玛曲县天然草原牧草生长盛期植被盖度及变化

作为黄河源区重要的水涵养区和草牧业生产基地,甘肃省玛曲县天然草原对涵养水源、保护黄河源区生态安全、确保当地草地畜牧业生产的健康发展具有十分重要的意义。植被盖度不仅是草原生态评价的一项重要指标,也是草地生产力评价的重要依据。为了解牧草生长期草原植被盖度及动态变化,将遥感与地面调查相结合,选择像元二分模型对牧草生长期玛曲县草地植被盖度及变化进行研究与评价。结果表明:6—8月植被平均盖度7月最高(75.63%),较6月高4.27个百分点,8月较7月低8.54个百分点;植被平均盖度依低地、高寒、山地草甸和高寒草原的顺序升高,均以7月最高(分别为75.63%、75.30%、79.57%和82.09%),8月最低(分别为65.92%、67.16%、67.00%和71.78%);6、7月植被平均盖度以Ⅰ级草地为主,分别占全县草地面积的61.03%和66.95%,其次为Ⅱ级草地,分别占25.21%和29.97%,8月平均盖度以Ⅱ级草地为主,占64.67%,其次为Ⅰ级,占26.96%,相比7月盖度级别较高;6、7月低地、高寒、山地草甸和高寒草原植被盖度均以Ⅰ级盖度草地为主,6月低地、高寒、山地草甸和高寒草原植被Ⅰ级盖度草地分别占45.67%、62.88%、62.95%和77.16%,7月分别占58.72%、66.53%、85.67%和96.03%;8月低地、高寒和山地草甸均以Ⅱ级草地占比最大,分别为78.93%、63.07%和70.89%,而高寒草原Ⅰ级占比达60.34%。分乡镇草地植被盖度变化趋势与全县一致。     

合作市高寒草甸牧草生长期植被盖度、可食牧草产量及养分含量动态分析

为制定合理的高寒草甸保护利用规划,将"3S"技术与地面调查、实验室检测相结合,通过像元二分模型、估产建模和克里金插值等方法,研究摸清甘肃省合作市高寒草甸牧草生长期植被盖度、可食牧草产量及分级,牧草养分含量及动态变化规律。结果表明:2017年6-8月植被盖度及盖度级别,可食牧草平均鲜草产量和总鲜草产量均随生长期延续而增大。6、7、8月植被平均盖度分别为55.79%、72.69%和78.89%,平均鲜草产量分别为1 214.85、4 797.75和5 550.90 kg/hm^2,以7月增幅较大。6月Ⅱ级盖度草地占79.05%,7月Ⅱ级盖度下降52.61%、Ⅰ级盖度占比增加到45.03%,8月Ⅰ级盖度草地占77.34%;鲜草产量从6月的<1 500 kg/hm^2为主,向7月的3 000~4 500 kg/hm2和8月的4 500~6 000 kg/hm^2产量级转变。以8月总鲜草产量为基础的高寒草甸适宜载畜量为20.80万个羊单位。高寒草甸可食牧草CP和P含量随牧草生长期延续而降低,而EE、NDF、ADF和Ca含量增加。单位面积CP、EE、NDF、ADF产量7月最高,分别为165.51、27.77、569.40和246.02 kg/hm^2;Ca产量7-9月变化幅度较小,在0.052~0.059 kg/hm^2之间,P产量8月达最高,为0.024 kg/hm^2。     

基于MODIS的青藏高原牧草生长季草地生物量动态

摘要：草地生物量是评价青藏高原生态脆弱性和敏感性的重要指标,也是度量草地退化的重要指标。本研究利用MODIS植被指数NDVI和EVI资料及青藏高原三江源地区326个样方实测数据,构建并优化了研究区不同类型草地生物量的预测模型,估算了2002-2009年期间草地生物量年际和月际变化特征。结果表明,高寒草甸地上生物量适宜植被指数为NDVI,反演模型为,y=6.202 5x2-574.89x+14 586,高寒草原地上生物量适宜植被指数为EVI,反演模型为,y=0.165 5x1.773 2。高寒草甸和高寒草原生物量在2002-2009年表现为波动状态,但高寒草甸比高寒草原波动幅度大。高寒草甸和高寒草原生物量在6-8月间均持续增加,9月开始下降,但7月高寒草原生物量波动大于高寒草甸,8月高寒草原生物量波动小于高寒草甸,6月和9月两种草地类型生物量波动不明显。     

近30年山丹天然草原面积及盖度变化

本研究将3S技术与地面调查相结合,选择决策树分类和像元二分模型等方法,对山丹草原资源和草地植被盖度现状及变化进行了研究与评价。结果表明:研究区草原总面积39.59万hm~2,其中高寒草甸、山地草甸、温性草原、温性荒漠和温性草原化荒漠分别为8.47,3.14,9.61,8.23和10.14万hm~2;2014年研究区草原总面积比1987年减少了2.59万hm~2,山地草甸、温性草原、温性草原化荒漠和温性荒漠分别减少了8592.75,2377.08,3357.69和11559.75hm~2。各类型草地平均盖度依山地草甸、高寒草甸、温性草原、温性草原化荒漠和温性荒漠次序降低,分别为82.35%,57.60%,33.79%,17.07%和9.94%,正常年份分别以Ⅱ,Ⅰ,Ⅳ,V和V级草地盖度为主;从1987年到2014年,山地草甸盖度呈现逐年降低的趋势,高寒草甸呈先上升后下降趋势,温性草原、温性草原化荒漠和温性荒漠呈先下降后上升趋势。     

新疆阜康市草地植被组成及生产力动态研究

本研究对阜康市的温性草原、温性荒漠草原、山地草甸草原、高寒草甸草原和温性草句草原等6个样区进行调查,通过样地植被组成、植被盖度、草群高度、物种数量、产草量等调查,了解阜康市2007-2011年草原资源与生态状况的动态变化情况。研究发现：各个样地的降水量在2008年出现最低值,当年各样地草群高度、植被盖度、产草量均有明显的下降;2009-2011年温性荒漠草原草群中优良牧草比重减少,草地植被中不可食草群高度、盖度增大,草地生产功能减弱;山地草甸草原和温性草甸草原的草群高度和产草量在2009年开始下降,但其盖度变化不大;温性草原的草群高度、植被盖度、产草量及各类主要植被的产草量受降雨影响较大;高寒草甸草原的草群高度、植被盖度、产草量波动较小。     

河北省草地资源分布及植被特征动态

根据河北省2005-2007年草地地面调查,结合1979-1984年河北省草地调查资料,确定了河北省草地类型、面积、分布及物种组成特征,并对河北省草地盖度、高度和产草量年际变化动态进行了监测研究。结果表明,1)草地类型、面积及分布:河北省有温性草甸草原、温性草原、暖性灌草丛、暖性草丛、山地草甸草原、低地草甸、沼泽草地等7个草地类型;草地分布分为坝上高原区、山地丘陵区草地及滨海平原区;2)草地产量(干草):暖性灌草丛(5 133.35 kg/hm²)＞暖性草丛(4 182.22 kg/hm²)＞山地草甸(坝上高原区)(3 268.35 kg/hm²)＞温性草甸草原(2 665.94 kg/hm²)＞山地草甸(山地丘陵区)(2 111.55 kg/hm²)＞低地草甸(1 872.44 kg/hm²)＞温性草原(1 103.29 kg/hm²),暖性灌草丛产量最高,温性草原产量最低。3)草地植被盖度:山地草甸(坝上高原区)(93.97%)＞山地草甸(山地丘陵区)(82.60%)＞低地草甸(82.26%)＞暖性灌草丛(79.70%)＞暖性草丛(76.91%)＞温性草甸草原(71.59%)＞温性草原(57.63%),山地草甸的植被盖度最大,温性草原的植被盖度最小。4)草地植被高度:暖性草丛(49.25 cm)＞暖性灌草丛(34.18 cm)＞山地草甸(坝上高原区)(28.88 cm)＞温性草甸(26.22 cm)＞山地草甸(山地丘陵区)(21.98 cm)＞温性草原(19.77 cm)＞低地草甸(18.77 cm),暖性草丛草地植被高度最高,低地草甸草地植被高度最低。5)草地植被动态:2006年草地植被基本以正向波动为主,2005和2007年基本以负向波动为主,其中2007年植被负向波动率大于2005年植被负向波动率。按草地类型,暖性草丛类草地年际波动幅度最大,温性草原草地次之,温性草甸草地的年际波动幅度最小,其他类草地年际波动幅度介于暖性草丛类草地、温性草原类草地与低地草甸类草地之间。     

禁牧封育措施改良高寒地区退化草地的效果

2003-2005年,通过对青海省玉树县上拉秀乡高寒草甸和高寒沼泽化草甸退化草地进行为期3年的禁牧封育改良试验,结果表明:禁牧封育措施对恢复高寒草甸、高寒沼泽化草甸退化草地植被有明显的效果,禁牧封育后草地中植物的盖度、高度和产草量明显提高;牧草成分发生显著变化,优良莎草科、禾本科牧草种类与产量增加,杂类草的种类、产量下降.     

高山草地植被盖度对气候变暖和人类活动的响应

高寒草地对气候变化和人类活动的干扰响应敏感,高寒草地植被盖度估算是了解高寒草地植被状况和评估退化草地修复效果的一个重要方法。目前,地面盖度估算的主要方法是数码照相法,其中基于多光谱照片的盖度提取是比较准确和高效的方法。本研究采用多光谱相机对疏勒河上游不同演替阶段高寒草地、围栏封育和翻耕补播草甸生长季内的植被盖度进行了观测,研究了气候变暖和人类活动干扰下高寒草地植被盖度的变化,同时对估算多光谱照片盖度的阈值法做了改进。结果表明,1）新阈值法的估算结果与真实值之间无显著差异（P=0.219）,而旧阈值法与真实值之间差异极显著（P=0.001）;2）处于不同演替阶段的草地类型具有不同的植被盖度,沼泽草甸最高,各草地类型盖度均在7月达到最大;3）在生产力较低的多年冻土区,围栏封育对高寒草地修复效果在短期内不明显,翻耕补播甚至会导致植被盖度进一步降低。     

祁连山自然保护区不同草地类型地上生物量和土壤微量元素特征分析

以祁连山保护区5个主要草地类型为研究对象,探讨了不同草地类型植被及土壤微量元素的分布特征,应用冗余分析(RDA)分析了微量元素对植被特征的解释关系.研究发现:1)不同类型草地植被总盖度依次为高寒草甸＞温性草原＞高寒草原＞温性荒漠＞高寒荒漠,草层高度依次为温性荒漠＞温性草原＞高寒草原＞高寒草甸＞高寒荒漠,地上生物量依次为...     

祁连山高寒牧区不同类型草地植被特征与土壤养分及其相关性研究

为探究祁连山高寒牧区不同类型草地植被特征、土壤养分及其相关性,以山地草原、高山草原、高寒草甸草原草原3个类型草地为研究对象,采用野外调查、室内测定和数据统计分析相结合的方法,研究了3个类型草地的植被特征、土壤养分特征及其之间的相关性。结果表明：不同类型草地群落盖度、地上生物量差异明显,均为高山草原>山地草原>高寒草甸草原（P<0.05）;群落多样性、草本植物高度差异明显,均为山地草原 > 高山草原 > 高寒草甸草原（P<0.05）;小灌木平均高度差异明显,为高寒草甸草原 > 高山草原 > 山地草原（P<0.05）;不同类型草地土壤有机质含量变幅较大,其中以高寒草甸草原最为丰富;pH值变幅较大,变化趋势与有机质相反,即有机质含量越高,则土壤pH值低,反之亦然;全氮含量较高,都为1~2级（> 0.2%）;全钾含量居中,山地草原为2级（2.5%~3.0%）,高山草原和高寒草甸草原为3级（2.0%~2.5%）;全磷含量最低,均为3~4级（0.05%~0.10%）,全量养分表现出以低磷高氮富钾为特征;速效养分以贫磷为特征;土壤保肥能力较强;各类型草地土壤肥力因子间的相关性各有特点;总体看来,高山草原土壤养分含量最高,其群落的生产力也最高,但群落物种多样性最低。磷在祁连山高寒牧区很缺乏,建议在进行草原管理和人工饲草种植时补充磷素。     

Heartworm in dogs in Canada in 1984

In late December 1984, 1853 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1984 and 35% of them responded. Veterinarians reported that 97,794 dogs were blood-tested to check for microfilariae and 1417 dogs (1.45% of those tested) were found with heartworm. Another 34 dogs were amicrofilaremic, but were diagnosed as having heartworm disease, to give the total number diagnosed in 1984 as 1451 (1.48%). Heartworm was reported from all provinces except Prince Edward Island and Newfoundland but most (1310) of the cases were in Ontario. In Quebec, 126 cases were reported mostly from west of Montreal.

Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 27% of the cases were observed with clinical signs of heartworm disease and 72% had a history of not having left Canada. Southwestern Ontario continued to be the primary focus of the infection.

     

Heartworm in dogs in Canada in 1983

In late December 1983, 2 800 veterinarians across Canada were sent a questionnaire in order to assess the status of heartworm disease in Canada in 1983 and 26% of them responded. Veterinarians reported that 59 504 dogs were blood-tested to check for microfilariae and 771 dogs (1.30% of those tested) were found with Dirofilaria immitis. Heartworm disease was diagnosed in all provinces except New Brunswick and Newfoundland but most (733) of the cases were in Ontario.

Heartworm disease was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 31% of the cases were observed with clinical signs of heartworm disease and 64% had a history of not having left Canada. Southwestern Ontario continues to be the focus of the infection and most of the dogs there had not left the province previously.

     

Heartworm in dogs in Canada in 1991

In late November 1991, 1883 clinics in Canada were sent a questionnaire to assess the status of Dirofilaria immitis in dogs in 1991 and there was a 60.0% response. There were 344,031 dogs tested for heart-worm (HW), 627 were found infected and the prevalence of HW infection was 0.18%. There were 417 dogs with HW in Ontario, 116 in Manitoba, 38 in Quebec, 53 in British Columbia, three in Alberta, and one in Nova Scotia. In British Columbia, all of the infected dogs but one were from the Okanagan valley which, as from 1991, is a new focus of infection in Canada. Most dogs with HW had not been on preventive medication in 1990, and the prevalence among dogs tested and unprotected was 0.59%. That prevalence was considerably higher in endemic areas. Companion dogs, over three years of age and maintained primarily outdoors in rural areas, were most frequently infected. One cat was diagnosed with D. immitis and 33 dogs had Dipetalonema reconditium.     

Heartworm in dogs in Canada in 1985

In late December 1985, 1485 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1985 and 44% of them responded. Veterinarians reported that 137,300 dogs were blood-tested to check for microfilariae and 1210 dogs were found with heartworm. Another 36 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number diagnosed in 1985 as 1247 (0.91%).

Heartworm was reported from all provinces except Prince Edward Island, Newfoundland and Saskatchewan but most (1126) of the cases were in Ontario. Southwestern Ontario continued to be the primary focus of the infection in Canada. From Quebec, 91 cases were reported mostly from and around Montreal. From Manitoba, 19 cases were reported from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 28% of the cases were observed with clinical signs of heartworm disease and 78% had a history of not having left Canada.

     

Heartworm in dogs in Canada in 1988

In late November 1988, 1581 small and mixed animal clinics and institutional veterinarians across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1988, and 46% of them responded. Veterinarians reported that 181,577 dogs were blood-tested for heartworm disease and 367 dogs were found with D. immitis microfilariae. Another 60 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1988 as 441 (0.24%).     

Heartworm in dogs in Canada in 1989

In late November 1989, 1732 clinics and institutional veterinarians were sent a questionnaire to assess the status of Dirofilaria immitis, and 51.7% responded. Of 247,716 dogs tested, 394 had D. immitis microfilariae and 51 were amicrofilaremic for a total of 445 cases and heartworm prevalence of 0.17%. Most (408) of these dogs had no preventive medication and the prevalence among dogs tested and unprotected was 1.01%. That prevalence was considerably higher in endemic areas. Thirty-seven dogs with heartworm had preventive medication. Heartworm was most frequent in companion dogs over three years of age maintained outdoors in rural areas. About 75% of the cases had never left Canada, 26% had clinical signs and 125 were not treated.

Heartworm was reported from British Columbia, Manitoba, Ontario, Quebec, Nova Scotia and Newfoundland, but 383 cases were in Ontario. South-western Ontario was the primary focus of infection. There were 33 cases in Quebec and 24 in Manitoba, mainly found in and around Metropolitan Montreal and Winnipeg respectively.

     

Heartworm in dogs in Canada in 1987

In late November 1987, 1246 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1987, and 50% of them responded. Veterinarians reported that 165,428 dogs were blood tested for heartworm disease and 511 dogs were found with D. immitis microfilariae. Another 78 dogs were amicrofilaremic but diagnosed with heartworm disease to give the total number of cases diagnosed in 1987 as 589 (0.35%).     

Heartworm in dogs in Canada in 1986

In late December 1986, 1224 institutional veterinarians and small and mixed animal clinics across Canada were sent a questionnaire in order to assess the status of Dirofilaria immitis in Canada in 1986; 46% of them responded. Veterinarians reported that 150,989 dogs were blood-tested for microfilariae and 869 dogs were found with heartworm. Another 65 dogs were amicrofilaremic but diagnosed with heartworm disease and one was found with heartworm at necropsy to give the total number diagnosed in 1986 as 935 (0.62%).

Heartworm was reported from Manitoba, New Brunswick, Ontario and Quebec, but most (810) of the cases were from Ontario. South-western Ontario continued to be the primary focus of the infection in Canada. There were 103 cases reported from Quebec, mostly from and around Montreal, and 21 cases from Manitoba, from Winnipeg and surrounding areas. Heartworm was found most frequently in companion dogs over three years of age maintained mainly outdoors in rural areas. About 33% of the cases were observed with clinical signs of heartworm disease and 81% had a history of not having left Canada.