Seguimiento Metabólico y Nutricional

The purpose of this thesis is to address several important knowledge gaps pertaining to the choice of seed origins for woodland creation under climate change, using methods from a

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range of fields. Chapters two and three are empirical, focussing on the specific case of Pinus sylvestris in Scotland as a study organism. However, it is hoped that the methods and

reasoning applied to this particular study system will be useful for other tree species. Chapter four is theoretical, and uses simulated data to generalise adaptive responses of trees although with no strong focus on any particular tree species. Chapter five is inductive, using

qualitative methods from social sciences to identify the socio-economic challenges and consequences of seed sourcing policies for all native trees and shrubs. The following key questions will be addressed:

i. Does the current system of seed zones for native Scots pine reflect realistic patterns of climatic and/or ecological variation?

Chapter two. Defining climatic and ecological groupings among the native pinewoods of Scotland.

The second chapter of the thesis investigates the specific situation for seed sourcing for Scots pine in its native range in the Scottish uplands. Concerns expressed about the relevance of the current system of seed zones (Ennos et al., 1998; Salmela et al., 2010; Whittet et al., 2016b) will be addressed using multivariate analyses of interpolated climatic covariates for each of the 84 ‘Caledonian’ pinewoods to identify natural climatically similar clusters of pinewoods, assessing whether the amount of climatic variation existing within the current seed zones can be minimised with an alternative grouping system. Reducing the climatic variation within groups but maximising variation between groups would provide a basis for delineation of ‘floating’ seed zones (sensu Rehfeldt, 1983) based on environmental distances rather than geographical proximity of seed source and planting site. Considerations often missing from seed transfer guidelines are aspects of the edaphic and biotic environment, although there is clear evidence from some tree species that local adaptation to these selective pressures does take place (Linhart and Grant, 1996; Viherä-Aarnio and Heikkilä, 2006; Smith et al., 2012; Pickles et al., 2015), and that community composition of associated species can be associated with tree genotype (Wimp et al., 2005; Davies et al., 2014; Sinclair et al, 2015; Bucharova et al., 2016a). To provide a broad description of ecological

dissimilarity among sites, vegetation survey and analyses were conducted, based on a subset of the ‘Caledonian’ pinewoods (n = 21), treating plant community dissimilarities as a surrogate for measured variation in non-climatic aspects of the environment. The chapter concludes with recommendations for further research required to refine and improve the biological relevance of seed sourcing guidelines.

31 Chapter three - Variation in the timing of pollen production indicates limited reproductive synchrony between distant native populations of Pinus sylvestris in Scotland.

In the third chapter, the potential for temporal variation in pollen production amongst populations to limit inter-population gene flow is assessed. This was achieved by making repeated sets of observations of the morphology of male strobili on trees growing in situ in three native populations in 2014, adding a further two populations to the assay for 2015 and 2016. In the absence of data regarding the timing of female strobilus receptivity, the time and space over which viable pollen can be transported between populations in the Scottish landscape and the direction and strength of winds at any given time; it is difficult to make predictions of the probabilities of gene flow amongst specific stands. However, the results are a useful step towards developing an understanding of patterns and possible barriers to pollen flow in the complex Scottish uplands (Whittet et al., 2017).

iii. What factors influence the suitability of implementing predictive provenancing?

Chapter four - Testing options for adaptive forest seed sourcing. Insights from individual based model simulations.

In chapter four, simulations from an individual based model (IBM) are used to investigate factors influencing the suitability of adopting alternative strategies for seed sourcing, aimed specifically at helping newly established plantations to adapt to unidirectional environmental change. A custom multi-patch (n = 11), bi-allelic IBM is developed and is used to generalise adaptive evolutionary responses to environmental change in a newly established population. The IBM considers adaptedness to more than one aspect of the environment, namely climate, which varies clinally and changes over time and ‘habitat’, which is considered to be a proxy for any non-climatic aspects of the environment. Contrasting with climate, ‘habitat’ variation amongst patches is randomly spatially arranged and remains constant over time.

Adaptedness to either of these selection pressures is determined by individuals’ genotypes. The individuals in the model therefore undergo simultaneous directional and stabilising natural selection on two genetically uncorrelated traits.

The main experimental treatment applied in the IBM is to establish a new population under different seed sourcing strategies. These are to continue the established practice of sourcing currently adapted, locally sourced seed; to source seed from a population which experiences conditions most similar to a correctly predicted future climate (i.e. nearer the equator); to source mixtures of currently adapted, local seed and from more equatorial populations and finally, to source seed randomly from the entire species range. The main outputs from the

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model are the amount of change to the mean phenotype of the population the number of trees surviving strong selective mortality in the first years after planting.

iv. What is the current status of the plant and seed supply chain in GB? Which practical considerations will limit implementation of science-based policies for seed sourcing?

Chapter five - Supplying trees in an era of environmental uncertainty: An analysis of the options for the forest nursery sector in Great Britain.

In applied forest science, it is important to understand the practical boundaries within which science-based policy can be implemented. Regarding seed sourcing for woodland creation and expansion, a clear practical and economic constraint upon the uptake of science based policy is that imposed by the commercial trade in forest plants and seed (Hubert and Cottrell, 2007; Buckley and Blakesley, 2008; O’ Neill et al., 2014; Broadhurst et al., 2016).

In this chapter, inductive methods from qualitative social sciences are used to provide an overview of the current status of the domestic forest nursery and seed supply sector in GB. To build this overview, semi-structured interviews were conducted in person with members of the domestic forest nursery and seed supply industry. Respondents included 14 private sector forest nurseries, one representative of the public sector organisation involved in plant and seed supply and the only major specialist tree and shrub seed merchant in the UK. The interview guideline included a mixture of quantitative (descriptive) and qualitative

(discursive) questions on seed procurement, plant production, sales and customer demand; grant schemes; attitudes to climate change and open questions regarding any other

bottlenecks in the plant and seed supply chain.

v. Chapter six - Discussion and conclusions

Chapter six will summarise the results from each of the main chapters of the thesis and discuss implications for forest management planning to encourage adaptation to climate change.

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