森林航空摄影比例尺和森林判读像片放大倍数的研究     

黄福奎  李留瑜  邓中畅 《遥感学报》1990,(1)

为了确定森林航空摄影的最佳比例尺和波段以及判读像片的放大倍数,我们在广东省南昆山林业遥感试验场,测定了地物光谱,拍摄了不同比例尺的多光谱片和彩色红外片,进行了内业判读、野外检测和综合分析。本文讨论了航空摄影机、胶片、地物光谱反射系数和摄影位移等因素对像片分辨力的影响,用经验关系式估算了南昆山像片的影像分辨力,阐述了内业判读和实地检测的情况。试验表明,在所试验的波长附围内绿波段表达森林影像的效果最佳,用于森林判读的影像分辨力宜放大到3.5线/毫米,若用新型航空摄影机和高分辨力胶片,则用于森林资源调查分类判读的像片比例尺可缩小到1:4.8万。  相似文献   

Assessing the potential of REDD+ in a production mangrove forest in Malaysia using stakeholder analysis and ecosystem services mapping     

《Marine Policy》2016

Mangrove forests are ecologically important and carbon-rich coastal ecosystems that provide direct and indirect livelihood support for coastal communities. In recent years there has been increased discussion in the policy and scientific communities over how to include mangrove forests in climate change mitigation initiatives such as REDD+. There are a number of challenges to establishing a successful REDD+ project in mangrove areas, with land tenure and stakeholder entitlements arguably the most challenging. This study examines how REDD+ approaches might be applied to better balance timber production and conservation objectives in the Matang Mangrove Forest Reserve (MMFR), a 40,466 ha mangrove forest area in Malaysia. Stakeholder profiles and needs are linked with ecosystem services to develop an integrated profile of this complex social-ecological system, which has been managed for timber production for more than 100 years, and has recently revealed evidence of declining ecosystem health. The results provide insights into how REDD+ might be operationalised in existing forest areas with traditions of multiple uses, potentially contributing to improved social-ecological outcomes for forests and their diverse stakeholders.  相似文献   

Titling land to conserve forests: The case of Cuyabeno Reserve in Ecuador     

《Global Environmental Change》2017

We used a mixed-methods approach to assess the impact of a ‘forest-friendly’ titling program on previously untitled lands surrounding the Cuyabeno Reserve in Ecuador. Such programs are part of an increasing trend in tenure formalization intended to simultaneously strengthen tenure security, reduce deforestation, and open the door for more incentive-based conservation programs. We use quasi-experimental methods to estimate and compare the impact of titling on forest outcomes for lands that are titled with certain limitations on the ownership bundle of rights, alongside lands titled but without these restrictions. This quantitative analysis is paired with results from a series of focus group interviews with landowners to understand their experiences with the titling effort, particularly tied to the restrictions. Our results point to a statistically significant impact of titling with restrictions on reducing deforestation by 34%, whereas titling without such restrictions resulted in no significant effect. When we explore impacts according to annual deforestation rates, the results suggest that titled lands are buffered from the surges in deforestation that otherwise occurred on untitled lands and more broadly across the region. While ‘forest-friendly’ restrictions had more of an effect on forest outcomes than titled lands without, the insights shared by landowners suggest important concerns about equity and unjust burdens on current households that could risk livelihood options for future generations.  相似文献   

Deforestation dynamics and drivers in different forest types in Latin America: Three decades of studies (1980–2010)     

《Global Environmental Change》2017

Over the last decades there have been a considerable number of deforestation studies in Latin America reporting lower rates compared with other regions; although these studies are either regional or local and do not allow the comparison of the intraregional variability present among countries or forest types. Here, we present the results obtained from a systematic review of 369 articles (published from 1990 to 2014) about deforestation rates for 17 countries and forest types (tropical lowland, tropical montane, tropical and subtropical dry, subtropical temperate and mixed, and Atlantic forests). Drivers identified as direct or indirect causes of deforestation in the literature were also analysed. With an overall annual deforestation rate of −1.14 (±0.092 SE) in the region, we compared the rates per forest type and country. The results indicate that there is a high variability of forest loss rates among countries and forest types. In general, Chile and Argentina presented the highest deforestation rates (−3.28 and −2.31 yearly average, respectively), followed by Ecuador and Paraguay (−2.19 and −1.89 yearly average, respectively). Atlantic forests (−1.62) and tropical montane forests (−1.55) presented the highest deforestation rates for the region. In particular, tropical lowland forests in Ecuador (−2.42) and tropical dry forests in Mexico (−2.88) and Argentina (−2.20) were the most affected. In most countries, the access to markets and agricultural and forest activities are the main causes of deforestation; however, the causes vary according to the forest types. Deforestation measurements focused at different scales and on different forest types will help governments to improve their reports for international initiatives, such as reducing emissions from deforestation and forest degradation (REDD+) but, more importantly, for developing local policies for the sustainable management of forests and for reducing the deforestation in Latin America.  相似文献   

Conditions influencing the adoption of effective anti-deforestation policies in South America’s commodity frontiers     

《Global Environmental Change》2017

Reducing large-scale deforestation in commodity frontiers remains a key challenge for climate change mitigation and the conservation of biodiversity. Public and private anti-deforestation policies have been shown to effectively reduce forest loss, but the conditions under which such policies get adopted are rarely examined. Here we propose a set of conditions that we expect to be associated with the adoption of effective anti-deforestation policies in commodity frontiers. We then examine whether these conditions have influenced policy adoption in South America’s major soy-and-cattle frontiers: the Brazilian Amazon, the Cerrado, the Chaco, the Chiquitano, and Paraguay’s Atlantic Forest. By collating empirical data from diverse sources, including literature review, extensive expert interviews, and analysis of primary and secondary data, we show that the Cerrado, the Chaco, and the Chiquitano differ from the Brazilian Amazon in multiple ways that might have inhibited adoptions of effective anti-deforestation instruments. These conditions include: a higher importance of the agricultural sector within the respective countries, lower carbon stocks and species richness, higher prevalence of private land tenure, and higher baseline compliance with forest reserve regulations on private lands. We also observe that the adoption of the most effective private anti-deforestation instrument, commodity moratoria, may respond to similar conditions as those influencing the adoption of public instruments. Incentivizing public and private actors to adopt effective anti-deforestation policies in the Cerrado, Chaco, and the Chiquitano will likely be more challenging than it has been in the Brazilian Amazon.  相似文献   

Past and future carbon sequestration benefits of China’s grain for green program     

《Global Environmental Change》2017

Carbon sequestration through ecological restoration programs is an increasingly important option to reduce the rise of atmospheric carbon dioxide concentration. China’s Grain for Green Program (GGP) is likely the largest centrally organized land-use change program in human history and yet its carbon sequestration benefit has yet to be systematically assessed. Here we used seven empirical/statistical equations of forest biomass carbon sequestration and five soil carbon change models to estimate the total and decadal carbon sequestration potentials of the GGP during 1999–2050, including changes in four carbon pools: aboveground biomass, roots, forest floor and soil organic carbon. The results showed that the total carbon stock in the GGP-affected areas was 682 Tg C in 2010 and the accumulative carbon sink estimates induced by the GGP would be 1697, 2635, 3438 and 4115 Tg C for 2020, 2030, 2040 and 2050, respectively. Overall, the carbon sequestration capacity of the GGP can offset about 3%–5% of China’s annual carbon emissions (calculated using 2010 emissions) and about 1% of the global carbon emissions. Afforestation by the GGP contributed about 25% of biomass carbon sinks in global carbon sequestration in 2000–2010. The results suggest that large-scale ecological restoration programs such as afforestation and reforestation could help to enhance global carbon sinks, which may shed new light on the carbon sequestration benefits of such programs in China and also in other regions.  相似文献   

Major forest changes and land cover transitions based on plant functional types derived from the ESA CCI Land Cover product     

《International Journal of Applied Earth Observation and Geoinformation》2016

Land use and land cover change are of prime concern due to their impacts on CO₂ emissions, climate change and ecological services. New global land cover products at 300 m resolution from the European Space Agency (ESA) Climate Change Initiative Land Cover (CCI LC) project for epochs centered around 2000, 2005 and 2010 were analyzed to investigate forest area change and land cover transitions. Plant functional types (PFTs) fractions were derived from these land cover products according to a conversion table. The gross global forest loss between 2000 and 2010 is 172,171 km², accounting for 0.6% of the global forest area in year 2000. The forest changes are mainly distributed in tropical areas such as Brazil and Indonesia. Forest gains were only observed between 2005 and 2010 with a global area of 9844 km², mostly from crops in Southeast Asia and South America. The predominant PFT transition is deforestation from forest to crop, accounting for four-fifths of the total increase of cropland area between 2000 and 2010. The transitions from forest to bare soil, shrub, and grass also contributed strongly to the total areal change in PFTs. Different PFT transition matrices and composition patterns were found in different regions. The highest fractions of forest to bare soil transitions were found in the United States and Canada, reflecting forest management practices. Most of the degradation from grassland and shrubland to bare soil occurred in boreal regions. The areal percentage of forest loss and land cover transitions generally decreased from 2000–2005 to 2005–2010. Different data sources and uncertainty in the conversion factors (converting from original LC classes to PFTs) contribute to the discrepancy in the values of change in absolute forest area.  相似文献   

A systematic comparison of different object-based classification techniques using high spatial resolution imagery in agricultural environments     

《International Journal of Applied Earth Observation and Geoinformation》2016

Geographic Object-Based Image Analysis (GEOBIA) is becoming more prevalent in remote sensing classification, especially for high-resolution imagery. Many supervised classification approaches are applied to objects rather than pixels, and several studies have been conducted to evaluate the performance of such supervised classification techniques in GEOBIA. However, these studies did not systematically investigate all relevant factors affecting the classification (segmentation scale, training set size, feature selection and mixed objects). In this study, statistical methods and visual inspection were used to compare these factors systematically in two agricultural case studies in China. The results indicate that Random Forest (RF) and Support Vector Machines (SVM) are highly suitable for GEOBIA classifications in agricultural areas and confirm the expected general tendency, namely that the overall accuracies decline with increasing segmentation scale. All other investigated methods except for RF and SVM are more prone to obtain a lower accuracy due to the broken objects at fine scales. In contrast to some previous studies, the RF classifiers yielded the best results and the k-nearest neighbor classifier were the worst results, in most cases. Likewise, the RF and Decision Tree classifiers are the most robust with or without feature selection. The results of training sample analyses indicated that the RF and adaboost. M1 possess a superior generalization capability, except when dealing with small training sample sizes. Furthermore, the classification accuracies were directly related to the homogeneity/heterogeneity of the segmented objects for all classifiers. Finally, it was suggested that RF should be considered in most cases for agricultural mapping.  相似文献   

大兴安岭地区森林沼泽生态系统火生态效应研究   总被引：1，自引：0，他引：1  

杨永兴  杨玉娟  庞志平  杨永海 《海洋与湖沼》1995,26(6):610-618

于１９９０年５月－１９９３年１０月，为查清火灾对森林沼泽生态系统，采取野外面上考察与定位观测，野外实验与室内分析化验，定性分析与定量分析相结合的方法，在阿木尔林业局长缨林场、红旗林场选取观测点进行森林沼泽生态系统火生态效应的对比观测与实验。  相似文献   

Performance of GNSS-R GLORI data for biomass estimation over the Landes forest     

《International Journal of Applied Earth Observation and Geoinformation》2019

The Above-Ground Biomass (AGB) is a key parameter used for the modeling of the carbon cycle. The aim of this study is to make an experimental assessment of the sensitivity of Global Navigation Satellite System (GNSS) reflected signals to forest AGB. This is based on the analysis of the data recorded during several GLORI airborne campaigns in June and July 2015, over the Landes Forest (France). Ground truth measurements of tree height, density and diameter at breast height (DBH), as well as AGB, were carried out for 100 maritime pine forest plots of various ages. The GNSS-R data were used to obtain the right-left (Γ_RL) and right-right (Γ_RR) reflectivity observables, which are geo-referenced in accordance with the known positions of relevant GPS satellites and the airborne receiver. The correlations between forest AGB and the GNSS-R observables yield the highest sensitivity at high elevation angles (70°-90°). In this case, for (Γ_RL) and the reflectivity polarization ratio (PR = Γ_RL/Γ_RR) estimated with a coherent integration time Tc = 20 ms, the coefficients of determination R² are equal to 0.67 and 0.51, with a sensitivity of −0.051 dB/[10⁶g (Mg) ha⁻¹], and −0.053 dB/[Mg ha⁻¹], respectively. The relationships between AGB and the observables are confirmed through the use of a 5-fold cross validation approach, with several different coherent integration times.  相似文献