scholarly journals Forest Cover Index for tree cover detection using Landsat-7 multispectral imagery

2019 ◽  
Author(s):  
Luisa Feliciano-Cruz ◽  
Sarah Becker ◽  
Kristofer Lasko ◽  
Craig Daughtry ◽  
Andrew Russ
Keyword(s):  
Forest Cover ◽  
Tree Cover ◽  
Multispectral Imagery ◽  
Landsat 7

scholarly journals Evaluating Forest Cover and Fragmentation in Costa Rica with a Corrected Global Tree Cover Map

2020 ◽  
Vol 12 (19) ◽  
pp. 3226
Author(s):  
Daniel Cunningham ◽  
Paul Cunningham ◽  
Matthew E. Fagan
Keyword(s):  
Costa Rica ◽  
Forest Cover ◽  
Agricultural Land ◽  
Forest Area ◽  
Tree Cover ◽  
Agricultural Crop ◽  
Forest Change ◽  
Alos Palsar ◽  
Tropical Regions ◽  
The Impact

Global tree cover products face challenges in accurately predicting tree cover across biophysical gradients, such as precipitation or agricultural cover. To generate a natural forest cover map for Costa Rica, biases in tree cover estimation in the most widely used tree cover product (the Global Forest Change product (GFC) were quantified and corrected, and the impact of map biases on estimates of forest cover and fragmentation was examined. First, a forest reference dataset was developed to examine how the difference between reference and GFC-predicted tree cover estimates varied along gradients of precipitation and elevation, and nonlinear statistical models were fit to predict the bias. Next, an agricultural land cover map was generated by classifying Landsat and ALOS PalSAR imagery (overall accuracy of 97%) to allow removing six common agricultural crops from estimates of tree cover. Finally, the GFC product was corrected through an integrated process using the nonlinear predictions of precipitation and elevation biases and the agricultural crop map as inputs. The accuracy of tree cover prediction increased by ≈29% over the original global forest change product (the R2 rose from 0.416 to 0.538). Using an optimized 89% tree cover threshold to create a forest/nonforest map, we found that fragmentation declined and core forest area and connectivity increased in the corrected forest cover map, especially in dry tropical forests, protected areas, and designated habitat corridors. By contrast, the core forest area decreased locally where agricultural fields were removed from estimates of natural tree cover. This research demonstrates a simple, transferable methodology to correct for observed biases in the Global Forest Change product. The use of uncorrected tree cover products may markedly over- or underestimate forest cover and fragmentation, especially in tropical regions with low precipitation, significant topography, and/or perennial agricultural production.

scholarly journals India’s Commitments to Increase Tree and Forest Cover: Consequences for Water Supply and Agriculture Production within the Central Indian Highlands

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 959
Author(s):  
Benjamin Clark ◽  
Ruth DeFries ◽  
Jagdish Krishnaswamy
Keyword(s):  
Groundwater Recharge ◽  
Forest Cover ◽  
Hydrological Modeling ◽  
Monsoon Season ◽  
Forest Policy ◽  
Central India ◽  
Field Measurements ◽  
Tree Cover ◽  
Policy Goals ◽  
The Impact

As part of its nationally determined contributions as well as national forest policy goals, India plans to boost tree cover to 33% of its land area. Land currently under other uses will require tree-plantations or reforestation to achieve this goal. This paper examines the effects of converting cropland to tree or forest cover in the Central India Highlands (CIH). The paper examines the impact of increased forest cover on groundwater infiltration and recharge, which are essential for sustainable Rabi (winter, non-monsoon) season irrigation and agricultural production. Field measurements of saturated hydraulic conductivity (Kfs) linked to hydrological modeling estimate increased forest cover impact on the CIH hydrology. Kfs tests in 118 sites demonstrate a significant land cover effect, with forest cover having a higher Kfs of 20.2 mm hr−1 than croplands (6.7mm hr−1). The spatial processes in hydrology (SPHY) model simulated forest cover from 2% to 75% and showed that each basin reacts differently, depending on the amount of agriculture under paddy. Paddy agriculture can compensate for low infiltration through increased depression storage, allowing for continuous infiltration and groundwater recharge. Expanding forest cover to 33% in the CIH would reduce groundwater recharge by 7.94 mm (−1%) when converting the average cropland and increase it by 15.38 mm (3%) if reforestation is conducted on non-paddy agriculture. Intermediate forest cover shows however shows potential for increase in net benefits.

scholarly journals Effects of Windthrows on Forest Cover, Tree Growth and Soil Characteristics in Drought-Prone Pine Plantations

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 817
Author(s):  
Jesús Julio Camarero ◽  
Michele Colangelo ◽  
Antonio Gazol ◽  
Manuel Pizarro ◽  
Cristina Valeriano ◽  
...  
Keyword(s):  
Vegetation Index ◽  
Forest Cover ◽  
Normalized Difference Vegetation Index ◽  
Pinus Halepensis ◽  
Soil Characteristics ◽  
Tree Cover ◽  
Mediterranean Forests ◽  
Soil Microbial Community Structure ◽  
Soil Features ◽  
Disturbance Intensity

Windstorms are forest disturbances which generate canopy gaps. However, their effects on Mediterranean forests are understudied. To fill that research gap, changes in tree, cover, growth and soil features in Pinus halepensis and Pinus sylvestris plantations affected by windthrows were quantified. In each plantation, trees and soils in closed-canopy stands and gaps created by the windthrow were sampled. Changes in tree cover and radial growth were assessed by using the Normalized Difference Vegetation Index (NDVI) and dendrochronology, respectively. Soil features including texture, nutrients concentration and soil microbial community structure were also analyzed. Windthrows reduced tree cover and enhanced growth, particularly in the P. halepensis site, which was probably more severely impacted. Soil characteristics were also more altered by the windthrow in this site: the clay percentage increased in gaps, whereas K and Mg concentrations decreased. The biomass of Gram positive bacteria and actinomycetes increased in gaps, but the biomass of Gram negative bacteria and fungi decreased. Soil gaps became less fertile and dominated by bacteria after the windthrow in the P. halepensis site. We emphasize the relevance of considering post-disturbance time recovery and disturbance intensity to assess forest resilience within a multi-scale approach.

Degradation or recovery of argan woodlands in South Morocco? Tree count from satellite imagery between 1967–2019 may underestimate pressures on dryland forests status

2021 ◽  
Author(s):  
Irene Marzolff ◽  
Mario Kirchhoff ◽  
Robin Stephan ◽  
Manuel Seeger ◽  
Ali Aït Hssaïne ◽  
...  
Keyword(s):  
Forest Cover ◽  
Canopy Cover ◽  
Biosphere Reserve ◽  
Agroforestry System ◽  
Tree Density ◽  
Tree Cover ◽  
Positive Development ◽  
Natural State ◽  
Remotely Sensed Data ◽  
Change Analysis

<p>In semi-arid to arid South-west Morocco, the once ubiquitous endemic argan tree (<em>Argania spinosa</em>) forms the basis of a traditional silvo-pastoral agroforestry system with complex usage rights involving pasturing and tree-browsing by goats, sheep and camels, smallholder agriculture and oil production. Widespread clearing of the open-canopy argan forests has been undertaken in the 12<sup>th</sup>–17<sup>th</sup> century for sugarcane production, and again in the 20<sup>th</sup> century for fuelwood extraction and conversion to commercial agriculture. The remaining argan woodlands have continued to decline due to firewood extraction, charcoal-making, overgrazing and overbrowsing. Soil and vegetation are increasingly being degraded; natural rejuvenation is hindered, and soil-erosion rates rise due to reduced infiltration and increased runoff. Numerous studies indicate that tree density and canopy cover have been generally decreasing for the last 200 years. However, there is little quantitative and spatially explicit information about these forest-cover dynamics.</p><p>In our study, the tree-cover change between 1967 and 2019 was analysed for 30 test sites of 1 ha each in argan woodlands of different degradation stages in the provinces of Taroudant, Agadir Ida-Outanane and Chtouka-Aït Baha. We used historical black-and-white satellite photography from the American reconnaissance programme CORONA, recent high-resolution multispectral imagery from the commercial WorldView satellites and ultrahigh resolution small-format aerial photography taken with an unmanned aerial system (UAS) to map the presence, absence and comparative crown-size class of 2610 trees in 1967 and 2019. We supplemented the remotely-sensed data with field observations on tree structure and architecture.</p><p>Results show that plant densities reach up to 300 argan trees and shrubs per hectare, and the mean tree density has increased from 58 trees/ha in 1967 to 86 trees/ha in 2019. While 7% of the 1967 trees have vanished today, more than one third of today’s trees could not be observed in 1967. This positive change has a high uncertainty, however, as most of the increase concerns small trees (< 3 m diameter) which might have been missed on the lower-resolution CORONA images.</p><p>When combined with our field data on tree architecture, tree count – albeit a parameter easily attained by remote sensing – is revealed as too simple an indicator for argan-forest dynamics, and the first impression of a positive development needs to be revised: The new small trees as well as trees with decreased crown sizes clearly show much stronger degradation characteristics than others, indicating increased pressures on the argan ecosystem during recent decades. Structural traits of the smaller trees also suggest that the apparent increase of tree count is not a result of natural rejuvenation, but mostly of stump re-sprouting, often into multi-stemmed trees, after felling of a tree. The density of the argan forest in the 1960s, prior to the general availability of cooking gas in the region and before the stronger enforcement of the argan logging ban following the declaration of the UNESCO biosphere reserve, may have marked a historic low in our study area, making the baseline of our change analysis far removed from the potential natural state of the argan ecosystem.</p>

scholarly journals Tree Cover Estimation in Global Drylands from Space Using Deep Learning

2020 ◽  
Vol 12 (3) ◽  
pp. 343 ◽  
Author(s):  
Emilio Guirado ◽  
Domingo Alcaraz-Segura ◽  
Javier Cabello ◽  
Sergio Puertas-Ruíz ◽  
Francisco Herrera ◽  
...  
Keyword(s):  
Forest Cover ◽  
Global Scale ◽  
Classification Model ◽  
Tree Cover ◽  
System Modelling ◽  
Earth System ◽  
Visual Interpretation ◽  
Food And Agriculture ◽  
Food And Agriculture Organization ◽  
The Cost

Accurate tree cover mapping is of paramount importance in many fields, from biodiversity conservation to carbon stock estimation, ecohydrology, erosion control, or Earth system modelling. Despite this importance, there is still uncertainty about global forest cover, particularly in drylands. Recently, the Food and Agriculture Organization of the United Nations (FAO) conducted a costly global assessment of dryland forest cover through the visual interpretation of orthoimages using the Collect Earth software, involving hundreds of operators from around the world. Our study proposes a new automatic method for estimating tree cover using artificial intelligence and free orthoimages. Our results show that our tree cover classification model, based on convolutional neural networks (CNN), is 23% more accurate than the manual visual interpretation used by FAO, reaching up to 79% overall accuracy. The smallest differences between the two methods occurred in the driest regions, but disagreement increased with the percentage of tree cover. The application of CNNs could be used to improve and reduce the cost of tree cover maps from the local to the global scale, with broad implications for research and management.

scholarly journals Tree Species Diversity and Socioeconomic Perspectives of the Urban (Food) Forest of Accra, Ghana

2018 ◽  
Vol 10 (10) ◽  
pp. 3417 ◽  
Author(s):  
Bertrand Nero ◽  
Nana Kwapong ◽  
Raymond Jatta ◽  
Oluwole Fatunbi
Keyword(s):  
Land Use ◽  
Tree Species ◽  
Forest Cover ◽  
Food System ◽  
Food Policy ◽  
Urban Forest ◽  
Urban Forestry ◽  
Tree Cover ◽  
Land Use Types ◽  
The City

Urban and peri-urban forestry has emerged as a complementary measure to contribute towards eliminating urban hunger and improved nutritional security. However, there is scanty knowledge about the composition, diversity, and socioeconomic contributions of urban food trees in African cities. This paper examines the diversity and composition of the urban forest and food trees of Accra and sheds light on perceptions of urbanites regarding food tree cultivation and availability in the city. Using a mixed methods approach, 105 respondents in six neighborhoods of Accra were interviewed while over 200 plots (100-m2 each) were surveyed across five land use types. Twenty-two out of the 70 woody species in Accra have edible parts (leaves, fruits, flowers, etc.). The food-tree abundance in the city is about half of the total number of trees enumerated. The species richness and abundance of the food trees and all trees in the city were significantly different among land use types (p < 0.0001) and neighborhood types (p < 0.0001). The diversity of food-bearing tree species was much higher in the poorer neighborhoods than in the wealthier neighborhoods. Respondents in wealthier neighborhoods indicated that tree and food-tree cover of the city was generally low and showed greater interest in cultivating food (fruit) trees and expanding urban forest cover than poorer neighborhoods. These findings demonstrate the need for urban food policy reforms that integrate urban-grown tree foods in the urban food system/culture.

scholarly journals Annual Detection of Forest Cover Loss Using Time Series Satellite Measurements of Percent Tree Cover

2014 ◽  
Vol 6 (9) ◽  
pp. 8878-8903 ◽  
Author(s):  
Xiao-Peng Song ◽  
Chengquan Huang ◽  
Joseph Sexton ◽  
Saurabh Channan ◽  
John Townshend
Keyword(s):  
Time Series ◽  
Forest Cover ◽  
Tree Cover ◽  
Satellite Measurements ◽  
Forest Cover Loss

Rock water as a key resource for ecosystems with thin soils: Digging deep trees subsidize patches of surficial grasses

2020 ◽  
Author(s):  
Nicola Montaldo ◽  
Roberto Corona ◽  
Serena Sirigu ◽  
Luca Piroddi ◽  
Matteo Curreli ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Leaf Area ◽  
Deep Water ◽  
Forest Cover ◽  
Water Flux ◽  
Soil Layer ◽  
Tree Cover ◽  
Hydraulic Redistribution ◽  
Water Yield ◽  
Drought Severity

&lt;p&gt;Mediterranean mountainous areas of shallow soil often display a mosaic of tree clumps surrounded by grass. During dry seasons, evapotranspiration (&lt;em&gt;ET&lt;/em&gt;) cannot be met by soil moisture. However, the combined role and dynamics of water extracted from the underlying rock, and the competition between adjacent patches of trees and grass, has not been investigated. We quantified the role rock water plays in the seasonal dynamics of evapotranspiration, and its components, over a patchy landscape in the context of current and past seasonal climate changes, and land-cover change strategies. Soil water budget, using precipitation (&lt;em&gt;P&lt;/em&gt;), &lt;em&gt;ET&lt;/em&gt;, and soil moisture changes (&amp;#916;&lt;em&gt;S&lt;/em&gt;; ~17 cm soil layer), suggests deep water uptake by roots of trees (&lt;em&gt;f&lt;sub&gt;d&lt;/sub&gt;&lt;/em&gt;; 0.8 &amp;#8211; 0.9 mm/d), penetrating into the fractured basalt below clumps and the surrounding pasture, subsidized grass transpiration in spring through hydraulic redistribution. However, in summer trees used all the deep water absorbed (0.79 mm/d; &lt;em&gt;f&lt;sub&gt;d&lt;/sub&gt;&lt;/em&gt; &gt; tree transpiration). A 15-year dataset shows that, with increasing seasonal drought-severity (potential &lt;em&gt;ET&lt;/em&gt;/&lt;em&gt;P&lt;/em&gt;) to &gt;1.34, the vertical water flux through the bottom of the thin soil layer transitions from drainage to uptake in support of &lt;em&gt;ET&lt;/em&gt;. A hypothetical grass-covered landscape, with no access to deep water, would require 0.68 &amp;#8211; 0.85 mm/d more than is available from &lt;em&gt;P&lt;/em&gt; and &amp;#916;&lt;em&gt;S&lt;/em&gt;, forcing shortened growing season and/or lower leaf area. In summer, &lt;em&gt;ET&lt;/em&gt; in such a landscape would be half that of the existing mosaic, with consequences to energy balance. The vegetation mosaic may represent trending equilibrium, as long-term decreasing winter precipitation and increasing spring potential evaporation suggest drying climate. Intervention policies to increase water yield by reducing tree cover will curtail grass access to rock moisture, while attempting to increase tree-related products by increasing forest cover will limit water availability per tree leaf area. Both changes may further reduce ecosystem stability.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Estimating carbon losses from disturbances in tropical moist forests (deforestation and forest degradation) since 2011

2020 ◽  
Author(s):  
Frederic Achard ◽  
Christelle Vancutsem ◽  
Valerio Avitabile ◽  
Andreas Langner
Keyword(s):  
Forest Cover ◽  
Moving Average ◽  
Forest Degradation ◽  
Tree Cover ◽  
Accurate Information ◽  
Natural Forests ◽  
Carbon Loss ◽  
Average Value ◽  
Large Trees ◽  
Carbon Losses

&lt;p&gt;The need for accurate information to characterize the evolution of forest cover at the tropical scale is widely recognized, particularly to assess carbon losses from processes of disturbances such as deforestation and forest degradation&lt;sup&gt;1&lt;/sup&gt;. In fact, the contribution of degradation is a key element for REDD+ activities and is presently mostly ignored in national reporting due to the lack of reliable information at such scale.&lt;br&gt;Recently Vancutsem et al.&lt;sup&gt;2&lt;/sup&gt; produced a dataset at 30m resolution which delineates the tropical moist forest (TMF) cover changes from 1990 to 2019. The use of the Landsat historical time-series at high temporal and spatial resolution allows accurate monitoring of deforestation and degradation, from which the carbon losses from disturbances in TMFs can be estimated. A degradation event is defined here as temporary absence of tree cover (visible within a Landsat pixel during a maximum of three years duration) and includes impacts of fires and logging activities.&lt;br&gt;We quantify the annual losses in above-ground carbon stock associated to degradation and deforestation in TMF over the period 2011-2019 by combining the annual disturbances in forest cover derived from the Landsat archive the pan-tropical map of aboveground live woody biomass density (AGB) from Santoro et al.&lt;sup&gt;3&lt;/sup&gt; at 100 m. To reduce the local variability within the estimation of AGB values, we apply a moving average filter under the TMF cover for the year 2010.&amp;#160;&lt;br&gt;The carbon loss due to degradation is accounted as full carbon loss within a pixel (like a deforestation). The reason is that logging activities usually remove large trees with higher biomass densities than the average value of the disturbed pixel indicated by the pan-tropical maps. To avoid double counting of carbon removal, deforestation happening after degradation is not accounted as carbon loss.&lt;br&gt;Our results are compared with estimates of previous studies that cover different periods and forest domains: (i) Tyukavina et al.&lt;sup&gt;4&lt;/sup&gt;&amp;#160;provide estimates of carbon loss from deforestation for the period 2000-2012 for all forests (evergreen and deciduous) discriminating natural forests from managed forests, and (ii) Baccini et al.&lt;sup&gt;5 &lt;/sup&gt;provide estimates of carbon loss from deforestation and degradation for the period 2003-2014 for both evergreen and deciduous forests.&lt;/p&gt;&lt;p&gt;In a further step, we will analyze the sensitivity of the results to the input AGB values by applying the same approach to other AGB maps (e.g. Baccini et al. 2012&lt;sup&gt;6&lt;/sup&gt;).&lt;br&gt;Finally we intend to use Sentinel-2 data (10 m) for monitoring the location and extent of logging activities and burnt areas and further improve the estimates of carbon losses from forest degradation.&amp;#160;&lt;/p&gt;&lt;p&gt;1. Achard F, House JI 2015 doi 10.1088/1748-9326/10/10/101002&lt;br&gt;2. Vancutsem C. et al. 2019 Submitted to Nat. Geoscience&lt;br&gt;3. Santoro M et al. 2018 doi 10.1594/PANGAEA.894711&lt;br&gt;4. Tuykavina A et al 2018 http://iopscience.iop.org/1748-9326/10/7/074002&lt;br&gt;5. Baccini A et al. 2017 doi 10.1126/science.aam5962&lt;br&gt;6. Baccini A et al. 2012 doi 10.1038/nclimate1354&lt;/p&gt;

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