TreeMAAP tasks:
- Development of measurement protocols
- Reconnaissance trip to Cameroon
- Preparation of fieldwork in French Guiana
- Two-month fieldwork in French Guiana
- Post-processing of images, samples (anatomy) and raw field data
- The ER received training: shoot architecture, whole-tree architecture, terrestrial LIDAR, shoot age.
- The ER gave training: anatomical lab work and image analysis, Wacom tablet, conductive sapwood staining, shoot architecture
- Data analysis
- Two manuscripts write up
- Literature review on the functional significance of wood and bark anatomical components
- The ER lodged an application for collaboration with AI researchers (under “AI4Life” EU funded scheme) to apply AI tools to anatomical images
- Multiple informal discussions about treeMAAP and wood anatomy (with >30 researchers, students, technicians)
- Disseminated the results and background knowledge
TreeMAAP results:
1) Tree species which produce large terminal shoots (large stem diameter at 0.7 m from shoot tip), also had larger stem volume, dry mass, produced large total leaf area, larger vessels, and larger conductive wood area in comparison with small shoots. Large vessels in combination with large conductive wood area resulted in high whole-shoot water conductivity.
2) Total volume of living tissues was higher in large shoots. This was driven chiefly by shoot size, not by living tissue fraction (volume of living tissue per volume of wood).
3) Taller, sun-exposed species had less dominant principal axis (umbrella-like tree architecture, with no obvious dominant axis) than shorter, shade-tolerant species (fir-like tree architecture with strong dominant axis). These taller species also built larger shoots which were more efficient in water transport. Presumably, that higher conductivity met larger transpiration demands in taller, sun-exposed trees.
4) Tree architecture was not self-similar, that is, highly branched shoots were not necessarily borne on highly branched trees. Likely, whole tree architecture and crown metrics are highly dependent on the neighbourhood conditions (e.g. larger neighbouring tree strongly limit expansion and canopy shape of the other tree) and on tree history (e.g. loss of branch due to mechanical damage).
5) Species which produced larger terminal shoots also widened their vessel diameter (from shoot to trunk base) at a slower rate, meaning, that their total water transport resistance was higher (everything else being equal). This indicates that they might use other anatomical adjustments (e.g. larger vessel pits) to lower water transport resistance.
Conclusions: 1) there are no functional trade-offs at the whole-shoot level, rather, traits coordinate to achieve larger overall values, for example, larger shoots (at a given distance from shoot tip) were more highly conductive due to larger vessels and larger conductive area. 2) there is a coordination between whole-shoot functions and whole-tree architecture (e.g. taller, sun-exposed trees with umbrella-like architecture had more conductive shoots). 3) Trunk and shoot growth rates are missing link in our understanding of carbon and water fluxes. Their measurements—in concordance with anatomy, physiology and architecture—is the priority for future research.
Result exploitation and dissemination.
The background knowledge on functional wood anatomy, methods and results have been communicated with broad scientific and non-scientific community:
1) Two seminar talks at the host lab
2) Led group discussion about tree architecture based on recent literature
3) One seminar talk in French Guiana
4) Two posters and pitch talks at the European Conference of Tropical Ecology 2022
5) Poster presentation at INTECOL 2022
6) Festival of Science, two weekends in two locations in Montpellier
7) Seminar talk at Ecological and Forestry Applications Research Centre in Barcelona, Spain
8) Guest lecture at the Montpellier University
9) Data shared with other researchers to develop grant proposal and to analyse a different aspect of plant function (metabolic scaling theory)
10) A subset of results included in an invited review
11) Two publications are in preparation (see figure)
