Covered with short grass and bushes and called llano estacado by Spanish explorers, the Texas Panhandle constitutes the southern part of the American High Plains. Following the decline of the open range cattle industry in the late nineteenth century, large-scale cattle ranches appeared, such as LIT, LS, and XIT. Irrigation has rapidly expanded in the region during the past fifty years. It supports production of corn and grain sorghum (milo) in the flat plains of the northern Panhandle and wheat and cotton in the southern Panhandle. Cattle ranches still dominate in the undulating and sloping country of the Canadian River valley. This paper examines the nature of cattle ranching in the Texas Panhandle during the age of irrigation that promoted differentiation of land use.
Hartley and Oldham counties are chosen for our intensive field study. Large-scale ranches are identified on the map using farm plats, topographic maps, and aerial photographs. They vary in size, from family-operated ranches of 2, 000 hectares to corporate ranches exceeding 40, 000 hectares. Historic ranch names such as LIT and LS are still maintained by contemporary owners. The cow-calf operation is still the basic method in this region, while some beef cattle ranches, not owning cows, depend on purchased yearlings. Others combine cow-calf operations with raising yearlings. As a single animal is given 12 hectares of pasture, 150 to 200 head are grazed on a 4, 000 hectares ranch. Calves born on the ranch during the spring are sold at livestock auctions in Dalhart and Amarillo to farmers, who graze them in wheat fields during the winter. In March, farmers sell their yearlings weighing around 200 kilograms at livestock auctions to ranchers. After being grazed on pasture and reaching 300 kilograms in the fall, they are finally sold to the neighboring feedlots for finishing. Therefore, cattle transactions at the Dalhart livestock auction have peak periods in March and October.
The Texas Panhandle has a concentration of feedlots. They fatten two-year old cattle weighing 300 kilograms for four months until they reach 570 kilograms. They are large-scale commercial feeders, with the largest raising 85, 000 head. Agribusiness companies such as Continental Grain and Cargill operate large feedlots. Some local feedlot owners operate large ranches in order to secure a supply of cattle. Large beef packing plants are also concentrated in the Texas Panhandle for processing locally finished beef cattle.
Beef packers, feedlots, ranches and wheat growers of the Texas Panhandle are interrelated, taking advantage of the groundwater resources of Ogallala Aquifer. Cattle ranches are the basis of the feedlot and beef-packing industries, while they depend on local wheat growers for winter grazing. Unlike the cattle industry in the late nineteenth century and first half of the twentieth century, contemporary cattle-ranching industry in the Texas Panhandle represents a regional change that took place in the American High Plains in response to the opportunities offered by groundwater exploitation.

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本研究では、南洋群島の旧日本委任統治領、パラオ共和国バベルダオブ島の3つの流域で行われた農地開拓とボーキサイト採掘を事例に、開拓の実態と現代への影響を分析した。農地開拓では、島内に4つの指定開拓村が設置され、1940年には合計1671人が2255町歩の土地に暮らし、主にパイナップルやキャッサバが栽培された。一方で、日本人が撤退した後65年を経た現代においても、当時の森林伐採と土地収奪的な営農による植生への影響、および、移入種Falcataria moluccanaによる固有種への影響が見られる。ボーキサイト採掘地は、島内2カ所に合計106ha設置され、島の一大産業であった。開拓面積は小さいものの、表土を剥がしとったために、採掘当時は多量の土砂が流出し、湿地と沿岸域に堆積した。また、パラオ人集落でも、土砂の埋立てと集落移転、インフラ設備の再利用、産業遺産の観光化など、少なからず日本の影響が見られる。開拓はいずれも水系を軸として流域を単位に進められており、開拓の影響は沿岸の生態系やパラオ人集落など、流域内の自然や社会に対して広域、かつ長期にわたる影響を与えている。

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