The merits of artificial selection for the development of restoration‐ready plant materials of native perennial grasses

Abstract

Although seed harvested from remnant, wildland perennial‐grass populations can be used for restoration in humid and subhumid temperate regions, seed harvested in semiarid and arid environments is often of low quality and highly variable in quantity. In addition, ongoing harvest of indigenous populations can be unsustainable, especially for those that are small. In such environments, dependable and repeatable broad‐scale restoration of degraded grasslands requires sufficient and consistent supplies of reliable, cost‐effective seed sources that can only result from intensively managed cultivated stands. But does the harvest of intensively managed seed‐production fields inadvertently compromise genetic diversity, thereby adversely affecting the restoration outcome? That is, are seed‐production systems a part of the solution for restoration, or do they create new unintended management issues? This article discusses the potential impacts of cultivated seed‐production systems and recurrent artificial selection for specific traits on genetic integrity and performance of native‐species perennial‐grass populations. Although genetic shift resulting from cultivated perennial‐grass seed production may be inevitable, genetic shifts that change phenological expression may be limited in genotypes that exhibit high seed retention. Artificial selection can improve plant material performance on the often‐harsh conditions of restoration sites, but sufficiently high‐effective population sizes (Ne) must be maintained to conserve genetic diversity, thereby precluding the inbreeding depression that can compromise plant performance. Potentially useful traits of native perennial‐grass species that respond to artificial selection include seed production, seed retention, seedling establishment, competitive ability against weeds, and herbicide tolerance. Potential trade‐offs between traits should also be considered to avoid undesirable inadvertent responses to selection.

Native Seed Supply and the Restoration Species Pool

“…), and other bottlenecks that can be encountered such as adaptations for cultivation or genetic diversity maintenance (Chivers et al . ). However, research findings are rarely accessible to public stakeholders involved in ER.…”

The European Native Seed Industry: Characterization and Perspectives in Grassland Restoration

“…Native seeds are most often harvested directly from wild or semi-managed populations by public, private or non-profit enterprises who may also use this seed for growing-on, with or without selecting specific traits and creating cultivars [9]. In certain circumstances, the multiplication of native seeds for ecological restoration in a farm setting becomes necessary when harvesting large volumes of seeds directly from natural habitats would damage the reproductive capabilities of the local populations [10][11][12], or donor communities of sufficient size have disappeared due to human impact [13].…”

Seed production areas for the global restoration challenge

“…Extreme cases of this type of selection are native plant cultivars or other improved varieties. Not only are improved varieties often phenotypically invariant (Espeland & Hammond, ; Leger & Baughman, ) and therefore unlikely to respond to selection imposed by climate change and other adaptive hurdles (Espeland et al., ), but they have often been developed specifically for traits such as above‐ground biomass accumulation, herbicide tolerance, or suitability for mechanized harvesting (Chivers, et al and references therein) that may be maladaptive in the long term in some restoration environments (Leger & Baughman, ). Although cultivars and non‐native species might be considered the most cost‐effective and readily available seed varieties when short‐term goals like soil stabilization cannot be achieved with native accessions (D'Antonio & Meyerson, ; Jones, Monaco, & Rigby, ), they cannot be considered a cost‐effective choice when the goal of restoration is to sustain diverse native landscapes and the native wildlife that depend on them (Kuebbing & Nuñez, ).…”