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"The cultivation technology of fast-growing and high-yield forest of North China larch"
IV. Analysis of Management Effects of Mother Trees
The seeds collected from mother trees showed superior quality compared to those from ordinary stands, resulting in better seedling quality and afforestation outcomes.
(a) Seed Quality
In 1979, which was the peak year for *Larix principis-rupprechtii* seed production in Northern Hebei Province, the germination potential and rate of mother tree seeds were significantly higher than those of timber forest and commercially acquired seeds. Specifically, the germination potential of mother tree seeds was 34.1% and 36% higher than that of timber forest and commercial seeds, respectively, while the germination rate was 19.8% and 25.3% higher. According to a sampling comparison conducted across five forest farms in the Mengzi Forestry Bureau of Hebei Province, the germination potential of mother tree seeds ranged from 27% to 40% higher, and the germination rate ranged from 18% to 36% higher than that of general commodity seeds.
Table 2-4: Comparison of Seed Quality of *Larix principis-rupprechtii*
| Seed Category | Germination (%) | Germination Rate (%) | Goodness | Note |
|-----------------------|------------------|------------------------|----------|--------------------------|
| Mother Tree Seeds | 73.7 | 43.6 | 77.7 | Produced in Longtoushan Forest Farm |
| Natural Forest Seeds | 77.7 | 55.7 | 96.0 | |
| Timber Seed | 34.3 | 45.7 | 38.7 | Average of several sources |
| Commodity Seeds | 33.6 | 47.7 | 36.7 | Average of several sources |
(b) Seedling Quality
Seedlings grown from mother tree seeds exhibited a 10% increase in base diameter and a 32% increase in height compared to those from ordinary seeds.
Table 2-5: Comparison of Seedling Quality
| Seedling Type | Base Diameter (m) | Ratio (%) | Seedling Height (m) | Ratio (%) |
|----------------------|-------------------|-----------|---------------------|-----------|
| Mother Tree Offspring | 0.49 | 110 | 32.5 | 132 |
| Timber Seed | 0.44 | 100 | 24.6 | 100 |
(c) Afforestation Effect
During the late 1970s and early 1980s, multi-year and multi-site comparisons of seedlings established in the original Longtoushan and Yinhe Forest Farms showed that planting mother tree seedlings resulted in genetic gains exceeding 10%. Over the period from 1980 to 2001, the 5,000 mu of improved *Larix principis-rupprechtii* mother trees at the Longtoushan seedling base produced 29,565 k of seeds, afforesting an area of 65,000 hectares and generating a profit of 250 million yuan.
The Establishment and Management of the Second Seed Park
I. The Significance of Establishing a Seed Park
A seed orchard is typically created using selected superior trees and a well-planned layout to produce high-quality seeds. The purpose of managing a seed orchard is to continuously improve the genetic quality of seeds, ensure stable high-yield seed production, and reduce the randomness in forest seed production. In the 21st century, the shift from traditional forestry to modern and ecological forestry is essential. Accelerating the development of high-yield and high-quality forests is crucial for increasing per-unit productivity, shortening resource cycles, improving wood quality, and reducing costs. It also plays a key role in China’s long-term timber production strategy. Forest seeds are the foundation for establishing high-yield and fast-growing forests, and seed orchards are the primary method for providing superior seeds through sexual reproduction. Seeds from orchards have greater genetic gains than those from mother trees or regular seed production areas. With proper multi-generation selection, the genetic quality of seed orchards will continue to improve over time.
*Larix principis-rupprechtii* is primarily propagated sexually. It is a fast-growing species with wide adaptability and strong cold resistance, commonly used in fast-growing and high-yield forest projects. Beyond normal afforestation in mountainous regions like Hebei and Shanxi Provinces, *Larix principis-rupprechtii* has thrived in the entire “Three North†region after years of regional testing, even outperforming local species in some areas such as Fukang in Xinjiang.
Table 2-6: Comparison of Growth of *Larix principis-rupprechtii* in Different Areas
| Introduction Area | Latitude | Altitude (m) | Average Temperature (°C) | Species | Forest Age | Breast Diameter (cm) | Tree Height (m) | Source |
|--------------------------------|----------|--------------|---------------------------|---------|------------|----------------------|------------------|--------|
| Xinjiang Fukang Tianchi Forest Area | 43°51′ | 1600 | ~2–2.8°C | *Larix* | 12 | 4.3 | 5.2 | Xinjiang Institute |
| Xingan Larch | – | – | – | – | – | 1.2 | 2.5 | – |
| *Larix principis-rupprechtii* | – | – | – | – | – | 4.4 | 5.0 | – |
| *Larix olgensis* | – | – | – | – | – | 5.1 | 6.1 | – |
Establishing a *Larix principis-rupprechtii* seed orchard provides high-quality seeds for afforestation, playing a significant role in advancing environmental construction in northern China and stimulating regional economic growth.
II. Conditions and Zoning of the Seed Garden
(A) Site Selection for the Seed Park
A seed orchard is a permanent breeding base that requires intensive management. Therefore, site conditions affect not only seed yield and quality but also operational costs due to poor accessibility. To cultivate high-quality seeds, seed orchards should be located in areas with favorable natural conditions and easy access. They must also provide suitable environmental conditions for the normal growth and flowering of the tree species, ensuring that the seeds produced are adapted for afforestation. The selection of a *Larix principis-rupprechtii* seed orchard considers the following factors:
1. Temperature and altitude: Annual average temperature above 1°C, growing season of at least 100 days, accumulated temperature above 10°C of 2500°C, and altitude around 1000–1200 m.
2. Topography and soil: Open terrain, sunny, with water sources and irrigation; deep, fertile soil with good aeration and drainage. Slightly acidic soil is ideal. If in mountainous areas, slope should be less than 20°, with terraces built.
3. Pollen isolation: No common stands or similar species within 200 meters. Natural isolation or evergreen conifers can serve as barriers, 10–20 meters wide.
4. Convenient transportation and management.
(B) Zoning of the Seed Garden
The establishment of a seed orchard should consider both seed yield and quality, as well as future application, promotion scope, and expected benefits. Based on these objectives, the Longtoushan Seedling Base was divided into functional areas:
1. Resource Collection Area: This area collects and preserves excellent germplasm resources, preventing loss and ensuring availability for future use. Currently, nearly 600 excellent resources have been collected, including *Larix principis-rupprechtii*, *Larix olgensis*, and hybrids. These resources support broader breeding channels and higher generations of seed orchards.
2. Graft Preparation Area: This area provides clonal plants or cuttings for orchard establishment. It allows for the replacement of dead or vacant grafted mother trees and ensures a continuous supply of high-quality material.
3. Genetic Determination Forest Area: This is a critical part of seed orchard construction, where progeny and clone tests are conducted to identify genetic advantages. By 2002, nearly 1050 acres of various test forests had been established, contributing to the development of elite seed bases.
4. Scion Area: A scion nursery is essential for producing large quantities of high-quality cuttings. It supports the propagation of improved varieties and ensures genetic quality. Scion nurseries offer advantages such as efficient management, high-quality cuttings, and disease control.
Due to the limited number of superior trees, the process often starts with establishing a scion nursery before creating a clone seed orchard. Sometimes, the resource collection garden also serves as a seedling source.