41年罗山自然保护区人地关系的演进与孤立生境的形成

Evolution of human-land relationship and its ecological isolation in Luoshan Nature Reserve

罗山自然保护区孑遗生境具有过渡性、稀有性和脆弱性,其生态走向关乎濒危物种的延续与北方干旱荒漠带宁夏段的生态平衡。利用Landsat MSS/TM/ETM+/OLI(1977—2017年)数据、SRTM DEM和罗山周边气象站点(1977—2017年)年均气温和降水数据,对流域内典型人文要素(人口、耕地、居民建设用地面积)和自然生态要素(NDVI)进行了定量化表达及相关性分析。研究发现:流域视角下罗山保护区一些人文、生态、景观地理学指标发生了变化,41年来(1977—2017年)真形(依比例)居民建设用地面积增加了3.09倍;生态移民使局部地区人口增长了34.30倍;土地利用方式发生了根本变化,旱作耕地大部分退耕还林,小部分转移为水浇地;近5a(2013—2017年)罗山自然保护区NDVI最大值、NDVI总和虽有轻微上升趋势,但仍低于历史较好时期。结果表明:(1)公路、铁路、围栏的建设将狭小的生态保护区分割包围,使景观格局严重破碎化,使动植物栖息环境高度隔离化。(2)红寺堡移民区快速城市化和高强度的农业开发,使流域人 地关系愈加紧张,加重了区域生态风险。

Relict habitat such as Luoshan Nature Reserve,with its species rarity and ecological vulnerability,was an indicator of regional ecological and environmental changes.To study its ecological trend plays an important role in protecting species and the ecological balance in Ningxia Section of Arid Desertification Belt in North China.Based on Landsat MSS/TM/ETM+/OLI(from 1977 to 2017)data,SRTM DEM,and the annual average temperature and precipitation(from 1977 to 2017)from meteorological stations around Luoshan Mountain,human impact variables(population,cultivated land,and residential area)and natural ecological elements(NDVI)were quantitatively expressed and analyzed using correlation analyses.This study found indicators that human influence has affected the watershed of the Luoshan Nature Reserve through ecological alteration of the geographic landscape.The area of true shaped residents(identifiable proportionately from remote sensing images)increased 3.09 times from 1977 to 2017.The population increased 34.30 times due to the immigration for poverty alleviation in the Hongsibu District.Before immigration,cultivated land area increased,but then decreased rapidly.Most dry cultivated lands were converted to forest lands, and a small part were converted to irrigated cultivation lands. Inthe last 5 years (2013 to 2017), although NVDI maximum and total values in the Luoshan Nature Reserve have showed aslight upward trend, they are still below the historic values. It can be concluded: (1) The landscape was severelyfragmented through the creation of roads, railways, and fences, isolating the habitats of animals and plants. (2) Due torapid urbanization and high intensity agricultural development in the Hongsibu Immigration District, water and landresources have been converted from decentralized traditional farming (semi arid agriculture) to the centralized developmentof modern agriculture (irrigated agriculture). So the human land relationship is increasingly under strain, aggravating therisk of regional ecological security.