1. Comparative Morphological Study on Pinus yunnanensis
Based on the principles and methods of ecology, this study systematically observed and statistically analyzed the morphological characters of bark, wood, needles and cones of 10 population of Pinus yunnanensis distributed in southeastern Yunnan, central Yunnan and northwestern Yunnan. The microstructure of needles, phloem and embryos was observed. Combined with environmental conditions, the morphological structure diversity and ecological adaptability of Pinus yunnanensis population were analyzed.
The morphological characteristics of Pinus yunnanensis population are polymorphic. With the increase of latitude or altitude (transect sampling), the general trend of morphological variation from southeast Yunnan to central Yunnan to northwest Yunnan is: the length of needles gradually decreases, the proportion of buds, 1 bundle of 3 needles, the number of needles on short branches, cones and scales, the width of growth ring and the broken area of needles (except altitude) are ". The length of leaf sheath, umbilical length, growth ring width of wood, the number of resin channels and the compactness of bud scale arrangement increase with the elevation.
Through a lot of observation, it is found that the tree with 3 needles 1 bundle is longer than the tree with 2 needles 1 bundle. The length of 2 needles 1 bundle is longer than that of 3 needles 1 bundle. The elongation growth of needles usually shows the principle of "dominant needle bundle dominant growth"
The internal structure of the needle shows that its basic structural characteristics are relatively stable, but the quantitative characteristic values of the constituent molecules change greatly, that is, with the change of ecological environment, the structure of the needle also shows certain diversity, and its cross-sectional shapes are mainly semicircular, fan-shaped, spindle-shaped and trapezoidal. The cross-sectional shapes of 4 needles in 1 bundle and 5 needles in 1 bundle show diversity and irregularity, and the proportion of single vascular bundle and transition between single and double vascular bundles increases.
In southeast Yunnan, there is a Kjeldahl zone in the endodermis of needles of Pinus yunnanensis, and the outer tangential wall and radial wall are thickened, which is more obvious in the endodermis of needles of Pinus yunnanensis and Pinus Simao, which grow in this area under humid and hot conditions. However, there is no Kjeldahl zone in the endodermis of Pinus yunnanensis leaves in central and northwest Yunnan. At the same time, large resin channels appeared in the transfer tissues of needles of Pinus yunnanensis in southeastern Yunnan and Pinus yunnanensis in central Yunnan, especially the tender needles of Pinus yunnanensis.
The vascular bundles of Yunnan pine needle leaves are mainly double vascular bundles, but there are also transitional types between single vascular bundles and single and double vascular bundles. The subcutaneous layer is a typical type II subcutaneous layer. The cuticle of epidermis is obvious; Resin channels are mostly typical exogenous types.
The number of xylem and phloem and the size of their constituent molecules in the vascular bundle of Yunnan pine needles in central Yunnan are less than those in southeastern Yunnan, and they are relatively small. However, the number of xylem and phloem in the vascular bundle of needle leaves of Pinus yunnanensis in central Yunnan is obviously higher than that of Pinus yunnanensis in central Yunnan, but the cell volume is relatively small. The increase of xylem cells in needles is an adaptation to dry environment.
The continuous cross section of the short branch at the base of the needle shows that the structure of the needle and the base is a continuous transitional structure. At first, all the vascular bundles in the needles are transformed into a single vascular bundle, and then the base of the needles gradually heals, and the thin-walled tissue similar to pulp gradually appears in the center, and the vascular bundles of different needles gradually heal, finally forming a complete typical structure with branches. There is still apical parenchyma at the tip of short branches, but it will not continue to differentiate due to the limitation of needle development.
The development of short branches comes from the lateral buds between bud scales on long branches. In the initial stage of development, lateral buds elongate and grow. In the process of elongation and growth, two "asymmetric" needle-like primordia, one large and one small, were first differentiated, and the big leaf primordia were further differentiated to form three needle-like primordia. In the process of asymmetric differentiation of needle primordium, it develops into a tender needle. According to the asymmetric development and differentiation of the needle primordium, if the temperature and humidity conditions are good, or if it is subjected to mechanical trauma, the asymmetric two or three needle primordium can be further differentiated into four or five needle primordium, forming four or five needles 1 bundle.
The anatomical structure of young seeds shows that the embryo of Pinus yunnanensis is straight and slender, and the embryo, hypocotyl, radicle and root cap are basically in a straight line. The embryo of curved Yunnan pine is shorter and slightly curved than that of straight-dried Yunnan pine. The embryo of Pinus elliottii is shorter and curved than that of Pinus yunnanensis. This shows that the embryo has shown some morphological characteristics of the mother.
The difference of bark type and phloem color of Pinus yunnanensis is caused by the difference of phloem tissue structure and cell content. The phloem tissue arrangement of rough type is inclined, irregular or oblique tangent; The phloem is thin and the tissue structure is arranged neatly. There are many inclusions in red phloem, tissues and cells; White phloem with few inclusions. The size and arrangement of phloem cells are closely related to the growth environment. Usually, hydrothermal conditions are good. Under the leeward condition, the phloem of Pinus yunnanensis is usually fine-skinned, while the phloem of Pinus yunnanensis growing on the windward side is mostly coarse-skinned. The color of phloem is related to the content and composition of cells, especially the content of tannin and resin in phloem parenchyma cells and their oxidation in air.
The diversity of morphological structure and its eco-geographical variation pattern of Pinus yunnanensis adapt to the climate characteristics of population distribution area. The morphological and structural characteristics of Pinus yunnanensis show a "divergence" trend in the distribution areas of southeast Yunnan, central Yunnan and northwest Yunnan, and a "convergence" trend in their respective distribution areas. The general trend shows that the morphological and structural characteristics of Pinus yunnanensis in southeast and northwest Yunnan are relatively stable, and the differentiation in central Yunnan is the strongest, which may be related to frequent interference and fire in central Yunnan.
The diversity of morphological structure of Pinus yunnanensis is an inevitable trend in the evolution process, and the complexity of ecological environment and the diversity of ecological factors are indispensable and important conditions in the process of population differentiation of Pinus yunnanensis. The evolution of Pinus yunnanensis is the result of the interaction between its genetic variation and ecological environment. At the same time, the diversity of morphological structure is the basis of ecological adaptation and evolution, and long-term evolution and adaptation have shaped the relative stability of morphological structure.
2. Comparative study on red wood type and variant white wood type of Larix gmelinii.
Larix gmelinii )Rupr。 Larix gmelinii, Larix gmelinii, Larix gmelinii, Larix gmelinii. )rupr。 Larix gmelinii, Larix gmelinii, Larix gmelinii. )rupr。 It is the main tree species in Daxinganling forest region of China, and it is also a fast-growing afforestation and regeneration tree species in Northeast China. Because of its large ecological range, there are many variation types in different habitats, the most obvious of which are mahogany type and white wood type. The former is a common type with brown to yellowish brown wood color, while the latter is a rare type with light yellow wood color. Through the investigation on the distribution of two types of Larix gmelinii in natural forests, the results show that Larix gmelinii is mainly grown in grass larch forests, accounting for 10% of natural forests. In the past, Chinese and foreign scholars have done a lot of research on Larix gmelinii, but most of them focused on taxonomy, and there was no report on red wood type and white wood type. In this paper, the natural growth of Larix gmelinii with two wood colors in Daxinganling forest region was studied deeply and systematically. Through the combination of field investigation and modern experimental means, biological research and wood research, science and technology and production practice, the differences between the two types of Larix gmelinii in morphology, wood physical mechanics, wood anatomy, ecology and biological characteristics are scientifically and systematically revealed, thus confirming that Larix gmelinii is a fast-growing and high-quality type. In this paper, the mechanism of intraspecific variation and evolution of Larix gmelinii was studied by means of molecular biology, and it was considered that the population had high genetic diversity. ...