scholarly journals Suffrutex grasslands in south-central Angola: belowground biomass, root structure, soil characteristics and vegetation dynamics of the ‘underground forests of Africa’

2021 ◽  
pp. 1-11
Author(s):  
Amândio L. Gomes ◽  
Rasmus Revermann ◽  
Francisco M. P. Gonçalves ◽  
Fernanda Lages ◽  
Marcos P. M. Aidar ◽  
...  
Keyword(s):  
Human Impact ◽  
Vegetation Dynamics ◽  
Vegetation Index ◽  
Belowground Biomass ◽  
Google Earth ◽  
Carbon Stocks ◽  
Miombo Woodlands ◽  
Central Plateau ◽  
South Central ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract Despite its importance for carbon stocks accounting, belowground biomass (BGB) has seldom been measured due to the methodological complexity involved. In this study, we assess woody BGB and related carbon stocks, soil properties and human impact on two common suffrutex grasslands (Brachystegia- and Parinari grasslands) on the Angolan Central Plateau. Data on BGB was measured by direct destructive sampling. Soil samples were analysed for select key parameters. To investigate vegetation dynamics and human impact, we used Moderate Resolution Imaging Spectroradiometer (MODIS) Enhanced Vegetation Index (EVI) and fire data retrieved via Google Earth Engine. Mean belowground woody biomass of sandy Parinari grasslands was 17 t/ha and 44 t/ha in ferralitic Brachystegia grasslands of which 50% correspond to carbon stocks. As such, the BGB of Brachystegia grasslands almost equals the amount of aboveground biomass (AGB) of neighbouring miombo woodlands. Almost the entire woody BGB is located in the top 30 cm of the soil. Soils were extremely acid, showing a low nutrient availability. Both grassland types differed strongly in EVI and fire seasonality. The Parinari grasslands burnt almost twice as frequent as Brachystegia grasslands in a 10-year period. Our study emphasizes the high relevance of BGB in suffrutex grasslands for carbon stock accounting.

scholarly journals Woody species of the Miombo woodlands and geoxylic grasslands of the Cusseque area, south-central Angola

Check List ◽  
2017 ◽  
Vol 13 (1) ◽  
pp. 2030 ◽  
Author(s):  
Rasmus Revermann ◽  
Francisco Maiato Gonçalves ◽  
Amândio Luis Gomes ◽  
Manfred Finckh
Keyword(s):  
Species Composition ◽  
Woody Species ◽  
Woody Vegetation ◽  
Growth Forms ◽  
Miombo Woodlands ◽  
Vegetation Survey ◽  
Central Plateau ◽  
South Central ◽  
Independence Era ◽  
Plant Families

The species composition of the vegetation in most regions of Angola has been poorly studied and most studies date back to the pre-independence era. In this study, we provide a detailed account of the woody flora of the Miombo woodlands and geoxylic grasslands of the Cusseque study site of “The Future Okavango” (TFO) project, situated on the Angolan Central Plateau. The checklist is based on a vegetation survey using vegetation plots of 1,000 m² and also includes records from botanical collections made elsewhere at the study site. In total, we documented 154 woody species belonging to 99 genera of 37 plant families in 100 km². The study represents the first comprehensive account of the woody vegetation of the area including all habitats and growth forms.

scholarly journals Mapping the Natural Distribution of Bamboo and Related Carbon Stocks in the Tropics Using Google Earth Engine, Phenological Behavior, Landsat 8, and Sentinel-2

2020 ◽  
Vol 12 (18) ◽  
pp. 3109 ◽  
Author(s):  
Manjunatha Venkatappa ◽  
Sutee Anantsuksomsri ◽  
Jose Alan Castillo ◽  
Benjamin Smith ◽  
Nophea Sasaki
Keyword(s):  
Vegetation Index ◽  
Google Earth ◽  
Carbon Stocks ◽  
Landsat 8 ◽  
Threshold Values ◽  
Landsat 8 Oli ◽  
Natural Distribution ◽  
Siem Reap ◽  
Google Earth Engine ◽  
Sentinel 2

Although vegetation phenology thresholds have been developed for a wide range of mapping applications, their use for assessing the distribution of natural bamboo and the related carbon stocks is still limited, especially in Southeast Asia. Here, we used Google Earth Engine (GEE) to collect time-series of Landsat 8 Operational Land Imager (OLI) and Sentinel-2 images and employed a phenology-based threshold classification method (PBTC) to map the natural bamboo distribution and estimate carbon stocks in Siem Reap Province, Cambodia. We processed 337 collections of Landsat 8 OLI for phenological assessment and generated 121 phenological profiles of the average vegetation index for three vegetation land cover categories from 2015 to 2018. After determining the minimum and maximum threshold values for bamboo during the leaf-shedding phenology stage, the PBTC method was applied to produce a seasonal composite enhanced vegetation index (EVI) for Landsat collections and assess the bamboo distributions in 2015 and 2018. Bamboo distributions in 2019 were then mapped by applying the EVI phenological threshold values for 10 m resolution Sentinel-2 satellite imagery by accessing 442 tiles. The overall Landsat 8 OLI bamboo maps for 2015 and 2018 had user’s accuracies (UAs) of 86.6% and 87.9% and producer’s accuracies (PAs) of 95.7% and 97.8%, respectively, and a UA of 86.5% and PA of 91.7% were obtained from Sentinel-2 imagery for 2019. Accordingly, carbon stocks of natural bamboo by district in Siem Reap at the province level were estimated. Emission reductions from the protection of natural bamboo can be used to offset 6% of the carbon emissions from tourists who visit this tourism-destination province. It is concluded that a combination of GEE and PBTC and the increasing availability of remote sensing data make it possible to map the natural distribution of bamboo and carbon stocks.

scholarly journals KARAKTERISTIK SPASIAL DAN POTENSI CADANGAN KARBON DI BENTANG ALAM MBELILING NUSA TENGGARA TIMUR

2021 ◽  
Vol 21 (2) ◽  
pp. 65
Author(s):  
Serlina H. Oktian ◽  
Luluk Setyaningsih ◽  
Nengsih Anen ◽  
Wahyu C. Adinugroho
Keyword(s):  
Aboveground Biomass ◽  
Carbon Stock ◽  
Vegetation Index ◽  
Model Development ◽  
Belowground Biomass ◽  
Carbon Stocks ◽  
Carbon Pools ◽  
Average Value ◽  
Comprehensive Information ◽  
Index Value

Providing comprehensive information on carbon stock data on all carbon pools needs to be done to plan and measure climate change mitigation efforts that are carried out. This research was conducted by analyzing spatial characteristics and estimating carbon stocks with model development. Spatial analysis is carried out to provide an overview of the distribution of spatial values that can use the built model. Estimation of carbon stock is carried out by building a carbon stock estimator model that correlates the value of remote sensing parameters with the value of carbon stocks in all carbon storage sources. The characteristics of the vegetation index value in the forest category are greater than in the non-forest category and vice versa for the distribution of the digital number average value. The model development is only carried out on aboveground biomass and belowground biomass carbon pools. The results of the analysis of the estimation of carbon stocks based on the selected model showed the potential for aboveground biomass was 5,200,841.45 tC and the potential for belowground biomass was 1,317,948.10 tC.

scholarly journals Short-Term Variability in Alaska Ice-Marginal Lake Area: Implications for Long-Term Studies

2021 ◽  
Vol 13 (19) ◽  
pp. 3955
Author(s):  
Anton M. Hengst ◽  
William Armstrong ◽  
Brianna Rick ◽  
Daniel McGrath
Keyword(s):  
Vegetation Index ◽  
Google Earth ◽  
Landsat 8 ◽  
Lake Area ◽  
Dynamic Features ◽  
Short Term ◽  
South Central ◽  
Short Term Variability ◽  
Long Term Studies

Lakes in direct contact with glaciers (ice-marginal lakes) are found across alpine and polar landscapes. Many studies characterize ice-marginal lake behavior over multi-decadal timescales using either episodic ~annual images or multi-year mosaics. However, ice-marginal lakes are dynamic features that experience short-term (i.e., day to year) variations in area and volume superimposed on longer-term trends. Through aliasing, this short-term variability could result in erroneous long-term estimates of lake change. We develop and implement an automated workflow in Google Earth Engine to quantify monthly behavior of ice-marginal lakes between 2013 and 2019 across south-central Alaska using Landsat 8 imagery. We employ a supervised Mahalanobis minimum-distance land cover classifier incorporating three datasets found to maximize classifier performance: shortwave infrared imagery, the normalized difference vegetation index (NDVI), and spatially filtered panchromatic reflectance. We observe physically-meaningful ice-marginal lake area variance on sub-annual timescales, with the median area fluctuation of an ice-marginal lake found to be 10.8% of its average area. The median signal (slow lake growth) to noise (physically-meaningful short-term area variability) ratio is 1.5:1, indicating that short-term variability is responsible for ~33% of observed area change in the median ice-marginal lake. The magnitude of short-term area variability is similar for ice-marginal and nonglacial lakes, suggesting that the cause of observed variations is not of glacial origin. These data provide a new context for interpreting behaviors observed in multi-decadal studies and encourage attention to sub-annual behavior of ice-marginal lakes even in long-term studies.

scholarly journals Diverse Responses of Vegetation Dynamics to Snow Cover Phenology over the Boreal Region

Forests ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 376
Author(s):  
Tao Xiong ◽  
Hongyan Zhang ◽  
Jianjun Zhao ◽  
Zhengxiang Zhang ◽  
Xiaoyi Guo ◽  
...  
Keyword(s):  
Snow Cover ◽  
Vegetation Dynamics ◽  
Vegetation Index ◽  
Vegetation Types ◽  
Enhanced Vegetation Index ◽  
Climate Gradients ◽  
Boreal Region ◽  
The North ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Snow Cover Duration

Snow cover phenology plays an important role in vegetation dynamics over the boreal region, but the observed evidence of this interaction is limited. A comprehensive understanding of the changes in vegetation dynamics and snow cover phenology as well as the interactions between them is urgently needed. To investigate this, we calculated two indicators, the start of the growing season (SOS) and the annual maximum enhanced vegetation index (EVImax), as proxies of vegetation dynamics using the Moderate Resolution Imaging Spectroradiometer (MODIS) enhanced vegetation index (EVI). Snow cover duration (SCD) and snow cover end date (SCE) were also extracted from MODIS snow cover datasets. Then, we quantified the spatial-temporal changes in vegetation dynamics and snow cover phenology as well as the relationship between them over the boreal region. Our results showed that the EVImax generally demonstrated an increasing trend, but SOS varied in different regions and vegetation types from 2001 to 2014. The earlier onset of SOS was mainly concentrated in the Siberian boreal region. In the Eurasian boreal region, we observed an advance in the SCE and decrease in the SCD, while in the North American boreal region, the spatial distribution of the trends exhibited substantial heterogeneity. Our results also indicated that the snow cover phenology had significant impacts on the SOS and the EVImax, but the effects varied in different regions, vegetation types, and climate gradients. Our findings provide strong evidence of the interaction between vegetation dynamics and snow cover phenology, and snow cover should be considered when analyzing future vegetation dynamics in the boreal region.

scholarly journals High altitudinal vegetation dynamics including treeline ecotone in Langtang National Park, Nepal

2021 ◽  
Vol 9 (2) ◽  
pp. 13-24
Author(s):  
Binod Baniya ◽  
Narayan Prasad Gaire ◽  
Qua-anan Techato ◽  
Yubraj Dhakal ◽  
Yam Prasad Dhital
Keyword(s):  
Vegetation Dynamics ◽  
National Park ◽  
Vegetation Change ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Kendall Test ◽  
Vegetation Density ◽  
Treeline Ecotone ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Linear Slope

Identification of high altitudinal vegetation dynamics using remote sensing is important because of the complex topography and environment in the Himalayas. Langtang National Park is the first Himalayan park in Nepal representing the best area to study vegetation change in the central Himalaya region because of the high altitudinal gradient and relatively less disturbed region. This study aimed at mapping vegetation in Langtang National Park and its treeline ecotone using Moderate Resolution Imaging Spectroradiometer (MODIS), Normalized Difference Vegetation Index (NDVI). Two treeline sites with an altitude of 3927 and 3802 meters above sea level (masl) were selected, and species density was measured during the field survey. The linear slope for each pixel and the Mann Kendall test to measure significant trends were used. The results showed that NDVI has significantly increased at the rate of 0.002yr-1 in Langtang National Park and 0.003yr-1 in treeline ecotone during 2000-2017. The average 68.73% equivalents to 1463 km2 of Langtang National Park are covered by vegetation. At the same time, 16.45% equivalents to 350.43 km2 are greening, and 0.25%, i.e., 5.43 km2 are found browning. In treeline ecotone, the vegetation is mostly occupied by grasses, shrublands and small trees where the NDVI was found from 0.1 to 0.5. The relative changes of NDVI in barren lands are negative and vegetative lands above 0.5 NDVI are positive between 2000 and 2017. The dominant treeline vegetation were Abies spectabilis, Rhododendron campanulatum, Betula utilis and Sorbus microphyla, with the vegetation density of 839.28 and 775 individuals per hectare in sites A and B, respectively. The higher average NDVI values, significantly increased NDVI, and higher density of vegetation in both A and B sites indicate that the vegetation in treeline ecotone is obtaining a good environment in the Himalayas of Nepal.

scholarly journals A Fused Variable by Night Light Images and MODIS Products for Improving Urban Built-Up Area Extraction

Technologies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 40
Author(s):  
Guang Yang ◽  
Yuntao Ma ◽  
Jiaqi Hu
Keyword(s):  
Surface Temperature ◽  
Land Surface ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Extraction Methods ◽  
Average Error ◽  
Geographic Coordinate System ◽  
Optimal Thresholds ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Spatial Locations

The boundary of urban built-up areas is the baseline data of a city. Rapid and accurate monitoring of urban built-up areas is the prerequisite for the boundary control and the layout of urban spaces. In recent years, the night light satellite sensors have been employed in urban built-up area extraction. However, the existing extraction methods have not fully considered the properties that directly reflect the urban built-up areas, like the land surface temperature. This research first converted multi-source data into a uniform projection, geographic coordinate system and resampling size. Then, a fused variable that integrated the Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) night light images, the Moderate-resolution Imaging Spectroradiometer (MODIS) surface temperature product and the normalized difference vegetation index (NDVI) product was designed to extract the built-up areas. The fusion results showed that the values of the proposed index presented a sharper gradient within a smaller spatial range, compared with the only night light images. The extraction results were tested in both the area sizes and the spatial locations. The proposed index performed better in both accuracies (average error rate 1.10%) and visual perspective. We further discussed the regularity of the optimal thresholds in the final boundary determination. The optimal thresholds of the proposed index were more stable in different cases on the premise of higher accuracies.

scholarly journals Constraints to Pearl Millet (Pennisetum glaucum) Production and Farmers’ Approaches to Striga hermonthica Management in Burkina Faso

2021 ◽  
Vol 13 (15) ◽  
pp. 8460
Author(s):  
Armel Rouamba ◽  
Hussein Shimelis ◽  
Inoussa Drabo ◽  
Mark Laing ◽  
Prakash Gangashetty ◽  
...  
Keyword(s):  
Burkina Faso ◽  
Pearl Millet ◽  
Management Practices ◽  
Pennisetum Glaucum ◽  
Control Measures ◽  
Striga Hermonthica ◽  
Soil Conditions ◽  
Management Options ◽  
Central Plateau ◽  
South Central

Pearl millet (Pennisetum glaucum) is a staple food crop in Burkina Faso that is widely grown in the Sahelian and Sudano-Sahelian zones, characterised by poor soil conditions and erratic rainfall, and high temperatures. The objective of this study was to document farmers’ perceptions of the prevailing constraints affecting pearl millet production and related approaches to manage the parasitic weeds S. hermonthica. The study was conducted in the Sahel, Sudano-Sahelian zones in the North, North Central, West Central, Central Plateau, and South Central of Burkina Faso. Data were collected through a structured questionnaire and focus group discussions involving 492 participant farmers. Recurrent drought, S. hermonthica infestation, shortage of labour, lack of fertilisers, lack of cash, and the use of low-yielding varieties were the main challenges hindering pearl millet production in the study areas. The majority of the respondents (40%) ranked S. hermonthica infestation as the primary constraint affecting pearl millet production. Respondent farmers reported yield losses of up to 80% due to S. hermonthica infestation. 61.4% of the respondents in the study areas had achieved a mean pearl millet yields of <1 t/ha. Poor access and the high cost of introduced seed, and a lack of farmers preferred traits in the existing introduced pearl millet varieties were the main reasons for their low adoption, as reported by 32% of respondents. S. hermonthica management options in pearl millet production fields included moisture conservation using terraces, manual hoeing, hand weeding, use of microplots locally referred to as ‘zaï’, crop rotation and mulching. These management techniques were ineffective because they do not suppress the below ground S. hermonthica seed, and they are difficult to implement. Integrated management practices employing breeding for S. hermonthica resistant varieties with the aforementioned control measures could offer a sustainable solution for S. hermonthica management and improved pearl millet productivity in Burkina Faso.

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