Betula alnoides Admixed with Castanopsis hystrix or Cunninghamia lanceolata from Two Reforestation Case Studies in Southeast China

Betula alnoides Buch.-Ham. ex D. Don belongs to genus Betula of family Betulaceae. In China the natural distribution of B. alnoides is concentrated in Yunnan, Guangxi and Guizhou provinces and it is a fast-growing tree species for timber production in tropical and subtropical regions. The mechanical properties of B. alnoides are strong and its wood property is well that no easy deformation with decorative pattern and beautiful color. It is widely used for indoor decoration, wooden floor and furniture, etc. B. alnoides is an optional tree species to develop for producing middle and high-grade wood in southern China for the market demand (Pang, 2011; Li, 2012).
       
Castanopsis hystrix Miq., belonging to genus Castanopsis of family Fagaceae, up to 25 m height and 1.5 m diameter at breast height, has hard wood. Due to less deformation with beautiful maroon heartwood color and texture, it can be made for high-grade furniture, shipbuilding, vehicles, craft carving, architectural decoration and other high-quality materials. There is natural distribution in Fujian province.
       
Cunninghamia lanceolata (Lamb.) Hook., belonging to genus Cunninghamia, family Taxodiaceae, is one of the popular tree species cultivated in southern China. The wood is yellow-white or reddish-brown, with a straight texture and easy to process widely used in house, bridge, ship and furniture making.
       
The growth and morphological characteristics of 20 B. alnoides clones at the age of 5 years old in Huizhou city, Guangdong province were determined and analyzed (Wang et al., 2017). The results showed there were significant differences among the clones except for tree height and branchiness.
 
B. alnoides provenances were introduced Fujian province in 2002. The trunk pests attacked B. alnoides. Zhao et al., (2011) found that B. alnoides was damaged by Anoplophora chinensis Forster in northern Guangdong; Liu et al., (2012a, 2012b), Huang (2012), Chen et al., (2016) and Pang et al., (2016) found B. alnoides was damaged by Arbela spp. in Guangxi. Chen (2013) found that the pest Phalera flavescens eating the leaves of B. alnoides in Guangxi. No literature showed superior provenance or clone of B. alnoides was selected for the development of southern Fujian, as well as no suitable reforestation mixed pattern for B. alnoides developed for preventing the trunk pests effectively. It is significant to select an optimal reforestation pattern for B. alnoides to be expanded in southern Fujian, therefore we introduced four tissue-cultured clones of B. alnoides from Guangxi and conducted its mixed forest tests in Fujian Hua’an Jinshan National Forest Farm (FHJNFF) and Fujian Longhai Jiulongling National Forest Farm (FLJNFF), mixed with C. hystrix and C. lanceolata, respectively.

Overview of the test site
 
The first site is located at Wanshiqing area, FHJNFF, 117°38'E and 24°44'N, with a typical south subtropical climate. The average annual temperature is about 18.0-19.0°C, the annual frost-free period is about 320 days and the average annual precipitation is about 1610.9 mm. The previous crops at this site were Eucalyptus urophylla × Eucalyptus grandis and miscellaneous woody plants, with an altitude of 500-600 m and 28 degree slope. The test site was on the lower and mid position of whole slope, westward, covered by red soil with soil layer of 80-100 cm thickness and humus layer of 5-10 cm thickness. The site quality wasa!-III grade (Fan et al., 2012).
       
The second site is located at Beijing area, FLJNFF, 117°43¢E and 24°21¢N. The average annual temperature is 20.5-21.0°C. The annual frost-free period is about 330 days and the average annual precipitation is about 1563 mm. The previous crops at this site were Pinus massoniana and miscellaneous woody plants, with an altitude of 200-300 m and 20 degree slope, covered by red soil. The overall slope orientation was southwestward and the test site was on the lower and mid position of whole slope. The site quality was II grade (Fan et al., 2012).
 
Material source and test design
 
The tissue-cultured seedlings of B. alnoides clones used in the experiments were used for reforestation in April 2017.
 
The experiment treatments setting at Wanshiqing area in April 2017
 
In the mixed forests of B. alnoides and C. hystrix at Wanshiqing area, five experiment treatments were set: T1, pure forest of B. alnoides (control); T2, B. alnoides and C. hystrix (admixed with 1:1 parallel row); T3, B. alnoides and C. hystrix (admixed with 2:2 parallel rows); T4, B. alnoides and C. hystrix (admixed with 2:4 parallel raws); T5, C. hystrix pure forest. The random block design, 0.333 hectares per plot, 4 repeats (blocks) and C. hystrix for protection lines were set in this experiment.
       
The forestland was prepared by vegetation burning, comprehensive clearing and hole preparation in November 2016. The hole size was 50 cm × 40 cm × 30 cm and the plant spacing of B. alnoides or C. hystrix was 1.8 m × 2.3 m. The tissue-cultured container seedlings of B. alnoides were used, with a seedling height of about 35 cm and the red soil container seedling of C. hystrix were applied, with a seedling height of about 25 cm in April 2017.

Tending management
 
1×1 square meter of block weeding around the plant for the first year after reforestation in September 2017, together with fertilizing 100 g plant^-1 first time in May 2017 and 100 g plant-1 second time September 2017 and chopping shrubs and grasses twice in 2017; fertilizing 200 g plant^-1 once, chopping shrubs and grasses twice and chemical weeding once in 2018; fertilizing 200g plant^-1 once, chopping shrubs and grasses twice comprehensively in 2019. The compound fertilizer consisted of 45% (N-P₂O₅-K₂O= 5-15-15). No fertilization and weeding in 2020.
 
The experiment treatments setting at Beijing area
 
In the mixed forests of B. alnoides and C. lanceolata at Beijing area, four treatments were set in April 2017: E1, Pure forest of B. alnoides (control); E2: B. alnoides and C. lanceolata admixed with 2:6 rows; E3, 1:3 cluster mixed, 4 plants per cluster for B. alnoides; E4, Pure forest of C. lanceolata. Random block design, 4 repeats and 0.333 hectares per plot were adopted and C. lanceolata was used as the protection lines.
       
The forestland was prepared by vegetation burning, comprehensive clearing and level belts with soil deeply turned in November 2016. The plant spacing was prepared with 2.0 m × 2.0 m for B. alnoides and 1.5 m × 1.5 m for C. lanceolata in November 2016. The tissue-cultured container seedlings of B. alnoides were adopted, with a seedling height of about 35 cm and the bare root seedling of C. lanceolata were applied with a seedling height of about 30 cm in April 2017.
       
Tending management: no weeding in 2017, but fertilizing with 100 g plant-1 first time in May 2017 and 100 g plant^-1 second time in September 2017; It was no weeding but fertilizing 200 g plant^-1 once in 2018; chopping shrubs and grasses twice comprehensively in 2019 and fertilizing 250 g/plant once. The compound fertilizer consisted of 45% (N-P₂O₅-K₂O= 5-15-15). No fertilization but weeding once in 2020.
 
Survey methods
 
Field survey in April 2020. A sample plot of 20 m × 30 m was set in each plot and each tree was investigated in the sample plot, including tree height (m), DBH (cm), pests and diseases and freeze injury.
 
Data analysis
 
The EXCEL and SPSS17.0 software were used to conduct Duncan variance analysis on the average height, DBH and volume of trees in each mixed forest and Origin 8.5 was used for drawing pictures.
 
Among them:
d_1.3 = Diameter of the breast height.
h    = Tree height.
f_1.3   = Form index of breast height.
f_1.3   = 0.45 for B. alnoides (Wang et al., 2013, 2017).
       
All experimental designs above were carried out by Fujian Academy of Forestry Sciences.

Results and analysis of the mixed forest of B. alnoides and C. hystrix at Wanshiqing area
 
The ANOVA analyzed by SPSS17.0 are shown in Table 1. From four reforestation patterns, there were no or highly significant differences among the four forestation patterns in tree height, DBH or volume of B. alnoides, all of which were “A” or “a” (Table 1). There were no significant or highly significant differences in tree height, DBH and volume per plant among the four forestation modes, all of which were “A” or “a” (Table 2).
 

 

 
Results and analysis of the mixed forest of B. alnoides and C. lanceolata at Beijing area
 
The results analyzed by SPSS17.0 are shown in Table 3. From the three forestation patterns, there were no significant or highly significant differences among the three reforestation patterns in DBH or volume of B. alnoides, all of which were “A” or “a”. While there were significant differences but no highly significant differences in tree height, i.e. E1 (pure forest) (a) was superior to E3 (cluster mixed) (b), while E2 (2:6 row mixed) (ab) had no significant difference to E1 and E3 (Table 3).
 

       
There was significant or highly significant difference in the tree height, DBH and individual volume of C. lanceolata. There were significant difference but no highly significant difference in the height and individual volume of C. lanceolata under treatments and highly significant difference in the DBH of C. lanceolata under treatments. In addition, E2 (Aa) and E4 (Aa) were all superior to E3 (Ab). The DBH of the treatments was high significant difference, i.e. both E2 (Aa) and E4 (Aa) were superior to E3 (Bb) (Table 4).
 

       
The B. alnoides in FLJNFF was harmed by termites and crickets in summer in the mixed forest of B. alnoides mixed with C. hystrix in FHJNFF. In May 2018 in FHJNFF, the adults of Anoplophora chinensis (Fig 1) and Batocera lineolata (Fig 2) were found damaging the trees of B. alnoides. In September 2018 it was found that longhorn beetles damaged a few stems of B. alnoides, but did not cause serious harm. In May 2019, it was found that the defoliator larvae of Lymantria xylina (Fig 3 and 4) were harmful to both of B. alnoides and C. hystrix. The adults of longicorn beetles mainly gnawed the epidermis of top branch or shoots, while the larvae of L. xylina fed on the leaves. As early as 2018, that the larvae of L. xylina were found to harm the pure forest of C. hystrix nearby which might be the host plant for this species. After reforestation, no serious damage by the adults of longhorn beetle and the larvae of L. xylina was found without any pesticide control (Meena et al., 2018; Jyothi and Hebsur, 2017; Kavipriya et al., 2019).
 

 

 

 

       
No any serious pests were found in the mixed forest of B. alnoides and C. lanceolata for 3 years at Beijing area of FLJNFF.

The pure forest B. alnoides was superior to the cluster mixed pattern on tree height, but no significant difference between the two patterns and 1:3 rows mixed pattern in FLJNFF. There were significant or highly significant differences in tree height, DBH and individual volume of C. lanceolata among the three reforestation patterns, i.e. there were significant differences but no highly significant differences in tree height or individual volume of C. lanceolata among each treatment and they were all 1:3 row mixed pattern and pure C. lanceolata forest superior to the cluster mixed forest.

The average tree height, average DBH and average individual volume of B. alnoides in Beijing Area of FLJNFF reached 7.41 m, 9.05 cm and 0.0223 m³ respectively; the average tree height, average DBH and average individual volume in Wanshiqing Area of FHJNFF reached 6.70 m, 8.34 cm and 0.0182 m³ respectively. In conclusion, the average annual growth of height, DBH and volume of B. alnoides reached 2.2-2.5 m, 2.8-3.0 cm and 0.0061-0.0074 m³ respectively. The 3-year growth performance of mixed reforestation experiment of B. alnoides admixed with B. alnoides and C. hystrix does not represent the later stage performance, thus the investigation and analysis should be continued in the future consequence study.

The study was sponsored by the National Key Research and Development Program of China: The High-efficiency Cultivation Technique of Betula alnoides in Southern Fujian Province (2016YFD0600604-03). The study was supported by the Key Laboratory of Timber Forest Breeding and Cultivation for Mountainous Areas in Southern China, China National Forestry and Grassland Bureau and the Key Laboratory of Forest Culture and Forest Product Processing Utilization of Fujian Province.

None.