We studied plant water use characteristics of the tree Theobroma grandiflorum (Cupuaçu, (Willd. ex Spreng.) Schum., Malvaceae) and the palm Euterpe precatoria (Açai, Mart., Arecaceae) both native to the Amazon and commonly occurring in the region. The tree species is occurring mainly in the terra firme forest whereas the palm species is restricted to the extreme habitats in stream valleys. This study was conducted in a small fruit plantation close to the city of Manaus, in the Central Amazon, Brazil. The main objective of this study was to compare water use characteristics in relation to plant structural traits. Three representative individuals of each species were equipped with Granier-type thermal dissipation probes to measure sap flux density. Water use scaled independent of species with the size of the conductive xylem area (r 2 = 0.85). Furthermore, we found a clear species-specific scaling of water use with plant-size. Overall, palms had a 3.5 fold higher water consumption compared to trees with similar stem diameter and/or plant height. Palms transpired a mean of 1.67 mm m-2 of water per unit crown projection area per day, whereas trees transpired only 0.30 mm m-2 per day, resulting in a 5.6 times lower transpiration rate. We assume that especially the unbalanced plant height/water use ratio of the palms might be limiting the height growth due to increasing hydraulic limitations. Hence, palms are restricted to extreme habitats with higher water availability and usually do not co-occur with more efficient and taller broad leaved tree species in the terra firme forest.
The expansion of oil palm (Elaeis guineensis Jacq.) cultivation in degraded areas has increased in the Brazilian Amazon. Cultivation of oil palm in diversified agroforestry systems may be a relatively sustainable alternative to monocultures for crop expansion. Here, we evaluated the effect of oil palm cultivation systems on soil C, an important indicator of the soil quality of production systems. We assessed:(1) whether these systems of oil palm cultivation alter the potassium permanganate oxidizable C content (POx-C) and the carbon management index (CMI); and (2) how the POx-C varied among management zones (harvest path, leaf pile, weeded circle, and diversified strip). The soil C indices of the oil palm cultivation systems were also compared with those of secondary forests. POx-C varied consistently based on the pattern agroforestry > secondary forest = monoculture, ranging from 0.95 ± 0.14 (agroforestry) to 0.66 ± 0.10 gÁkg À1 (monoculture). The POx-C pattern among management zones was pile > diversified strip = weeded circle > harvest path. The CMI was higher in agroforestry than in monoculture. We found that these indices are sensitive to land-use systems and management practices that affect organic matter input. Organic fertilization and species diversity likely drive the improvement of soil quality in agroforestry systems than in monocultures through C input to the soil directly and indirectly, by creating favorable conditions for the action of root and fauna that in turn positively affect soil C. Therefore, we postulate that soil quality improves through oil palm agroforestry than through oil palm monocultures.
Native fruiting plants are widely cultivated in the Amazon, but little information on their water use characteristics can be found in the literature. To explore the potential impacts of plantations on local to regional water balance, we studied plant water use characteristics of two native fruit plants commonly occurring in the Amazon region. The study was conducted in a mixed fruit plantation containing a dicot tree species (Cupuaçu, Theobroma grandiflorum) and a monocot palm species (Açai, Euterpe oleracea) close to the city of Manaus, in the Central Amazon. Scaling from sap flux measurements, palms had a 3.5-fold higher water consumption compared to trees with a similar diameter. Despite the high transpiration rates of the palms, our plantation had only one third of the potential water recycling capacity of natural forests in the area. Converting natural forest into such plantations will thus result in significantly higher runoff rates.
OPEN ACCESSForests 2015, 6 2531
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.