Author
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Submitted to: Journal of Range Management
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 10/28/2000 Publication Date: 1/20/2001 Citation: Clark, Patrick, Seyfried, Mark S., Point Sampling Validation for Leaf Area Index Assessment in Shrub Steppe Communities, Journal of Range Management, pp 589-594, v. 54, 2001. Interpretive Summary: Although point sampling has be used for more than 30 years to quantify leaf area index (LAI), this field technique has not been rigorously evaluated in shrub steppe plant communities. Leaf area index estimates obtained using different sampling pin inclinations from the horizontal or different combinations of pin inclinations was evaluated in Wyoming big sagebrush, low sagebrush, and mountain big sagebrush communities within the Reynolds Creek Experimental Watershed (RCEW) near Boise, Idaho. Leaf area index values determined by clipping and processing green foliage through a leaf area meter were used as evaluation standards. Point sampling with pins inclined at 13o from the horizontal provided very poor estimates of total LAI and shrub LAI in the Wyoming big sagebrush and low sagebrush communities. Estimating of total LAI for all 3 sagebrush communities combined based on point data from the combination of pins inclined at 52o and 90o angles resulted in better model fit with LAI standards than when either 52o or 90o point data were used alone. Point data collected with either 52o or 90o angle pins for estimating shrub, graminoid, and forb LAI produced model fits which were similar to that obtained when the combination of 52o and 90o angle data were used. The 52o angle data performed as well as the 90o angle data for estimation of total LAI in the Wyoming big sagebrush and better than the 90o angle data for total LAI estimation in the mountain big sagebrush community. Although collecting point data using 52o angle pins most often provided the best model fit with LAI standards, using pins inclined at 90o appeared to be more practical in shrub vegetation and may be a better compromise between practicality, efficiency and accuracy than 52o angle pins. Technical Abstract: Although point sampling has be used for more than 30 years to quantify leaf area index (LAI), this field technique has not been rigorously evaluated in shrub steppe plant communities. Leaf area index estimates obtained using different sampling pin inclinations from the horizontal or different combinations of pin inclinations was evaluated in Wyoming big sagebrush, low sagebrush, and mountain big sagebrush communities within the Reynolds Creek Experimental Watershed (RCEW) near Boise, Idaho. Leaf area index values determined by clipping and processing green foliage through a leaf area meter were used as evaluation standards. Point sampling with pins inclined at 13o from the horizontal provided very poor estimates of total LAI and shrub LAI in the Wyoming big sagebrush and low sagebrush communities. Estimating of total LAI for all 3 sagebrush communities combined based on point data from the combination of pins inclined at 52o and 90o angles resulted in better model fit with LAI standards than when either 52o or 90o point data were used alone. Point data collected with either 52o or 90o angle pins for estimating shrub, graminoid, and forb LAI produced model fits which were similar to that obtained when the combination of 52o and 90o angle data were used. The 52o angle data performed as well as the 90o angle data for estimation of total LAI in the Wyoming big sagebrush and better than the 90o angle data for total LAI estimation in the mountain big sagebrush community. Although collecting point data using 52o angle pins most often provided the best model fit with LAI standards, using pins inclined at 90o appeared to be more practical in shrub vegetation and may be a better compromise between practicality, efficiency and accuracy than 52o angle pins. |
