date: Wed Jan 6 12:39:45 1999 from: Keith Briffa subject: Opinion - Fellowship Application AS/47 to: pav@nerc.ac.uk >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 >candidate. > >Yours sincerely > >K R Briffa > > >---------------------------------------------------------------------------------------- > > >Confidential > >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 >variability?