荒漠河岸林区3种典型植物群落下土壤碳氮含量特征     

陈雨晴  席海洋  程文举  赵欣悦 《中国沙漠》2023,43(1):150-159

以黑河下游荒漠河岸林区3种典型植物(苦豆子(Sophora alopecuroides)、胡杨(Populus euphratica)、柽柳(Tamarix ramosissima))群落下的土壤为研究对象,分析了0～280 cm土层土壤碳氮含量特征,运用Pearson相关分析、通径分析方法揭示了土壤碳氮含量与其他理化性质的关系。结果表明：(1)苦豆子、胡杨、柽柳群落下的土壤平均碳含量分别为16.35、20.23、17.23 mg·g^-1,平均氮含量分别为0.47、0.69、0.61 mg·g^-1,植被类型导致的土壤碳氮含量的差异主要表现在0～10 cm表层。(2)荒漠河岸林区0～160 cm土壤碳储量柽柳(444.64 t·hm-2)>胡杨(398.60 t·hm^-2)>苦豆子(368.95 t·hm^-2),土壤氮储量柽柳(12.46 t·hm^-2)>胡杨(11.88 t·hm^-2)>苦豆子(10.60 t·hm^-2  相似文献   

利用Sentinel-2影像超分辨率重建的红树林冠层氮含量反演     

甄佳宁  蒋侠朋  赵德梅  王俊杰  苗菁  邬国锋 《遥感学报》2022,26(6):1206-1219

氮素是植被整个生命周期的必要元素,红树林冠层氮素含量（CNC）遥感估算对红树林健康监测具有重要意义。以广东湛江高桥红树林保护区为研究区,本文旨在基于Sentinel-2影像超分辨率重建技术进行红树林CNC估算和空间制图。研究首先基于三次卷积重采样、Sen2Res和SupReMe算法实现Sentinel-2影像从20 m分辨率到10 m的重建;然后以重建后的影像和原始20 m影像为数据源构建40个相关植被指数,采用递归特征消除法（SVM-RFE）确定CNC估算的最优变量组合,进而构建CNC反演的核岭回归（KRR）模型;最后选取最优模型实现CNC制图。研究结果表明：基于Sen2Res和SupReMe超分辨率算法的重建影像不仅与原始影像具有很高的光谱一致性,且明显提高了影像的清晰度和空间细节。红树林CNC反演波段主要集中在红（B4）、红边（B5）、近红外波段（B8a）以及短波红外波段（B11和B12）,与“红边波段”相关的植被指数（RSSI和TCARIre1/OSAVI）也是红树林CNC反演的有效变量。基于3种方法重建后10 m的影像构建的模型反演精度（R²val>0.579）均优于原始20 m的影像（R²val=0.504）;基于Sen2Res算法重建影像构建的反演模型拟合精度（R²val=0.630,RMSE_val=5.133,RE_val=0.179）与基于三次卷积重采样重建影像的模型拟合精度（R²val=0.640,RMSE_val=5.064,RE_val=0.179）基本相当,前者模型验证精度（R²cv=0.497,RMSE_cv=5.985,RE_cv=0.214）较高且模型变量选择数量最为合理。综合重建影像光谱细节及模型精度,基于Sen2Res算法重建的Sentinel-2影像在红树林CNC估算中具有良好的应用潜力,能为区域尺度红树林冠层健康状况的精细监测提供有效的方法借鉴和数据支撑。  相似文献   

Catching a wave? A case study on incorporating storm protection benefits into Habitat Equivalency Analysis     

《Marine Policy》2017

Since Hurricane Sandy, there has been heightened attention to increasing the resilience of coastal communities to extreme events, including storm protection provided by coastal ecosystems. Storm protection benefits (SPB) are the ability of ecosystems, including wetlands, reefs, and beaches/dunes, to attenuate waves and storm surge. SPB are a topic of growing interest in the scientific and policy spheres, including discussions of how to incorporate SPB into existing policies. As an engine for restoration and a leading mechanism for the evaluation of ecosystem services, Natural Resource Damage Assessment (NRDA) provides a platform for better internalizing this and other services into decision-making particularly using Habitat Equivalency Analysis (HEA). HEA does not explicitly account for impacts to ecosystem services that flow from one habitat to an adjacent one. This study examines a hypothetical case study of an oil spill that impacts a marsh with resulting impacts on SPB to the adjacent upland forest. To more fully assess these impacts, a “nested HEA” was developed which accounts for cross-habitat ecosystem service flows. The nested HEA captures the impacts of the marsh loss on the forest due to wave and saltwater intrusion that would not be captured by a traditional HEA. By adapting the HEA approach with a nested HEA, NRDA could quantify direct ecosystem services losses as well as additional cross-service flows between habitats. However, additional data are needed in order to perform a nested HEA, and in the case of SPB, location-specific data likely will be needed to appropriately specify the model.  相似文献   

基于NDVI阈值法的森林冰冻受灾范围精确提取     

王学成  杨飞  高星  李丽 《地球信息科学学报》2017,19(4):549-558

快速提取森林冰雪受灾范围,有利于准确掌握森林受灾情况,为此类灾害性气候事件防灾减灾、森林资源管理和生态保护提供科学依据。本文利用2001-2007年NDVI数据,提取灾前植被NDVI参考值和正常波动范围,结合2008年NDVI数据提取冰雪冻灾范围。该方法弥补了基于单一时相的传统方法（NDVI差值法）忽略植被指数正常波动的问题,分像元提取植被NDVI正常波动范围,使提取结果更加客观合理。与传统方法提取结果对比,省级尺度的验证结果相同（即森林受灾率均为34.72%,而实地调查森林受灾率35.3%）,但2种方法在县市行政单元提取的森林受灾率相差较大。NDVI阈值法提取的森林冰雪受灾范围主要分布于湖南省南部地区,北部地区分布相对较少,而传统方法提取结果主要分布于湖南省北部地区,南部地区分布相对较少。根据实地考察资料显示,相比于传统方法,NDVI阈值法提取结果与实际森林冰雪冻灾空间分布信息更接近,精度更高,更适合于区域大尺度提取森林冰雪受灾范围。  相似文献