| Larch(Larix gmelinii) is a typical tree species in the Northest area. Northeast region is one of the areas receiving the greatest influence from climatic changes in our country. In general, climate and soil conditions are important ones among the environmental factors. How do the environmental factors influence the typical tree species grwowth and how does the the physiology and ecology of larch get adapted to the oil conditions? In this paper, through determining ring growth, soil respirationg, branch respirationg and C4photosynthetic enzyme, to discuss how tree growth and respirationg get adapted to the climate increasing and the influence of photosynthesis process on soil nutrient deficiency in Larch, and the following conclusions are drawn from the study:1. The ring growth on larch (L. gmelinii).Through collecting meteorological data, sampling and standardizing tree rings’data of larch(Larix gmelinii), we tried to analyze the climatic changes in Maoershan region and its influences on tree ring features in this paper. In the past50years, significant increases in temperature were found (p<0.05),i.e., about0.4℃per decade in average annual temperature,0.3℃per decade years in average annual maximum temperature as well as0.5℃every per decade in annual average minimum temperature were observed. However, no significant changes in annual precipitation was found (p>0.05). Average monthly temperature (average temperature, average maximum temperature, average minimum temperature) also showed increasing tendency and The most significant month was in winter of February, about0.9-1℃per decade. Much smaller temperature increases,0.2-0.7℃per decade was found in summer of June to August). No significant changes in monthly precipitations were found in most months (p>0.05). During the coming climate warming, width of early and whole tree rings (p<0.05) may be decreased with the temperature enhancement in summer (June to July), while width of early and the growth of tree rings would increase with the temperature increases in spring (May). The width of late may be increase with the temperature increases in autumn (September). Although non-significant changes in precipitations, the significant correlations between annual precipitation and variable tree rings indices indicate growth of early wood and whole tree rings may be positivity affected by amount of annual precipitations. Considering the warming trend of the climate change significantly in northeast China in future but the rainfall does not. The growth of tree rings caused by spring and autumn temperatures could be offseted by too high temperatures in summer which inhabited the tree ring growth. Therefore, the influence on the radial growth of the Larix might be little.2. The soil respiration and stem respiration in larch and others The thinning larch made the subtotal of soil respiration in larch forest from720.36gC·m-2·yr-1to736.27gC·m-2·yr-1,that below767.20gC·m-2·yr-1in Korean-pine forest and896.46gC·m-2·yr-1in Fraxinus mandshurica forest. Through calculating Q10showed that the Q10in Fraxinus mandshurica higher than that in in Korean-pine forest, and the Q10in n Korean-pine forest higher than that in larch on total soil respirationg. Through combining the Q10in different management measures larch, we found that cutting larch (2.82) was higher than thinning larch (2.13), thinning larch higher than larch (2.08), The respiration of each part takes up different proportions in different forest. Microbial respiration occupies the largest proportion which exceeds50%, while the proportions of litter and root respirations are relatively small. But in larch three breathing stand proportion are not significant. Usually stem respiration displays the highest value in summer (July) and the lowest value in early spring (May), autumn (October). Through calculating Q10showed that larch (2.68) was lower than Korean-pine forest (2.94), Korean-pine forest lower than Fraxinus mandshurica forest (4.00).3. Influences of the needles and branch on photosynthetic physiological signs in larchCa deficient treatment forces the decrease of Ca element and the increase of Mg and K in the needles of larch, yet it does not take any significant influence on the chlorophyll content and composition in the needle of larch, as well as the caudex and stem length. At the same time, Ca deficient treatment causes sharp increase of PEPC content in the needles and significant decrease of B, P and N elements in the branches of larch, while the chlorophyll a/b in the branches are significantly reduced. P deficient treatment results in significant decrease of P content in the needles of larch, and increase of K element as well as ME enzymatic activity. Moreover, P deficient treatment also causes reduction of B and N contents in the needles. K deficient treatment actualizes reduction of K element and increase of Ca, Mg and B, moreover the caudex and stem length of larch also decline. Besides, reduction of N content and chlorophyll a/b in the needles, as well as the declination of PPDK and MDH are also observed after K deficient treatment. N deficient treatment results in death of larch needles, decrease of B content and significant increase of Ca and K content, as well as distinctive reduction of chlorophyll a/b and stem length. Mg deficient treatment brings the reduction of Mg and P contents, increase of Ca and K contents and significant decrease of chlorophyll a/b and stem length. B deficient treatment causes reduction of B and P elements in needles, significant increase of Ca and Mg and K, and distinctive decrease of chlorophyll a/b and stem length. B deficient treatment also brings down N content in branches, yet causes increase of ME enzyme content in the branches. |
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