Seed sourcing strategies for ecological restoration under climate change: A review of the current literature

Abstract

Climate change continues to alter the seasonal timing and extremes of global temperature and precipitation patterns. These departures from historic conditions along with the predicted variability of future climates present a challenge to seed sourcing, or provenance strategy decisions, within the practice of ecological restoration. The “local is best” for seed sourcing paradigm is predicated upon the assumption that ecotypes are genetically adapted to their local environment. However, local adaptations are potentially being outpaced by climate change, and the ability of plant populations to naturally migrate or shift their distribution accordingly may be limited by habitat fragmentation. Restoration practitioners and natural area managers have a general understanding of the importance of matching the inherent adaptations of source populations with the current and/or future site conditions where those seeds or propagules are planted. However, for many species used in seed-based restoration, there is a lack of empirical evidence to guide seed sourcing decisions, which are critical for the longevity and ecological function of restored natural communities. With the goal of characterizing, synthesizing, and applying experimental research to guide restoration practice, we conducted a systematic review of the literature on provenance testing of taxa undertaken to inform seed sourcing strategies for climate resiliency. We found a strong bias in the choice of study organism: most studies have been conducted on tree species. We also found a strong bias regarding where this research has been conducted, with North America (52%) and Europe (31%) overrepresented. Experiments were designed to assess how propagule origin influences performance across both climatic (26%) and geographic (15%) distance, with some studies focused on determining how climate normal conditions (39%) impacted performance related to survivorship, growth and other parameters. We describe the patterns and gaps our review identified, highlight specific topics which require further research, and provide practical suggestions of immediate and longer-term tools that restoration practitioners can use to guide and build resilient natural communities under future climate scenarios.

The eco‐evolutionary risks of not changing seed provenancing practices in changing environments

“…Moving forward, empirical evidence will be critical to address barriers and knowledge gaps that currently limit context‐dependant provenancing decisions and deriving practical guidance on provenancing choice (Breed et al., 2018; Vitt et al., 2022). Increasing direct evidence from both research and industry will greatly benefit evidence‐based decision‐making (Bailey et al., 2021).…”

“…Hancock et al., 2023), concerns remain about the risk of using non‐local provenances, with some sectors continuing to recommend only local provenancing (Hancock & Encinas‐Viso, 2021). Such hesitance may reflect limited evidence on outcomes of using non‐local or mixed provenance strategies (Twardek et al., 2023; Vitt et al., 2022). While risks associated with introducing non‐local provenances are valid, equally valid are the risks of using local provenances under current and future conditions.…”

¿Es la semilla de origen local el mejor material genético para efectos de restauración?

“…El cambio climático está alterando los patrones globales de temperatura y precipitación, de modo que estas desviaciones de las condiciones históricas, y la variabilidad prevista de los climas futuros dificultan las estrategias y decisiones de abastecimiento de semillas de las procedencias idóneas para la práctica de la restauración ecológica. El paradigma de "lo local es lo mejor", sustentado en el principio de que los ecotipos están genéticamente adaptados a su entorno local, se debilita debido a que las adaptaciones locales comienzan a ser superadas por el cambio climático (Vitt et al, 2022). En esta situación normalmente falta evidencia empírica para gestionar el abastecimiento de semillas, adecuadas para garantizar la longevidad y la función ecológica de las comunidades naturales restauradas.…”