The photosynthetic characteristics of saplings of eight canopy tree species in a disturbed neotropical rain forest :
Foliar gas exchange characteristics, understorey microclimate, and crown irradiation were assessed for saplings of eight canopy tree species in two plots of neotropical rain forest with different degrees of canopy opening. Species studied belonged to different putative guilds: shade intolerants (both short-lived-pioneers-and long-lived), intermediates, and shade-tolerants. A considerable overlap was recorded between species in values of the photosynthetic rate per unit leaf area (P subíndice N). The highest median P subíndice N (1.26 ¿mol m-2 s exponente -1) was recorded in the pioneer Croton killipianus, while slightly lower median values were recorded in simarouba amara and Pentaclethra macroloba, and markedly lower values in two species of Vochysiaceae (Qualea paraense and Vochysia ferruginea), both putative intolerants. Highest median stomatal conductance (g subíndice s) was also shown by C. killipianus, while S. amara, P. macroloba, and L. procera exhibited intermediate values, and the lowest g subíndice s was shown by V. ferruginea and Q. paraense. Overall irradiance and crown irradiation, P subíndice N, and g subíndice s of saplings were higher in the plot which had previously received a silvicultural treatment. Most values of photosynthetic photon flux density (PPFD) were <100 ¿mol m-2 s-1 in both plots, with shortlived peaks of up to 2000 ¿mol m-2 s-1 in the treated plot. When the relationship between P subíndice N and irradiance (I) was examined by fitting P subíndice N/I curves, the degree of fit varied markedly between species, values of the regression coefficient r exponente 2 were between 0.09 and 0.51. No significant differences between species were recorded in P subíndice max and species also demostrated little variation in the predicted values of dark respiration (R subíndice D), values varying between -0.51 and -1.46 ¿mol m-2 s-1 in Q. paraense and Minquartia guianensis, respectively. Fitted values of apparent quantum efficiency were also fairly uniform, generally falling within the range 0.02-0.03 mol(CO2) mol-1 (photon).
| Auteurs principaux: | , , |
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| Format: | biblioteca |
| Langue: | eng |
| Publié: |
1999
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| Sujets: | CROTON KILLIPIANUS, SIMAROUBA AMARA, PENTACLETHRA MACROLOBA, QUALEA PARAENSE, VOCHYSIA FERRUGINEA, BOSQUE INTERVENIDO, BOSQUE HUMEDO, FOTOSINTESIS, FACTORES CLIMATICOS, MICROCLIMA, ILUMINACION, REGIMENES DE LUZ, HOJAS, ANATOMIA DE LA PLANTA, ZONA ATLANTICA, MANEJO FORESTAL, MODELOS, COSTA RICA, |
| Accès en ligne: | http://link.springer.com/article/10.1023/A%3A1007076103204 |
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