Optical instruments for measuring leaf area index in low vegetation : application in Arctic ecosystems
van Wijk, Mark T.
MetadataShow full item record
KeywordArctic tundra; LAI; Leaf area index; Low-stature vegetation; Normalized difference vegetation index; Optical instruments; Sweden; Uncertainty analysis
Leaf area index (LAI) is a powerful diagnostic of plant productivity. Despite the fact that many methods have been developed to quantify LAI, both directly and indirectly, leaf area index remains difficult to quantify accurately, owing to large spatial and temporal variability. The gap-fraction technique is widely used to estimate the LAI indirectly. However, for low-stature vegetation, the gap-fraction sensor either cannot get totally underneath the plant canopy, thereby missing part of the leaf area present, or is too close to the individual leaves of the canopy, which leads to a large distortion of the LAI estimate. We set out to develop a methodology for easy and accurate nondestructive assessment of the variability of LAI in low-stature vegetation. We developed and tested the methodology in an arctic landscape close to Abisko, Sweden. The LAI of arctic vegetation could be estimated accurately and rapidly by combining field measurements of canopy reflectance (NDVI) and light penetration through the canopy (gap-fraction analysis using a LI-COR LAI-2000). By combining the two methodologies, the limitations of each could be circumvented, and a significantly increased accuracy of the LAI estimates was obtained. The combination of an NDVI sensor for sparser vegetation and a LAI-2000 for denser vegetation could explain 81% of the variance of LAI measured by destructive harvest. We used the method to quantify the spatial variability and the associated uncertainty of leaf area index in a small catchment area.
Author Posting. © Ecological Society of America, 2005. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 15 (2005): 1462–1470, doi:10.1890/03-5354.
Showing items related by title, author, creator and subject.
Rocha, Adrian V.; Shaver, Gaius R. (Ecological Society of America, 2011-03)Burned landscapes present several challenges to quantifying landscape carbon balance. Fire scars are composed of a mosaic of patches that differ in burn severity, which may influence postfire carbon budgets through damage ...
Variation in Serripes groenlandicus (Bivalvia) growth in a Norwegian high-Arctic fjord : evidence for local- and large-scale climatic forcing Ambrose, William G.; Carroll, Michael L.; Greenacre, Michael; Thorrold, Simon R.; McMahon, Kelton W. (2006-03-03)We examined the growth rate of the circumpolar Greenland Cockle (Serripes groenlandicus) over a period of 20 years (1983-2002) from Rijpfjord, a high-Arctic fjord in northeast Svalbard (80º10´N, 22°15´E). This period ...
Barrett, Kirsten; Rocha, Adrian V.; van de Weg, Martine J.; Shaver, Gaius R. (2012-01-27)With anticipated climate change, tundra fires are expected to occur more frequently in the future, but data on the longer term effects of fire on tundra vegetation composition are scarce. This study therefore addresses ...