Continuous observation of tree leaf area index at ecosystem scale using upward-pointing digital cameras

Anderson, 1966, Stand structure and light penetration. 2. A theoretical analysis, Journal of Applied Ecology, 3, 41, 10.2307/2401665 Angert, 2005, Drier summers cancel out the CO2 uptake enhancement induced by warmer springs, Proceedings of the National Academy of Sciences of the United States of America, 102, 10823, 10.1073/pnas.0501647102 Archibald, 2007, Leaf green-up in a semi-arid African savanna — Separating tree and grass responses to environmental cues, Journal of Vegetation Science, 18, 583 Baldocchi, 1995, Scaling carbon dioxide and water vapour exchange from leaf to canopy in a deciduous forest. II. Model testing and application, Plant Cell and Environment, 18, 1157, 10.1111/j.1365-3040.1995.tb00626.x Baldocchi, 2004, How plant functional-type, weather, seasonal drought, and soil physical properties alter water and energy fluxes of an oak–grass savanna and an annual grassland, Agricultural and Forest Meteorology, 123, 13, 10.1016/j.agrformet.2003.11.006 Baret, 2010, GAI estimates of row crops from downward looking digital photos taken perpendicular to rows at 57.5° zenith angle: Theoretical considerations based on 3D architecture models and application to wheat crops, Agricultural and Forest Meteorology, 150, 1393, 10.1016/j.agrformet.2010.04.011 Barr, 2004, Inter-annual variability in the leaf area index of a boreal aspen–hazelnut forest in relation to net ecosystem production, Agricultural and Forest Meteorology, 126, 237, 10.1016/j.agrformet.2004.06.011 Botta, 2000, A global prognostic scheme of leaf onset using satellite data, Global Change Biology, 6, 709, 10.1046/j.1365-2486.2000.00362.x Chase, 1996, Sensitivity of a general circulation model to global changes in leaf area index, Journal of Geophysical Research-Atmospheres, 101, 7393, 10.1029/95JD02417 Chen, 2006, Leaf area index measurements at Fluxnet-Canada forest sites, Agricultural and Forest Meteorology, 140, 257, 10.1016/j.agrformet.2006.08.005 Chen, 2012, Effects of foliage clumping on the estimation of global terrestrial gross primary productivity, Global Biogeochemical Cycles, 26 Chen, 1997, Leaf area index of boreal forests: Theory, techniques, and measurements, Journal of Geophysical Research-Atmospheres, 102, 29429, 10.1029/97JD01107 Chen, 2008, Modeling radiation and photosynthesis of a heterogeneous savanna woodland landscape with a hierarchy of model complexities, Agricultural and Forest Meteorology, 148, 1005, 10.1016/j.agrformet.2008.01.020 Fang, 2008, Spatially and temporally continuous LAI data sets based on an integrated filtering method: Examples from North America, Remote Sensing of Environment, 112, 75, 10.1016/j.rse.2006.07.026 Fuentes, 2008, An automated procedure for estimating the leaf area index (LAI) of woodland ecosystems using digital imagery, MATLAB programming and its application to an examination of the relationship between remotely sensed and field measurements of LAI, Functional Plant Biology, 35, 1070, 10.1071/FP08045 Garrigues, 2008, Validation and intercomparison of global leaf area index products derived from remote sensing data, Journal of Geophysical Research-Biogeosciences, 113 Hanninen, 2007, A framework for modelling the annual cycle of trees in boreal and temperate regions, Silva Fennica, 41, 167, 10.14214/sf.313 He, 2012, Global clumping index map derived from the MODIS BRDF product, Remote Sensing of Environment, 119, 118, 10.1016/j.rse.2011.12.008 Higgins, 2011, Is there a temporal niche separation in the leaf phenology of savanna trees and grasses?, Journal of Biogeography, 38, 2165, 10.1111/j.1365-2699.2011.02549.x Jolly, 2005, A generalized, bioclimatic index to predict foliar phenology in response to climate, Global Change Biology, 11, 619, 10.1111/j.1365-2486.2005.00930.x Kim, 2006, Upscaling fluxes from tower to landscape: Overlaying flux footprints on high-resolution (IKONOS) images of vegetation cover, Agricultural and Forest Meteorology, 136, 132, 10.1016/j.agrformet.2004.11.015 Kobayashi, 2012, Modeling energy and carbon fluxes in a heterogeneous oak woodland: A three-dimensional approach, Agricultural and Forest Meteorology, 152, 83, 10.1016/j.agrformet.2011.09.008 Kobayashi, 2005, Atmospheric conditions for monitoring the long-term vegetation dynamics in the Amazon using normalized difference vegetation index, Remote Sensing of Environment, 97, 519, 10.1016/j.rse.2005.06.007 Kobayashi, H., Ryu, Y., Baldocchi, D. D., Welles, J. M., & Norman, J.M. (in review). On the correct estimation of gap fraction: how to remove scattered radiation in the gap fraction measurements? Agricultural and Forest Meteorology. Kucharik, 1998, Measurements of branch area and adjusting leaf area index indirect measurements, Agricultural and Forest Meteorology, 91, 69, 10.1016/S0168-1923(98)00064-1 Lang, 1986, Estimation of leaf area index from transmission of direct sunlight in discontinuous canopies, Agricultural and Forest Meteorology, 37, 229, 10.1016/0168-1923(86)90033-X Lefsky, 2002, Lidar remote sensing for ecosystem studies, Bioscience, 52, 19, 10.1641/0006-3568(2002)052[0019:LRSFES]2.0.CO;2 Leuning, 1995, Leaf nitrogen, photosynthesis, conductance and transpiration — Scaling from leaves to canopies, Plant, Cell & Environment, 18, 1183, 10.1111/j.1365-3040.1995.tb00628.x Liu, 2010, Retrieval of leaf area index from top-of-canopy digital photography over agricultural crops, Agricultural and Forest Meteorology, 150, 1485, 10.1016/j.agrformet.2010.08.002 Ma, 2007, Inter-annual variability in carbon dioxide exchange of an oak/grass savanna and open grassland in California, Agricultural and Forest Meteorology, 147, 157, 10.1016/j.agrformet.2007.07.008 Macfarlane, 2011, Classification method of mixed pixels does not affect canopy metrics from digital images of forest overstorey, Agricultural and Forest Meteorology, 151, 833, 10.1016/j.agrformet.2011.01.019 Macfarlane, 2007, Estimation of leaf area index in eucalypt forest using digital photography, Agricultural and Forest Meteorology, 143, 176, 10.1016/j.agrformet.2006.10.013 Macfarlane, 2012, Automated estimation of foliage cover in forest understorey from digital nadir images, Methods in Ecology and Evolution, 3, 405, 10.1111/j.2041-210X.2011.00151.x Morisette, 2009, Tracking the rhythm of the seasons in the face of global change: Phenological research in the 21st century, Frontiers in Ecology and the Environment, 7, 253, 10.1890/070217 Myneni, 2002, Global products of vegetation leaf area and fraction absorbed PAR from year one of MODIS data, Remote Sensing of Environment, 83, 214, 10.1016/S0034-4257(02)00074-3 Nilson, 1971, Theoretical analysis of frequency of gaps in plant stands, Agricultural Meteorology, 8, 25, 10.1016/0002-1571(71)90092-6 Nilson, 1999, Inversion of gap frequency data in forest stands, Agricultural and Forest Meteorology, 98–99, 437, 10.1016/S0168-1923(99)00114-8 Nilson, 2004, Improved algorithm for estimating canopy indices from gap fraction data in forest canopies, Agricultural and Forest Meteorology, 124, 157, 10.1016/j.agrformet.2004.01.008 Norman, 1989, Canopy structure, 301 Parmesan, 2003, A globally coherent fingerprint of climate change impacts across natural systems, Nature, 421, 37, 10.1038/nature01286 Peñuelas, 2009, Phenology feedbacks on climate change, Science, 324, 887, 10.1126/science.1173004 Peckham, 2008, Fire-induced changes in green-up and leaf maturity of the Canadian boreal forest, Remote Sensing of Environment, 112, 3594, 10.1016/j.rse.2008.04.016 Penuelas, 2001, Phenology — Responses to a warming world, Science, 294, 793, 10.1126/science.1066860 Pisek, 2011, Estimating leaf inclination and G-function from leveled digital camera photography in broadleaf canopies, Trees - Structure and Function, 25, 919, 10.1007/s00468-011-0566-6 Privette, 2002, Early spatial and temporal validation of MODIS LAI product in the Southern Africa Kalahari, Remote Sensing of Environment, 83, 232, 10.1016/S0034-4257(02)00075-5 Richardson, 2009, Near-surface remote sensing of spatial and temporal variation in canopy phenology, Ecological Applications, 19, 1417, 10.1890/08-2022.1 Rodriguez-Iturbe, 1999, Tree–grass coexistence in savannas: The role of spatial dynamics and climate fluctuations, Geophysical Research Letters, 26, 247, 10.1029/1998GL900296 Rosin, 2001, Unimodal thresholding, Pattern Recognition, 34, 2083, 10.1016/S0031-3203(00)00136-9 Ross, 1981 Ryu, 2011, Integration of MODIS land and atmosphere products with a coupled-process model to estimate gross primary productivity and evapotranspiration from 1 km to global scales, Global Biogeochemical Cycles, 25 Ryu, 2008, Interannual variability of evapotranspiration and energy exchanges over an annual grassland in California, Journal of Geophysical Research-Atmospheres, 113 Ryu, 2010, Testing the performance of a novel spectral reflectance sensor, built with light emitting diodes (LEDs), to monitor ecosystem metabolism, structure and function, Agricultural and Forest Meteorology, 150, 1597, 10.1016/j.agrformet.2010.08.009 Ryu, 2010, On the correct estimation of effective leaf area index: Does it reveal information on clumping effects?, Agricultural and Forest Meteorology, 150, 463, 10.1016/j.agrformet.2010.01.009 Ryu, 2010, How to quantify tree leaf area index in a heterogeneous savanna ecosystem: A multi-instrument and multi-model approach, Agricultural and Forest Meteorology, 150, 63, 10.1016/j.agrformet.2009.08.007 Sankaran, 2004, Tree–grass coexistence in savannas revisited — Insights from an examination of assumptions and mechanisms invoked in existing models, Ecology Letters, 7, 480, 10.1111/j.1461-0248.2004.00596.x Scholes, 1997, Tree–grass interactions in savannas, Annual Review of Ecology and Systematics, 28, 517, 10.1146/annurev.ecolsys.28.1.517 Scholes, 2004, Canopy structure in savannas along a moisture gradient on Kalahari sands, Global Change Biology, 10, 292, 10.1046/j.1365-2486.2003.00703.x Sea, 2011, Documenting improvement in leaf area index estimates from MODIS using hemispherical photos for Australian savannas, Agricultural and Forest Meteorology, 151, 1453, 10.1016/j.agrformet.2010.12.006 Sonnentag, 2011, Tracking the structural and functional development of a perennial pepperweed (Lepidium latifolium L.) infestation using a multi-year archive of webcam imagery and eddy covariance measurements, Agricultural and Forest Meteorology, 151, 916, 10.1016/j.agrformet.2011.02.011 Sonnentag, 2012, Digital repeat photography for phenological research in forest ecosystems, Agricultural and Forest Meteorology, 152, 159, 10.1016/j.agrformet.2011.09.009 Sprintsin, 2011, Long term and seasonal courses of leaf area index in a semi-arid forest plantation, Agricultural and Forest Meteorology, 151, 565, 10.1016/j.agrformet.2011.01.001 Tan, 2006, The impact of gridding artifacts on the local spatial properties of MODIS data: Implications for validation, compositing, and band-to-band registration across resolutions, Remote Sensing of Environment, 105, 98, 10.1016/j.rse.2006.06.008 Vargas, 2010, Effects of a hurricane disturbance on aboveground forest structure, arbuscular mycorrhizae and belowground carbon in a restored tropical forest, Ecosystems, 13, 118, 10.1007/s10021-009-9305-x Verger, 2011, A multisensor fusion approach to improve LAI time series, Remote Sensing of Environment, 115, 2460, 10.1016/j.rse.2011.05.006 Welles, 1991, Instrument for indirect measurement of canopy architecture, Agronomy Journal, 83, 818, 10.2134/agronj1991.00021962008300050009x White, 2009, Intercomparison, interpretation, and assessment of spring phenology in North America estimated from remote sensing for 1982–2006, Global Change Biology, 15, 1, 10.1111/j.1365-2486.2009.01910.x Xu, 2004, Seasonal variation in carbon dioxide exchange over a Mediterranean annual grassland in California, Agricultural and Forest Meteorology, 123, 79, 10.1016/j.agrformet.2003.10.004 Xu, 2004, How soil moisture, rain pulses, and growth alter the response of ecosystem respiration to temperature, Global Biogeochemical Cycles, 18 Zhang, 2003, Monitoring vegetation phenology using MODIS, Remote Sensing of Environment, 84, 471, 10.1016/S0034-4257(02)00135-9