Direct Seeding Afforestation Techniques for Castanopsis fissa

    Castanopsis fissa is one of the fine broadleaf trees in Guangdong. It is an evergreen tree with a straight trunk, dense branches and leaves, and a well-developed root system. It has strong sprouting ability, tolerates cold, dryness and poor soil, and has wide adaptability. Its fallen leaves decompose easily and can reduce runoff. It is suited to lateritic red soils developed from granite and sandstone-shale. It is not only an important tree species for building water-conservation forests and soil-and-water protection forests, but also an excellent native tree species for managing small-diameter timber, industrial raw material forests and ecological public welfare forests.

    I. Selection of Afforestation Site 

    1. Sparse residual forest land. Because some sparse residual forest is scattered across such land, the surrounding vegetation is intact and rich, the forest land has a certain degree of canopy closure, and the intensity of direct sunlight is relatively weak, the Castanopsis fissa seedlings on the forest land can rely on natural conditions for shade and seedling protection. They can survive the summer safely and grow normally, making this the preferred forest land for direct seeding. 

    2. Cutover land. Cutover land generally has only the trees removed, without extensive damage to the forest land vegetation, so the intensity of direct sunlight on the forest land is relatively low. When direct seeding afforestation is carried out on cutover land, shading and seedling protection by cuttings must be adopted, and Castanopsis fissa seedlings can also grow normally and survive the summer safely. 

    3. Burned land. Because not a blade of grass remains on burned land, and Castanopsis fissa seedlings are very delicate, they will suffer sunscald under improper management. Therefore, direct seeding to create pure stands is generally not suitable on burned land, and other afforestation methods should be used instead. A mixed stand approach can be adopted, with Castanopsis fissa mixed with other tree species; on burned land, Castanopsis fissa grows better than on other forest lands. 

    II. Afforestation Methods 

    1. Pure stand afforestation. Because Castanopsis fissa has few pests and diseases, with the main serious damage caused by longhorn beetles, for smaller forest land areas a pure stand afforestation method can be adopted, and major pest and disease damage will not occur. 

    2. Mixed stand afforestation. For larger forest land areas, according to the growth and distribution of Castanopsis fissa in various places, Castanopsis fissa can be mixed with coniferous forests (such as Masson pine or loblolly pine), and both tree species can grow normally. When establishing mixed stands, for ease of management, block mixing or strip mixing can be used, and row mixing or plant-by-plant mixing can also be used. 

    III. Afforestation Site Preparation 

    1. Preparation of sparse residual forest land. Because after direct seeding of Castanopsis fissa, the sparse residual forest needs to provide a certain shading effect, hole cultivation site preparation is generally used on sparse residual forest land, with a spacing of 2×2 m, and hole dimensions of 30×30×20 cm. After the seedlings grow taller, strip clearing or no strip clearing may be carried out. 

    2. Preparation of cutover land. After hole cultivation site preparation, strip clearing may be carried out, or the strips may be cut directly and holes dug for site preparation, with a spacing of 2×2 m, and the vegetation between strips retained as much as possible. 

    3. Preparation of burned land. On burned land, strip cultivation site preparation is generally used (for direct seeding afforestation of Castanopsis fissa, slash-and-burn site preparation is generally not used; if it is carried out here, a mixed stand must be established). The strip spacing is mostly 2 m or 2.5 m, and the plant spacing depends on the mixed tree species: 2 m for Castanopsis fissa, and 2.5-3 m for Pinus species.

    IV. Direct Seeding Afforestation

    1. Seed treatment. Castanopsis fissa seeds are extremely susceptible to damage by weevils and rats, and control must be emphasized. 

    (1) Weevil control. Weevils lay eggs in Castanopsis fissa seeds, which then hatch into larvae that feed on the seeds; in severe cases they can hollow out the seeds and affect seed germination. Therefore, before direct seeding, spraying or seed soaking should be adopted to kill weevil larvae. A 1000-fold dilution of trichlorfon can be sprayed on the seeds, which are then piled together to kill the weevils, or the seeds can be packed in gunny bags and soaked in clean water for 3 days before direct seeding. 

    (2) Rat damage control. Based on the habit of rats coming down the mountain to drink water every day, rat poison is placed around the holes from the mountainside to the foot of the mountain during afforestation, once before direct seeding, and then 1-3 more times after direct seeding depending on the situation. 

    2. Afforestation. In direct seeding afforestation of Castanopsis fissa, generally 3-5 seeds are placed per hole. They should be sown at the slope-facing wall of the hole, occupying two-thirds of the hole near the slope, sown in rows, and then covered with about 3-5 cm of soil. 

    V. Tending and Management 

    1. Fertilization. The new leaves from germinated Castanopsis fissa seeds are red. When the first leaf turns from red to blue-green, the first fertilization can be carried out. Dig a circular shallow trench about 10 cm from the seedlings and apply a small amount of urea. Subsequent fertilization should be applied outside the outer edge of the crown. Apply less at a time but frequently, so as to avoid fertilizer damage to the seedlings.