator of possible management interventions. The study uses the FCD model with Landsat TM and Landsat 8 OLI images to assess canopy density in India’s Manipur valley and surrounding hills. Normalized difference built-up index (NDBI) was used to extract built-up areas and population density was retrieved from LandScan data, while elevation and slope were obtained from ASTER DEMs (30 m). Four types of canopy density were delineated with crown cover above 71%, 41–70%, 11–40%, below 10% and areas with no canopy cover, that is 0%. A sharp decline in forest area occurred during 1989–2016 at a rate of loss of 2.9 % year-1 with an average rate of deforestation of 3051 ha year-1. Dense forests exhibited remarkable degradation, especially towards the central valley. The variation in the topographical (elevation and slope) gradient resulted in significant differences in the canopy density over the study area barring some hill slopes. Population pressure and various developmental activities in recent decades led to forest degradation in this fragile yet rich Eastern Himalaya biodiversity hotspot.  相似文献   

Forest Fire Alert System: a Geo Web GIS prioritization model considering land susceptibility and hotspots – a case study in the Carajás National Forest,Brazilian Amazon     

Marcelo Roberto Barbosa  Mario Guimarães Buratto  Leonardo Santana de Oliveira Dias  João Paulo Carvalho Raivel  Flavio Lobos Martins 《International journal of geographical information science》2013,27(6):873-901

To increase the monitoring potential of forest fires, an alert classification methodology using satellite-mapped hotspots has been established to help forest managers in the prioritization of which hotspot to be verified in the field, thus potentially improving the distribution of fire-fighting resources. A computer application was developed based on web-distributed geographical information technology whose main function is to interact automatically generated satellite hotspots and risk areas indicated in fire-susceptibility maps and classify them into five alert levels. The location of the hotspots is available continuously every 4 h, and a susceptibility map is produced daily through map algebra algorithm, which uses static (topography, vegetation and land use) and dynamic (weather) variables. Every process runs through automated geoprocessing routines. The methodology was tested during the dry period of 2007 in the Carajás National Forest, in the Brazilian Amazon, within an area of 400,000 ha. It is a critical area constantly threatened by fires caused by invasions and deforestation owing to intense agribusiness advances and mining activities in its surroundings. This situation results in observations of many hotspots inside the study area for the same day and almost the same time period, in places of extreme opposites, demanding complex rapid analysis and hindering the decision of the displacement of fire-fighting teams. Further, a major mining company operates within the National Forest area, maintaining actions of protection as part of its environmental mining license. Results are presented under three aspects: (i) the credibility of the daily susceptibility map (algorithm), which showed strong correlation between areas of greatest risks and the confirmed forest fires; (ii) the reliability of hotspots (alert levels), confirming 71% of fires; (iii) accuracy in the decision of which hotspot to be checked, which revealed the same number of verifications at different alert levels, 82% confirmed alert 5 hotspots (maximum) and only 50% from alert 1 (minimum), resulting in faster fire-fighting actions, minimizing burned areas and, in some cases, allowing fire control before its spreading. Therefore, the methodology demonstrated that GIS routines are able to determine the relationship between a reality-based, interpreted susceptibility map of the area and satellite-generated hotspots, highlighting the ones of highest hazard level through the alert classification, becoming an important tool to help decisions from the fire-control center, especially for high-risk regions. The methodology may be extrapolated to other forested areas.  相似文献   

Using live vegetation volume to analyze the effects of plot Pinus massoniana Lamb on water and soil conservation under natural rainfall events   总被引：1，自引：0，他引：1  

Zhu-jun GU  Xiao-xia WU  Xiao-lei WANG  Shao-yun PENG  Hao LUO  Xue-zheng SHI  Dong-sheng YU 《国际泥沙研究》2013,28(4):579-587

The 3-D spatial distributions of vegetation are of great significance for water and soil conservation but are rarely concerned in literatures. The live vegetation volume （LVV） was used to relate to water/soil loss under 144 natural erosive rainfall events from 2007 to 2010 in a typical water-eroded area of southern China. Quadratic polynomial regression models were established for five pure tree （Pinus massoniana Lamb） plots between LVV and water （rtmoff）/soil conservation effects （RE/SE）. RE/SE corresponds to the ratios of runoff depth/soil loss of the pure tree plots to that of the control plot under each rainfall event. Increasing LVV exhibits descending （DS）, descending-ascending （DA）, ascending-descending （AD）, and ascending （AS） trends in the LVV-RE and LVV-SE curves. The effects of soil conservation on the plots were generally more noticeable than the effects of water conservation, and most of the RE and SE values reflected the positive effects of water and soil conservation. The effects were mainly positive under heavy rains （e.g., rainfall erosivity, R = 140 MJ mm ha-l h, maximum 30 min intensity, I30 = 16 mm h-l）, whereas the effects were mainly negative under light rains （e.g., R = 45 MJ mm ha-1 h, I30 = 8 mm h-l）. The trees＇ water/soil conservation effects notably transformed when rainfall erosivity and intensity were lower than the positive or negative effects to a certain threshold. About 50% rainfall events led to obvious transform effects when LVVs were near 0.5 or 0.6. These results are able to aid in the decision making on the forest reconstruction in water-eroded areas.  相似文献   

南瓮河湿地森林火灾预防管理对策分析     

吴炳岩  殷纪秋  何立忠  刘志强 《湿地科学与管理》2013,(2):55-56

针对南瓮河湿地森林火灾发生的特点,科学分析了南瓮河湿地森林火灾影响因素,在总结多年森林防火工作经验的基础上,提出森林防火必须准确把握火灾发生规律,不断提高火灾防范能力,建立健全防火长效治本机制,从根本上减少或避免特大森林火灾发生。  相似文献   

Stochastic gradient boosting classification trees for forest fuel types mapping through airborne laser scanning and IRS LISS-III imagery     

《International Journal of Applied Earth Observation and Geoinformation》2013

This paper presents an application of Airborne Laser Scanning (ALS) data in conjunction with an IRS LISS-III image for mapping forest fuel types. For two study areas of 165 km² and 487 km² in Sicily (Italy), 16,761 plots of size 30-m × 30-m were distributed using a tessellation-based stratified sampling scheme. ALS metrics and spectral signatures from IRS extracted for each plot were used as predictors to classify forest fuel types observed and identified by photointerpretation and fieldwork. Following use of traditional parametric methods that produced unsatisfactory results, three non-parametric classification approaches were tested: (i) classification and regression tree (CART), (ii) the CART bagging method called Random Forests, and (iii) the CART bagging/boosting stochastic gradient boosting (SGB) approach. This contribution summarizes previous experiences using ALS data for estimating forest variables useful for fire management in general and for fuel type mapping, in particular. It summarizes characteristics of classification and regression trees, presents the pre-processing operation, the classification algorithms, and the achieved results. The results demonstrated superiority of the SGB method with overall accuracy of 84%. The most relevant ALS metric was canopy cover, defined as the percent of non-ground returns. Other relevant metrics included the spectral information from IRS and several other ALS metrics such as percentiles of the height distribution, the mean height of all returns, and the number of returns.  相似文献   

Airborne laser scanning of forest resources: An overview of research in Italy as a commentary case study     

《International Journal of Applied Earth Observation and Geoinformation》2013

This article reviews the recent literature concerning airborne laser scanning for forestry purposes in Italy, and presents the current methodologies used to extract forest characteristics from discrete return ALS (Airborne Laser Scanning) data. Increasing interest in ALS data is currently being shown, especially for remote sensing-based forest inventories in Italy; the driving force for this interest is the possibility of reducing costs and providing more accurate and efficient estimation of forest characteristics. This review covers a period of approximately ten years, from the first application of laser scanning for forestry purposes in 2003 to the present day, and shows that there are numerous ongoing research activities which use these technologies for the assessment of forest attributes (e.g., number of trees, mean tree height, stem volume) and ecological issues (e.g., gap identification, fuel model detection). The basic approaches – such as single tree detection and area-based modeling – have been widely examined and commented in order to explore the trend of methods in these technologies, including their applicability and performance. Finally this paper outlines and comments some of the common problems encountered in operational use of laser scanning in Italy, offering potentially useful guidelines and solutions for other countries with similar conditions, under a rather variable environmental framework comprising Alpine, temperate and Mediterranean forest ecosystems.  相似文献   

100 global bright spots of green growth: Co-occurrence of nighttime light gain and forest gain, 1990–2015     

《Global Environmental Change》2022

Economic growth commonly occurs at the expense of environmental quality, but there are exceptions. Here we use satellite data to identify places where exceptional economic growth and exceptional environmental improvement co-occurred between 1990 and 2015. We term as “bright spots of green growth” those spatial clusters with the most cells above the 95th percentile within their world region in both economic growth (as proxied by increase in nighttime lights) and one aspect of environmental improvement (forest area). Because the locations of bright spots are sensitive to methodological choices, we applied two different approaches to identifying bright spots. The two approaches differed in their choice of nighttime lights data (DSMP-OLS in Approach A vs. DSMP-VIIRS composite in Approach B); choice of forest area data (forest cover vs. forest land-use); time period (2000–2010 vs. 1990–2015); and clustering technique (visual inspection vs. HDBSCAN algorithm). We identified the top five bright spots in each of ten world regions using each of two approaches, for a total of 100 global bright spots of green growth. We then tested the extent to which the attributes of bright spots were consistent with four non-mutually exclusive theories of green growth. Of the bright spots we identified, around two-thirds (65% using Approach A; 71% using Approach B) had significantly higher-than-regional-average growth in the share of labor employed in services, consistent with sectoral shift and “tertiarization.” Fewer than half (38%; 46%) had significantly higher growth in income, consistent with the “Environmental Kuznets Curve” theory. Some (54%; 29%) had significantly higher growth in timber plantation area, consistent with “eco-industry”-driven rural development. Few (0%; 10%) had significantly higher growth in protected area coverage, consistent with public policy-induced forest conservation. Our findings suggest sectoral shift toward services, rather than rising income per se, may be a promising pathway for other regions seeking to combine economic growth and environmental improvement.  相似文献   

The political ecology playbook for ecosystem restoration: Principles for effective,equitable, and transformative landscapes     

《Global Environmental Change》2021

The urgency of restoring ecosystems to improve human wellbeing and mitigate climate and biodiversity crises is attracting global attention. The UN Decade on Ecosystem Restoration (2021–2030) is a global call to action to support the restoration of degraded ecosystems. And yet, many forest restoration efforts, for instance, have failed to meet restoration goals; indeed, they worsened social precarities and ecological conditions. By merely focusing on symptoms of forest loss and degradation, these interventions have neglected the underlying issues of equity and justice driving forest decline. To address these root causes, thus creating socially just and sustainable solutions, we develop the Political Ecology Playbook for Ecosystem Restoration. We outline a set of ten principles for achieving long-lasting, resilient, and equitable ecosystem restoration. These principles are guided by political ecology, a framework that addresses environmental concerns from a broadly political economic perspective, attending to power, politics, and equity within specific geographic and historical contexts. Drawing on the chain of explanation, this multi-scale, cross-landscapes Playbook aims to produce healthy relationships between people and nature that are ecologically, socially, and economically just – and thus sustainable and resilient – while recognizing the political nature of such relationships. We argue that the Political Ecology Playbook should guide ecosystem restoration worldwide.  相似文献   

A spatial stochastic algorithm to reconstruct artificial drainage networks from incomplete network delineations     

J.S. Bailly  F. Levavasseur  P. Lagacherie 《International Journal of Applied Earth Observation and Geoinformation》2011

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3D modeling of light interception in heterogeneous forest canopies using ground-based LiDAR data     

Dimitry Van der Zande  Jan Stuckens  Willem W. Verstraeten  Simone Mereu  Bart Muys  Pol Coppin 《International Journal of Applied Earth Observation and Geoinformation》2011

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