Seed provenancing is a seed-sourcing strategy that focuses on the geographic location of seed sources, in the context of ecological restoration and forestry. Seed provenance refers to the geographic location of a parent plant from which seeds were collected. The genetic material of seed differs between collection locations. Selecting the appropriate provenance is an important decision to ensure the long-term success of restoration efforts by maintaining local genetic-environmental relationships and adaptive potential, while avoiding the risks of outbreeding depression or other harmful genetic effects. The traditional approach to provenancing has been to source seed from within the restoration site (local provenancing), but the threats of climate change have sparked debate on whether the use of nonlocal provenances may be beneficial to the longevity of broadscale restoration efforts under specific circumstances.
Provenancing strategies
Local provenancing Local provenancing is a strategy that relies exclusively on using seeds sourced either from within the restoration site (strict local provenance) or from nearby areas (relaxed local provenance) and has long been the focus of restoration guidelines. This strategy is grounded in the concept of local adaptation, maintaining that the use of locally adapted seed is best for the longevity of restoration projects because of their increased fitness in the local environment, decreasing the risk of maladaptation to local conditions and outbreeding depression. It has also been found that the use of local seed can be important to protect important biotic interactions, including pollinator interactions and pathogen resistance. In the use of local provenancing for broadscale restoration, it can be difficult to define a "local" provenance. It has been argued that the most useful approach to defining a local provenance is one that is genetically informed, such as using significant genetic differentiation (e.g. differentiation in neutral or adaptive genetic markers) to describe provenances. However, this may not be feasible for all restoration practitioners due to the time and costs required of this approach.
Nonlocal provenancing strategies Although it has been long-maintained that the use of local provenance is best since local seed will be best adapted to the conditions, arguments have been made to move away from the strict use of local provenance for populations that are expected to face rapidly changing environmental conditions in the face of climate change. This is because the use of local provenancing can establish a population that does not have sufficient adaptive genetic variation to cope with future environmental changes, thus compromising the longevity of broadscale restoration efforts. Additionally, the strict use of local provenance has the potential to encourage inbreeding and low genetic variation in a population, further threatening a population's ability to persist long-term. With this, many new provenancing strategies have been proposed to supplement local provenances with nonlocal ones to maximize evolutionary potential to increase the long-term success of restored populations that are facing changing environmental conditions; these proposed strategies include admixture, composite, climate-adjusted, and predictive provenancing. These proposed provenancing techniques are not applicable to all restoration efforts, and the success of each one depends on the contextual factors of each population, which include:
Plant species biology, demography, and evolutionary history Landscape heterogeneity and dynamics Priorities, resources, and scale of the restoration practitioner These recently proposed techniques are based upon a more theoretical foundation, as there has been limited experimental testing done. Thus, there is much future research needed to create a framework to guide a practical application of these proposed provenancing techniques in restoration contexts; this research may focus on gathering evidence-based restoration practices via field testing, furthering knowledge of adaptive processes, and assessing potential risks and benefits of each provenancing technique.
Admixture provenancing Admixture provenancing mixes a wide variety of provenances across a species range, providing seed from each provenance in equal proportions. The purpose of this provenancing technique is to increase standing genetic variation in a population, thus increasing the adaptive potential.
Composite provenancing Composite provenancing aims to mimic gene flow dynamics as a way to build adaptive potential into a restored population; this is done by mixing seed from both local and non-local provenances but with a larger proportion of local seed and progressively smaller amounts of seed from more distant provenances.
Climate-adjusted provenancing Climate-adjusted provenancing aims to enhance the climate resilience of a restored population. It incorporates a mix of local and non-local provenances from a climatic gradient, using more seeds from environments more likely to be encountered in the future. This strategy would introduce pre-adapted genotypes into the population, maintaining genetic variation and improving the evolutionary resilience of the population.
Predictive provenancing Predictive provenancing is a strategy designed to increase a restored population's adaptive capacity in the face of a changing climate. In this strategy, it is proposed to source seed from plants that are naturally adapted to future climatic conditions the target population is predicted to face, introducing pre-adapted genotypes.
Practical applications
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