过去300 a大清河上游南部流域耕地变化重建

过去300 a耕地变化重建是环境变化研究的基础。华北地区河湖演变对历史土地开垦的影响需要在历史耕地重建时予以考虑。论文基于清代地方志、民国统计资料和现代土地利用数据,通过量化坡度和历史时期潜在耕地垦殖率因子,建立宜垦性模型,重建过去300 a白洋淀与大清河上游南部流域5个时间断面上空间分辨率为1 km×1 km的耕地变化,并结合大清河南支的河道变迁和白洋淀演变过程分析了县域尺度下河道变迁、湖群演变对土地开垦过程的影响。结果表明：① 近300 a来研究区开垦范围向山区扩展,开垦强度不断加深,平均垦殖率由1646年的0.162增至1980年代的0.579;② 白洋淀收缩为安新、容城、任丘、高阳和蠡县土地开垦提供良好的物质基础,清中后期5县垦殖率较同期周围县高约3%~40%不等,且增长速度明显快于周围县;③ 古河道为肃宁、河间、任丘和安国的土地开垦提供了物质基础,河流改道后肃宁、河间和任丘的垦殖率分别增长为原来的2.12、2.6和2.86倍;安国垦殖率增长了37%,为同期增长最为显著的县;④ 新河道虽会冲毁部分土地,但泛滥区却能为土地开垦提供物质基础,故途经地垦殖率有增有减,蠡县和高阳的垦殖率分别增加为原来的1.80倍和1.88倍,望都、清苑垦殖率分别增加3%、4%,定州垦殖率减少4%。

Reconstruction of cropland change in the southern area of the Daqing River Basin over the past 300 years

Reconstruction of cropland change over the past 300 years forms the basis for environmental change studies. The influence of changes in river and lake areas in North China can provide a reference and validation for the reconstruction of historical arable land. Based on the local historical documents of the Qing Dynasty, the statistical data of the Republic of China, and the data of modern land use, this study reconstructed the cropland change of five time periods in the Baiyangdian Lake and the southern area of the Daqing River Basin in the past 300 years. It established the reclamation model by quantifying the slope and the potential cultivated land reclamation rate in historical periods. The spatial resolution of the analysis is 1 km × 1 km. This study also analysed the influence of river and lake evolution on the cultivation ratio via the changes of the Baiyangdian Lake and the southern branches of the Daqing River. The results show that: 1) Land reclaimation in the research area has expanded to the mountainous areas, and reclamation has constantly intensified over the past 300 years. Average cultivation ratio increased from 0.162 in 1646 to 0.579 in the 1980s. 2) The contraction of the Baiyangdian Lake provided a good material basis for land reclamation in Anxing, Rongcheng, Renqiu, Gaoyang, and Lixian Counties. The reclamation rate of the five counties in the middle and late Qing period was about 3%-40% higher than that of the surrounding counties, and the growth rate was faster too than that of the surrounding counties. 3) The old river channel provided material basis for land reclaimation of Suning, Hejian, Renqiu, and Anguo Counties. After the river diversion, the reclamation rates of the former three counties increased by 2.12, 2.6, and 2.86 times respectively. The reclamation rate in Anguo County increased by 37%, the most significant increase in the same period. 4) Although the new river could destroy some of the land, the floodplain, however, can provide a material basis for land reclamation. Therefore the cultivation ratio of the counties along the new river can increase or decrease. The reclamation rates of Lixian and Gaoyang have increased to 1.80 times and 1.88 times respectively. The reclamation rate of Wangdu and Qingyuan increased by 3% and 4%, and that of Dingzhou decreased by 4%.