Bactris

Abstract: In a test of the following hypotheses, the first was rejected and the second accepted. Rejected: (1) "The farther a freshly cleaned [pile of] palm nuts] (endocarp) is placed from a fruiting parent, the lower will be the probability of the nut[s'] being found by a bruchid." Accepted: (2) "The larger the pile of freshly cleaned nuts at a site where there is no parent, the more likely that it will be found by bruchids." The study was carried out in a palm forest in Guanacaste Province, Costa Rica, from March until July 1971. In addition to testing the above hypotheses, the study generated natural history data on bruchid oviposition behavior, oviposition intensity, survivorship of the larvae, 8and developmental rate. Beetles of the family Bruchidae are important predators on the seeds of a wide variety of plants (Janzen 1969). These small "pea weevils" lay their eggs on seeds or seed pods and the larvae develop inside the seed while feeding on the endosperm and embryo of the seed. The intensity and pattern of this seed predation may have a variety of effects on the population biology of the host plants (Janzen 1970). This study is a direct test of the following two hypotheses posed in Janzen's (1971) Costa Rican study of predation by bruchids on Scheelea rostrata seeds beneath the parent palm: (1) "The farther a freshly cleaned [pile of] palm nuts] (endocarp) is placed from a fruiting parent, the lower will be the probability of the nutss] being found by a bruchid." (2) "The larger the pile of freshly cleaned nuts at a site where there is no parent, the more likely that it will be found by bruchids." (This experiment mimics the effect of a rodent leaving a pile of nuts at a feeding site in the forest.) MATERIALS AND METHODS The seeds were set out in the relatively undisturbed hillside forest at the "Barranca site" along the PanAmerican highway in Guanacaste Province, Costa Rica (Janzen 1971). This small palm forest has a density of adult Scheelea palms of about 8-20/ha mixed in with at least 20 other genera of large dicot trees (e.g., Luhea, Licania, Enterolobium, Chlorophora, Gyrocarpus, Brosimnum, Terminalia, Lonchocarpus, Albizzia, Ficus, Guazuma, Apeiba, Tabebuia, Lysiloma, Schizolobiurn, Bursera, Spondias, Pseudo' Received October 14, 1971; accepted May 5, 1972. 2 Present address: Bird and Mammal Laboratories, Bureau of Sport Fisheries and Wildlife, National Museum of Natural History, Washington, D.C. 20560. 2 Present address: Department of Zoology, University of Michigan, Ann Arbor, Michigan 48104. boinbax, A nacardiurn, Sterculia, Triplaris, Pithecellobium). The understory vegetation contains a large amount of a forest grass (Pharus) mixed with Marantaceae, a variety of herbaceous dicots, 1to 3-m tall shrubs (e.g., Bactris, Bixa, Ardisia, Capparis, Cassia, Stemmadenia), and saplings of the canopymember trees. Although this sole remnant of Guanacaste lowland forest (Tropical moist forest, following the Holdridge terminology) along the Pan-American highway from Puntarenas to Libera is not larger than 100 ha, it still contains a substantial rodent population, including agoutis (Dasyprocta punctata), pacas (Cuniculus paca), and squirrels (Scittruis variegatoides). The site experiences a severe dry season from late December through most of April (cf. Fig. 1 in Janzen 1967). but has a nearly permanent stream running through it. Nuts (properly, the seed contained in a bony endocarp) were put out in the forest during the last half of the dry season (March 12, 1971) and about I month before normal fruit drop occurs. The first rain was on April 3 and rainy weather started between April 14 and 18 (Fig. 1). The nuts used in the experiment were obtained by cutting a large mature infrutescence from a precocious tree at the Barranca site and allowing the fruits to rot and desiccate for several weeks. The husk and pulp (exocarp) were then scraped by hand from the nut to a level approximating the degree of cleanliness achieved when a rodent eats off the pulp. (In a pilot experiment, where more than 1,500 fruits were put out without first removing the pulp, all were removed by rodents in 3 days, and presumably discarded at other places once the pulp was eaten.) The cleaned nuts were then placed under 40by 20by 15-cm screen cages with 1-cm mesh at five kinds of locations: This content downloaded from 157.55.39.177 on Wed, 16 Nov 2016 04:24:31 UTC All use subject to http://about.jstor.org/terms Late Summer 1972 SCHEELEA PALM SEEDS AND BRUCHID BEETLES 955

Abstract: Palms and Cultural Landscapes.- Acrocomia aculeate.- Aiphanes aculeate.- Aphandra Natalia.- Astrocaryum acaule.- Astrocaryum aculeatum.- Astrocaryum chambira.- Astrocaryum gynacanthum.- Astrocaryum jauari.- Astrocaryum murumuru.- Astrocaryum vulgare.- Attalea butyracea.- Attalea maripa.- Attalea phalerata.- Attalea racemosa.- Attalea sagotii.- Attalea speciosa.- Attalea spectabilis.- Bactris acanthocarpa.- Bactris bidentula.- Bactris bifida.- Bactris brongniartii.- Bactris concinna.- Bactris gasipaes.- Bactris hirta.- Bactris major.- Bactris maraja.- Bactris martiana.- Bactris riparia.- Copernicia alba.- Desmoncus polyacanthos.- Elaeis oleifera.- Euterpe catinga.- Euterpe oleracea.- Euterpe precatoria.- Geonoma deversa.- Geonoma macrostachys.- Geonoma maxima.- Iriartea deltoidea.- Iriartella setigera.- Leopoldinia major.- Leopoldinia piassaba.- Leopoldinia pulchra.- Lepidocaryum tenue.- Manicaria saccifera.- Mauritia carana.- Mauritia flexuosa.- Mauritiella armata.- Oenocarpus bacaba.- Oenocarpus bataua.- Oenocarpus distichus.- Oenocarpus mapora.- Phytelephas macrocarpa.- Raphia taedigera.- Socratea exorrhiza.- Syragus inajai.- Wettinia maynensis.- References.- Appendix 1.- Appendix 2.

Abstract: The partitioning of rain water into throughfall, stemflow and interception loss when passing through plant canopies depends on properties of the respective plant species, such as leaf area and branch angles. In heterogeneous vegetation, such as tropical forest or polycultural systems, the presence of different plant species may consequently result in a mosaic of situations with respect to quantity and quality of water inputs into the soil. As these processes influence not only the water availability for the plants, but also water infiltration and nutrient leaching, the understanding of plant effects on the repartitioning of rain water may help in the optimization of land use systems and management practices. We measured throughfall and stemflow in a perennial polyculture (multi-strata agroforestry), monocultures of peach palm (Bactris gasipaes) for fruit and for palmito, a monoculture of cupuacu (Theobroma grandiflorum), spontaneous fallow and primary forest during one year in central Amazonia, Brazil. The effect on rain water partitioning was measured separately for four useful tree species in the polyculture and for two tree species in the primary forest. Throughfall at two stem distances, and stemflow, differed significantly between tree species, resulting in pronounced spatial patterns of water input into the soil in the polyculture system. For two tree species, peach palm for fruit (Bactris gasipaes) and Brazil nut trees (Bertholletia excelsa), the water input into the soil near the stem was significantly higher than the open-area rainfall. This could lead to increased nutrient leaching when fertilizer is applied close to the stem of these trees. In the primary forest, such spatial patterns could also be detected, with significantly higher water input near a palm (Oenocarpus bacaba) than near a dicotyledonous tree species (Eschweilera sp.). Interception losses were 6·4% in the polyculture, 13·9 and 12·3% in the peach palm monocultures for fruit and for palmito, respectively, 0·5% in the cupuacu monoculture and 3·1% in the fallow. With more than 20% of the open-area rainfall, the highest stemflow contributions to the water input into the soil were measured in the palm monocultures and in the fallow. Copyright © 1999 John Wiley & Sons, Ltd.

Abstract: Endogeic earthworms Pontoscolex corelhrurus were inoculated at four different biomasses (ie 0, 100, 400 and 800 mg/15 kg dry soil) in pots containing seedlings of three tropical fruit trees: Bactris gasipaes (peach palm), Bixa orellana and Eugenia stipitata After 120 days, significant increases of plant growth were observed in Bixa (14–24 times the control value) and Eugenia (16–25) as a result of earthworm inoculation irrespective of the inoculated biomass; an inverse effect (−18 to −27 times the control) was observed with seedlings of Bactris There was a significant effect of plant species on earthworm growth and significant effects of earthworms on mineralization of nitrogen and microbial biomass accumulation at some dates Different conditions in the rhizosphere of these species may explain these results Kinetics of soil variables during the experiment were complex It is suggested that in some pots an excessive earthworm activity resulted in the sealing of surface with compact casts and further changes in water dynamics which affected both earthworms and microbial communities