A question of origin: Where and how to collect seed for ecological restoration

Abstract

Native plant species are routinely planted or sown in ecological restoration projects, but successful establishment and survival depend on where and how seeds are collected. Research suggests that it is important to use locally adapted seeds. Local populations often show a home-site advantage and non-local genotypes may be maladapted to local environmental conditions. Furthermore, intraspecific hybridisation of local and non-local genotypes may have a negative impact on the genetic structure of local populations via mechanisms such as outbreeding depression. Many species show a strong small-scale genetic differentiation between different habitats so that matching habitats of the restoration and donor site can be more important than minimizing geographical separation. It is a challenge to identify appropriate seed sources because strong small-scale population differentiation makes it difficult to delineate geographically defined seed zones to which seed exchange should be limited. Moreover, it is important to consider the genetic diversity of introduced material because it may be crucial to avoid genetic bottlenecks, inbreeding depression and poor establishment of plant populations. Repeated propagation in stock, which is often required to obtain a sufficient amount of seeds, can further reduce genetic diversity and may select for particular genotypes. Negative impacts of improper seed choice for nursery planting stock may become detectable only after many years, especially in long-lived and slow growing plants. Although scientific information on many species remains limited, the increasing demand for translocation of seed means that mandatory regulations are necessary. Guidelines should prescribe a specification of seed provenance, a record of genetic diversity of wild collections and rules for subsequent processing such as direct transfer and propagation of stock or seed orchards. We use a literature review to evaluate current legislation and to develop recommendations for herbaceous and woody species.

Variability in seed germination and seedling growth at the intra- and inter-provenance levels of Nothofagus glauca (Lophozonia glauca), an endemic species of Central Chile

“…Therefore, field studies will be necessary to resolve the adaptive effects of the field phenotypes associated with the observed variations in germination, survival and growth traits reported here. Also, non-local genotypes may suffer from maladaptation to the local environment resulting in a lower fitness (Vander Mijnsbrugge et al 2010), so reciprocal transplant experiments (RTEs) are needed to test how the species would respond to changing climates.…”

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

“…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]. Moreover, sourcing local seeds and maintaining the genetic variability of the native populations is key to ecosystem conservation through improvement in long-term restoration trajectories [3,7,11,14]. Based on national acts occurring in a few European countries [15,16], the newly released International Standards for the Practice of Ecological Restoration [17], and other published works [2,13], restoration practitioners should avoid using seed mixtures that include non-native species, seed of unknown origin or seed sourced from genetically uniform populations.…”

“…Within Europe, trade and use of herbaceous seeds are less regulated when compared to forest reproductive material [3]. More attention should be given to grasslands conservation, as they are counted among both the most species-rich vegetation types in Europe [4,5] and among the most extensively degraded and least protected habitats at both the European [4] and global scale, making them identifiable as a biome at risk [6].…”

Using recycled aggregates in green roof substrates for plant diversity

“…Once this phase has passed, seeds that were not in the original mix (such as Chenopodium album, as found in this study) were able to colonise the substrates (Madre et al 2014). However some invaders may be of the same speciespossibly with a more hardy advantage over the commercially bought seeds (Vander Mijnsbrugge et al 2010) -resulting in reduced individual plant numbers over time but a constant number of species maintained within the substrates. It should be noted that this was a short-term study and that the number of species may be reduced in subsequent years, as found by Dunnett et al (2008), Nagase & Dunnett (2010) and Benvenuti (2014) as some species become more dominant.…”