Shading by shrubs in a desert system reduces the physiological and demographic performance of an associated herbaceous perennial

Citation
In. Forseth et al., Shading by shrubs in a desert system reduces the physiological and demographic performance of an associated herbaceous perennial, J ECOLOGY, 89(4), 2001, pp. 670-680
Citations number
53
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
JOURNAL OF ECOLOGY
ISSN journal
0022-0477 → ACNP
Volume
89
Issue
4
Year of publication
2001
Pages
670 - 680
Database
ISI
SICI code
0022-0477(200108)89:4<670:SBSIAD>2.0.ZU;2-#
Abstract
1 A 2-year field study examined the demographic consequences of association with shrubs in an herbaceous perennial, Cryptanthaflava. Physiological dat a were collected to evaluate whether shrub effects were mediated primarily through water, nutrient or light availability. 2 Microclimatic conditions under the north side of shrubs differed from ope n microhabitats, primarily in light availability. Due to little photosynthe tic acclimation to light, daily photosynthesis for plants under shrubs was reduced proportionally to the light regime. 3 Shading did not reduce stomatal conductance proportionally to photosynthe sis, which led to decreased water use efficiency for plants under shrubs. F ew differences were found in leaf water potential between microhabitats, in dicating that little competition for water was occurring. 4 There was little evidence for shrub-induced nutrient island effects. Soil nitrogen, phosphorus and organic content did not differ between open and s hrub microhabitats. Leaf nitrogen content also differed little between plan ts in the two microhabitats. 5 Growth and flowering responses of individuals under shrubs were reduced r elative to those in the open, even for plants located on the south side of shrubs. 6 Over this 2-year period of average to above-average rainfall, association of C. flava with shrubs was dominated by competition for light, rather tha n for water or nutrients. Future investigations will address whether this a symmetric competitive interaction changes during years with below-average r ainfall to a facilitative interaction, or one of increased competition for water.