Temilola Fatoyinbo

Height and biomass of mangroves in Africa from ICESat/GLAS and SRTM

The accurate quantification of the three-dimensional (3-D) structure of mangrove forests is of great importance, particularly in Africa where deforestation rates are high and the lack of background data is a major problem. The objectives of this study are to estimate (1) the total area, (2) canopy height distributions, and (3) above-ground biomass (AGB) of mangrove forests in Africa. To derive the 3-D structure and biomass maps of mangroves, we used a combination of mangrove maps derived from Landsat Enhanced Thematic Mapper Plus (ETM+), lidar canopy height estimates from ICESat/GLAS (Ice, Cloud, and land Elevation Satellite/Geoscience Laser Altimeter System), and elevation data from SRTM (Shuttle Radar Topography Mission) for the African continent. The lidar measurements from the large footprint GLAS sensor were used to derive local estimates of canopy height and calibrate the interferometric synthetic aperture radar (InSAR) data from SRTM. We then applied allometric equations relating canopy height to biomass in order to estimate AGB from the canopy height product. The total mangrove area of Africa was estimated to be 25,960 km2 with 83% accuracy. The largest mangrove areas and the greatest total biomass were found in Nigeria covering 8573 km2 with 132 × 106 Mg AGB. Canopy height across Africa was estimated with an overall root mean square error of 3.55 m. This error includes the impact of using sensors with different resolutions and geolocation error. This study provides the first systematic estimates of mangrove area, height, and biomass in Africa.

Flood extent mapping for Namibia using change detection and thresholding with SAR

A new method for flood detection change detection and thresholding (CDAT) was used with synthetic aperture radar (SAR) imagery to delineate the extent of flooding for the Chobe floodplain in the Caprivi region of Namibia. This region experiences annual seasonal flooding and has seen a recent renewal of severe flooding after a long dry period in the 1990s. Flooding in this area has caused loss of life and livelihoods for the surrounding communities and has caught the attention of disaster relief agencies. There is a need for flood extent mapping techniques that can be used to process images quickly, providing near real-time flooding information to relief agencies. ENVISAT/ASAR and Radarsat-2 images were acquired for several flooding seasons from February 2008 to March 2013. The CDAT method was used to determine flooding from these images and includes the use of image subtraction, decision-based classification with threshold values, and segmentation of SAR images. The total extent of flooding determined for 2009, 2011 and 2012 was about 542 km 2 , 720 km 2 , and 673 km 2 respectively. Pixels determined to be flooded in vegetation were typically <0:5% of the entire scene, with the exception of 2009 where the detection of flooding in vegetation was much greater (almost one third of the total flooded area). The time to maximum flooding for the 2013 flood season was determined to be about 27 days. Landsat water classification was used to compare the results from the new CDAT with SAR method; the results show good spatial agreement with Landsat scenes.

TanDEM-X Pol-InSAR Inversion for Mangrove Canopy Height Estimation

This paper presents mangrove canopy height estimations using single- and dual-pol TanDEM-X (TDX) data by means of Pol-InSAR techniques. Using the TDX data for forest applications, the penetration capability of X-band into the volume and the polarimetric diversity of interferometric coherence can create false effects that could sometimes lead to biased three-dimensional (3-D) forest parameter estimation. Moreover, in the case of single-pol TDX acquisition (i.e., one independent complex interferometric coherence), it is not possible to perform the inversion without external topographic information due to the underdetermined problem for Pol-InSAR inversion. To solve these problems, the ground phase in the Pol-InSAR model has been estimated directly from TDX interferograms with an assumption that the underlying topography (i.e., water surface level) over mangroves is flat and negligible. With the estimated ground phase that represents water-level elevation in mangroves, the Pol-InSAR inversion from the single- and dual-pol TDX data did not rely on an external DTM data set. The inversion results were validated against airborne lidar measurements in Campeche, Mexico, and in the Zambezi Delta, Mozambique. The single- and dual-pol inversion results showed a successful inversion performance with a high correlation coefficient (0.851-0.919) and with low RMSEs (1.069-1.727 m). The entire inversion performance quality over mangroves at X-band could reach to 10% height estimation accuracy. In addition to Pol-InSAR inversion results, the location of phase center was checked and assessed. The results showed a surprisingly deep location of phase centers from top mangrove canopy (5-7 m, up to 12.36 m) with a similarity at HH and VV polarization.

Ecosar: A P- band digital beamforming Polarimetric Interferometric SAR instrument to measure ecosystem structure and biomass

In this paper we describe the EcoSAR concept, an airborne Polarimetric and Interferometric P- band SAR instrument that will provide unprecedented two- and three dimensional fine scale measurements of terrestrial ecosystem structure and biomass. These measurements are directly traceable to upcoming international radar missions and the National Research Councils Decadal Survey ecosystem measurement requirements.

The ecosystems SAR (EcoSAR) an airborne P-band polarimetric InSAR for the measurement of vegetation structure, biomass and permafrost

EcoSAR is a new synthetic aperture radar (SAR) instrument being developed at the NASA/ Goddard Space Flight Center (GSFC) for the polarimetric and interferometric measurements of ecosystem structure and biomass. The instrument uses a phased-array beamforming architecture and supports full polarimetric measurements and single pass interferometry. This Instrument development is part of NASAs Earth Science Technology Office Instrument Incubator Program (ESTO IIP).

A Comparison of Mangrove Canopy Height Using Multiple Independent Measurements from Land, Air, and Space

Canopy height is one of the strongest predictors of biomass and carbon in forested ecosystems. Additionally, mangrove ecosystems represent one of the most concentrated carbon reservoirs that are rapidly degrading as a result of deforestation, development, and hydrologic manipulation. Therefore, the accuracy of Canopy Height Models (CHM) over mangrove forest can provide crucial information for monitoring and verification protocols. We compared four CHMs derived from independent remotely sensed imagery and identified potential errors and bias between measurement types. CHMs were derived from three spaceborne datasets; Very-High Resolution (VHR) stereophotogrammetry, TerraSAR-X add-on for Digital Elevation Measurement, and Shuttle Radar Topography Mission (TanDEM-X), and lidar data which was acquired from an airborne platform. Each dataset exhibited different error characteristics that were related to spatial resolution, sensitivities of the sensors, and reference frames. Canopies over 10 m were accurately predicted by all CHMs while the distributions of canopy height were best predicted by the VHR CHM. Depending on the guidelines and strategies needed for monitoring and verification activities, coarse resolution CHMs could be used to track canopy height at regional and global scales with finer resolution imagery used to validate and monitor critical areas undergoing rapid changes.

Characterization of community composition and forest structure in a Madagascar lowland rainforest

This study documents the community composition and forest structure of lowland rainforest in eastern Madagascar, with a first quantitative description of the primary lowland rainforest of Reserve Naturelle Intégrale de (RNI) Betampona. An intensive field survey of vegetation and environmental factors was conducted over two consecutive field campaigns in RNI Betampona, an isolated primary forest reserve located ca. 40 km northwest of the city of Toamasina. One hundred 10 m-diameter vegetation survey plots were inventoried and re-measured in 2004 and 2005. Two hundred forty-four tree species belonging to 49 families comprised the 2,487 stems greater than or equal to 5cm diameter at breast height (DBH) measured in 2004, with an average of 19.27 species per plot (2,227 and 15.71 respectively in 2005). Stem density per plot ranged from 12 to 52 for trees ≥5cm-DBH in 2004 (12 to 38 in 2005), while regeneration stems less than 5cm-DBH had a per-plot average of 57.28 in 2005 (range 19 to 140) and 94.19 (range 22 to 224) per hectare in 2004. The substantial decrease in ≥5cm-DBH trees and in stems ≥5cm-DBH from 2004 to 2005 suggests a forest undergoing thinning, perhaps following recovery from gap formation. Importance Value Indices (IVI) calculated for tree species indicated that an unidentified Uapaca species, Ravenala madagascariensis, Anthostema madagascariensis, Canarium spp and Cassipourea lanceolata were the most important species according to their overall frequency, dominance and abundance values, and accounted for 10% of the overall IVI.

ECOSAR: P-band digital beamforming polarimetric and single pass interferometric SAR

EcoSAR is a state-of-the-art beamforming synthetic aperture radar (SAR) recently developed at the NASA/ Goddard Space Flight Center (GSFC) for the measurement of ecosystem structure and biomass. The airborne instrument operates at a center frequency of 435 MHz (P-band), and uses a multi-channel reconfigurable architecture to implement fully polarimetric and “single pass” interferometric measurements. The instrument architecture allows for the real-time configuration radar parameters, including center frequency, resolution, incidence angle, and number of beams, among others. The system is also designed to operate in standard or ping pong interferometric modes, and in full, orthogonal, or hybrid polarimteric modes. The instrument development was recently completed, and its first flight campaign successfully conducted in March 2014 over areas of Bahamas and Costa Rica.

The EcoSAR P-band Synthetic Aperture Radar

The EcoSAR instrument is a new concept in Synthetic Aperture Radar for the polarimetric and interferometric measurements of biomass and ecosystem structure. EcoSAR will employ a digital beamforming architecture, a highly capable digital wave-form generator and receiver system, and advanced dual-polarization array antennas with an interferometric baseline of 25 m on the NASA P3 aircraft.

High-Resolution Forest Canopy Height Estimation in an African Blue Carbon Ecosystem

Abstract Mangrove forests are one of the most productive and carbon dense ecosystems that are only found at tidally inundated coastal areas. Forest canopy height is an important measure for modeling carbon and biomass dynamics, as well as land cover change. By taking advantage of the flat terrain and dense canopy cover, the present study derived digital surface models (DSMs) using stereo‐photogrammetric techniques on high‐resolution spaceborne imagery (HRSI) for southern Mozambique. A mean‐weighted ground surface elevation factor was subtracted from the HRSI DSM to accurately estimate the canopy height in mangrove forests in southern Mozambique. The mean and H100 tree height measured in both the field and with the digital canopy model provided the most accurate results with a vertical error of 1.18–1.84 m, respectively. Distinct patterns were identified in the HRSI canopy height map that could not be discerned from coarse shuttle radar topography mission canopy maps even though the mode and distribution of canopy heights were similar over the same area. Through further investigation, HRSI DSMs have the potential of providing a new type of three‐dimensional dataset that could serve as calibration/validation data for other DSMs generated from spaceborne datasets with much larger global coverage. HSRI DSMs could be used in lieu of Lidar acquisitions for canopy height and forest biomass estimation, and be combined with passive optical data to improve land cover classifications.