Category:Trees Working Group

Overview

In the Linked Earth context, a working group (WG) is a self-organized coalition of knowledgeable experts, whose activities are governed herewith. This page is dedicated to the discussion of data and metadata standards for trees (see this page for a definition of the wood archive), and aims to formulate a set of recommendations for such a standard. Note that chronological aspects should be discussed within the Chronologies WG.

Specific tasks

We recommend that discussions focus on the following techniques, and explore potential commonalities.

For each chronology type, we recommend:

• structuring discussions around what scientific questions one would want to ask of the data
• listing essential, recommended, and optional information for:
  • the measurements themselves
  • any inference made from the measurements (e.g. calibration to temperature)
  • the underlying uncertainties, and what those numbers correspond to (e.g. 1-sigma or 2-sigma?)
• provide an ideal data table for each type of observation, so the community knows what to report and how to report it.
• provide separate recommendations for new and legacy datasets

Scope

Tree rings are used by many different researchers, for many different reasons. The LinkedEarth community is well rooted in the paleoclimate community and while the ontology and data standard has great potential for use outside this community, we need to decide how to address the overlap in our discussions. Should be concentrate on the needs of the paleoclimate community exclusively to begin with, and intend to go back and revise at a later date? Or should we attempt to accommodate all potential users of tree-ring data from day 1?

The discussion within this group can build upon the work done by the Tree Ring Data Standard (TRiDaS) consortium ^[1]. While the contributors were weighted towards dendroarchaeologists, the standard was intended to be universal for all uses of tree-ring data. The requirements laid out be the TRiDaS contributors are therefore going to largely be relevant to discussions here.

Sensors

An initial recommendation is to focus on different sensors:

Measurement variables

The traditional variable measured in dendrochronology is of course the whole ring-width. It is common now to collect a wealth of other variables from tree-rings including:

• Whole ring width
• Early wood width
• Late wood width
• Whole ring density
• Early wood density
• Late wood density
• Maximum density
• Latewood percentage
• Vessel size
• Blue intensity (density proxy)

Event information

Tree-rings provide the potential to store information about specific events. The most common of these is a forest fire (stored as a fire scar or other anatomical damage), but may include the effects of defoliating insects, volcanic eruptions etc. This sort of event data is represented as binary yes/no occurrences in particular rings and is quite distinct from the continuous measurement variables (e.g. ring-widths, isotope concentrations etc) that are typical with most proxies.

Tree rings

Detrending

Maintaining references back to raw ring-width measurements is important to maintain data transparency. When detrending has been performed a detailed record of what has been done should be stored along with the software/library used. Implementations of different detrending techniques in different software can produce different results.

How to document the type of detrending applied to enable reproducibility.

Stable water isotopes

Here are polls that the group might want to consider:

References

1. ↑ JANSMA, E., BREWER, P. W. & ZANDHUIS, I. (2010) TRiDaS 1.1: The tree ring data standard. Dendrochronologia 28, 99-130. - Science Direct