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  • agroforestry  (2)
  • Aboveground growth  (1)
  • Carbon isotope discrimination  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Water supply regulates structure, productivity, and water use efficiency of Acacia koa forest in Hawaii (1999)
    Springer
    Oecologia 121 (1999), S. 458-466 
    Details
    ISSN: 1432-1939
    Keywords: Key words Forest productivity ; Koa ; Hawaii mountain forests ; Water supply ; Carbon isotope discrimination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  We studied changes in stand structure, productivity, canopy development, growth efficiency, and intrinsic water use efficiency (WUE=photosynthesis/stomatal conductance) of the native tree koa (Acacia koa) across a gradient of decreasing rainfall (2600–700 mm) with increasing elevation (700–2000 m) on the island of Hawaii. The stands were located on organic soils on either smooth (pahoehoe) or rough (aa) lava flows. In the greenhouse, we also examined growth and WUE responses to different water regimes of koa seedlings grown from seeds collected in the study area. We tested the hypotheses that (1) stand basal area, aboveground net primary productivity (ANPP), leaf area index (LAI), and growth per unit leaf area decreased with decreasing rainfall, (2) WUE increased with decreasing rainfall or water supply, and (3) WUE responses were caused by stomatal limitation rather than by nutrient limitations to photosynthesis. The carbon isotope composition of phyllode tissues (δ13C) was examined as an integrated measure of WUE. Basal area and LAI of koa stands on both pahoehoe and aa lava flows, and ANPP on aa lava flows decreased with elevation. Basal area, LAI, and ANPP of koa in mixed stands with the exotic tropical ash (Fraxinus udhei) were lower compared to single-species koa stands at similar elevations. Along the gradient, phyllode δ13C (and therefore WUE) increased with elevation from –30.2 to –26.8‰. Koa in mixed stands exhibited higher (less negative) δ13C than in single-species stands suggesting that koa and tropical ash competed for water. In the greenhouse, we observed the same trend observed in the field, as phyllode δ13C increased from –27.7 to –24‰ as water supply decreased. Instantaneous gas exchange measurements in the greenhouse showed an inverse correlation of both maximum (morning) photosynthesis (A) and conductance (g) with δ13C values and, also, a good agreement between instantaneous (A/g) and integrated measures of WUE. Phyllode δ13C was not correlated with foliar concentrations of N or other nutrients in either the field or the greenhouse, indicating that differences in δ13C were caused by stomatal limitation rather than by nutrient-related changes in photosynthetic capacity. This study provided evidence that long-term structural and growth adjustments as well as changes in WUE are important mechanisms of koa response to water limitation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004420050952
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Ecophysiology of exotic and native shrubs in Southern Wisconsin (1989)
    Springer
    Oecologia 80 (1989), S. 368-373 
    Details
    ISSN: 1432-1939
    Keywords: Aboveground growth ; Carbon gain ; Exotic shrubs ; Leaf area ; Shrub productivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In this study we compared the aboveground growth rates of two exotic shrubs (Rhamnus cathartica and Lonicera X bella) and two native shrubs (Cornus racemosa and Prunus serotina) that are important in southern Wisconsin hardwood forests. For all species except P. serotina, aboveground growth rates in an open habitat were greater than in an understory environment. Growth rates differed among species in the open habitat and were significantly correlated with woody production per unit leaf area. All species had greater leaf area per unit wood biomass in the understory than in the open habitat. A comparison of above-ground growth and annual carbon gain suggests much greater respiratory costs in the open habitat, especially for P. serotina. The data from this study were used to examine mechanisms of species response to different light availabilities. We found that the species that increased their production per unit leaf area in response to increased light did not increase their leaf area per unit wood biomass in response to low light, and vice versa. Production of proportionately high leaf area may be important for the growth of C. racemosa in low light.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379038
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Indigenous agroforestry of Pohnpei (1991)
    Springer
    Agroforestry systems 16 (1991), S. 139-157 
    Details
    ISSN: 1572-9680
    Keywords: Pacific islands ; Micronesia ; agroforestry ; species diversity ; cultivars ; indigenous agriculture ; low-input agriculture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant species and cultivars of the indigenous agroforestry system of Pohnpei were surveyed in transects through 54 randomly-selected farms. The agroforestry system was characterized by extensive cultivation of yams (Dioscorea), aroids (Alocasia), and Piper methysticum under a permanent overstory of breadfruit, coconut, and forest remnant trees and a middle canopy of Hibiscus tiliaceus, Musa spp., and Morinda citrifolia. In the 10 ha of survey plots, 161 species were found, of which 102 were trees, shrubs, and crops and 59 were uncultivated herbaceous plants. Numbers of tree, shrub, and crop species per farm ranged from 16 to 37 with an average of 26. Twenty-eight breadfruit and 38 yam cultivars were found in the survey plots, showing that cultivar diversity is an important component of the biological diversity maintained and utilized in Pohnpeian agroforests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00129745
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Indigenous agroforestry of Pohnpei (1991)
    Springer
    Agroforestry systems 16 (1991), S. 159-165 
    Details
    ISSN: 1572-9680
    Keywords: Pacific islands ; Micronesia ; agroforestry ; traditional agriculture ; low-input agriculture ; spatial pattern ; succession
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A vegetation survey of 54 randomly-selected Pohnpeian land holdings quantified agroforest vegetation patterns in terms of horizontal distribution in the landscape and changes over time. Spatial distribution of species, expressed as distance from the main household, varied greatly with successional stages to produce the characteristic pattern of the Pohnpeian agroforest. Food crops, bananas, and Piper methysticum were planted around the house compound first, then gradually planted further away over time. Upland forest and secondary successional trees were removed by girdling, and gradually replaced by annual and perennial crops and breadfruit and other trees. A fallow or reduced management stage was discerned, characterized by low densities of early successional crops and higher densities of weedy secondary successional species; this stage resulted from a reduction in management intensity, mainly due to a variety of socioeconomic factors. Although the indigenous Pohnpeian agroforestry system is permanent and thought to be sustainable, it is dynamic in space and time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00129746
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    Paper (German National Licenses)
    Fulltext
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