caa a22 4500 469096373 CHVBK 20180323133032.0 cr unu---uuuuu 170328e19921101xx s 000 0 eng 10.1007/BF00317359 doi (NATIONALLICENCE)springer-10.1007/BF00317359 Seasonal patterns of acid fluctuations and resource storage in the arborescent cactus Opuntia excelsa in relation to light availability and size [Elektronische Daten] [Manuel Lerdau, N. Holbrook, Harold Mooney, Paul Rich, Julie Whitbeck] Summary: We investigated relationships between light availability, diel acid fluctuation, and resource storage in the arborescent cactus Opuntia excelsa growing in western Mexico. We compared canopy and understory individuals from a deciduous forest as well as open-grown plants of the same approximate size as those in the understory. During the wet season light availability and daily fluctuations in titratable acidity (an index of carbon uptake) were lower in the understory than in unshaded habitats. In the dry season all plants had reduced levels of acid fluctuation, with the smallest individuals, regardless of habitat, showing the greatest reduction. These data suggest that light availability in the forest understory constrains carbon assimilation during the wet season, but that a factor associated with plant size, possibly water status, limits carbon gain during the dry season. Plants in all habitats remained physiologically active for at least five months into the dry season. We suggest that this was possible due to the maintenance of constant concentrations of water and nitrogen in the photosynthetically active chlorenchyma. Parenchyma in terminal cladodes showed a different seasonal pattern of resource storage; water content and nitrogen concentration were reduced from the wet to the dry season in the parenchyma. Using the parenchyma to supply photosynthetic tissues during times of reduced resource availability allows O. excelsa to assimilate carbon during times of the year when most other trees in the forest are leafless. Springer-Verlag, 1992 Crassulacean acid metabolism nationallicence Light availability nationallicence Opuntia excelsa nationallicence Resource storage nationallicence Tropical deciduous forest nationallicence Lerdau Manuel Department of Biological Sciences, Stanford University, 94305-5020, Stanford, CA, USA aut Holbrook N. Department of Biological Sciences, Stanford University, 94305-5020, Stanford, CA, USA aut Mooney Harold Department of Biological Sciences, Stanford University, 94305-5020, Stanford, CA, USA aut Rich Paul Department of Biological Sciences, Stanford University, 94305-5020, Stanford, CA, USA aut Whitbeck Julie Department of Biological Sciences, Stanford University, 94305-5020, Stanford, CA, USA aut Oecologia Springer-Verlag 92/2(1992-11-01), 166-171 0029-8549 92:2<166 1992 92 442 https://doi.org/10.1007/BF00317359 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00317359 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Lerdau Manuel Department of Biological Sciences, Stanford University, 94305-5020, Stanford, CA, USA aut NATIONALLICENCE 700 1- Holbrook N. Department of Biological Sciences, Stanford University, 94305-5020, Stanford, CA, USA aut NATIONALLICENCE 700 1- Mooney Harold Department of Biological Sciences, Stanford University, 94305-5020, Stanford, CA, USA aut NATIONALLICENCE 700 1- Rich Paul Department of Biological Sciences, Stanford University, 94305-5020, Stanford, CA, USA aut NATIONALLICENCE 700 1- Whitbeck Julie Department of Biological Sciences, Stanford University, 94305-5020, Stanford, CA, USA aut NATIONALLICENCE 773 0- Oecologia Springer-Verlag 92/2(1992-11-01), 166-171 0029-8549 92:2<166 1992 92 442 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer