Predictions of field productivity for Agave lechuguilla.

Published online
14 Jan 1988
Content type
Journal article
Journal title
Journal of Applied Ecology
DOI
10.2307/2404001

Author(s)
Quero, E. & Nobel, P. S.

Publication language
English
Location
USA & Mexico

Abstract

Net CO2 uptake over 24-h periods was determined in the field under various conditions. In Saltillo, Coahuila, Mexico, which is near the centre of distribution of A. lechuguilla, net CO2 uptake at a dry time of the year could be increased 4-fold by irrigation and nearly 3-fold by increasing total daily photosynthetically active radiation (PAR) intercepted by leaves of different orientation from 6 to 17 mol m-2. The number of leaves that unfolded each month, which relates directly to productivity for agaves, was highly correlated with an environmental productivity index (EPI) based on component indices representing the influences of water status, temperature, and PAR on net CO2 uptake (r2 averaged 0.77 for 7 sites in Coahuila and Nuevo León over the 1-year study period). Based on data from 300 weather stations, EPI was determined in 0.5° increments of latitude and longitude throughout its range in 11 states in Mexico and 2 in the United States. Annual EPI varied from 0.12 in the northern part of the whole region to 0.49 in the southern part, primarily reflecting the 3-fold higher water index caused by a 4-fold increase in annual precipitation to the south. The map showing the EPI isolines indicates that the distributional limits of A. lechuguilla are not primarily determined by low plant productivity.

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