Xeromorphic traits help to maintain photosynthesis in the perhumid climate of a Taiwanese cloud forest
- 382 Downloads
Previous flux measurements in the perhumid cloud forest of northeastern Taiwan have shown efficient photosynthesis of the endemic tree species Chamaecyparis obtusa var. formosana even under foggy conditions in which leaf surface moisture would be expected. We hypothesized this to be the result of ‘xeromorphic’ traits of the Chamaecyparis leaves (hydrophobicity, stomatal crypts, stomatal clustering), which could prevent coverage of stomata by precipitation, fog, and condensation, thereby maintaining CO2 uptake. Here we studied the amount, distribution, and composition of moisture accumulated on Chamaecyparis leaf surfaces in situ in the cloud forest. We studied the effect of surface tension on gas penetration to stomata using optical O2 microelectrodes in the laboratory. We captured the dynamics of condensation to the leaf surfaces with an environmental scanning electron microscope (ESEM). In spite of substantial surface hydrophobicity, the mean water film thickness on branchlets under foggy conditions was 80 µm (upper surface) and 40 µm (lower surface). This amount of water could cover stomata and prevent CO2 uptake. This is avoided by the clustered arrangement of stomata within narrow clefts and the presence of Florin rings. These features keep stomatal pores free from water due to surface tension and provide efficient separation of plant and atmosphere in this perhumid environment. Air pollutants, particularly hygroscopic aerosol, may disturb this functionality by enhancing condensation and reducing the surface tension of leaf surface water.
KeywordFog Clustered stomata Gas exchange LMA ESEM Xeromorphism
This work was supported by Deutscher Akademischer Austauschdienst (DAAD 56186816), Germany, Taiwan Ministry of Science and Technology (MOST: 102-2911-I-259-502) and Deutsche Forschungsgemeinschaft (BU 1099/7-1, 7-2). We thank Knut Wichterich for his help with the ESEM measurements, I-Ling Lai for advice.
Author contribution statement
SP, S-CC, and JB designed the study, SP, S-CC, DZ, and JB performed the field experiments, SP, MH, and JB designed and performed the ESEM studies, SP, DZ, HZ, and JB performed the O2 measurements, SP performed the statistical analysis, and SP, DZ, DAG, and JB performed the lab analysis and wrote the manuscript, with revision by all authors.
- Abramoff MD, Magalhães PJ, Ram SJ (2004) Image processing with image. J. Biophotonics Int 11(7):36–42Google Scholar
- Bruijnzeel LA, Kappelle M, Miulligan M, Scatena FN (2010) Tropical Monatane Cloud Forests: state of knowledge and sustainability perspectives in a changing world. In: Bruijnzeel LA, Scatena FN, Hamilton LS (eds) Tropical Monatane Cloud Forests: science for conservation and management. Cambridge University Press, Cambridge, pp 691–740Google Scholar
- Cornelissen JHC, Lavorel S, Garnier E, Diaz S, Buchmann N, Gurvich DE, Reich PB, ter Steege H, Morgan HD, van der Heijden MGA, Pausas JG, Poorter H (2003) A handbook of protocols for standardised and easy measurement of plant functional traits worldwide. Aust J Bot 51(4):335–380CrossRefGoogle Scholar
- Florin R (1931) Untersuchungen zur Stammesgeschichte der Coniferales und Cordaitales. KungligaSvenska Vetenskapsakademiens Handlingar 10:1–588Google Scholar
- Lai IL, Chang SC, Lin PH, Chou CH, Wu JT (2006) Climatic characteristics of the subtropical mountainous cloud forest at the Yuanyang lake long-term ecological research site. Taiwan. Taiwania 51(4):317–329Google Scholar
- Lin C-S, Lin Y-H, Wu J-T (2012) Biodiversity of the epiphyllous algae in a Chamaecyparis forest of northern Taiwan. Bot Stud 53(4):489–499Google Scholar
- Marzol-Jaen MV (2010) Historical backgrounds of fog water collection studies in the Canary islands. In: Bruijnzeel LA, Scatena FN, Hamilton LS (eds) Tropical Monatane Cloud Forests: science for conservation and management. Cambridge University Press, Cambridge, pp 352–358Google Scholar
- Oladele FA (1983) Scanning electron microscope study of stomatal-complex configuration in Cupressaceae. Can J Bot-Rev Canadienne De Botanique 61(4):1232–1240Google Scholar
- Quere D (2008) Wetting and roughness. Annual review of materials research, Annual Reviews. Palo Alto, Santa Clara, pp 71–99Google Scholar
- Sack L, Scoffoni C, PrometheusWiki contributors (2011) Minimum epidermal conductance (gmin, a.k.a. cuticular conductance), http://prometheuswiki.publish.csiro.au/tiki-index.php?page=Minimum+epidermal+conductance+(gmin,+a.k.a.+cuticular+conductance) (Accessed April 2, 2017)
- Zhang D, Christian T (2013) Chamaecyparis obtusa var. formosana. In: The IUCN red list of threatened species 2013: e.T34076A2843748. doi: 10.2305/IUCN.UK.2013-1.RLTS.T34076A2843748.en
- Zobel BD, Lin DB, Liu VT (1978) Stomatal distribution on leaves of three species of Chamaecyparis. Taiwania 23:1–6Google Scholar