نتایج جستجو برای: lai

تعداد نتایج: 4952  

2012
miina rautiainen Janne heiskanen lauri Korhonen

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-...

1996
HEIKKI SMOLANDER PAULINE STENBERG

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 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 a circular plot with a radius of 25 m. An LAI-20...

2009
Kaiguang Zhao Sorin Popescu

a r t i c l e i n f o Keywords: Leaf area index LAI Airborne laser Forest ecosystems Lidar GLOBCARBON Carbon cycling Hemispherical photograph scale Lidar provides enhanced abilities to remotely map leaf area index (LAI) with improved accuracies. We aim to further explore the capability of discrete-return lidar for estimating LAI over a pine-dominated forest in East Texas, with a secondary goal ...

2004
Richard A. Fernandes John R. Miller Jing M. Chen Irene G. Rubinstein

Leaf area index (LAI) is an important surface biophysical parameter as a measure of vegetation cover, vegetation productivity, and as an input to ecosystem process models. Recently, a number of coarse-scale (1-km) LAI maps have been generated over large regions including the Canadian boreal forest. This study focuses on the production of fine-scale (V 30-m) LAI maps using the forest light inter...

2006
Torbern Tagesson

Two sites in Sweden are investigated for a potential deep repository of the nuclear waste, the Laxemar investigation area (57°5’N, 16°7’E) and the Forsmark investigation area (60°4’N, 18°2’E). In the characterisation of these sites, development of site descriptive models is an important part. Leaves are the main surface were an exchange of matter and energy between the atmosphere and the biosph...

2005
D. L. VERBYLA

The Moderate Resolution Imaging Spectroradiometer (MODIS) Leaf Area Index (LAI) Product (MOD15A2) was evaluated for the growing seasons of 2000 through 2004 in Alaska. The LAI estimate may be affected by three factors not directly related to canopy leaf area: snow melt, cloud contamination and conifer forest versus broadleaf shrub canopy type. Increases in MODIS LAI values occurred during the s...

2017
Xiangqin Wei Xingfa Gu Qingyan Meng Tao Yu Xiang Zhou Zheng Wei Kun Jia Chunmei Wang

Leaf area index (LAI) is an important vegetation parameter that characterizes leaf density and canopy structure, and plays an important role in global change study, land surface process simulation and agriculture monitoring. The wide field view (WFV) sensor on board the Chinese GF-1 satellite can acquire multi-spectral data with decametric spatial resolution, high temporal resolution and wide c...

2004
K. S. Lee Y. I. Park S. H. Kim J. H. Park C. S. Woo K. C. Jang

This study attempts to find a new and better approach to estimate forest LAI in fully closed canopy condition. Although there have been many previous studies to estimate LAI using optical remote sensor data, there are not enough evidences whether the red and near-IR reflectance are still effective to estimate forest LAI in closed canopy situation. In this study, we have conducted a simple corre...

2015
Eero Nikinmaa

Leaf area index (LAI) is a key variable for many ecological models, but it is typically not available from basic forest inventories. In this study, we (1) construct a high-resolution LAI map using k nearest-neighbor (k-NN) imputation based on National Forest Inventory data and Landsat 5 TM images (Landsat-NFI LAI), and (2) examine a moderate-resolution LAI map produced based on reduced simple r...

2007
Hongliang Fang Shunlin Liang John R. Townshend Robert E. Dickinson

Leaf Area Index (LAI) is an important biophysical variable for characterizing the land surface vegetation. Global LAI product has been routinely produced from the MODerate resolution Imaging Spectroradiometer (MODIS) aboard the Terra and Aqua satellite platforms. However, the MODIS standard LAI product is not continuous both spatially and temporally. To fill the gaps and improve the quality, we...

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