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Abstract. The CO2 assimilation of tree saplings in a Costa Rican premontane forest characterized by highly dynamic light was measured using a rapidly responding system for the analysis of leaf gas exchange. Experiments were carried out on light compensation point and apparent (incident) quantum yield of dynamic photosynthesis. Because of the large variability in photosynthetic induction by light,...
Abstract. This study assessed the effects of salinity changes over space and time upon leaf gland secretion in Avicennia germinans trees growing naturally in an area featuring markedly seasonal rainfall. Soil ( soil ; MPa) during the wet season was 0.950.05 and 2.120.08at low and high salinity sites, respectively. During the dry season, these values decreased to 3.240.09at low salinity and to 5.750...
Abstract. Stem orientation is an important factor for fruit tree growth and branching habit since it influences fruit production as well as training practices. A mechanical model of the bending of a stem under axillary load was written and evaluated using experimental data on apricot trees (Prunus armeniaca L.). A set of 15 1-year-old stems of various shapes was observed during the early stage of...
Abstract. The physical characteristics of wood are not usually taken into account in the genetic improvement of perennial species cultivated for their fruits or seeds. Yet in coffee trees, stem breakage during harvesting, or lodging during their development are major defects in some cultivars. Such defects are linked to certain mechanical properties of the wood, such as stiffness, which can be characterized...
Abstract. We investigated the effects of endogenous and exogenous abscisic acid (ABA) on polyamines (PAs) and ethylene synthesis and their relevance to leaf senescence in 1-year-old intact cuttings of a drought-sensitive poplar genotype Populus euramericana cv. I-214 (cv. Italica) and a drought-tolerant genotype P. popularis 3544 (P. popularis). P. popularis exhibited a transitory and moderate increase...
Abstract. Eucalypt forest attributes describing structure are required for a range of management and inventory programs. The characterization of vegetation structure can be a laborious task and so managers and researchers are seeking alternatives through the use of remote sensing. Forest structure and the distribution of biomass through the forest canopy has a significant effect on radar backscatter...
. Recent advances in our knowledge of the genetic architecture of mangrove species are reviewed and the consequences of this genetic architecture for species response to environmental change are inferred. The origins of mangrove taxa have been discussed many times, particularly in the context of centers of origin and continental drift. While global patterns of mangrove species diversity have been...
Abstract. A common practice in tropical mangrove forests is to widen, deepen or extend the natural channels, or create new channels, in order to increase drainage to limit mosquito breeding habitats. Such excavations were made around 1984 in the upper shore regions of a forest near Darwin in northern Australia. To determine whether changes near the channels appeared to be affecting the mangroves,...
. By taking samples along individual branches and measuring leaf size, thickness and Na+ and K+ concentrations, we have shown in Bruguiera cylindrica, Avicennia rumphiana and Avicennia marina that there are two phases of salt accumulation by leaves. This is confirmed by re-analysis of published data for other species. The first phase is a rapid increase in leaf content as it grows from bud to maturity;...
. Mangroves are important wetlands along tropical and subtropical coasts that have been seriously damaged due to excessive exploitation. The need to conserve mangroves has been recognized since the 1970s. The degree of mangrove conservation ranges from rigid ecological conservation (for "posterity") to sustainable exploitation (for "prosperity"), dependent on the needs and requirements...
. Mangroves are often described as a group of plants with common features and common origins based mostly on their broad distributional patterns, together with an erroneous view of comparable abilities in long-distance dispersal. However, whilst mangroves have common needs to adapt to rigorous environmental constraints associated with regular seawater inundation, individual taxa have developed different...
Abstract. Macroecology is an emerging subdiscipline within ecology that explores effects of large-scale processes on local, regional, and global patterns of species diversity and taxon-independent scaling of structural and functional relationships. Statistical analysis of these patterns yields hypotheses concerning the processes determining population, community, and ecosystem-level patterns, which...
. To analyze the potential of the active oxygen-scavenging system of the cytosol in leaves of salt-stressed Bruguiera gymnorrhiza, we isolated a full-length cDNA encoding a 153-amino-acid sequence of cytosolic Cu/Zn superoxide dismutase (SOD) and a partial cDNA encoding catalase. Northern blot analyses showed that the transcript level of cytosolic Cu/Zn-SOD increased after 1 and 5 days NaCl treatment,...
Abstract. To analyze the potential of the active oxygen-scavenging system of the cytosol in leaves of salt-stressed Bruguiera gymnorrhiza, we isolated a full-length cDNA encoding a 153-amino-acid sequence of cytosolic Cu/Zn superoxide dismutase (SOD) and a partial cDNA encoding catalase. Northern blot analyses showed that the transcript level of cytosolic Cu/Zn-SOD increased after 1 and 5days NaCl...
Abstract. Dynamics of nutrients (carbon, nitrogen and phosphorus) in decomposing leaves was studied using litterbags in a subtropical mangrove dominated by Bruguiera gymnorrhiza (L.) Lamk and Kandelia candel (L.) Druce (Okinawa, Japan). In addition to fresh yellow leaves, degradation of treated leaves (dried at 50C and 80C) was also investigated. Comparison was made between species, locations (lower...
Abstract. Various studies on mangroves and other tall trees rooting in high-salinity water have given compelling evidence that tension is not the only factor in water lifting as thought by plant physiologists. A characteristic feature of these trees is that the tissue cells, the apoplastic space and, in particular, the lumen and the inner walls of many xylem vessels of the roots, the trunk and the...
. Effects of submergence and shading of hypocotyls on leaf conductance were examined in 12- to 18-month-old seedlings of Rhizophora stylosa. The net photosynthetic rates of hypocotyls increased with increase in incident photosynthetic photon flux density (PPFD) to a maximum of 2.7 µmol CO2 m–2 s–1 at a PPFD of about 300 µmol m–2 s–1. This maximal photosynthetic rate was 80% of the dark respiration...
. A new technique (Aerial Video Manta Analysis) was developed for the rapid assessment of mangrove degradation due to logging and conversion for shrimp aquaculture. Video recordings were made of mangroves along the Andaman Sea coastline, Thailand, during a 2-day aerial survey (16–17 September 1997) in a small Cessna 206 aircraft at an altitude of 800–1,000 feet and flying speed of 100 knots/h. The...
Abstract. Recent advances in our knowledge of the genetic architecture of mangrove species are reviewed and the consequences of this genetic architecture for species response to environmental change are inferred. The origins of mangrove taxa have been discussed many times, particularly in the context of centers of origin and continental drift. While global patterns of mangrove species diversity have...
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