Integrating climate change and habitat fragmentation to identify candidate seed sources for ecological restoration

Abstract

Anthropogenic change (climate change and habitat fragmentation) is driving a growing view that local seed collections may need to be supplemented with nonlocal seed as a strategy to bolster genetic diversity and thus increase evolutionary potential of plantings. While this strategy is becoming widely promoted, empirical support is limited, and there is a lack of accessible research tools to assist in its experimental testing. We therefore provide the Provenancing Using Climate Analogues (PUCA) framework that integrates the principles of the climate‐adjusted provenancing strategy with concepts from population genetics (i.e. potential inbreeding in small fragmented populations) as both a research and operational‐ready tool to guide the collection of nonlocal seed. We demonstrate the application of PUCA using the Midlands of Tasmania, Australia, a region that is currently undergoing large‐scale ecological restoration. We highlight multiple nonlocal seed sources for testing by identifying actual species distribution records that currently occupy environments similar to that projected to occur at the restoration site in the future. We discuss the assumptions of PUCA and the ecological considerations that need to be tested when moving nonlocal genotypes across the landscape.

Priority Actions to Improve Provenance Decision-Making

“…A principal concern in the seedsourcing debate is climate change, and much of our current predictive knowledge relies on habitat suitability models that incorporate climate projections (Elith and Leathwick 2009). Although habitat suitability models provide a way to select provenances for restoration plantings (Harrison et al 2017), they are often based on environmental layers that assume equal weighting of these factors on fitness. Extensions of these models to include both genetic information (Kilkenny 2015, Ikeda et al 2017 and ecophysiological limits (e.g., mechanistic models; Kearney et al 2009, Caddy-Retalic et al 2017 provide an increased realism to their predictions.…”

Stability of species and provenance performance when translocated into different community assemblages

“…For long‐lived species such as trees, future climate models are being used to guide translocation decisions with the aim to develop resilient plantings better adapted to future climates (Harrison et al ). Assisted gene flow (the movement of germplasm within the species' natural distribution) and assisted migration (the movement of germplasm within or outside their natural distribution) are thus being increasingly integrated into conservation strategies (Aitken & Whitlock ; Gray et al ).…”

“…The present study examines whether biotic interactions cause GxE by assessing the stability of species and provenance performance of two focal eucalypt tree species— Eucalyptus pauciflora and Eucalyptus tenuiramis —when planted in different community assemblages. These two similar‐sized focal eucalypts (Boland et al ) are key tree species being used for forest and woodland restoration in the southern midlands area of Tasmania (Bailey et al ; Harrison et al ). Here, we test for interactions with different community treatments and compare the patterns of performance of provenances sampled from along a similar environmental gradient.…”

Temperature and Rainfall Are Separate Agents of Selection Shaping Population Differentiation in a Forest Tree

“…Greenhouse and field common-garden trials were established to test various provenancing strategies, using seed sourced from provenances throughout the full geographic and ecological ranges of E. pauciflora in Tasmania. In this context, a focus was climate-adjusted provenancing, which aims to enhance climate resilience by enriching local seed sources with those collected from along a gradient of predicted climate change [28,29]. A key assumption of this approach is that climate is a major driver of adaptation.…”