Friday, March 30, 2012


date: Wed Jan 6 12:39:45 1999
from: Keith Briffa <>
subject: Opinion - Fellowship Application AS/47

>Dear Mr Vernon
>The following is my assessment of Dr. S. Watmough�s application
>for a NERC fellowship. Please note that I have based this on a
>reading of the proposal and references only. I have not had the
>opportunity to locate or read the published papers cited by the
>Yours sincerely
>K R Briffa
>Comments on Application for NERC Postdoctoral
>Fellowship by
>S.A. Watmough
>Application N�. AS/47
>Overall I would rate this proposal Alpha 3.
>Specific Requested Comments
>1. The candidate appears suitable as regards general competence
>- the range of work proposed is very wide and while it is clear that
>the candidate is well versed in the chemical analysis techniques,
>I am not convinced he has a �thorough� grasp of tree-ring analysis
>techniques or the statistical problems that would arise. The candidate
>clearly does offer considerable promise.
>2. The novelty of much of what is suggested is not clear. The major
>novelty would appear to be the combined analysis of several data
>sources in parallel, but again, the novelty of this approach beyond
>the candidates past work is not made explicit.
>3. The availability of required facilities for chemical analysis appear
>to be available at the host institution. I am not aware that dendro-
>chronological equipment are available. If not, the requirements for
>a basic system are not great, however.
>I think the case for support is not a foregone conclusion. The final
>opinion should be made in the light of the candidate�s responses to
>a number of issues that should be raised in the interview. These
>issues are discussed in the following pages.
>General Comments
>My impression of the proposed work is that it is �worthy� but
>overambitious, and even naive, in stating that the proposer will
>�directly assess the impact of several pollutants� on tree growth
>- not only in the past but in the future. The proposer even
>concludes that the techniques (combining data on all levels and
>sources of sulphur and carbon, and changes in soil chemistry
>and trace metal deposition) will put him in a position to assess
>forests and future changes in tree growth and forest composition,
>both in Europe and, ultimately, in temperate forests worldwide!
>In many respects, the impression is given that much of the
>application of dendrochemistry is new, whereas there is a very
>large literature on the subject going back decades - much of which
>shows that there are very serious interpretational problems relating
>chemical measurements in individuals or groups of tree rings - both
>at the individual tree and stand level, to specific potential growth
>forcing agents. I also get the strong impression that the candidate
>is not sufficiently aware of the complexity and statistical problems
>that must be addressed when trying to establish direct causality
>between one of multiple (some likely synergistic) influences and
>tree-ring growth. Timeseries of the latter require statistical
>modification to account for expected changes related to tree age
>or competitional status and there is a significant literature discussing
>the limitations that such modification may impose on the subsequent
>interpretation of correlative associations, the more so where these
>are based largely on coincident trends.
>The candidate states that absolute concentrations (pollutant loadings)
>can be historically reconstructed by direct interpretation of measured
>wood concentrations of various cations, heavy metals or specific
>isotope ratios. Yet he lists together such �stresses� on forest growth
>as �acid rain�, tropospheric ozone, trace metals and climate change
>which is strangely defined as �increasing CO2�. This is the crux of
>my concern. The roles of all of these factors have been studied
>(in different areas and species) with very little consensus as to their
>larger-scale significance. The truth is that they may all exert some,
>likely time-transgressive, effect, but even the sign, let alone the
>quantitative magnitude of their effect, will vary. Disentangling their
>influences is not the straightforward task implied in this proposal.
>The atmospheric loadings of the different factors listed above will have
>changed through time, but many of these changes will be parallel.
>All of their effects are likely modified through the influence of climate
>variability itself, as is tree growth regardless of their effect, in a complex
>way. This issue - that of the direct and complex influence of climate
>variability on tree growth in non-marginal regions is not addressed in
>the proposal.
>I believe that there is much important work to be done to establish
>the true feasibility of using dendrochemistry as a means of
>reconstructing temporal changes in past tree health. The isotopic
>aspects of this proposal are, in my opinion, the most promising - but
>even here there is not sufficient acknowledgement of the previous
>work (e.g. in Cambridge) and the real problems in interpreting
>measured carbon ratios in tree-rings in terms of direct climate
>forcing, increasing anthropogenic influence, and the separate
>influence of acidic pollution.
>The Board could usefully solicit additional opinions from the Godwin
>Laboratory, Cambridge, on this topic.
>I have little doubt that the candidate has expertise in the analytical
>techniques of chemical measurement in wood. I have not had the
>opportunity to read his published papers. Nevertheless, the Board
>may wish to discuss with him the problem of radial translocation of
>cations, and heavy metals in woody tissue and the particular
>problem of heartwood/sapwood transfer. Also there is much published
>evidence for Europe (and France in particular) of increasing net
>primary productivity in �natural� and managed woodlands that may be
>associated either with nitrogen or increasing CO2 or both. Contrast
>this with the still controversial question of large-scale acid-rain-related
>forest decline? To what extent is this issue now generally considered
>urgent, or even real? How realistically does the candidate believe he
>can reconstruct changes in past soil chemistry at different sites and
>distinguish cause and effect with changing tree health and climate

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