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3
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2942674077
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note
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Shifting cultivation involves clearing and burning an area, cropping it for a short period, abandoning cropping for a several-to many-year fallow period (during which the success of useful species may be favored), and then repeating the cycle. Agricultural intensification uses inputs (of Labor or other factors) to sustain cropping and increase overall yield.
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14
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2942637110
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note
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Landesque capital intensification alters physical features of the land in ways that favor agricultural production-as with irrigation works, pondfield systems, and terraces. Cropping cycle intensification uses continuing inputs of labor and other factors to enhance productivity and shorten or eliminate fallow periods. The extensive earth and stone walls of the Kohala field system (fig. S1) suggest that it exhibits elements of both cropping cycle and landesque capital intensification.
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15
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0002666162
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A. Keast, S. E. Miller, Eds. (SPB Academic Publishing Amsterdam)
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D. A. Clague, in The Origin and Evolution of Pacific Island Biotas, New Guinea to Eastern Polynesia: Patterns and Processes, A. Keast, S. E. Miller, Eds. (SPB Academic Publishing Amsterdam, 1996), pp. 35-50.
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(1996)
The Origin and Evolution of Pacific Island Biotas, New Guinea to Eastern Polynesia: Patterns and Processes
, pp. 35-50
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Clague, D.A.1
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20
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2942674076
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We focus on Large, intensive dryland systems here. Smaller-scale dryland agriculture was practiced more widely across the archipelago, in environments ranging from heavily mulched settlement gardens to terraces at the base of colluvial slopes.
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21
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2942652177
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note
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Materials and methods are available as supporting material on Science Online.
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27
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0003601711
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State of Hawaii Department of Land and Natural Resources Report R76, Honolulu, HI
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T. W. Giambelluca, M. A. Nutlet, T. A. Schroeder, Rainfall Atlas of Hawaii (State of Hawaii Department of Land and Natural Resources Report R76, Honolulu, HI, 1986).
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(1986)
Rainfall Atlas of Hawaii
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Giambelluca, T.W.1
Nutlet, M.A.2
Schroeder, T.A.3
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30
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2942674078
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note
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We believe that this area was not included in the Kohala field system because its surface topography is rougher and because sites with suitable rainfall and soil fertility are at higher elevation and farther from the coast than is most of the field system.
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2942686822
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Nitrogen also limits plant productivity in many areas, especially intensive agricultural systems. The greater mobility of N compared to P makes it difficult to relate current levels of N availability to past levels, and we know little of how Hawaiian cultivators managed N in dryland systems. However, spatial variation in the current ratio of C to N here suggests that N cycling slows and N availability declines above the upper boundary of the field system (fig. S5).
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34
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84874974546
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A. C. Kurtz, L. A. Derry, O. A. Chadwick, M. J. Alfano, Geology 28, 683 (2000).
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(2000)
Geology
, vol.28
, pp. 683
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Kurtz, A.C.1
Derry, L.A.2
Chadwick, O.A.3
Alfano, M.J.4
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35
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0003982832
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Bishop Museum, Honolulu, HI
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E. S. C. Handy, E. G. Handy, Native Planters in Old Hawai'i: Their Life, Lore, and Environment (Bishop Museum, Honolulu, HI, 1972).
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(1972)
Native Planters in Old Hawai'i: Their Life, Lore, and Environment
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Handy, E.S.C.1
Handy, E.G.2
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37
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2942632552
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note
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While mulching by Polynesian cultivators was not responsible for the presence of enriched soils within the field system, it could have contributed to the sharpness of the transition in soil properties from within the field system to just outside it (Fig. 3).
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38
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2942661129
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Although intensive agriculture expanded to the boundaries of suitable climates and soils in leeward Kohala, variation in the density of walls and trails suggests that the degree of agricultural intensification differed within the system (17).
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39
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0033545308
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O. A. Chadwick, L. A. Derry, P. M. Vitousek, B. J. Huebert, L. O. Hedin, Nature 397, 491 (1999).
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(1999)
Nature
, vol.397
, pp. 491
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Chadwick, O.A.1
Derry, L.A.2
Vitousek, P.M.3
Huebert, B.J.4
Hedin, L.O.5
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42
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2942674075
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unpublished data
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O. A. Chadwick, unpublished data.
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Chadwick, O.A.1
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46
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2942637109
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note
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Supported by NSF grant BCS-0119819. We thank the State of Hawai'i for permission to carry out this research; Kahua, Parker, and Ponoholo Ranches and other Kohala Landowners for access to their lands; D. Turner, S. Robinson, J. P. Fay, M. Vitousek, N. Boes, and V. Bullard for assistance with graphics and laboratory analyses; and J. Diamond and G. C. Daily for comments on an earlier draft of this manuscript.
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