The effect of water and nitrogen amendments on photosynthesis, leaf demography, and resource-use efficiency in <i>Larrea tridentata,</i> a desert evergreen shrub

TitleThe effect of water and nitrogen amendments on photosynthesis, leaf demography, and resource-use efficiency in Larrea tridentata, a desert evergreen shrub
Publication TypeJournal Article
Year of Publication1989
AuthorsLajtha K., Whitford WG
JournalOecologia
Volume80
Pagination341-348
Date Published1989
KeywordsLarrea tridentata, leaf demography, nutrient resportion, nutrient-use efficiency, photosynthesis, water-use efficiency
Abstract

In the Chihuahuan Desert of southern New Mexico, both water and nitrogen limit the primary productivity of Larrea tridentata, a xerophytic avergreen shrub. Net photosynthesis was positively correlated to leaf N, but only in plants that received supplemental water. Nutrient-use efficiency, defined as photosynthetic carbon gain per unit N invested in leaf tissue, declined with increasing leaf N. However, water-use efficiency, defined as the ratio of photosynthesis to transpiration, increased with increasing leaf N, and thus these two measure of resource-use efficiency were inversely correlated Resorption efficiency was not significantly altered over the nutrient gradient, nor was it affected by irriation treatments. Leaf longevity decreased significantly with fertilization although the absolute magnitude of this decrease was fairly small, in part due to a large background of insect-induced mortality. Age-specific gas exchange measurements support the hypothesis that leaf aging represents a redistribution of resources, rather than actual deterioration or declining resoruce-use efficiency.

URL/files/bibliography/350.pdf
DOI10.1007/BF00379035