Department of Biology, University of Puerto Rico, San Juan, Puerto Rico, United States of America.
PLoS One. 2012;7(8):e43943. doi: 10.1371/journal.pone.0043943. Epub 2012 Aug 29.
Monitoring land change at multiple spatial scales is essential for identifying hotspots of change, and for developing and implementing policies for conserving biodiversity and habitats. In the high diversity country of Colombia, these types of analyses are difficult because there is no consistent wall-to-wall, multi-temporal dataset for land-use and land-cover change.
METHODOLOGY/PRINCIPAL FINDINGS: To address this problem, we mapped annual land-use and land-cover from 2001 to 2010 in Colombia using MODIS (250 m) products coupled with reference data from high spatial resolution imagery (QuickBird) in Google Earth. We used QuickBird imagery to visually interpret percent cover of eight land cover classes used for classifier training and accuracy assessment. Based on these maps we evaluated land cover change at four spatial scales country, biome, ecoregion, and municipality. Of the 1,117 municipalities, 820 had a net gain in woody vegetation (28,092 km(2)) while 264 had a net loss (11,129 km(2)), which resulted in a net gain of 16,963 km(2) in woody vegetation at the national scale. Woody regrowth mainly occurred in areas previously classified as mixed woody/plantation rather than agriculture/herbaceous. The majority of this gain occurred in the Moist Forest biome, within the montane forest ecoregions, while the greatest loss of woody vegetation occurred in the Llanos and Apure-Villavicencio ecoregions.
The unexpected forest recovery trend, particularly in the Andes, provides an opportunity to expand current protected areas and to promote habitat connectivity. Furthermore, ecoregions with intense land conversion (e.g. Northern Andean Páramo) and ecoregions under-represented in the protected area network (e.g. Llanos, Apure-Villavicencio Dry forest, and Magdalena-Urabá Moist forest ecoregions) should be considered for new protected areas.
在多个空间尺度上监测土地变化对于识别变化热点以及制定和实施保护生物多样性和栖息地的政策至关重要。在哥伦比亚这样一个生物多样性丰富的国家,由于缺乏一致的、全方位的、多时相的土地利用和土地覆盖变化数据集,因此进行此类分析具有一定难度。
方法/主要发现:为了解决这个问题,我们使用 MODIS(250 米)产品结合 Google Earth 中的高空间分辨率图像(QuickBird)参考数据,绘制了哥伦比亚 2001 年至 2010 年的年度土地利用和土地覆盖图。我们使用 QuickBird 图像对 8 个土地覆盖类别的百分比进行目视解译,用于分类器训练和精度评估。基于这些地图,我们评估了四个空间尺度(国家、生物群落、生态区和市)的土地覆盖变化。在 1117 个市中,有 820 个市的木本植被(28092 平方公里)呈净增长,而 264 个市的木本植被呈净减少(11129 平方公里),导致全国范围内木本植被净增加 16963 平方公里。木本植被的再生主要发生在先前被归类为混合木本/人工林而非农业/草本的地区。这一增长主要发生在潮湿森林生物群落内的山地森林生态区,而木本植被损失最大的地区则在 Llanos 和 Apure-Villavicencio 生态区。
出乎意料的森林恢复趋势,特别是在安第斯山脉,为扩大现有保护区和促进栖息地连通性提供了机会。此外,土地转换强烈的生态区(如北部安第斯高山湿地)和保护区网络代表性不足的生态区(如 Llanos、Apure-Villavicencio 干燥森林和 Magdalena-Urabá 潮湿森林生态区)应考虑设立新的保护区。