我国长期处于封建主义社会,生产力水平低下,农业经济落后,人民不可能有充分抗御自然灾害的能力,加上历代统治阶级的搜刮掠夺,不关心有效的防灾建设。因此我国灾荒之多,世界罕见。就文献可考的记载来看,从公元前18世纪,直到公元20世纪,...我国长期处于封建主义社会,生产力水平低下,农业经济落后,人民不可能有充分抗御自然灾害的能力,加上历代统治阶级的搜刮掠夺,不关心有效的防灾建设。因此我国灾荒之多,世界罕见。就文献可考的记载来看,从公元前18世纪,直到公元20世纪,将近四千年间,几乎无年不灾,也几乎无年不荒,西欧学者甚至称我国为“饥荒的国度”(The land of Famine)。综计历代史籍中所有灾荒的记载,灾情的严重和次数的频繁是非常惊人的。展开更多
Kalimeris integrifolia Turcz. is a root sucker form perennial herb of Compositae. In die late period of growing season, fresh fleshy radicels grow up above the soil surface to develop root-borne buds, which in turn gr...Kalimeris integrifolia Turcz. is a root sucker form perennial herb of Compositae. In die late period of growing season, fresh fleshy radicels grow up above the soil surface to develop root-borne buds, which in turn grow into ramets and taproot. On the basis of observation on numerous samples, methods to classify the age of ramets and buds for the root sucker herbaceous plant population and to estimate the ages of taproots were established according to their morphology. The age of ramets was classified based on the regeneration times of taproot buds. Ramets developed from new root sucker buds were classified as 1 a. After 1 a ramets died, the ramets reproduced from the taproots were 2 a, and so on. New buds from a root sucker were 0 a buds, other age classes of buds were consistent with that of ramets, i.e. buds produced from taproots of I a ramets were 1 a buds, and so on. In the hay clipping meadows of the Songnen Plains, for K. integrifolia population, there are three age classes of ramets, representing a steady age structure. The maximal age of taproots of ramets is 4 a. Among all age classes, the population productivity of 2 a ramets was the highest, and that of I a ramets was the lowest. The ramet productivity increased with ramet age. During the early period of growing season, the productivity of 3 a ramets was the highest, but after the middle of growing season, I a ramets showed the greatest relative growth rate. The population size and age structure in the next year could be accurately forecasted by the number of fresh roots with budlet and present population in late autumn. The potential population in the bud banks was more than two times of the present population, which may provide sufficient substitution in the future.展开更多
文摘我国长期处于封建主义社会,生产力水平低下,农业经济落后,人民不可能有充分抗御自然灾害的能力,加上历代统治阶级的搜刮掠夺,不关心有效的防灾建设。因此我国灾荒之多,世界罕见。就文献可考的记载来看,从公元前18世纪,直到公元20世纪,将近四千年间,几乎无年不灾,也几乎无年不荒,西欧学者甚至称我国为“饥荒的国度”(The land of Famine)。综计历代史籍中所有灾荒的记载,灾情的严重和次数的频繁是非常惊人的。
文摘Kalimeris integrifolia Turcz. is a root sucker form perennial herb of Compositae. In die late period of growing season, fresh fleshy radicels grow up above the soil surface to develop root-borne buds, which in turn grow into ramets and taproot. On the basis of observation on numerous samples, methods to classify the age of ramets and buds for the root sucker herbaceous plant population and to estimate the ages of taproots were established according to their morphology. The age of ramets was classified based on the regeneration times of taproot buds. Ramets developed from new root sucker buds were classified as 1 a. After 1 a ramets died, the ramets reproduced from the taproots were 2 a, and so on. New buds from a root sucker were 0 a buds, other age classes of buds were consistent with that of ramets, i.e. buds produced from taproots of I a ramets were 1 a buds, and so on. In the hay clipping meadows of the Songnen Plains, for K. integrifolia population, there are three age classes of ramets, representing a steady age structure. The maximal age of taproots of ramets is 4 a. Among all age classes, the population productivity of 2 a ramets was the highest, and that of I a ramets was the lowest. The ramet productivity increased with ramet age. During the early period of growing season, the productivity of 3 a ramets was the highest, but after the middle of growing season, I a ramets showed the greatest relative growth rate. The population size and age structure in the next year could be accurately forecasted by the number of fresh roots with budlet and present population in late autumn. The potential population in the bud banks was more than two times of the present population, which may provide sufficient substitution in the future.
