2 M ETHODOLOGY
2.3 Field setup, instrumentation and methods
2.3.6 Selected tree physiological and morphological parameters measured in 50
To analyse the influence of tree height or wood density on several tree physiological and morphological attributes, 50 trees from the control plots (Tab. 2.5), most of them equipped with sap flux sensors (Tab. 2.4), were chosen for the investigation of several parameters.
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Chapter 2 Methodology Tab. 2.5: Biometric characteristics of the 50 investigated tree individuals from the control plots. Number of tree individuals (n), range of tree height (H) and DBH, and total above ground biomass (AGB) per species for this forest stand for all trees DBH > 2 cm, for further information see Culmsee et al. (2010).
H DBH AGB
Species Family (n)
(m) (cm) (MG ha-1)
Santiria apiculata A.W. Benn. Burseraceae 8 17.4 - 29.4 14.6 - 58.2 7.3 Vernonia arborea Buch.-Ham. Compositae 5 19.5 - 28.7 20.1 - 43.0 4.3 Castanopsis acuminatissima (Blume) Rheder Fagaceae 12 17.6 - 50.6 11.8 - 66.0 52.4 Platea excelsa Bl. var. borneensis (Heine) Sleum. Icacinaceae 5 15.4 - 33.2 11.7 - 45.7 5.6 Cryptocarya laevigata Blume Lauraceae 8 12.3 - 24.7 11.2 - 27.9 2.0
Myrtaceae spec. Myrtaceae 2 13.1 - 17.4 11.0 - 14.0 1.3
Palaquium luzoniense (Fern.-Vill.) Vidal Sapotaceae 3 31.8 - 44.3 53.7 - 95.0 30.9 Pouteria firma (Miq.) Baehni Sapotaceae 7 12.8 - 36.1 14.7 - 66.5 19.7
The following parameters were measured:
o Diameter at breast height (DBH, cm).
o Tree height (H, m). See chapter 3.2.5.
o Stem wood density (ρ, g cm-3) determined with wood cores extracted at breast height. See chapter 4.2.2.
o Twig hydraulic properties. These were leaf-specific conductivity (LSC, kg m-1 MPa-1 s-1) and specific conductivity (ks, kg m-1 MPa-1 s-1). See chapter 3.2.3.
o Mean leaf size (AL, cm2), specific leaf area (SLA, cm2 g-1) and Huber value (HV, 10-4). See chapter 6.2.10.
o Leaf nutrient contents and isotope ratios of carbon, nitrogen and oxygen (δ13C, δ15N and δ18O). See chapter 6.2.10.
o Xylem sap flux density (XFD, g cm-2 d-1). See chapter 2.3.3.
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Chapter 2 Methodology
2.4 REFERENCES
Aldrian E and Susanto RD (2003): Identification of three dominant rainfall regions within Indonesia and their relationship to sea surface temperature. International Journal of Climatology 23: 1435-1452.
Cabibel B and Do F (1991): Mesures thermiques des flux de sève dans les troncs et les racines et fonctionnement hydrique des arbres. I. Analyse théorique des erreurs sur la mesure des flux et validation des mesures en présence de gradients thermiques extérieurs. Agronomie 11: 669-678.
Culmsee H and Pitopang R (2009): Tree diversity in sub-montane and lower montane primary rain forests in Central Sulawesi. Blumea 54(1-3) 119-123.
Culmsee H, Leuschner Ch, Moser G and Pitopang R (2010): Forest aboveground biomass along an elevational transect in Sulawesi, Indonesia and the role Fagaceae in tropical montane rain forests.
Journal of Biogeography 37(5): 960-974.
Granier A (1985): Une nouvelle methode pour la mesure du flux de seve brute dans le tronc des arbres. Annals of Forest Science 42: 193-200.
Granier A (1987): Evaluation of transpiration in a Douglas-fir stand by means of sap flow measurements. Tree Physiology 3: 309-319.
Hertel D, Moser G, Culmsee H, Erasmi S, Horna V, Schuldt B and Leuschner Ch (2009): Below- and above-ground biomass and net primary production in a paleotropical natural forest (Sulawesi, Indonesia) as compared to neotropical forests. Forest Ecology and Management 258: 1904-1912.
Leitner D (2010): Auswirkungen von ENSO-Trockenperioden und Landnutzungspraktiken auf die Dynamik von C, N und P in einem tropischen Regenwald und in Agroforst-Systemen in Zentral-Sulawesi, Indonesien. PhD thesis. University of Göttingen, Germany.
Lu P, Urban L and Zhao P (2004): Granier's thermal dissipation probe (TDP) method for measuring sap flow in trees: Theory and practice. Acta Botanica Sinica 46: 631-646.
Van Straaten O (2010): Drought effects on soil carbon dioxide efflux in two ecosystems in Central Sulawesi, Indonesia. PhD thesis. University of Göttingen, Germany.
Whitten AJ, Mustafa M and Henderson GS (Eds.) (1988): The ecology of Sulawesi. Gadja Mada University Press. Yogyakarta, Indonesia.
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3 THIRD CHAPTER
VESSEL DIAMETER AND XYLEM HYDRAULIC CONDUCTIVITY INCREASE WITH TREE HEIGHT IN TROPICAL RAINFOREST TREES IN SULAWESI, INDONESIA
Chapter 3 Tree height and twig hydraulic properties
Vessel diameter and xylem hydraulic conductivity increase with tree height in tropical rainforest trees in Sulawesi, Indonesia
Alexandra ZACH1, Bernhard SCHULDT1, Sarah BRIX1, Viviana HORNA1, Heike CULMSEE2 and ChristophLEUSCHNER1
1 Plant Ecology, Albrecht von Haller Institute for Plant Sciences, University of Göttingen Germany
2 Vegetation and Phytodiversity Analysis, Albrecht von Haller Institute for Plant Sciences, University of Göttingen, Germany
Abstract
In humid environments, where trees rarely experience severe soil water limitations, the hydraulic system of trees requires a functional architecture for an effective transport of water to the crown despite of a comparably low atmospheric evaporative demand for most of the year. Strategies in adapting hydraulic properties of tropical trees to an aseasonally wet climate are less studied, as is the impact of tree height growth on the hydraulic conductivity and vessel anatomy of tropical canopy trees. We analyzed the dependence of hydraulic architecture on tree height in several phylogenetically different canopy tree species growing under the aseasonally humid climate of a lower montane rainforest in Sulawesi, Indonesia.
We determined leaf-specific conductivity (LSC), sapwood-area specific hydraulic conductivity (ks), and wood anatomy (vessel diameter and density) of exposed twigs and the trunk of 51 trees of eight abundant species ranging in tree height between 6.5 and 44 m. Rates of LSC as well as ks significantly increased with tree height (r2adj = 0.50 and 0.46, respectively) and this increase with tree height was closely coupled with an increase in mean vessel diameters along the height gradient. We found this trend consistent for both the trunk (r2adj = 0.61) and the twig (r2adj = 0.47) xylem vessel diameters. In contrast, the negative relationship between vessel density and height was significant for twigs, but not for the trunks. We assume that under conditions of prevailing high atmospheric humidity, it seems more advantageous for tall trees to focus on a high plant hydraulic conductance in the trunk- as well as the upper crown conducting-tissue, rather than to minimize the drought-induced risk of xylem embolism. However, the tree size-effect in our study has to be validated at a broader species-level before universal rules could be deduced.
Key words: adaptation, hydraulic architecture, leaf specific conductivity, tree size, vessel density, vessel size.
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Chapter 3 Tree height and twig hydraulic properties