Contrasting water use patterns of two important agroforestry tree species in the Mt Elgon region of Uganda

Figures & data

Table 1. Summary of maximum, minimum and average daily sap flow per tree and sap flow standardised to tree area for Albizia coriaria and Cordia africana over a 10-month period of the experiment

			Daily sap flow (l day^−1)			Daily sap flow (l day^−1 cm^−2)
Tree species	Tree ID	DBH (cm)	Min	Max	Average	Tree	Overall
Albizia coriaria	Tree 1	40.9	−0.8	87.6	24.8	0.019	0.015
A. coriaria	Tree 2	52.5	−5.8	34.7	20.6	0.010
A. coriaria	Tree 3	51.4	−8.2	75.4	31.5	0.015
Cordia africana	Tree 1	36.6	1.3	48.7	15.3	0.015	0.018
C. africana	Tree 2	31.6	1.2	41.5	12.8	0.016
C. africana	Tree 3	28.3	0.5	52.3	15.2	0.024

DBH, diameter at breast height.

Figure 1. Daily average sap flow in Albizia coriaria and Cordia africana over a 10-month period. Rainfall events indicate the early wet season (April–June) and the start of the late wet season (August–November)

Figure 2. Radial changing of sap velocity in Albizia coriaria registered by the inner and outer thermocouples (data presented are average values from the three trees)

Table 2. Pearson’s correlation coefficients between rainfall and seasonal daily sap flow in Cordia africana and Albizia coriaria

Tree species	Pearson’s correlation coefficients
	Dry season	Wet season	All
Albizia coriaria	0.326*	−0.107^ns	0.136*
Cordia africana	−0.199*	−0.149^ns	−0.228*

Correlations significant, at the level of P < 0.05. are indicate by *; those that are non-significant are labelled as ns.

Table 3. A two-way ANOVA to assess the interaction between tree species and season on daily sap flow

Tests of between-subjects’ effects
Dependent variable: Daily sapflow
Source	Type III sum of squares	Df	Mean square	F	Sig.
Corrected model	36 480.043^a	3	12 160.014	103.258	0.000
Intercept	255 990.935	1	255 990.935	2173.781	0.000
Tree species	32 422.605	1	32 422.605	275.321	0.000
Season	169.577	1	169.577	1.440	0.231
Interaction between tree species and season	6651.270	1	6651.270	56.480	0.000
Error	64 534.101	548	117.763
Total	358 618.298	552
Corrected total	101 014.144	551

^aR² = 0.361 (adjusted R² = 0.358).

Figure 3. Key agroforestry systems and phenological events in Mt Elgon region of Uganda, indicated in terms of 2016 rainfall for the region

Table 4. Tree water use and tree parameters including method used for different tree species

Tree species	Method^a	DBH (cm)	Water use	Source
Acacia aneura	CHPM	12	14 kg day^−1	(O’Grady et al. 2009)
A. tortilis	TTD	17	48 l day^−1	(Do et al. 2008)
Eucalyptus camaldulensis	CHPM	18	87 kg day^−1	(O’Grady et al. 2009)
E. grandis	CHPM	30	141 kg day^−1	(Dye 1996)
E. pilularis	CHPM	11–14	18 l day^−1	(Adrienne et al. 2013)
Grevillea robusta	CHPM	n/a	12 kg day^−1	(Lott et al. 1996)
Cordia alliodora	CHPM	34	42 kg day^−1	(Meinzer et al. 2004)
Anacardium excelsum	CHPM	98	785 kg day^−1	(Meinzer et al. 2004)
Vitellaria paradoxa	HRM	55.5	151 l day^−1	(Bazié et al. 2017)
Senna spectabilis	CHPM	7.9	4.8 kg day^−1	(Namirembe et al. 2008)

^aMethods used is indicated by compensation heat pulse method (CHPM), heat ratio method (HRM), transient thermal dissipation (TTD).

DBH, diameter at breast height.

O’Grady AP, Cook PG, Eamus D, Duguid A, Wischusen JDH, Fass T, Worldege D. 2009. Convergence of tree water use within an arid-zone woodland. Oecologia. 160:643–655.

 PubMed Web of Science ®Google Scholar

Do FC, Rocheteau A, Diagne AL, Goudiaby V, Granier A, Lhomme J-P. 2008. Stable annual pattern of water use by Acacia tortilis in Sahelian Africa. Tree Physiology. 28:95–104.

 PubMed Web of Science ®Google Scholar

Dye PJ. 1996. Response of Eucalyptus grandis trees to soil water deficits. Tree Physiology. 16:233.

 PubMed Web of Science ®Google Scholar

Adrienne BN, Smith RGB, Ryde J, Dane ST, David IF, Philip JA, Jürgen B. 2013. Changes in whole-tree water use following live-crown pruning in young plantation-grown Eucalyptus pilularis and Eucalyptus cloeziana. Forests. 4:106–121.

 Web of Science ®Google Scholar

Lott JE, Khan AAH, Ong CK, Black CR. 1996. Sap flow measurements of lateral tree roots in agroforestry systems. Tree Physiology. 16:995–1001.

 PubMed Web of Science ®Google Scholar

Meinzer FC, James SA, Goldstein G. 2004. Dynamics of transpiration, sap flow and use of stored water in tropical forest canopy trees. Tree Physiology. 24:901–909.

 PubMed Web of Science ®Google Scholar

Bazié HR, Sanou J, Bayala J, Bargués-Tobella A, Zombré G, Ilstedt U. 2017. Temporal variations in transpiration of Vitellaria paradoxa in West African agroforestry parklands. Agroforestry Systems. 92:1673–1686.

 Web of Science ®Google Scholar

Namirembe S, Brook RM, Ong CK. 2008. Manipulating phenology and water relations in Senna spectabilis in a water limited environment in Kenya. Agroforestry Systems. 75:197.

 Web of Science ®Google Scholar