Jim Kellner

Brown University · Institute at Brown for Environment and Society

The Global Ecosystem Dynamics Investigation (GEDI) is a waveform lidar instrument on the International Space Station used to estimate aboveground biomass density (AGBD) in temperate and tropical forests. Algorithms to predict footprint AGBD from GEDI relative height (RH) metrics were developed from simulated waveforms with leaf-on (growing season)...

The Global Ecosystem Dynamics Investigation (GEDI) lidar is a multibeam laser altimeter on the International Space Station (ISS). GEDI is the first spaceborne instrument designed to measure vegetation height and to quantify aboveground carbon stocks in temperate and tropical forests and woodlands. This document describes the algorithm theoretical b...

The NASA’s Global Ecosystem Dynamics Investigation (GEDI) lidar mission is collecting spaceborne full waveform lidar data with a primary science goal of producing accurate estimates of forest aboveground biomass density (AGBD). We test the performance of GEDI L4A biomass models against National Forest Inventory (NFI) data collected in Spain under s...

Remote sensing of solar-induced chlorophyll fluorescence (SIF) advances our ability to monitor gross primary productivity. Because SIF is usually <5% of recorded canopy radiance, sources of measurement error must be reduced for accurate SIF retrieval. Here we quantify the impact of spectral stray light on SIF retrieval using a high-resolution imagi...

Accurate estimation of aboveground forest biomass stocks is required to assess the impacts of land use changes such as deforestation and subsequent regrowth on concentrations of atmospheric CO2. The Global Ecosystem Dynamics Investigation (GEDI) is a lidar mission launched by NASA to the International Space Station in 2018. GEDI was specifically de...

The Global Ecosystem Dynamics Investigation (GEDI) lidar is a multibeam laser altimeter on the International Space Station (ISS). GEDI is the first spaceborne instrument designed to measure vegetation height and to quantify aboveground carbon stocks in temperate and tropical forests and woodlands. This document describes the algorithm theoretical b...

Accurate estimation of aboveground forest biomass stocks is required to assess the impacts of land use changes such as deforestation and subsequent regrowth on concentrations of atmospheric CO2. The Global Ecosystem Dynamics Investigation (GEDI) is a lidar mission launched by NASA to the International Space Station in 2018. GEDI was specifically de...

NASAs Global Ecosystem Dynamics Investigation (GEDI) is collecting space-borne full waveform lidar data with a primary science goal of producing accurate estimates of forest aboveground biomass density (AGBD). This paper presents the development of the models used to create GEDIs footprint-level (~25 m) AGBD (GEDI04_A) product, including a descript...

is collecting spaceborne full waveform lidar data with a primary science goal of producing accurate estimates of forest aboveground biomass density (AGBD). This paper presents the development of the models used to create GEDI's footprint-level (~25 m) AGBD (GEDI04_A) product, including a description of the datasets used and the procedure for final...

The distribution of canopy heights in tropical rainforests directly affects carbon storage and the maintenance of biodiversity. We report results from a unique 20‐year record of annual monitoring of canopy‐height distributions across an old‐growth tropical rainforest landscape at the La Selva Biological Station in Costa Rica. Canopy heights to 15 m...

For decades, the dynamic nature of chlorophyll a fluorescence (ChlaF) has provided insight into the biophysics and ecophysiology of the light reactions of photosynthesis from the subcellular to leaf scales. Recent advances in remote sensing methods enable detection of ChlaF induced by sunlight across a range of larger scales, from using instruments...

Field measurements demonstrate a carbon sink in the Amazon and Congo basins, but the cause of this sink is uncertain. One possibility is that forest landscapes are experiencing transient recovery from previous disturbance. Attributing the carbon sink to transient recovery or other processes is challenging because we do not understand the sensitivit...

The lack of genomic resources for tropical canopy trees is impeding several research avenues in tropical forest biology. We present genome assemblies for two Neotropical hardwood species, Jacaranda copaia and Handroanthus (formerly Tabebuia) guayacan, that are model systems for research on tropical tree demography and flowering phenology. For each...

We applied a supervised individual-tree segmentation algorithm to ultra-high-density drone lidar in a temperate mountain forest in the southern Czech Republic. We compared the number of trees correctly segmented, stem diameter at breast height (DBH), and tree height from drone-lidar segmentations to field-inventory measurements and segmentations fr...

This dataset contains gridded forest characterization products derived from full-waveform lidar data acquired by NASA's airborne Land, Vegetation, and Ice Sensor (LVIS) instrument for five forested sites in Gabon, Africa, during the 2016 NASA-ESA AfriSAR campaign. The LVIS lidar instrument was flown over study sites in Lope, Mondah/Akanda, Pongara,...

Aim Mapping tree species richness across the tropics is of great interest for effective conservation and biodiversity management. In this study, we evaluated the potential of full‐waveform lidar data for mapping tree species richness across the tropics by relating measurements of vertical canopy structure, as a proxy for the occupation of vertical...

Obtaining accurate and widespread measurements of the vertical structure of the Earth’s forests has been a long-sought goal for the ecological community. Such observations are critical for accurately assessing the existing biomass of forests, and how changes in this biomass caused by human activities or variations in climate may impact atmospheric...

Estimates of the magnitude and distribution of aboveground carbon in Earth's forests remain uncertain, yet knowledge of forest carbon content at a global scale is critical for forest management in support of climate mitigation. In light of this knowledge gap, several upcoming spaceborne missions aim to map forest aboveground biomass, and many new b...

Large trees, here defined as ≥60 cm trunk diameter, are the most massive organisms in tropical rain forest, and are important in forest structure, dynamics and carbon cycling. The status of large trees in tropical forest is unclear, with both increasing and decreasing trends reported. We sampled across an old-growth tropical rain forest landscape a...

Current and planned space missions will produce aboveground biomass density data products at varying spatial resolution. Calibration and validation of these data products is critically dependent on the existence of field estimates of aboveground biomass and coincident remote sensing data from airborne or terrestrial lidar. There are few places that...

Several upcoming satellite missions have core science requirements to produce data for accurate forest aboveground biomass mapping. Largely because of these mission datasets, the number of available biomass products is expected to greatly increase over the coming decade. Despite the recognized importance of biomass mapping for a wide range of scien...

Temperature and precipitation explain about half the variation in aboveground net primary production (ANPP) among tropical forest sites, but determinants of remaining variation are poorly understood. Here, we test the hypothesis that the amount of leaf area, and its vertical arrangement, predicts ANPP when other variables are held constant. Using m...

Supporting Information S1

Aim Large tropical trees form the interface between ground and airborne observations, offering a unique opportunity to capture forest properties remotely and to investigate their variations on broad scales. However, despite rapid development of metrics to characterize the forest canopy from remotely sensed data, a gap remains between aerial and fie...

Aim: Large tropical trees form the interface between ground and airborne observations, offering a unique opportunity to capture forest properties remotely and to investigate their variations on broad scales. However, despite rapid development of metrics to characterize the forest canopy from remotely sensed data, a gap remains between aerial and fi...

Significance An important class of negative feedbacks in population dynamics is the activity of host-specific enemies that disproportionately kill individuals in locations where they are common. This mechanism, called the Janzen–Connell hypothesis, has been proposed as a determinant of the large number of species in tropical forests. A critical but...

Aim: Large tropical trees form the interface between ground and airborne observations, offering a unique opportunity to capture forest properties remotely and to investigate their variations on broad scales. However, despite rapid development of metrics to characterize the forest canopy from remotely sensed data, a gap remains between aerial and fi...

Aim: Large tropical trees form the interface between ground and airborne observations, offering a unique opportunity to capture forest properties remotely and to investigate their variations on broad scales. However, despite rapid development of metrics to characterize the forest canopy from remotely sensed data, a gap remains between aerial and fi...

Tropical secondary forests (TSF) are a global carbon sink of 1.6 Pg C ∙ year−1. However, TSF carbon uptake is estimated using chronosequence studies that assume differently aged forests can be used to predict change in aboveground biomass density (AGBD) over time. We tested this assumption using two airborne lidar datasets separated by 11.5 years o...

Have tropical rain forest landscapes changed directionally through recent decades? To answer this question requires tracking forest structure and dynamics through time and across within-forest environmental heterogeneity. While the impacts of major environmental gradients in soil nutrients, climate and topography on lowland tropical rain forest (TR...

Turnover. Mean rates of turnover ± 1 S.E.M. for old growth forest in 18 0.50 ha plots at the La Selva Biological Station, Costa Rica. (TIF)

CARBONO plots static structure data. CARBONO plot stem inventory data 1997–2014 for 18 0.5 ha plots in old-growth Tropical Wet Forest at the La Selva Biological Station, Costa Rica. (CSV)

Multidecadal trends in recruitment. Multidecadal trends in recruitment in old-growth forests on residual and alluvial soils at the La Selva Biological Station, Costa Rica. Data from 1969–1982 are from OTS Plot 1 (4.4 ha, alluvial soil) and OTS Plot 3 (4.0 ha, residual soil) [17]). Data from 1997 onward are from the 6 0.5 ha CARBONO Project plots on...

Stem density through time in three different edaphic conditions. Mean stem density in 18 0.50 ha plot in three edaphic conditions ±1 S.E.M. (TIF)

CARBONO plot growth data. CARBONO plot stem growth data 1997–2014 for 18 0.5 ha plots in old-growth Tropical Wet Forest at the La Selva Biological Station, Costa Rica. (CSV)

Location of CARBONO project forest inventory plots. Locations of the 18 0.50 ha 50 x 100 m permanent forest inventory plots at the La Selva Biological Station, Puerto Viejo de Sarapiquí, Costa Rica. Plots were sited with a stratified random design within three principal upland landscape units: flat sites on old alluvial soils (plots shown in tan),...

Estimated basal area by edaphic condition. Mean basal area (±1 S.E.M.) in three different landscape types at the La Selva Biological Station, Costa Rica. N = 6 0.50 ha plots per edaphic category. (TIF)

Recruitment. Mean rates of recruitment ± 1 S.E.M. for old growth forest in 18 0.50 ha plots at the La Selva Biological Station, Costa Rica. (TIF)

We developed a statistical framework to quantify mortality rates in canopy trees observed using time series from high-resolution remote sensing. By timing the acquisition of remote sensing data with synchronous annual flowering in the canopy tree species Handroanthus guayacan, we made 2,596 unique detections of 1,006 individual adult trees within 1...

We used measurements from airborne imaging spectroscopy and LiDAR to quantify the bio-physical structure and composition of vegetation on a dryland substrate age gradient in Hawaii. Both vertical stature and species composition changed during primary succession, and reveal a progressive increase in vertical stature on younger substrates followed by...

Advances in wildlife telemetry and remote sensing technology facilitate studies of broad-scale movements of ungulates in relation to phenological shifts in vegetation. In tropical island dry landscapes, home range use and movements of non-native feral goats (Capra hircus) are largely unknown, yet this information is important to help guide the cons...

Predictions of climate-related shifts in species ranges have largely been based on correlative models. Due to limitations of these models, there is a need for more integration of experimental approaches when studying impacts of climate change on species distributions. Here we used controlled experiments to identify physiological thresholds that con...

Remote identification and mapping of canopy tree species can contribute valuable information towards our understanding of ecosystem biodiversity and function over large spatial scales. However, the extreme challenges posed by highly diverse, closed-canopy tropical forests have prevented automated remote species mapping of non-flowering tree crowns...

QuestionHow do canopy disturbance and soil properties structure vascular plant community species composition and resilience to encroachment by exotic species in a tropical montane wet forest?LocationHawai'i Experimental Tropical Forest (HETF), a tropical montane wet forest, on Mauna Kea, Hawai'i Island, Hawai'i, USA.Methods Previous studies employi...

Giri and Long (1) agree with our conclusion (2) that the expansion of mangroves from 1984 to 2011 near their range limit on the Atlantic coast of Florida is a threshold response to fewer days below −4 °C. However, they suggest that our conclusions would have been “substantially different” had we included one additional year of data in the analyses,...

The conservation of species at risk of extinction requires data to support decisions at landscape to regional scales. There is a need for information that can assist with locating suitable habitats in fragmented and degraded landscapes to aid the reintroduction of at-risk plant species. In addition, desiccation and water stress can be significant b...

Trees compete for space in the canopy, but where and how individuals or their component parts win or lose is poorly understood. We developed a stochastic model of three-dimensional dynamics in canopies using a hierarchical Bayesian framework, and analysed 267 533 positive height changes from 1.25 m pixels using data from airborne LiDAR within 43 ha...

The emergence of macrosystems ecology (MSE), which focuses on regional- to continental-scale ecological pat- terns and processes, builds upon a history of long-term and broad-scale studies in ecology. Scientists face the difficulty of integrating the many elements that make up macrosystems, which consist of hierarchical processes at interacting spa...

Macrosystems ecology is the study of diverse ecological phenomena at the scale of regions to continents and their interactions with phenomena at other scales. This emerging subdiscipline addresses ecological questions and environmental problems at these broad scales. Here, we describe this new field, show how it relates to modern ecological study,...

Significance Coastal mangrove forests support a diverse array of associated species and provide ecosystem services to human communities. Mangroves cannot tolerate extreme freezing temperatures and so are generally limited to tropical environments. However, climate change in the form of increasing temperatures has the potential to facilitate increas...

Tropical rainforests have experienced major episodes of severe heat and drought in recent decades, and climate models project a warmer and potentially drier tropical climate over this century. But likely responses of tropical rainforests are poorly understood due to a lack of frequent long-term measurements of forest structure and dynamics. We anal...

Canopy gaps express the time-integrated effects of tree failure and mortality as well as regrowth and succession in tropical forests. Quantifying the size and spatial distribution of canopy gaps is requisite to modeling forest functional processes ranging from carbon fluxes to species interactions and biological diversity. Using high-resolution air...

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The dynamics of the tallest trees in tropical forests are of special interest due to their carbon content, canopy dominance, and the large canopy gaps created when they die. Known ecological mechanisms that may influence tall tree survival lead to conflicting predictions. Hydraulic stress and exposure to high winds and desiccation should increase d...

Despite the importance of measuring tropical forest biomass, the accuracy of biomass estimates is poorly constrained due to fundamental weaknesses in the design and implementation of field studies. We identify these issues and propose a radical paradigm shift to advance tropical forest biomass research to a firmer theoretical and empirical basis.

We used aerial photography from 1954 and airborne LiDAR and imaging spectroscopy from 2008 to infer changes in extent and location of tall-stature woody vegetation in 127 km(2) of subalpine dry forest on the island of Hawai'i (Pohakuloa Training Area), and to identify 25.8 km(2) of intact woody vegetation for restoration and management. Total cover...

We quantified rates, sizes, and spatial properties of prevailing disturbance regimes in five tropical rain forest landscapes on a substrate-age gradient in Hawaii. By integrating measurements from airborne LiDAR with field studies and statistical modeling, we show that the structure and dynamics of these forests respond to processes that change dur...

Escape from natural enemies is a widely held generalization for the success of exotic plants. We conducted a large-scale experiment in Hawaii (USA) to quantify impacts of ungulate removal on plant growth and performance, and to test whether elimination of an exotic generalist herbivore facilitated exotic success. Assessment of impacted and control...

Background/Question/Methods Ecological restoration is a priority in ecosystems where invasive species are abundant. However, restoration can be difficult when invasive species have had large impacts on ecosystem properties and land-use has caused significant environmental degradation. Restoration is also challenging in landscapes where resources...

Background/Question/Methods: A major problem at the intersection of basic and applied forest ecology is the role of tropical forests in the global carbon (C) cycle. Although they represent just 13% of the terrestrial biosphere, tropical forests contribute nearly half of the global biomass C pool. Atmospheric modeling studies suggest the terrestrial...

Background/Question/Methods We used airborne imaging spectroscopy and LiDAR to quantify the structure and condition of tropical dry forest in Hawaii dominated by the endemic tree species Myoporum sandwicense and Sophora chyrsophylla (MSDF). The study site provides critical habitat to the endangered Hawaiian honeycreeper Loxoides bailleui, but littl...

Technical and analytical improvements in aircraft-based remote sensing allow synoptic measurements of structural and chemical properties of vegetation across whole landscapes. We used the Carnegie Airborne Observatory, which includes waveform light detection and ranging (LiDAR) and high-fidelity imaging spectroscopy, to evaluate the landscapes surr...

We obtained spatially extensive canopy height measurements using airborne remote sensing to characterize the structure and dynamics of a tropical rain forest landscape. Light detection and ranging (LiDAR) is a remote-sensing technology that acquires measurements of canopy height and ground elevation. By recording the return time of laser pulses emi...

Size frequency distributions of canopy gaps are a hallmark of forest dynamics. But it remains unknown whether legacies of forest disturbance are influencing vertical size structure of landscapes, or space-filling in the canopy volume. We used data from LiDAR remote sensing to quantify distributions of canopy height and sizes of 434,501 canopy gaps...

A fundamental property of all forest landscapes is the size frequency distribution of canopy gap disturbances. But characterizing forest structure and changes at large spatial scales has been challenging and most of our understanding is from permanent inventory plots. Here we report the first application of light detection and ranging remote sensin...

New roads, agricultural projects, logging, and mining are claiming an ever greater area of once-pristine Amazonian forest. The Millennium Ecosystems Assessment (MA) forecasts the extinction of a large fraction of Amazonian tree species based on projected loss of forest cover over the next several decades. How accurate are these estimates of extinct...

Logistical constraints on sample size and spatial scale limit individual-based field research on tropical trees. With remote sensing data, we may escape these limitations if fates of individuals can be tracked rigorously. We assessed the potential of readily available, commercial satellite data (QuickBird, 0.7 m pixels) obtained in 2003, to track t...