Numerical experiments with the global model of the European Centre for Medium-Range Weather Forecasts (ECMWF) were devoted to the sensitivity of the modelled evaporation and precipitation to the vegetation Leaf Area Index (LAI). The temporally static LAI-distribution was replaced with a seasonally varying LAI, derived from Normalized Difference Vegetation Index (NDVI) archives. The seasonality ...

Leaf area index (LAI) is a crucial biophysical parameter that is indispensable for many biophysical and climatic models. A neural network algorithm in conjunction with extensive canopy and atmospheric radiative transfer simulations is presented in this paper to estimate LAI from Landsat-7 Enhanced Thematic Mapper Plus data. Two schemes were explored; the first was based on surface reflectance, ...

We assessed the accuracy with which the LAI-2000 plant canopy analyzer measured changes in leaf area index (LAI) and plant area index (PAI) in a 25-year-old Scots pine (Pinus sylvestris L.) stand. Stand density was 2100 stems ha(-1) and mean tree height was 8.7 m. Needle and branch areas of the stand were reduced progressively to zero by the stepwise removal of branches on all trees growing in ...

When crops senescence, leaves remain until they fall off or are harvested. Hence, leaf area index (LAI) stays high even when chlorophyll content degrades to zero. Current LAI approaches from remote sensing techniques are not optimized for estimating LAI of senescent vegetation. In this paper a two-step approach has been proposed to realize simultaneous LAI mapping over green and senescent cropl...

The Normalized Difference Vegetation Index (NDVI) is widely used for Leaf Area Index (LAI) estimation. It is well documented that the NDVI is extremely subject to the saturation problem when LAI reaches a high value. A new multi-angular vegetation index, the Hotspot-darkspot Difference Vegetation Index (HDVI) is proposed to estimate the high density LAI. The HDVI, defined as the difference betw...

The photosynthetic leaf area may be influenced by soil texture. The objective of this experiment was to evaluate photosynthetic leaf area under different soil textures, based on soil electric conductivity (EC) measurements, tillage systems, and N rates in dryland corn (Zea mays L.) from 2007 to 2009. A commercially available soil electric conductivity (EC) measurement system (Veris Technologies...

Seasonal change in leaf area index (LAI) is highly important in remote sensing of land surface phenology because LAI is a main driving factor of forest reflectance. We present a time series of in situ measurements of boreal forest LAI expanding throughout the growing period from budburst to senescence. We measured the LAI of 20 stands at approximately two-week intervals between mid-May and mid-...

a r t i c l e i n f o Keywords: Crop model CSM DSSAT Genetic algorithm Hyperspectral LAI Model inversion Nitrogen Optimization PEST PROSAIL Simulation Wheat Yield Remote sensing technology can rapidly provide spatial information on crop growth status, which ideally could be used to invert radiative transfer models or ecophysiological models for estimating a variety of crop biophysical propertie...

LAI (leaf area index) estimation from direct measurement is tedious or impossible in tree canopies because of the high number of leaves and the large plant size. Methods based on inversion of gap fraction measurements have therefore been proposed, where gap fraction is measured from light sensors (e.g. ceptometer, Cohen et al. 1995, LAI-2000, Stenberg et al., 1994) or fisheye photographs (e.g. ...

The aim of this paper is to investigate the feasibility of using Landsat ETM+ data for the determination of leaf area index (LAI). The investigation is prompted by the need for obtaining spatially distributed data on LAI to be used as input for carbon modelling of northern boreal forests. Detailed field data have been collected in a coniferous forest area in Uppland, central Sweden, dominated b...