No abstract

Forest–agriculture complex management is an efficient planting mode that can effectively improve soil utilization and bring greater economic value. However, this planting model has not yet been systematically carried out in the northeast of China. Thus, to provide a theoretical basis for agriculture and forestry intercropping in northeast China, the variation in the growth and wood characteristics of Populus cathayana × canadansis ‘xin lin 1’ and the economic benefits of intercropping crops under different intercropping patterns were analyzed. The results of a variance analysis show that there were significant differences in tree growth and wood characteristics among the different intercropping modes (p < 0.01). The variation coefficients of growth and wood characteristics ranged from 28.23% to 55.79% and 2.03% to 10.65%, respectively. There were significant correlations among tree height, diameter at breast height, ground diameter and wood volume of ‘P. ‘xin lin 1’, as well as between cellulose, hemicellulose, lignin, fiber length and fiber aspect ratio (r < 0.05). Meanwhile, we comprehensively evaluated intercropping modes based on growth traits such as tree height, chest diameter, diameter, wood volume and crown width. The ‘P. ‘xin lin 1’ + soybean’ mode proved to be the best intercropping mode, in which the gain of tree height, chest diameter, diameter, wood volume and crown width were 26.80%, 20.09%, 15.76%, 63.41% and 8.33%, respectively. When considering wood traits, the optimal intercropping pattern was ‘P. ‘xin lin 1’ + Cilantro + Cabbage’, but the gain of each wood trait in this pattern was not obvious compared with the total average. Among the six intercropping modes, ‘P. ‘xin lin 1’ + Watermelon + Chinese cabbage’ and ‘P. ‘xin lin 1’ + Cilantro + Chinese cabbage’ have the highest economic benefits, reaching 48,138 CNY/hm2 and 39,990 CNY/hm2, respectively. From our results, the poplar growth and wood characteristics under different intercropping modes are better than those of the pure forest, except for ‘P. ‘xin lin 1’ + Corn’, and each intercropping mode has higher economic benefits. These findings provide a scientific basis for alleviating the competition between local forestry and agriculture for land and address the selection of forestry and agricultural intercropping modes.

Birch (Betula platyphylla Suk.), distributed in Eurasia, North America, and Australia, is a kind of cold-resistant, fast-growing, and vital pulpwood tree species. It is also one of the most important ecological restoration tree species with high values of economic benefits in Northeast China. To improve the genetic gain and expand the economic benefit of B. platyphylla, many genetic improvements have been carried out. In China, B. platyphylla is widely distributed and varied, and there are many varieties with excellent genetic characteristics. In this paper, the genetic improvement of B. platyphylla was reviewed, and the previous research results were discussed from two aspects: conventional breeding and molecular breeding. Some problems and corresponding solutions in the genetic improvement were put forward to provide ideas for B. platyphylla breeding in the future.

This study aimed to explore and improve the different economic values of Pinus koraiensis (Siebold and Zucc.) by examining the variations in 6 growth traits and 9 physicochemical wood properties among 53 P. koraiensis half-sib families. Growth traits assessed included height, diameter at breast height, volume, degree of stem straightness, stem form, and branch number per node, while wood properties assessed included density, fiber length and width, fiber length to width ratio, and cellulose, hemicellulose, holocellulose, lignin, and ash contents. Except for degree of stem straightness and branch number per node, all other traits exhibited highly significant variations (P < 0.01) among families. The coefficients of variation ranged from 5.3 (stem form) to 66.7% (ash content), whereas, the heritability ranged from 0.136 (degree of stem straightness) to 0.962 (ash content). Significant correlations were observed among growth traits and wood physicochemical properties. Principal component analysis identified four distinct groups representing growth traits, wood chemical and physical properties, and stem form traits. Multi-trait comprehensive evaluation identified three groups of elite families based on breeding objectives, including rapid growth, improved timber production for building and furniture materials, and pulpwood production. These specific families should be used to establish new plantations.