林地调查说明 Review of Forest Survey
During October and November in 2022, MTP team had planed to conduct forest survey in the forest which we planted from 2007 to 2022. But due to the heavy snow and the large-scale lockdowns in Inner Mongolia, our team had only completed the forest survey in a few forests that were planted from 2010 to 2021. There left only 7 days for the team to conduct the survey. The survey covered 15 forest plots, 106 sample sites and 3241 sample trees. The survey ratio was 0.12% among total number of the trees planted by MTP. The team restarted the forest survey in March, 2023, before the growing season. The forest sites planted in 2013, 2014 and 2017 weren't surveyed due to the flooded roads and standstorm strikes. The spring survey covered 6 forest plots, 67 sample sites and 2250 sample trees. The total sample size of 2022 forest survey was 5491 trees, 0.2% among all the trees.
Fig. 1 The numer and ratio of the trees sampled during the forest sruvey each year
MTP team mearsuring trees during the survey
林地概况 Forest Basic Information
To date, MTP has successfully planted 2,727,979 trees on 40 forest plots, covering an area of 37,519.15 Mu (23.45 km2) in Inner Mongolia. In 2022, a new plot of 961 Mu was planted, marked as plot 2022-1. More details are given in the graph below. (1 Hectare=15 Mu)
Fig. 2 Planting Areas of Each Year
栽植树种 Type of Trees
2022年度，在鄂尔多斯市杭锦旗栽植了花棒、沙枣10万余株，但由于疫情没能开展秋季存活情况调查，暂不纳入计算。 截止2022年，栽植树种8种，分别为：杂交杨树（通林5，哲林4，白城杨，小黑杨等）1年和2年生裸根苗；文冠果播种苗；五角枫播种苗；樟子松3年生容器苗；榆树2年生苗；柠条（1年生容器苗），柳树2年生苗，黄菠萝2年生苗以及云杉3年生苗。 其中，杨树和樟子松依旧为主要造林树种，分别达总造林数量的54%和37%，其他树种占比不足10%。
In 2022, we've planted more than 100,000 Hedysarum scoparium and Elaeagnus angustifolia in Hangjin Qi, Ordos, Inner Mongolia. But we weren't able to conduct the forest survey in the autumn, so the number of surviving saplings wasn't counted yet and the data thus was not included in the followings. To date, we’ve planted 8 types of tree species in MTP forests, including 1-year-old and 2-year-old hybrid poplar bare-root seedlings, yellow horn seedlings, maple (Acer Mono) seedlings, 3-year-old container pine tree seedlings, 2-year-old elm seedlings, 1-year-old Caragana Microphylla container seedlings, 2-year-old willow seedlings, 2-year-old Phellodendron amurense seedlings, and 3-year-old spruce seedlings. Poplars and pines made up for the majority of the trees planted, the percentages being 54% and 37% respectively, and other tree species combined less than 10%.
图 3. 树种数量对比
Fig.3 Types of trees
林地保存率 Forest Survival Rate
MTP team conducted surveys in the autumn of 2022 and in the following spring of 2023 on 21 forest plots, which were planted from 2010 to 2021. The surveys last 11 days, covering 173 sample sites and 5491 tree samples. The survey measurements included the survival rate, height, basal diameter, diameter at breast height, crown width and spacing in the rows. Based on our survey results, the overall survival rate of the sampled MTP forests in 2022 was 73.83%.
图 4. 历年保存率变化
Fig.4 Survival rates over the years
In 2022, rainfall was very frequent in the summer in Tongliao. The rainy weather was beneficial for the trees to grow, so most of the forests were preserved better than before. Some forests was flooded and a large part of the ground was soaked. This cased the death of some trees. Generally speaking, the rainy weather made sure that the forests mostly grow well. The measured trees in these forests maintained a survival rate of around 70%.
Among the sampled forest, the trees in the 2012-7 forest plot grew unevenly because of the consistent grazing. For the poplars and pines in the 2012-4 forest plot, the pines were preserved rather poorly than poplars, which was caused by the frequent inter-planting between pine tree lines. This affected the average survival rate. The survial rate of 2019 forest didn't increase much, due to the complicated terrain.
图 5. 主要树种的保存率对比
Fig.5 Survival rates of the three main type of trees
图 6. 2022年度各林地保存率
Fig.6 Survival rates of the forest plots in 2022
As shown in the figure above, the survival rate of most plots is higher than 60%, basically reaching our expectation.
风速测量 Wind Velocity Measurement
Korqin Sandy land lies in very windy areas. The wind carries the particles on the ground, turning into wind-blown sand. Wind erosion leads to desertification. The vegetation coverage on the ground can help to decrease the wind speed, absorb the wind power and stop some wind-blown particles. Regulating the wind is an important ecological function of afforestation. To evaluate the ecological functions of the MTP forests, our teams started measuring wind velocity in 7 different kinds of grounds (depending on the vegetation coverage) by measuring the wind speed in different heights on the same sample spots. The measurements will be used for further analysis.
图 7. 生长期平均风速对比
Fig.7 Wind speed of different vegetaion coverages in the growing seasn
The results showed that trees and shrubs both helped decreasing the wind speed, which is regarded as the ecological function of regulating the wind, easing the wind erosion, especially at the height of wind-blown sand level (0-0.3m). Our team will continue to include this in the forest survey, to improve the methods and collect more data for further analysis.
Measuring wind speed in the plots
The 2022 survey had similar results as 2021. Most of the forests are stable. The rainfall provided great conditions for the trees to grow in the past year, but a few forests were affected by the flood. The forests were generally growing healthy.