|Review of Manuscript CP-2018-6 entitled “Leaf wax n-alkane distributions record ecological changes during the Younger Dryas at Trzechowskie paleolake (Northern Poland) with temporal delay|
Overall this is an interesting manuscript, tacking an area of key importance for paleoclimate reconstructions using leaf wax lipids - the issue of temporal incorporation into sediments. The authors do a thorough job of interpreting and discussing their data, and their figures are well put together and provide clear illustration of the main points of the text.
The authors have clearly made a number of revisions to the manuscript during the first round of reviews, addressing some of the more important issues and substantially improved the text. They use appropriate methods, which are clearly explained, to arrive at their conclusions and given the broad interest in the use of leaf wax biomarkers in paleoclimate and paleoecology, this study is suitable for publication in Climate of the Past.
There are however a couple of areas where some further clarification would be beneficial:
(1) There have been limited studies seeking to use pollen data to interpret leaf wax n-alkane trends, as in this current submission. One key reference that seems to be missing from this manuscript is Feakins (2013), where paired pollen and leaf wax hydrogen isotope data were used to construct a vegetation-corrected hydrogen isotope record from northeast Africa during the late Miocene:
Feakins, S. (2013) Pollen-corrected leaf wax D/H reconstructions of northeast African hydrological changes during the late Miocene, Palaeogeography, Palaeoclimatology, Palaeoecology, Volume 374, Pages 62-71
The Feakins study considers a number of potential complications that may arise when using pollen data to interpret biomarker information, such as the potential for differential transport for pollen from different species, and variation in catchment scales for pollen versus biomarkers. This current submission does a fantastic job of discussing time lags between pollen and leaf wax data, but would benefit from some further comment on the potential complications of varying catchment scales for pollen and biomarkers in this particular study site, and potentially a brief consideration of how to approach such issues in other depositional settings to assist readers wishing to adopt these methods.
(2) Leaf wax ratios (e.g. C27 vs C31) have been widely applied to distinguish inputs from grasses and trees, however they have recently been shown to be very poor indicators of such vegetation shifts. Bush and McInerney (2013), cited in the text here, clearly state that due to the significant heterogeneity in leaf wax distribution patterns both between species and within individuals of a single species, the use of ratios of C27, C29, and C31 to distinguish between grasses and woody plants or shrubs is to be avoided.
While the authors are using local paired pollen data here to attempt to limit the impact of these potential confounding factors, given the potential complications (see above with regard to transport and catchment scales) some further sentences considering the type of depositional environment where such an approach would be valid (and conversely, where it would be discouraged) would be helpful. Would the overall recommendation be to use this paired pollen and biomarker method in a well-constrained environment, but perhaps only apply it with more caution in, for example, marine settings?