广西壮族自治区草原综合植被盖度监测研究

通过草原综合植被盖度监测,主要调查草原样地基本特征、地理位置(经纬度)、主要植物种类、样地综合植被盖度等要素,综合测算广西草原综合植被盖度。结果表明,本次调查广西共布设监测样地812个,测算出草原综合植被盖度为82.76%,较2019年提高0.93%,其中,热性草丛类、热性灌草丛类、暖性灌草丛类植物的综合植被盖度分别为84.11%、82.88%、89.00%。同时对关系草原综合植被盖度变化原因及存在问题进行分析,提出相关建议,以期为广西全面建成小康社会统计监测指标体系和广西绿色发展指标体系提供重要基础指标数据。

甘肃省不同生态功能区草地资源综合评分及其原因分析

根据甘肃省自然气候的地域分异性规律,将全省草原划分为甘南高寒草原生态功能区,祁连山-阿尔金山山地草甸、草原生态功能区,河西走廊荒漠草原生态功能区,黄土高原干旱草原生态功能区,陇南山地草丛草原生态功能区5个草原生态功能区。从甘肃省林草资源现状数据库中,提取草地图斑和相关属性因子,形成草原专题数据库。分别计算全省5个草原生态功能区的草原综合植被盖度、单位面积牧草产量、可食牧草占比、草原载畜能力4个指标。结果表明,通过加入权重系数计算求得全省草原不同生态功能区草地资源综合分析评价得分,并对计算结果采取百分制赋分,得分最高的陇南山地草丛草原生态功能区赋值100分,则甘南高寒草原生态功能区百分制得分为94.11分,黄土高原干旱草原生态功能区百分制得分为50.41分,河西走廊荒漠草原生态功能区百分制得分为26.07分,祁连山-阿尔金山山地草甸、草原生态功能区百分制得分为18.36分。

2021年度青海省草原监测概要

2021年是青海省林草生态综合监测的第一年,在草原生态监测方面对草原综合植被盖度、鲜草产量、草原物候期及植被长势等指标开展了监测工作,其中物候期和草原植被盖度根据地面实测数据进行遥感建模反演。结果显示,2021年全省草原综合植被盖度为57.8%,比上年提高0.4个百分点,比前5 a均值增加了1.6个百分点;草原鲜草平均产量为3 336.0 kg/hm^(2),比上年增加210.0 kg/hm^(2),增幅达到6.7%,草原生态保持良好,产草量平稳增长。物候方面,2021年4月10日前仅少量草原返青,面积约占7.35%,5月20日,全省返青面积增加至63.2%,大部分区域返青,较过去5 a平均水平推迟5 d;2021年全省草原枯黄期平均在第270 d左右,与过去5 a枯黄期持平,较2020年提前3 d。受监测区域广、异质性强及技术手段等条件限制,目前无法应用遥感结合地面实测数据的方法,开展时效性较强的草原生态状况评估工作。健全草原生态监测指标体系建设,改进监测技术手段和方法,才能为草原资源管理和保护提供科学有效的数据支撑。

辽宁省草原植被生长状况简析——以2023年为例

受2023年辽宁省主要草原区降水量较上年偏少影响,全省草原植被长势差于上年同期,返青期、盛期、枯黄期较上年推迟。草原植被平均高度、产草量较上年有所下降。2023年全省草原综合植被盖度值为67.35%,草原生态水平为良,保持基本稳定趋势。

Effects of Vegetation Coverage and Management Practice on Soil Nitrogen Loss by Erosion in a Hilly Region of the Loess Plateau in China

Soil erosion and nutrient loss due to erosion are world-wide problems. Similar to soil loss by erosion, soil nitrogen (N) loss by erosion in small catchments is affected by vegetation coverage. The practice of comprehensive management for catchments mainly by adjusting cropland, grassland and woodland areas was widely adopted to reduce soil and water loss in catchments of the Chinese Loess Plateau. Three experiments under natural and artificial rainfall conditions on N loss by erosion for a model catchment and for an actual catchment in Zhifanggou of Ansai County in China was performed to determine the relationships between comprehensive management and N loss by runoff in small catchments. The results for vegetation coverage of 60%, 40%, 20% and 0 show that runoff loss of ammonium, nitrate, and total N were 87.08, 44.31, 25.16, 13.71 kg/km(2); 85.50, 74.06, 63.95, 56.23 kg/km(2); and 0.18, 1.18, 1.98, 7.51 t/ km(2), respectively. Due to reduction in the size of cropped area on steeply sloping land, soil N loss by erosion in the catchments was decreased by 15.8% as compared with that in 1992, i.e., from 8 758.5 kg in 1992 to 7 562.2 kg in 1998. Whereas, catchments act as a filter for ammonium and nitrate in rain, the catchment filtering effects on nitrate is remarkably higher than that on ammonium. The enrichment of < 20 mum aggregate in sediment results in the enrichment of organic matter and total N in flood sediment. Greater vegetation coverage can effectively decrease soil erosion and total N loss. However, soil mineral N loss increased as vegetation coverage increased.