Detailed Explanation of Key Techniques for Transplanting Large Spruce Saplings
Seedling transplanting is one of the main greening methods for urban streets, landscaping, and the construction of ecologically prosperous villages and towns. In recent years, the transplanting of large saplings has become particularly important because it takes effect quickly, achieves remarkable results, and is not easily damaged by human activity, and it has gained widespread recognition. However, large sapling transplanting is also constrained by factors such as high cost, large investment, and low survival rates. Therefore, mastering transplanting techniques according to the biological characteristics of different tree species, improving survival rates, and increasing green areas play a positive role in promoting ecological civilization construction. Qinghai spruce (Picea crassifolia) is a tree species unique to the Qilian Mountains. Because it stays green year-round and its root system is shallowly distributed in the soil, making it easy to dig and plant, it is highly popular. In recent years, Haxi Forest Farm in Tianzhu County, Gansu Province, has carried out a large number of Qinghai spruce large sapling transplants in the low-altitude plains of Wuwei City, the industrial park of Wuhai City in the Inner Mongolia Autonomous Region, and Yinchuan City in the Ningxia Hui Autonomous Region. Based on its biological characteristics combined with the features of different regions, the main technical measures for improving the survival rate of large spruce sapling transplants have been summarized.
I. Transplanting and planting large saplings is the key
1. Dig the transplanting holes well and irrigate with sufficient bottom water. The size of the transplanting holes should be determined according to the size of the Qinghai spruce saplings. Generally, for saplings over 6 m tall, the hole depth should be greater than 1.5 m and the diameter no less than 1.8 m; for saplings 5-6 m tall, the hole depth should be greater than 1.3 m and the diameter no less than 1.5 m; for saplings 4-5 m tall, the hole depth should be greater than 1.1 m and the diameter no less than 1.3 m; for saplings 3-4 m tall, the hole depth should be greater than 1.0 m and the diameter no less than 1.1 m; for saplings 2-3 m tall, the hole depth should be greater than 1.0 m and the diameter no less than 1.0 m; for saplings 1-2 m tall, the hole depth should be greater than 0.6 m and the diameter no less than 0.8 m. After the transplanting holes are dug, irrigate once with bottom water before transplanting the saplings, with the water volume equal to half the hole depth.
2. Prepare the planting soil well. Remove all stones, grass roots, construction waste, discarded plastic bags, and other debris from the planting soil. If conditions permit, some farmyard manure can also be mixed in to facilitate rooting and nutrient absorption after planting.
3. Plant the saplings firmly and straighten them, and irrigate with sufficient settling water. When planting large saplings, first fill the hole with 30 cm of planting soil, then position the sapling once according to the crown shape, minimizing the number of times the sapling is moved within the hole, especially for large saplings over 4 m, so as to avoid damaging the root system due to the weight of the soil ball and crown. After the sapling is positioned, fill in 1/3 of the transplanting soil, tamp it firmly with a wooden stick between the hole and the soil ball, then fill the hole completely and tread it firm with the foot. Build a water-holding basin and irrigate slowly with a small flow, irrigating with sufficient settling water, then irrigate again with root-establishing water after one week. This second irrigation has a relatively large impact on the survival rate and is quite critical.
4. Set up protective frames and secure the saplings. Because spring winds are strong and the soil is relatively soft after watering the trees, the holding capacity is low, and the trees are easily blown askew or down, or sway with the wind, causing damage to root growth and affecting survival.
II. Dig large soil balls and wrap the root system to prevent root dehydration
1. Dig soil balls of the specified size and reduce the wounded surface area of the root system. When digging saplings, the size of the soil ball is generally determined according to the size of the sapling. For saplings over 6 m tall, the diameter of the dug soil ball should be 1.5-1.6 m and the thickness 1-1.2 m; for saplings 5-6 m tall, the diameter of the dug soil ball should be 1.2-1.3 m and the thickness 0.8-1.0 m; for saplings 4-5 m tall, the diameter of the dug soil ball should be 1.0-1.2 m and the thickness 0.6-0.8 m; for saplings 3-4 m tall, the diameter of the dug soil ball should be 0.8-1.0 m and the thickness 0.5-0.6 m; for saplings 2-3 m tall, the diameter of the dug soil ball should be 0.6-0.8 m and the thickness no less than 0.5 m; for saplings 1-2 m tall, the diameter of the soil ball should be no less than 0.6 m and the thickness no less than 0.4 m. When lifting the saplings, cut off excessively long roots with a sharp axe to prevent the roots from splitting, enlarging the wounded surface area, making healing difficult, and affecting survival.
2. Wrap the soil ball and tie up the crown. Wrap the dug sapling's soil ball densely and tightly with straw rope to prevent it from loosening during transport and loading and unloading, which would expose the roots and cause dehydration. To protect the crown shape, use straw rope to tie the sapling crown upward along the trunk to facilitate loading, unloading, transport, and planting. After planting, cut the straw rope and release the tree shape.
III. Closely link the planting steps
After the saplings are dug, they should be loaded and transported immediately, with the tarpaulin well covered to prevent dehydration from wind, without stopping midway, and planted immediately upon arrival at the destination. Transport from Tianzhu, Gansu, to Wuhai City in the Inner Mongolia Autonomous Region for transplanting shows that for Qinghai spruce, for every 24 hours extended in the digging and planting steps, the transplant survival rate decreases by 15%-20%. The longer the daytime transport time, the lower the survival rate.
In short, the survival rate of large Qinghai spruce sapling transplants is affected by many factors such as digging, packaging, transport, planting, moisture, soil, and management. In practice, we need to gradually master the key factors affecting transplant survival under different regions and different environmental conditions, and improve the survival rate. This meets the growing needs of ecological villages and towns and urban landscaping, and plays a positive role in increasing green areas and promoting ecological civilization construction.