Integrating genetic concepts into planning rangeland seedings.

Abstract

Choice of plant materials is a fundamental component of any rangeland rehabilitation, reclamation, or restoration project. We describe here an integrated approach for such decision-making. This approach considers site potential, desired landscape, seeding objectives, conflicting land use philosophies, appropriate plant materials, weed invasion, community seral status, and economic limitations. Technical limitations are considered in generating a plan that has the greatest potential for success. Determining whether native-site plant material is best depends on objectives, heterogeneity of the site's environment, uniqueness of the site, plant population size, and biotic or abiotic site disturbance. Fixation of alien genes into a population is referred to both as introgression, which may ensure maintenance of genetic variation critical for adaptation to a changing environment, and as genetic pollution, with the potential for swamping native cross-pollinating annual or short-lived perennial gene pools. Precautionary procedures during seed increase minimize genetic shift, which may be reversible, but genetic drift could result in permanent loss of desirable genes. A variety of germplasm classes, ranging from site-specific to widely adapted and varying in degrees of heterozygosity and heterogeneity should be considered.. Material originating from multiple sites may increase the opportunity for natural selection. An understanding of the magnitude and nature of a species' genetic variation, its relationship to ecological adaptation, and its interaction with other ecosystem components contribute to informed decision-making. Though often unavailable, experience is the best guide for predicting performance of materials on non-native sites.