نتایج جستجو برای: vegetation canopy

تعداد نتایج: 59140  

2014
Piedad M. Cristiano Paula I. Campanello Sabrina A. Rodríguez Yong-Jiang Zhang Laureano Oliva Carrasco Guillermo Goldstein

The canopy photosynthesis and carbon balance of the subtropical forests are not well studied compared to temperate and tropical forest ecosystems. The main objective of this study was to assess the seasonal dynamics of Normalized Difference Vegetation Index (NDVI) and potential canopy photosynthesis in relation to seasonal changes in leaf area index (LAI), chlorophyll concentration, and air tem...

Journal: :Remote Sensing 2017
Livia Piermattei Markus Hollaus Milutin Milenkovic Norbert Pfeifer Raphael Quast Yuwei Chen Teemu Hakala Mika Karjalainen Juha Hyyppä Wolfgang Wagner

Radar sensors have the potential to retrieve vertical forest structure measurements thanks to their capability to penetrate into the foliage. However, studies are needed in order to understand better the interaction of radar beams with the canopy. The most commonly used radar technique for estimating forest parameters operates from spacecraft at different wavelength (X-, C-, and L-band). In ord...

Journal: :desert 2010
hosein azarnivand hamed joneidi jafari sh. nikoo mohamad zare chahouki a. malekian

abstract the objective of current research is to investigate distribution patterns of vegetation types and its relation with environmental factors in southern margin of haj aligholi kavir of damghan. three vegetation types including halecnemum strobilaceum, sedlitzia rosmarinus and artemisia sieberi were studied in marginal arid regions and uplands of the study area. firstly, geographic locatio...

2011
G.vanN. du Toit H. A. Snyman

________________________________________________________________________________ Abstract Grazing levels and rotational schemes need to be tailored to each individual farm or pasture, and more studies are needed on the resilience of rangelands and on separating the effects of grazing and climate. The direct short-term impact of three rates of stocking (4, 8 and 16 Small Stock Units-SSU/ha) was ...

Journal: :Remote Sensing 2016
Dan J. Krofcheck Marcy E. Litvak Christopher D. Lippitt Amy Neuenschwander

The rapid and accurate assessment of above ground biomass (AGB) of woody vegetation is a critical component of climate mitigation strategies, land management practices and process-based models of ecosystem function. This is especially true of semi-arid ecosystems, where the high variability in precipitation and disturbance regimes can have dramatic impacts on the global carbon budget by rapidly...

Journal: :Remote Sensing 2015
Parviz Fatehi Alexander Damm Michael E. Schaepman Mathias Kneubühler

Spatial information of forest structural variables is crucial for sustainable forest management planning, forest monitoring, and the assessment of forest ecosystem productivity. We investigate a complex alpine forest ecosystem located in the Swiss National Park (SNP) and apply empirical models to retrieve the structural variables canopy closure, basal area, and timber volume at plot scale. We u...

2004
Driss Haboudane John R. Miller Elizabeth Pattey Pablo J. Zarco-Tejada Ian B. Strachan

A growing number of studies have focused on evaluating spectral indices in terms of their sensitivity to vegetation biophysical parameters, as well as to external factors affecting canopy reflectance. In this context, leaf and canopy radiative transfer models are valuable for modeling and understanding the behavior of such indices. In the present work, PROSPECT and SAILH models have been used t...

Journal: :The New phytologist 2017
Cecilia Chavana-Bryant Yadvinder Malhi Jin Wu Gregory P Asner Athanasios Anastasiou Brian J Enquist Eric G Cosio Caravasi Christopher E Doughty Scott R Saleska Roberta E Martin France F Gerard

Leaf aging is a fundamental driver of changes in leaf traits, thereby regulating ecosystem processes and remotely sensed canopy dynamics. We explore leaf reflectance as a tool to monitor leaf age and develop a spectra-based partial least squares regression (PLSR) model to predict age using data from a phenological study of 1099 leaves from 12 lowland Amazonian canopy trees in southern Peru. Res...

Journal: :The New phytologist 2015
John S Sperry David M Love

Climate change exposes vegetation to unusual drought, causing declines in productivity and increased mortality. Drought responses are hard to anticipate because canopy transpiration and diffusive conductance (G) respond to drying soil and vapor pressure deficit (D) in complex ways. A growing database of hydraulic traits, combined with a parsimonious theory of tree water transport and its regula...

Journal: :Remote Sensing 2016
Elsa Carla De Grandi Edward T. A. Mitchard Dirk H. Hoekman

Three-dimensional information provided by TanDEM-X interferometric phase and airborne Light Detection and Ranging (LiDAR) Digital Elevation Models (DEMs) were used to detect differences in vegetation heterogeneity through a disturbance gradient in Indonesia. The range of vegetation types developed as a consequence of fires during the 1997–1998 El Niño. Two-point statistic (wavelet variance and ...

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