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Task 4 : Seed Scenarios for Assisted Migration

lundi 7 novembre 2011, par Minh Ha Duong

Objectives and success indicators

The main objective of this task is to provide different “seed scenarios” for creating a target forest adapted to climate change. In this context, a “seed scenario” is a combination of present day genetic sources, with legal basis, that are known as a “provenance”. As detailed next, different seed sources can be combined in several ways depending on the desired criteria of responses to climate change. In short, this task will provide a set of ecological tools for assisted migration.

Success of this task will be measured in the practical value of the different “seed
scenarios” produced by modeling in terms of the management of forest genetic
resources under current, or modified European and French regulations, and for
the ability of incorporating recommendations of the “real world” through the
different meetings with stakeholders.

Detailed program outline .

We will compare different rules for the choice of seeds using the following approaches.

First, after the due review of existing propositions in the literature, we will use a simulation approach to compute an ensemble of scenarios. Using fitness based data derived from field tests (published data and data gathered the first year in by task 3) of target tree species to simulate combinations of seed sources needed to provide forest adaptation to climate conditions for 2100 for a chosen region. Results will be a large set of diverging ecological scenarios : different seed choices with different tree fitness under different climates. These will allow understanding the uncertainties related to (a) climate change models ; (b) the tree growth model as well as the uncertainties in (c) parameters for initial conditions.

Second, we will compare the different seeds choice rules for different formal
decision-making under uncertainty criteria. The benchmark criterion is the maximization of inter-temporal expected utility, assuming a known probability
distribution on the uncertain parameters above. We will determine an optimal
“portfolio” of seeds for these criteria.

Third, we will build upon more recent research on uncertainty and
precaution . Recognizing that we only have an imprecise knowledge about the
future climate and other parameters, we will compare the seed mixes not only for classical optimality, using decision making criteria that account for robustness. Two approaches will be examined. One is Hurwicz’s rule, which weight the expected value with the worst and the best case. Depending upon the chosen weights, this criterion encompasses the maximin and the maximax criteria. The other approach will be decision making with imprecise probabilities (Ha-Duong, 2008 ; Hall et al., 2007 ; Walley, 2000), which includes admissibility, maximality, E-admissibility, Γ-maximax, Γ-maximin. The result will be alternative portfolios of seeds which, although not as "optimal" as the one determined above, may however be more robust in front of existing uncertainties.

Fourth, we will analyze the feasibility of applying these decision rules under
current legislations. For example, how ecological models agree or disagree with
present day classification of seed sources ? To what extent should collection
regions be modified ? How can we integrate the notion of uncertainty of seed
choices for the regulation of commerce of seeds ? Is the precautionary principle
applicable to the seed/forest protection system ? And so forth.


The main deliverables of this task are several sets of “seed scenarios” for the chosen pilot reforestation program, that will be used not only for scientific publications in peer reviewed journals but for the discussions in latter stages of the project with policy makers and forest managers.