The landcover6k project had its annual workshop in a converted church in Utrecht, The Netherlands, 14-16 June 2016, partly supported by the Copernicus Institute for Sustainable Development. The meeting had two goals:
- to update each other on the work of the subgroups
- to plan for the future.
As with any meeting organised by Marie-Jose Gaillard, the atmosphere was friendly and collaborative, and the project as a whole seems to be making good progress. It was intersting to hear a variety of aspects of the work of different sub-groups, and of course to realise how important the work of OUR subgroup is for the overall project – Pollen Productivity estimates are problematic in many ways, and perhaps are less glamorous and exciting than giant databases, but they really matter.
In this post I’m just going to quickly outline a few points relevant to SubGroup9 activities – your input and comments welcome!
Initial estimates from new environments: using what you have
Starting in a new geographic area or environment is always a challenge, especially where vegetation survey is challenging due to remoteness, taxonomic challenges or simple lack of resources. However, an initial estimate of pollen productivity can be obtained using ANY systematically-collected dataset of paired vegetation survey and pollen sample data – the south Swedish values used for much of the modelling and first reconstruction work in Northern Europe (Sugita et al. 1999) were derived from surface samples from single woodland inventory quadrats, not from any form of “walking in circles” surveying, and although further work has refined these values, they have not been shown to be seriously misleading. Working with subgroup7 (Methodology focused on the tropics), which has a particular interest in “quick and dirty” methods, a small project is planned for this summer around this approach – email me if you want to play!
When the subgroup was launched, we suggested that writing a collective review paper (updating Broström et al. 2008 and Mazier et al. 2012 and extending them beyond Europe) would be an appropriate product. However, I now know of at least three individuals/groups working on global or regional review papers, two of whom at least are ECRs, and feel that overlapping with such efforts is not a good use of our time (unless they specifically want input from us!). Therefore we discussed what form a product of this subgroup should take, and have identified two paper ideas we want to explore further:
“Dirty Linen” Paper [credit to Martin Theuerkauf for the working name]
We all know that there are many, many problems with current estimates of pollen productivity and that we don’t have really robust methods in place – there are many unknowns which hinder our ability to confidently measure a consistent value. That’s not to say the effort is pointless, of course, but we felt that this would be a good time to write a critical review of the limitations of the current methods and to lay out a research programme to address some of them. This would build on the paper by Jackson & Lyford (1999) which some of us agreed has been overlooked and neglected by our field.
Simulations to explore the effects of landscape structure and survey detail on RPP estimates
Anyone who works with pollen data for a time develops what some call “gut instinct” and others call “informed opinions” about how the system works! Discussing these different ideas is one of the fun things that happens at workshops – for example, we had a lively discussion about WHICH model of aerial transport is most appropriate, and about how the heterogenity of the regional vegetation (i.e. within 50-100km radius of the sample point) might affect the RSAP and pollen productivity values. Some of these things could be explored using the HUMPOL simulation software, and it was suggested that a group of people could get together to design the experiments and to share the work of running them, speeding up the process.
(SELF-PROMOTION: The latest version of HUMPOL allows a wider choice of dispersal and deposition models, and we hope by the end of the summer to have tested the option to use Lagrangian as well as Gaussian models – see e.g. Theuerkauf et al. 2016)
It was agreed that we’d add a page to this website to contain short summaries on the different methods of quantitative reconstruction of aspects of past vegetation from pollen records, such as biomisation, pseudobiomisation, the MAT, the LRA, the MSA, or MARCO POLO (presented as a post, accepted for publication), which would mostly consist of annotated bibliographies. A blank space is now there… any volunteers to start filling it up??
I think we should try and have a subgroup 9 focused meeting next year, 2017 – this might be joint with subgroup 8 (methodologies for the tropics) or alone. We’ll need to apply for INQUA funding in January, so I’ll be looking for ideas before then!
There was some discussion about the potential importance of water-borne taphonomies for pollen records from some sites, especially in semi-arid and tropical environments (Subgroup 7 in particular were interested in this), and I had some great discussions especially with Professors Xu and Li from Hebei Normal University – we’ll be putting together a grant to work on this further
Apologies for the relatively late nature of this update – but BREXIT and other conferences rather occupied my time). At least we now have growing lists of PP-estimating projects “in progress”, so things are happening!
Broström, A., Nielsen, A.B., Gaillard, M.-J., Hjelle, K., Mazier, M., Binney, H., Bunting, J., Fyfe, R., Meltsov, V., Poska, A., Räsänen, S., Soepboer, W., von Steding, H., Suutari, H. and Sugita, S. (2008: DOI 10.1007/s00334-008-0148-8) Pollen productivity estimates of key European plant taxa for quantitative reconstruction of past vegetation: a review. Vegetation History and Archaeobotany. 17(5) 461-478
Jackson, S.T., & M.E. Lyford. 1999. Pollen dispersal models in Quaternary plant ecology: assumptions, parameters, and prescriptions. Botanical Review 65(1): 39-75.
Mazier, F., Gaillard, M-J., Kunes, P., Sugita, S., Trondman, A.-K., Broström, A., 2012a. Testing the effect of site selection and parameter setting on REVEALS-model estimates of plant abundance using the Czech Quaternary Palynological Database. Review of Palaeobotany and Palynology 187, 38-49
Sugita, S., Gaillard, M.-J., Broström, A., 1999. Landscape openness and pollen records: a simulation approach. The Holocene 9, 409-421.