Submitted to: Journal of Freshwater Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/16/2007
Publication Date: 6/1/2007
Citation: Spencer, D.F., Sher, A., Thornby, D., Ksander, G.G. 2007. Non-destructive assessment of arundo donax (poaceae) leaf quality. Journal of Freshwater Ecology. 22(2):277-285. Interpretive Summary: Giant reed (Arundo donax L.) is a tall perennial plant that has invaded streamside habitats where it changes important ecosystem properties. Leaf quality information (i.e., leaf nitrogen content) is especially useful for understanding interactions between plants and insects that eat them, and may be important in developing control methods for the invasive riparian plant. In some cases, such as the long-term evaluation of the effects of biocontrol agents, non-destructive sampling methods may be desirable. In order to provide rapid non-destructive leaf quality estimates in these circumstances we derived an equation for estimating leaf nitrogen from values from a hand-held chlorophyll meter. We tested it against an independent data set, and the equation provided accurate estimates of leaf nitrogen for plants growing from northern California to southern Texas. This equation may give useful estimates from remote sensing technologies, allowing large-scale assessment of the variation in giant reed leaf quality.
Technical Abstract: Leaf quality information (i.e., leaf C content, leaf N content, leaf C:N ratio) is especially useful for understanding plant-herbivore interactions and may be important in developing control methods for the invasive riparian plant Arundo donax L. We measured leaf C content, leaf N content, leaf C:N ratio and leaf chlorophyll index (SPAD 502 reading) for 768 leaves from A. donax collected over a 5 year period at several locations in California, Nevada, and Texas. Leaf N and leaf C:N ratio were more variable than leaf C. We developed linear regression equations for estimating A. donax leaf N and leaf C:N ratio from leaf chlorophyll index (SPAD reading). The equation, leaf N content % = -0.63 + 0.081 x SPAD, explained 67% of total variation, while that for leaf C:N ratio, C:N = 50.05 - 0.80 x SPAD explained 72% of total variation. When applied to a a third data set, the equations produced realistic estimates that matched seasonal trends reported from a natural A. donax population. Used in conjunction with the handheld SPAD 502 meter, the equations provide a rapid, non-destructive method for estimating A. donax leaf quality.