地球遥感期刊官网投稿入口

This conclusion has been reached from data compiled by NASA's Aqua and Terra earth observation satellites.

From 2000 to 2017, the global areas covered by greenery increased by 5%, of which, 25% of such territory lies in China. In fact, China only accounts for 6.6% of global vegetation coverage. So, how did these changes happen?

To this end, we have invited experts from the Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences who have been engaged in monitoring vegetation change for a long period of time, to explain the process with the sufficient statistical data and satellite remote sensory images.

今年早些时候，一篇由美国波士顿大学领衔、美国宇航局主要资助的多国合作研究论文发表在《自然-可持续发展》期刊上，这篇题为《中国和印度通过土地利用管理引领世界变绿》的论文发现：2000—2017年，中国和印度主导了全球陆地变绿（植被叶面积的增加）。更重要的是，在中国变绿的过程中，森林贡献了42%，大于农用地的32%，远大于印度4.4%的森林贡献率。

Earlier this year, a multinational cooperative research paper led by Boston University and mainly funded by NASA was published in Nature Sustainability . The paper was entitled ' China and India Lead in Greening of the World Through The Land-Use Management ', and found that during the period from 2000 to 2017, China and India dominated global land greening (increases in leaf-covered areas). More importantly, in the process of turning China greener, forests contributed 42%, greater than the 32% contribution of agricultural land and much more than India's forest contribution of 4.4%.

▲ Source: https://zhuanlan.zhihu.com/p/56452684,

China's afforestation and forest protection are crucial parts of the results achieved.

从20世纪70年代以来，中国先后启动了许多重大生态建设工程，其中与陆地变绿直接相关的至少有6个：“三北”防护林工程、天然林资源保护工程、退耕还林（草）工程、长江/珠江流域防护林工程、京津风沙源治理工程、退牧还草工程。这些工程覆盖了中国的绝大部分地区。

Since the 1970s, China has successively launched many large ecological projects, including six projects which are directly related to land greening: the "Three-North" Shelter Forest Program, the Natural Forest Resource Protection Project, the Project of Returning Farmland to Forest (Grass), the Shelterbelt Forestry Project of the Yangtze/Pearl River Basin, the Beijing-Tianjin Sandstorm Source Control Project and the Project of Returning Grazing Lands to Grasslands. These projects cover most of the regions of China.

“三北”防护林工程 ，1979年开始实施，涉及13个省市区，工程建设总面积406.9万平方公里，占全国陆地总面积的42.4%，至今总投资约500多亿元。

Beginning in 1979, the "Three-North" Shelter Forest Program involving 13 provinces, autonomous regions and municipalities directly under the Central Government, has achieved a total construction area of 4.069 million square kilometers, accounting for 42.4% of China's total land area , with total investment adding up to more than 50 billion yuan so far.

天然林资源保护工程， 1998年开始试点，涉及17个省区、724个县、160个重点企业、14个自然保护区等，到2004年累积投资488.3亿元。

Beginning in 1998, the Natural Forest Resource Protection Project involving 724 counties, 160 key enterprises and 14 nature reserves in 17 provinces and autonomous regions, reached cumulative investment of 48.83 billion yuan by 2004.

退耕还林（草）工程， 始于1999年，涉及25个省区、1897个县区， 是迄今为止世界上最大的生态建设工程 ，仅中央投入的工程资金就超过4300多亿元。

Having been started in 1999, the Project of Returning Farmland to Forest (Grass) involves 1,897 counties in 25 provinces and autonomous regions. It is one of the largest ever ecological project to be carried out worldwide. The central government alone has invested more than 430 billion yuan in the project.

长江/珠江流域防护林工程 ，一期为1989—2010年，根据森林清查资料及林业统计年鉴，共造林约6.3万平方公里、育林约5.5万平方公里。二期涉及的范围更广，其中长江流域防护林二期工程包括17个省（市）的1033个县（市、区），规划造林任务6.9万平方公里。

Phase I of the Shelterbelt Forestry Project of the Yangtze/Pearl River Basin was carried out between 1989 and 2010. According to forest inventory data and the forestry statistical yearbook, a total of 63,000 square kilometers of forest were planted and 55,000 square kilometers were afforested. The Phase II covers a wider range, of which the Shelterbelt Forestry Project of the Yangtze River Basin Phase II includes 1,033 counties (cities and urban districts) in 17 provinces (municipalities directly under the Central Government) with a planned afforestation task of 69,000 square kilometers.

京津风沙源治理工程， 始于2002年，涉及北京、天津、河北、山西及内蒙古等五省（区、市）的75个县，总面积45.8万平方公里，一期工程初步匡算投资558亿元。

Having begun in 2002, the Beijing-Tianjin Sandstorm Source Control Project involves 75 counties across five provinces (autonomous region and municipalities directly under the Central Government) including Beijing, Tianjin, Hebei, Shanxi and Inner Mongolia, with a total area of 458,000 square kilometers. The initial estimated investment for Phase I is 55.8 billion yuan.

退牧还草工程， 自2003年以来，北方7省区退牧还草工程约64万平方公里，中央已累计投入资金295.7亿元。

Since 2003, the Project of Returning Grazing Lands to Grasslands has covered 640,000 square kilometers in seven northern provinces and autonomous regions. The Central Government has invested 29.57 billion yuan in the project.

The most effective way to understand the results of these afforestation projects in China is to observe changes in collected data. In the field of ecological environment change monitoring, the most widely used technology is that of acquiring images of the earth for continuous monitoring through remote satellite sensing.

Here are a few sets of data and images which illustrate the reasons behind this green miracle.

In the field of remote sensing applications, the "vegetation index" is widely used for evaluating vegetation coverage and vegetation growth and the "normalized difference vegetation index" (NDVI) is most widely used. In general, the higher the NDVI, the higher the vegetation coverage.

The NDVI(at the national level) in China, India and most European countries show significant increases in 2015 compared with 1982, indicating that the land of these countries has turned significantly green. However, the NDVI in the countries in North America, Australia, Africa and South America showed a decreasing trend in 2015 compared with 1982.

Another measurement indicator is net primary productivity (NPP) .

NPP is the amount of photosynthetic products or organic carbon formed by plants after converting the carbon dioxide in the atmosphere through photosynthesis, and is the material basis for the survival and reproduction of other organisms in the ecosystem.

We quantifies moderate-resolution imaging spectroradiometer (MODIS) NPP from 2000 to 2014 at the country level, and the results show that the combined NPP for 53 countries represents >90% of global NPP. The top three and top 12 countries accounted for 30% and 60% of total global NPP, respectively. China accounts for about 5% of the world's total NPP, ranking 4th globally. However, it cannot be ignored that western China is mostly covered by desert or sparse vegetation, and the average NPP per unit area in China is about 300gC/㎡/y — not high in the global ranking, at a similar level compared to Canada, Australia, India and other countries.

Spatial distribution of annual total NPP at national scale

（c）国家尺度单位面积NPP值空间分布

Spatial distribution of mean national NPP per unit area

（d）占全球NPP总量90%以上的前53个国家NPP总量

Average annual country-level NPP (2000–2014) for the top 53 countries representing >90% of the total global NPP

Source: direct.com/science/article/pii/S0048969716319507

就2000—2014年变化趋势来看， 中国大面积区域NPP是在上涨的，尤其是西部区域。 几个NPP大国中，中国的NPP年净增加约11Tg C，远大于NPP总量排在第一位的巴西（5Tg C/y）、第三位的美国（2Tg C/y）。

According to the trend of change from 2000 to 2014, NPP in large parts of China is rising, especially in western regions. Among several countries with high NPP, China's NPP has increased by about 11Tg C per year, far exceeding that of Brazil (~5Tg C/y) — ranking 1st in terms of total NPP — and the United States (~2Tg C/y) — ranking 3rd.

▲ （a）2000—2014年像元尺度NPP年际变化率空间分布

Pixel scale: Spatial distribution of inter-annual variation rate of NPP from 2000 to 2014

（b）2000—2014年国家尺度NPP年变化率空间分布

National Scale: Spatial distribution of inter-annual variation rate of NPP from 2000 to 2014

Source:

对于2000—2014年中国区域的NPP年际变化率来说，“三北”防护林工程的大部分区域都呈现增加的趋势，尤其是陕西省。

For the inter-annual variation rate of NPP in China from 2000 to 2014, most areas of the "Three-North" Shelter Forest Program show an increasing trend, especially in Shaanxi Province.

▲ 2000—2014年中国像元尺度NPP年际变化率空间分布（图中墨绿色粗线为“三北”防护林工程五期界线）

Spatial distribution of the inter-annual variation rate of NPP at the pixel scale in China from 2000 to 2014 (The dark green thick line in the figure is the boundary line of Phase V of the "Three-North" Shelter Forest Program)

除了变化的数字之外，一目了然的图像更能说明问题。

In addition to the statistical changes, the image is fairly self-explanatory.

首先看看 陕西省榆林市 。

The first area reviewed is the city of Yulin in Shaanxi Province .

通过美国Landsat系列卫星的1987、2014年数据进行分类，可以发现：榆林市2014年林地面积约是1987年的4倍，2014年裸土面积仅是1987年的四分之一；不仅如此，草地面积也增加了0.3万平方公里。

According to the classification from the American Landsat series satellite images of 1987 and 2014, the forested land area in Yulin in 2014 was about four times higher than that of 1987, and the bare land area in 2014 was only one quarter of that of 1987. In addition, the grassland area increased by 3,000 square kilometers.

从下面这两幅卫星影像中能更直观地看出榆林这一区域的情况，1984年还是大片沙地或裸土的区域，2016年已经被植被大面积覆盖了。

The following two satellite images show Yulin clearly. It was a large area of sand or bare land in 1984, but was covered in vegetation by 2016.

▲ 以东经108°43′14.916″，北纬37°41′0.996″为观测中心点拍摄的榆林

Yulin, taken at 108°43′14.916″E-37°41′0.996″N

再看看同属 陕西省的宝鸡市 。

Another illustration covers the city of Baoji in Shaanxi Province .

宝鸡市附近，1984年虽然有些植被，但植被覆盖率不过40%左右，而32年后的2016年，植被覆盖率达90%以上。据《中国林业统计年鉴》，宝鸡仅2002—2016年间，总造林4064.9平方公里，人工造林2117.06平方公里，飞播造林779.51平方公里，新封山育林1168.33平方公里。

Although there was some vegetation in the vicinity of Baoji in 1984, the vegetation coverage rate was only about 40%, while 32 years later in 2016, the vegetation coverage rate exceeded 90%. According to the China Forestry Statistical Yearbook, from 2002 to 2016, Baoji introduced a total afforestation area of 4,064.9 square kilometers, including an artificial afforestation area of 2,117.06 square kilometers, an aerial afforestation area of 779.51 square kilometers and newly closed hillsides for afforestation of 1,168.33 square kilometers.

▲ 以东经107°10′50.01″，北纬34°52′04.29″为观测中心点拍摄的宝鸡附近

Vicinity of Baoji, taken at 107°10′50.01″ E-34°52′04.29″N

还有 甘肃省天水市 。

The next illustration is the city of Tianshui, Gansu Province .

从卫星影像上看，20世纪80年代所见之处多为裸地，据《中国林业统计年鉴》，仅2002—2016年间，天水总造林3427.56平方公里，人工造林2877.52平方公里，飞播造林29.45平方公里，新封山育林520.59平方公里。如今的天水市一片郁郁葱葱，享有西北“小江南”之称。

The satellite images show that duringthe 1980s, most of the land in the area was bare. According to the China Forestry Statistical Yearbook , during the period from 2002 to 2016 alone, Tianshui benefited from afforestation of 3,427.56square kilometers, including artificial afforestation of 2,877.52 square kilometers, afforestation by aerial seeding of 29.45 square kilometers and newly closed hillsides for afforestation covering 520.59 square kilometers. Today, Tianshui is a lush city, enjoying the fame of “rich area south of the Yangtze River” in the northwest.

▲ 以东经106°10′53.97″，北纬34°53′11.03″为观测中心点拍摄的天水

Tianshui, taken at 106°10′53.97″E-34°53′11.03″ N

The most noteworthy is the green miracle — Saihanba, Hebei Province .

从下面两幅卫星影像中能直观地看出：相对于1984年，2016年塞罕坝森林覆盖率得到了明显提高。

The two satellite images below show that the forest coverage rate of Saihanba increased significantly in 2016 compared to 1984.

▲ 以东经117°25′34.824″，北纬42°28′57.36″为观测中心点拍摄的塞罕坝

Saihanba, taken at 117°25′34.824″ E-42°28′57.36″N

从资料图片上也可以看出，新中国成立前塞罕坝区域基本上全是荒漠，而经过三代人50多年的不懈努力，塞罕坝的森林覆盖率从11.4％提高到80％。如今的塞罕坝已是连片的人工林海。2017年12月联合国环境规划署宣布，中国塞罕坝林场建设者获得2017年联合国环保最高荣誉——“地球卫士奖”。

This photo shows that the Saihanba area was basically desert before the founding of the People's Republic of China. After more than 50 years of unremitting efforts across three generations, the forest coverage rate of Saihanba increased from 11.4% to 80%. Now, Saihanba is a contiguous artificial forest. In December 2017, the United Nations Environment Programme announced that the builders of the Saihanba Forest Farm in China were to be awarded the "Champions of the Earth" prize in 2017 — the United Nations' highest honor for environmental protection.

新中国成立前的塞罕坝荒漠

Saihanba desert before the founding of the People's Republic of China in 1949.

▲ Source:

Now, Saihanba is home to the largest contiguous artificial forest in China.

一、遥感平台的种类1. 地面平台2. 航空平台3. 航天平台3-1. 低高度、短寿命卫星 军用3-2. 中高度、长寿命卫星 陆地卫星 海洋卫星 气象卫星 遥感卫星的主体，这三类卫星统称为地球环境卫星；3-3. 高高度、长寿命卫星 地球同步卫星或静止卫星；二、卫星的轨道1. 卫星在空间中的位置和姿态 符合开普勒三大定律： 椭圆轨道； 地球位于一个焦点上，单位时间扫过的面积相等； 周期的平方和轨道平均半径的立方成正比； 描述卫星的参数有六个： 六个元素中，a、e确定了轨道的大小和形状；i、Ω、ω确定了轨道面在空间的位置；t 确定了卫星过近地点的时刻。1-1. 轨道长半径（a） 卫星轨道远地点到椭圆中心的距离。1-2. 轨道偏心率（e） 采用近圆形轨道，卫星运行速度均匀，便于曝光时间的控制和获取全球范围内比例尺趋于一致的图像。1-3. 轨道面倾角（i） 卫星轨道面与地球赤道面之间的夹角。 顺轨就是和地球自转方向相同；1-4. 升交点赤经（Ω） 春分点： 春分约发生在 3月20日或者3月21日，这一天时昼夜等长，故称为“分”。简单的说；春分点与秋分点就是太阳直射地球赤道的那一刻。 Ω 卫星轨道的升交点与春分点之间的角距。1-5. 近地点角距（ω） 卫星轨道升交点向径与近地点向径之间的夹角。1-6. 卫星过近地点的时刻（t）和运行周期（T） 卫星过近地点的时间。2. 卫星轨道的种类2-1. 地球同步轨道 运行周期等于地球的自转周期，表面上看起来是相对于地球静止不动。 高度很高，大约36 000 km 可以对地面上特定区域进行不间断的重复观测，并且观测范围也很大。2-2. 太阳同步轨道 一般和地球自转方向垂直 地方时相同，光照程度相同三、主要遥感卫星简介1. 陆地卫星1-1. Landsat 卫星系列 中等高度卫星 卫星高度太小，大气摩擦力会降低卫星的寿命； 卫星高度太高，分辨率会下降； 偏心率不大：接近圆形 近极地轨道1-2. SPOT 卫星系列1-3. 中巴地球资源卫星1-4. 环境与灾害监测预报小卫星1-5. 高分辨率陆地卫星 IKONOS 卫星 QuickBird 卫星 OrbView 卫星2. 气象卫星2-1. 极地轨道气象卫星2-2. 静止轨道气象卫星3. 海洋卫星3-1. Radarsat 系列卫星3-2. ERS 系列卫星