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Publications (274)
Data from the DLR Earth Sensing Imaging Spectrometer (DESIS), mounted on the International Space Station (ISS), were used to develop and test algorithms for remotely retrieving ecosystem productivity. Twenty DESIS images were used from three widely separated forested study sites representing deciduous and conifer forests. Gross primary production (...
Consideration of scale is essential when examining structural relationships in forests. In this study, we present a parameterization of the FORMIND individual-based forest model for old growth Atlantic lowland rainforest in La Selva, Costa Rica. Results show that the simulated forest reproduces the structural complexity of Costa Rican rainforest wi...
The boreal zone of Alaska is dominated by interactions between disturbances, vegetation, and soils. These interactions are likely to change in the future through increasing permafrost thaw, more frequent and intense wildfires, and vegetation change from drought and competition. We utilize an individual tree-based vegetation model, the University of...
Larch-dominant communities are the most extensive high-latitude forests in Eurasia and are experiencing the strongest impacts from warming temperatures. We analyzed larch (Larix dahurica Turcz) growth index (GI) response to climate change. The studied larch-dominant communities are located within the permafrost zone of Northern Siberia at the north...
Siberian silkmoth (Dendrolimus sibiricus Tschetv.) is a dangerous pest that has affected nearly 2.5 × 10⁶ ha of "dark taiga" stands (composed of Abies sibirica, Pinus sibirica and Picea obovata) within the latitude range of 52°-59° N. Here we describe a current silkmoth outbreak that is occurring about half degree northward of its formerly document...
Stereogrammetry applied to globally available high resolution spaceborne imagery (HRSI; < 5 m spatial resolution) yields fine-scaled digital surface models (DSMs) of elevation. These DSMs may represent elevations that range from the ground to the vegetation canopy surface, are produced from stereoscopic image pairs (stereopairs) that have a variety...
The forest above-ground biomass (AGB) and spatial distribution of vegetation elements have profound effects on the productivity and biodiversity of terrestrial ecosystems. In this paper, we evaluated biomass estimation from L-band Synthetic Aperture Radar (SAR) data acquired by National Aeronautics and Space Administration (NASA) Uninhabited Aerial...
Increased dieback and mortality of “dark needle conifer” (DNC) stands (composed of fir (Abies sibirica), Siberian pine (Pinus sibirica) and spruce (Picea obovata)) were documented in Russia during recent decades. Here we analyzed spatial and temporal patterns of fir decline and mortality in the southern Siberian Mountains based on satellite, in sit...
The phenomenon of tree waves (hedges and ribbons) formation within the alpine ecotone in Altai Mountains and its response to observed air temperature increase was considered. At the upper limit of tree growth Siberian pine (Pinus sibirica) forms hedges on windward slopes and ribbons on the leeward ones. Hedges were formed by prevailing winds and or...
Fire history within the northern larch forests of Central Siberia was studied (65 + °N). Fires within this area are predominantly caused by lightning strikes rather than human activity. Mean fire return intervals (FRIs) were found to be 112 ± 49 years (based on firescars) and 106 ± 36 years (based on firescars and tree natality dates). FRIs were in...
Advanced Digital Beamforming (DBF) Synthetic Aperture Radar (SAR) technology is an area of research and development pursued at the NASA Goddard Space Flight Center (GSFC). Advanced SAR architectures enhances radar performance and opens a new set of capabilities in radar remote sensing. DBSAR-2 and EcoSAR are two state-of-the-art radar systems recen...
In the taiga–tundra ecotone (TTE), site-dependent forest structure characteristics can influence the subtle and heterogeneous structural changes that occur across the broad circumpolar extent. Such changes may be related to ecotone form, described by the horizontal and vertical patterns of forest structure (e.g., tree cover, density, and height) wi...
Monitoring current forest characteristics in the taiga−tundra ecotone (TTE) at multiple scales is critical for understanding its vulnerability to structural changes. A 30 m spatial resolution Landsat-based tree canopy cover map has been calibrated and validated in the TTE with reference tree cover data from airborne LiDAR and high resolution spaceb...
Wildfire number and burned area temporal dynamics within all of Siberia and along a south-north transect in central Siberia (45°-73° N) were studied based on NOAA/AVHRR (National Oceanic and Atmospheric Administration/ Advanced Very High Resolution Radiometer) and Terra/MODIS (Moderate Resolution Imaging Spectroradiometer) data and field measuremen...
Climate impact on landslide occurrence and spatial patterns were analyzed within the larch-dominant communities associated with continuous permafrost areas of central Siberia. We used high resolution satellite imagery (i.e. QuickBird, WorldView) to identify landslide scars over an area of 62 000 km2. Landslide occurrence was analyzed with respect t...
In the taiga-tundra ecotone (TTE), vegetation structure change can be subtle and site-dependent, yet occur across the circumpolar region. This asynchronous change may be related to the horizontal and vertical patterns of vegetation structure such as tree density and height within TTE forest patches (i.e., ecotone form) that is driven by local site...
The aim of this work is an analysis of the causes of spruce (Picea abies L.) decline and mortality in Belarus. The analysis was based on forest inventory and Landsat satellite (land cover classification, climate variables (air temperature, precipitation, evaporation, vapor pressure deficit, SPEI drought index)), and GRACE-derived soil moisture esti...
Aim: estimation of larch (Larix gmelinii) growth response to current climate changes. Location: permafrost area within the northern part of Central Siberia (~65.8°N, 98.5°E). Method: analysis of dendrochronological data, climate variables, drought index SPEI, GPP (gross primary production) and EVI vegetation index (both Aqua/MODIS satellite derived...
Time series of remote sensing data offers the opportunity to predict changes in vegetation extent and to estimate forest parameter change such as biomass. However, as sensors and technology advance, it is important to ensure that estimates obtained from different time periods or using different, but related, instruments are consistent in order to h...
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 polarim...
The Forest Light (FLIGHT) radiative transfer model was used to examine the uncertainty of vegetation structure measurements from NASA 's planned ICESat-2 photon counting light detection and ranging (LiDAR) instrument across a synthetic Larix forest gradient in the taiga-tundra ecotone. The simulations demonstrate how measurements from the planned s...
Current researches based on areal or spaceborne stereo images with very high resolutions ( Keywords: ASTER GDEM; NED; photogrammetry; stereo-mapping; vegetation canopy height Document Type: Research Article DOI: http://dx.doi.org/10.1080/17538947.2013.861025 Affiliations: 1: State Key Laboratory of Remote Sensing Science, Institute of Remote Sensin...
Satellite-based estimates of vegetation structure capture broad-scale vegetation characteristics as well as differences in vegetation structure at plot-scales. Active remote sensing from laser altimetry and radar systems is regularly used to measure vegetation height and infer vegetation structural attributes, however, the current uncertainty of th...
The estimation of forest biomass from synthetic aperture radar (SAR) data is limited by the lack of forest structure information. Interferometric synthetic aperture radar (InSAR) provides a means for the extraction of forest structure. The crucial issue in InSAR application is to parameterize forest structure and to link the parameter with InSAR ob...
LiDAR waveform data from airborne LiDAR scanners (ALS) e.g. the Land Vegetation and Ice Sensor (LVIS) have been successfully used for estimation of forest height and biomass at local scales and have become the preferred remote sensing dataset. However, regional and global applications are limited by the cost of the airborne LiDAR data acquisition a...
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. Th...
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The goal of the study was to provide an analysis of climate impact before, during, and after the Little Ice Age (LIA) on the larch (Larix gmelinii) tree line at the northern extreme of Siberian forests. Recent decadal climate change impacts on the tree line, regeneration abundance, and age structure were analyzed. The location of the study area was...
The boreal forest accounts for one-third of global forests, but remains largely inaccessible to ground-based measurements and monitoring. It contains large quantities of carbon in its vegetation and soils, and research suggests that it will be subject to increasingly severe climate-driven disturbance. We employ a suite of ground-, airborne- and spa...
The combination of LiDAR and optical remotely sensed data provides unique information about ecosystem structure and function. Here, we describe the development, validation and application of a new airborne system that integrates commercial off the shelf LiDAR hyperspectral and thermal components in a compact, lightweight and portable system. Goddar...
The causes and resulting spatial patterns of Siberian pine mortality in eastern Kuznetzky Alatau Mountains, Siberia were analyzed based on satellite (Landsat, MODIS) and dendrochronology data. Climate variables studied included temperature, precipitation and Standardized Precipitation-Evapotranspiration Index (SPEI) drought index. Landsat data anal...
The synergistic use of active and passive remote sensing (i.e., data fusion) demonstrates the ability of spaceborne light detection and ranging (LiDAR), synthetic aperture radar (SAR) and multispectral imagery for achieving the accuracy requirements of a global forest biomass mapping mission (+20 Mg ha(-1) or 20%, the greater of the two, for at lea...
The Trans-Baikal (or Zabailkal’e) region includes the forest-steppe ecotones south and east of Lake Baikal in Russia and has experienced drought for several years. The decline and mortality of birch (Betula pendula) stands within the forest-steppe ecotone Trans-Baikal region was studied based on a temporal series of satellite data, ground measureme...
A space-based full-waveform LiDAR system, optimised for vegetation analysis, offers the opportunity for global biophysical parameter retrieval of the world's forests. However the conditions under which signals from the ground and vegetation can be detected will vary as a result of sensor specifications, vegetation characteristics and underlying sur...
A fire history of northern larch forests was studied. These larch forests are found near the northern limit of their range at ,718N, where fires are predominantly caused by lightning strikes rather than human activity. Fire-return intervals (FRIs) were calculated based on fire scars and dates of tree natality. Tree natality was used as an approxima...
The Digital Beamforming Synthetic Aperture Radar instrument demonstrated its first polarimetric polarization operation during the Eco-3D flight campaign, on board the NASA P3 aircraft in the summer/fall 2011. The measurements acquired during the campaign are currently being used to demonstrate DBSAR's science utility by providing critical informati...
The Eco3D campaign was conducted in the Summer of 2011. As part of the campaign three unique and innovative NASA Goddard Space Flight Center airborne sensors were flown simultaneously: The Digital Beamforming Synthetic Aperture Radar (DBSAR), the Slope Imaging Multi-polarization Photon-counting Lidar (SIMPL) and the Cloud Absorption Radiometer (CAR...
The circumpolar taiga–tundra ecotone was delineated using an image-segmentation-based mapping approach with multi-annual MODIS Vegetation Continuous Fields (VCF) tree cover data. Circumpolar tree canopy cover (TCC) throughout the ecotone was derived by averaging MODIS VCF data from 2000 to 2005 and adjusting the averaged values using linear equatio...
The Eurasian boreal forest is the largest continuous forest in the world
and contains a vast quantity of carbon stock that is currently
vulnerable to loss from climate change. We develop and present an
approach to map the spatial distribution of above ground biomass
throughout this region. Our method combines satellite measurements from
the Geoscie...
Detailed information on the quantity and distribution of aboveground
biomass (AGB) is needed to understand how it varies across space and
changes over time. Waveform LiDAR data is routinely used to derive the
heights of scattering elements in each illuminated footprint, and the
vertical structure of vegetation is related to AGB. Changes in LiDAR
wa...
One of the important consequences of observed and predicted climate
change is regional desertification and conversion of forest lands into
steppes. We documented progressive forest decline in the trans-Baikal
Lake mountains (center point coordinates ~ 51°30'N/116°30'E).
This area has a sever continental climate and is a transition area
between the...
The use of lidar and radar instruments to measure forest structure attributes such as height and biomass at global scales is being considered for a future Earth Observation satellite mission, DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice). Large footprint lidar makes a direct measurement of the heights of scatterers in the illumina...
Human and natural forces are rapidly modifying the global distribution and structure of terrestrial ecosystems on which all of life depends, altering the global carbon cycle, affecting our climate now and for the foreseeable future, causing steep reductions in species diversity, and endangering Earth's sustainability. To understand changes and tren...
A spaceborne lidar mission could serve multiple scientific purposes including remote sensing of ecosystem structure, carbon storage, terrestrial topography and ice sheet monitoring. The measurement requirements of these different goals will require compromises in sensor design. Footprint diameters that would be larger than optimal for vegetation st...
Trees in the southern Siberian Mountains forest-tundra ecotone have considerably increased their radial and apical growth increments during the last few decades. This leads to the widespread vertical transformation of mat and prostrate krummholz forms of larch (Larix sibirica Ledeb) and Siberian pine (Pinus sibirica Du Tour). An analysis of the rad...
The fire history of the northern larch forests within the permafrost zone in a portion of northern Siberia (~66°N, 100°E) was studied. Since there is little to no human activity in this area, fires within the study area were mostly caused by lightning. Fire return intervals (FRI) were estimated on the basis of burn marks on tree stems and dates of...
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 ba...
Assessment of the effect of multiangular polarized incident light on the bidirectional reflectance factor (BRF) of vegetation and soil samples is presented in this paper. The samples were evaluated with a reference to 99% white Spectralon calibration standard in the UV-VIS-NIR spectral range. The BRF of the samples was found to be strongly influenc...
1. ABSTRACT 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 Na...
The proposed DESDynI mission is being planned by NASA to study earth change in three distinct disciplines - ecosystems, solid earth, and cryospheric sciences. DESDynI would provide unique and unprecedented capabilities to the science community, with an imaging L-band radar proposed to include new modes and observational techniques, and a first-of-...
In 2007, NASA received directions from the National Academy of Science through its report ``Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond'' report to launch a mission to study the Earth's forested ecosystems, ice sheets and glaciers and areas prone to volcanoes and earthquakes. Two complementary tech...
We present ongoing research efforts at NASA/Goddard Space Flight Center (GSFC)to retrieve forest biomass using the GSFC digital beamforming SAR (DBSAR). DBSAR is a state-of-the-art multimode radar system designed for the development, implementation, and testing of advanced radar applications. The system combines phased-array architecture, reconfigu...
The aim of this study is to evaluate topographic features of high elevation mountain environments govern spatial distribution and climate-driven dynamics of the forests growing there. The study area included upper mountain forest stands formed by larch (Larix sibirica Ledeb) and Siberian pine(Pinus sibirica Du Tour) (elevation range 1800-2600 m) in...
Aim To evaluate the hypothesis that topographic features of high‐elevation mountain environments govern spatial distribution and climate‐driven dynamics of the forest.
Location Upper mountain forest stands (elevation range 1800–2600 m) in the mountains of southern Siberia.
Methods Archive maps, satellite and on‐ground data from1960 to 2002 were use...
Monitoring the dynamics of the circumpolar boreal forest (taiga) and Arctic tundra boundary is important for understanding the causes and consequences of changes observed in these areas. Because of the inaccessibility and large extent of this zone, remote sensing data can play an important role for the purposes. In this study, climate-related chang...
The elevational tree-line change within the transitional zone between boreal forest and Mongolian steppes was quantified for the last millennium. The basic approach included studies along transects and measurements of tree-line positions to identify current, historical, refugee and regeneration tree lines. Tree mortality and natality were determine...
The NASA's DESDynI mission will provide global systematic lidar point-sampling data and areal coverage of L-band SAR data with polarimetric capabilities for 3-D structural studies of vegetation. The combined use of lidar's direct sampling measurements and radar's global areal mapping capabilities creates a real opportunity to map global ecosystem s...
The effect of forest disturbance on the lidar waveform and the forest biomass estimation was demonstrated by model simulation. The results show that the correlation between stand biomass and the lidar waveform indices changes when the stand spatial structure changes due to disturbances rather than the natural succession. This has to be considered i...
A laboratory-based Bidirectional Reflectance Factor (BRF) polarization study of vegetation is presented in this paper. The BRF was measured using a short-arc Xenon lamp/monochromator assembly producing a tunable light source with a well-defined spectral bandpass at the following visible and near-infrared wavelengths: 340nm, 470 nm, and 870 nm. All...
Lidar-based aboveground biomass is derived based on the empirical relationship between lidar-measured vegetation height and aboveground biomass, often leading to large uncertainties of aboveground biomass estimates at large scales. This study investigates whether the use of any additional lidar-derived vegetation structure parameters besides height...
The tree response to climate trends is most likely observable in the forest-tundra ecotone, where temperature limits tree
growth. Here we show that trees in the forest-tundra ecotone of the mid of the south Siberian Mountains responded strongly
to warmer temperatures during the past two decades. There was a growth increment increase, stand densific...
Dark needle coniferous (DNC: Siberian pine, spruce, fir) expansion into larch dominated area was investigated along transects, oriented from the west and south borders of the larch dominated communities to its centre. The expected invasion of DNC into larch habitat was quantified as an increase of the proportion of those species both in the oversto...