A Synthesis of Tree Water Use Research in the Tropics Reveals Water
Relation of Plant Functional Traits, Research Biasness and the Way
Forward
Shawkat Sohel1*, John Herbohn1,2,3
1Tropical
Forestry Group, School of Agriculture and Food Sciences, The University of Queensland, Australia
Research Centre, University of the Sunshine Coast, Queensland, 4558 Australia
3Tropical Forests and People Research Centre, University of the Sunshine Coast, Queensland, 4558 Australia
2Forest Industries
Outline
1. Introduction
a) Why Tropical Forest matter in hydrological cycle?
b) Need for reforestation in the tropics
2. Objective
3. Methods
4. Results
a) distribution of research output
b) Geographical distribution of research on tree water use in the tropical forest
C) Research focus on tree species
d) Tree architecture and tree water use nexus
5. Research needs and Gaps
Introduction
Why Forest matter in hydrological cycle?
 Does forests increase rainfall?
 Does forests increase stream flow?
 Does forests use more water?
 …………………………………….
WATER FLOW
Introduction
Need for reforestation in the tropics
Source: FAO 2010
Objectives
 To highlight the publication trend in tree water use research, geographical
distribution of research on tree water use and research focus on tree species
 Influence of tropical Tree architecture on tree water use pattern
Methods
Systematic review
Table. 1. Key words used for literature search
ID
Key term
Expanded term
1
Sap flow
2
Water use
Water use* OR “Water use efficiency”
3
Plantations
Planted* OR reforest* OR afforest OR “Two species mixture” OR
“multi species mixture” OR “mixed stand” OR “mixed
plantation”
4
Forest
Forest* OR agroforest* OR “agro forest”
Table. 2. Total publication found using the keyword combination
ID
1
2
3
Combination of keywords for literature search
1 AND 2 AND 3
1 AND 2 AND 4
1 AND 2 AND 3 AND 4
Total
WoS
(Web of science) all database
177
916
112
1205
 99 articles that cover only tree water use of the tropical forest areas
 covering the period from 1980 –2013
Methods
Systematic review
• Wood density data were collected from world Agroforestry centre wood
density database (http://db.worldagroforestry.org/wd) and Global wood
density database developed by Zanne et al. 2009
(http://hdl.handle.net/10255/dryad.235).
• Seed mass data were collected from Kew royal botanic garden seed mass
database (http://data.kew.org/sid/).
• To confirm the species family name Species2000 database were used
(http://www.catalogueoflife.org/annual-checklist/2014/ ).
Result
Publication trend in tree water use research
16
Number of paper Publised
14
12
10
8
6
4
2
0
1983
1988
1993
1998
Year
2003
2008
2013
Fig. Increase in studies of tree water use in the tropical forest over time (1980-2013)
Country
Result
Geographical distribution of research
Venezuela
Tunisia
Thiland
South Africa
Senegal
Philippines
Panama
Mexico
Malaysia
Madagascar
Kenya
Indonesia
Ghana
French Guiana
Ethiopia
Ecuador
Costa Rica
China
Burkina Faso
Brunei
Brazil
Australia
0
5
10
15
20
25
30
Number of case study
35
40
Result
Research focus on tree species
Result
Influence of tropical Tree architecture on tree water use
r=0.97
r=0.86
r = -0.24
r=0.42
Fig. (a) the relationship between Water use (kg/day) and Sapwood area (m2). Data presented show species with data for 42 trees; (b) the
relationship between Water use (kg/day) and DBH (cm). Data presented show species with data for 107 trees; (c) the relationship
between Water use (kg/day) and seed mass (g). Data presented show species with data for 106 trees; (d) the relationship between Water
use (kg/day) and wood density (g cm-3). Data presented show species with data for 138 trees.
Result
Influence of tropical Tree architecture on tree water use
• Multiple linear regressions was also conducted for 73 trees taking into
considerations of DBH, seed mass, wood density and water use.
• A probability level of 0.1 was assumed given the exploratory nature of the
study
• The multiple linear regression suggests that wood density (p = 0.06) is
negatively related and seed mass (p = 0.08) is positively related to water use
• Due to data shortage of sapwood area was not considered for multiple linear
regression analysis.
Research needs and knowledge gaps
Q. How water uptake by various forms (native vs exotic plantation, monoculture vs mixed
plantation, agroforestry) of plantations varies?
Q. How forestry practices and changes to forest design affects water use in the face of
climate change?
0
years
8
years
15
years
Fig. Hypothetical Forest/plantation design, management and their water use
Research needs and knowledge gaps
Q. how realistic is scaling plant water use data from whole trees to
stands and catchments?
Thanks for listening !!!