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苗木的质量,过去多按经验分级,如依据当地造林用苗习惯,提出苗木高、径下限,或者从经济效果出发,提出可供造林的苗数应占总产的百分比,来划定合格苗和非合格苗标准的界限,这样,其结果不但因人而异,而且缺乏科学性和严密性,无法解释苗木个体之间“质”的差别。随着科学技术的发展,用数学分析方法,对事物进行分类,再结合专业知识加以解释,已是研究工作的重要手段。苗木在生长发育过程中,由于种子品质(或具有种子意义材料的品质)和生态环境的影响,以及技术措施的制约,使其对各个质量指标的表现能力不同,将自己分成若干性质大致相同的自然群体,这就成了用数学手段对它们进行分级的基础。
In the past, the quality of seedlings should be graded according to their experiences. For example, based on the habit of using local afforestation, put forward the planted height and diameter limit, or set out the percentage of the total number of seedlings available for afforestation, And non-qualified Miao standard boundaries, so that the results not only vary from person to person, but also the lack of scientific and rigorous, unable to explain the difference between the “quality” seedlings individuals. With the development of science and technology, using mathematical analysis methods to classify things, combined with professional knowledge to explain, is an important means of research. Seedlings in the process of growth and development, due to the quality of the seed (or seed with a sense of the quality of the material) and the impact of ecological environment, as well as technical measures to make it different from the performance of various quality indicators, will own a number of roughly the same nature Natural groups, which became the basis for the grading of them mathematically.