Study On Population Age Structure And Spatial Distribution Pattern Of Dryopteris Crassirhizoma Nakai

Dryopteris crassirhizoma is the perennial herbaceous plant of the shield fern family, shield fern genus. It is the original plant recorded in the national codex and distributed in the northeast of China and northeast of Hebei province, North Korea and Japan. It is grown under the forest, about 300-1200m altitudeThe dryopteris crassirhizoma had a long life-span, some could even live up to over 30 years. Because the capacity of natural renovation and the growth of the medical part were relatively slowly, the ecological carrying capacity of the development of the resources was not strong as well. In order to realize the sustainable utilization of resources, we must have scientific knowledge of the growth regularity of the population. By far, there was not such report on the morphological character, age structure and distribution pattern of the dryopteris crassirhizoma population. For this reason, on the basis of the research and investigation to the dryopteris crassirhizoma population distributed over the Changbai Mountain area in Jilin Province, this research made some preliminary analysis on the morphological characters, population distribution pattern, the methods on differentiating the individual age of the dryopteris crassirhizoma and the nondestructive ways to investigate the age pattern of the population which aimed at revealing its morophogenesis and regeneration regularity, thus provided reliable scientific basis for the further development and utilization of this kind of Chinese herbal medicine.The field research of this study was from June 11th to 22nd August 2004 in Linjiang City which is south of the Changbai Mountain in Jilin Province. The geographical position lies in 126°11'~ 127°35'longitude and 41°27'~42°4'north latitude, in the hinterland of the southwest part of the Changbai Mountain, upper reaches of the Yalu River. The forest coverage rate is up to 83.4%. By fully investigation, three different community types had been chosen, namely the typical location of the weighty elm forest, the secondary miscellaneous forest and the mixed forest of the theropencedrymion cutting blank which basically reflected the suitable living conditions of the dryopteris crassirhizoma. The main results were as follows:1. The field investigation result indicated that dryopteris crassirhizoma grew only one circle of leaves within one growing season, which displayed a tweezers order. The leaves died naturally when they stopped growing and left the incomplete bottom part of the leaf whichwas not rotten. Thus, this essay provided a method of judging the individual age of the dryopteris crassirhizoma through calculating the number of incomplete circles on the basis of leaves which grew with the increase of circles. Through the research, this way of research was reliable and could be used as well as could be tried to use in the research of other similar pteridophyte and perennial herbs. There was obvious connection between the age of the dryopteris crassirhizoma and the morphological indexes above ground part. The age of the individuals increased with the number of the leaves and the height of the plant which indicated that the method of judging the individual age of the according to the upper ground characters was reliable.2. The research results of the population characteristic of the dryopteris crassirhizoma indicated: among the three kinds of sample places, the secondary miscellaneous forest population had the largest density and the interspecies competition. Located in an open area, the population density of ropencedrymion of cutting blank was also relatively large, the plant grew vigorously, and the body size and the dry matter of each modular were generally large. The associated tree apecies was Korean pine in the weighty elm forest where the herbaceous vegetation coverage degree was extremely low (for 10%) and the canopy density was big. Though the dryopteris crassirhizoma was the herbal dominant species, the above ground of the plant grew less vigorously and the dry matter was small. The t-test and analysis of the single sample indicated that morphological character was significantly different, and the significance level of per morphological index was comparatively big in the interspecies. F-test indicated:A. The number of leaves, the leaf length, the leaf width, the plant height, the crown diameter and the number of spore leaves had not significant difference within the 3 population;B. The difference of leaf fresh weight among the population was significant, and the difference of the number of new buds, the leaf dry weight, the length of petiole, the fresh weight of the rhizome, the dry weight of rhizome, the diameter of rhizome, the diameter of petiole and the length of rhizome among the population were significant;C. Each characters of the plants under 60cm (including 60cm) had little significant difference among the population ,but the plants above 60cm had great significant difference in the length of leaves and petiole, the number of spore leaves, the fresh weight of leaves and the fresh weight of rhizome and dry weight of rhizome. While the difference of the diameter ofpetiole, the number of new buds, the weight of dry leaf, the height of the plant and the length and diameter of the rhizome were great significance among the population.3. The research results of the population growth and individual age of the dryopteris crassirhizoma indicated: among the three sample places, the dryopteris crassirhizoma in the weighty elm forest had the least average number of leaves, the lowest average height of plants and the least average age the population (15 years). In the secondary miscellaneous forest, it had the moderate number of leaves, height of plants and average age (17 years) but the largest mean diameter crown. The dryopteris crassirhizoma had the most leaves, highest plants and oldest average age (19 years) in the theropencedrymion cutting blank. It also had a comparatively large age span— one year for the youngest and 33 years for the oldest. These showed that the growing situation and the individual age were obviously influenced by the living situation. The weighty elm forest had a high canopy density, enjoys a bad illumination. At the same time, the individual growth was weak, the life span was short and the death rate was high. The theropencedrymion cutting blank had the best illumination, the individual growth was strong and the aging pattern within the population was relatively complete among the three sample places. Whereas, the growing environment for the secondary miscellaneous forest was between the other two, the growing situation and the individual age of the dryopteris crassirhizoma was also between them even more similar with the weighty elm forest.4. The research result of the aging structure of the dryopteris crassirhizoma indicated: among the three populations there were far more plants in prime life than the ones in early and old ages; the potential of reproduction was big. The rate of early-age plants in the population was low and the old-age plants high, the population was in aged period; the death rate was higher than birth rate that displayed a declining type. These showed that the theropencedrymion cutting blank had a long life span but not strong renewing ability in the three sample places. Further analysis indicated that the population renewing was not only affected by the illumination situation but also some other factors. Pteridophytes were high level plants which had clear alternation of generation. The zoogamy process had still been depending on water in its history of living. In the analysis of the age structure indicated that there was obviously discontinuity which might had certain connection with the influence of the climate in the period of zoogamy and needs a further research.5. The point pattern analysis result on the dryopteris crassirhizoma indicated:A. The distribution character of dryopteris crassirhizoma in the three sample places under different scales. It had the similar space distribution pattern in the weighty elm forest and the secondary miscellaneous forest, both shown a random distribution under short scales while group distribution and edge of random distribution under long scales. Under long scales, the space distribution patterns of both populations were random distribution. While in the theropencedrymion cutting blank, it showed group distribution under short scales, but tended to random distribution under long scales.B. The population distribution pattern of Dryopteris crassirhizoma plant height in different sample places: all sample places, and all height class were random distribution under long scales. But under short scales it showed a different distribution character.C. The association analysis for dryopteris crassirhizoma among different plant height class in different sample plots indicated: There was association among different plant height classes in every sample plot, but the association degree was not significant and it had different with the change of scales. The study on association among plant height classes in different sample plots reflected the dryopteris crassirhizoma in different height classes and the characteristic of self-thinning inside population.