Ecofisiolgia de espécies arbóreas de campina na Amazônia Central

Abstract

Ecophysiology of arboreal species of Campina in the Central Amazonia. Campina species are frequently exposed to periods of high irradiance, temperature and water limitation. Environmental microclimate traits and the oligotrophic soil, drive the characteristics of campina plants. Different species developed different strategies that converge in abilities of survival and colonization. The knowledge of functional traits becomes necessary to understand the plant responses to actual environmental conditions, and how the physiology behavior could be affected by climate changes. Was studied the diurnal and seasonal photosynthetic efficiency of quantum capture and energy transfer; the leaf gas exchange responses to light, CO2, and leaf temperature; leaf mass per area (MSA); chloroplast pigments; leaf anatomics features; soil nutrient content; young, adult and senescent leaves nutrient content; and photosynthetic nutrient use efficiency of Pagamea duckei (PD), Pradosia schomburgkiana (PS), Ouratea spruceana (OS) and Swartzia dolichopoda (SD) species on Reserva Biológica de Campina do INPA, Manaus, AM, Brazil, and data was analyzed on different rainy periods. The maximum quantum efficiency of photosystem II was reduced which ranged from 8.5 % (SD) to 14 % (PD). All species showed a decrease in maximum fluorescence throughout the day in the dry season. The maximum photosynthesis of PS and OS present reduction in the dry period of 32 % and 31 % , respectively. The species PD, PS and OS showed higher stomatal conductance in the rainy season and the SD did not differ between periods. The MSA was proportional to the efficient use of nitrogen, phosphorus and potassium, with lower values for PD. The PD had the lowest stomatal index . These data suggest that in the dry, with low water availability and high light intensities, due to the accumulation of the quinone reduced throughout the day, probably increasing the fluorescence maximum, beyond the lower activity of Rubisco in response to stomatal closure. Species more acclimated to microclimate conditions of Campina had higher rates of energy dissipation, such as PD and SD. The lower leaf water potential resulted in lower photosynthetic rates and reduced stomatal conductance, as is common to other species scleromorphic. Given this, climatic variations throughout the year should set the annual carbon balance. The species with higher MSA offset the high cost of leaf construction with greater efficiencies in the use of nutrients such as N, P and K. Therefore, the species are subject to dynamic stress on the photosynthetic apparatus in the rainy season and the dry season, to chronic stress. Photosynthetic characteristics for classifying species PS and OS as sensitive to drought and PD and SD as drought tolerant. Above 38 ° C leaf species have decrease in photosynthesis. The nutrient limitation and water are the major abiotic factors that guided the functional characteristics of the leaves of the species studied.