TITLE: An email about resprouting in the SEOSAW database
DATE: 2024-04-30
AUTHOR: John L. Godlee
====================================================================
I help to manage the SEOSAW database. A database of tree stem
measurements from vegetation monitoring plots in African woodlands.
We gather data on tree size (stem diameter, height, crown
dimensions), floristic composition (species names), growth and
mortality dynamics. A colleague of mine is conducting a study into
the resprouting behaviour of trees using data from SEOSAW. We got
into a long conversation about what constitutes resprouting and how
that information is represented within the SEOSAW database. Here is
an email I sent to clarify my thinking:
[SEOSAW database]:
https://seosaw.github.io/
stem_status can have four possible values:
- "a" - the stem shows signs of life above the POM (point of
measurement for stem diameter), for example green leaves or sap
below the bark.
- "r" - the stem has no signs of life above the POM, but there
are signs of life elsewhere on the tree. This could be signs of
life on the same stem, or elsewhere on the individual.
- "d" - the stem has no signs of life and there are no other
signs of life elsewhere on the tree.
- NA - data missing, unknown
This info is in the SEOSAW field manual, section 4.5.
In our meeting the other day you asked whether stems with
stem_status "r" could be interpreted as "resprouting". Indeed, the
abbreviation "r" is derived from "resprouting", but I find that
definitions of resprouting vary and are not always clear, hence the
very strict definitions of stem_status in the SEOSAW database. I
read through these papers to refamiliarise myself with common
definitions of resprouting:
- Lawes and Clarke (2011)
- Clarke et al. (2012)
[Lawes and Clarke (2011)]:
https://doi.org/10.1007/s11258-011-9994-z
[Clarke et al. (2012)]:
https://doi.org/10.1111/nph.12001
Do you define a resprouting stem as one where the mature crown is
dead and new shoots are growing from the same stem below the crown?
These stems would be classified as "r" in the SEOSAW database.
Do you also include in your definition stems where the crown is
dead and new shoots are growing from elsewhere on the tree, for
example from belowground budbanks in the rootstock? These stems
would also be classified as "r" in the SEOSAW database.
Do you also include in your definition stems where the crown is
dead (stem A) and there is another mature (i.e. diameter larger
than plot minimum diameter threshold) living stem (stem B) growing
from the base of the same tree? Stem A would be classified as "r"
and stem B would be classified as "a" in the SEOSAW database. Yet,
it is unclear whether the tree is "resprouting" to produce stem B
(i.e. regeneration following a disturbance) or if it is just
"sprouting" another stem. Resprouting ultimately implies response
to disturbance.
I think you should be able to say that single-stemmed trees with
stem_status "r" are definitely "resprouting", by common definitions.
I think that for multi-stemmed trees you will also be able to say
that the tree is resprouting if all stems have stem_status "r".
I think that if the multi-stemmed tree has some stems with
stem_status "r" and some "a", then it is unclear if the tree has
resprouted or is just multi-stemmed.
I hope that helps to decide whether stem_status can be used to
imply resprouting. Personally I think it can. Even if stem_status
"r" doesn't always map perfectly to functional definitions of
resprouting, it correlates pretty strongly.
