Studies On Population Ecology Of Several Plants In The Northeast China's Oligotrophic Mires

The formation of oligotrophic mires resulted from special complex effects of climate, physiognomy, hydrology etc. They are mainly distributed in sub-frigid zone and frigid-temperate zone. In China, the mountain region of Northeast China, including Daxing'an Mountains, Xiaoxing'an Mountains and Changbai Mountains are concentrated distribution areas of oligotrophic mires. Hani mire in the foot of Changbai Mountains and Tangbei Forestry Centre mire in the east part of the south slope of Xiaoxing'an Mountains were chosen as the study areas. Population ecology of plants, mainly including Sphagnum magellanicum, S. papillosum, S. girgensohnii, Polytrichum juniperum, Ledum palustre var. angustum, Chamaedaphne calyculata and Carex middendorffii were studied.(1) Non-increased age structure is predominant in the six plant populations. The ramets of S. papilloum, P. juniperum and Ch. calyculata and rhizomes of C. middendorffii showed a declined age structure. Ramets of S. magellanicum population and L. pallustre var. angustum population in open area and the ramets and active buds of C. middendorffii population showed stable age structure. Only ramets of I. pallustre var. angustum in the margin of mire showed an increased age structure.(2) Accumulative biomass of ramets in All the five evergreen plant populations showed a declined age structure, while accumulative biomass of ramets and that of rhizomes in C middendorffii population showed an increased and a declined age structure respectively.(3) Biomass of ramets in all the six populations showed age dependence. Mean biomass of ramets in every age class increased with a linear rule as the ramets aged in the three bryophyte populations, while an exponential increased rule was found in L. pallustre var. angustum population. In margin of the oligotrophic mire, base of dry materials accumulation in L. pallustre var. angustum was higher than that in Ch. Calyculata, but with a lower increscent rate. Due to a high proportion of sexual reproductive ramtes in 2 a ramets,mean biomass of 1 a and 2 a ramets was similar, and 2 a ramets were lighter.(4) Height of ramtes in the three bryophytes and two dwarf shrubs populations linearly increased with the ramtes aging. The increscent rate of S. magellanicum was higher than that of S. papillosum. No significant difference was found in P. juniperum populations no matter with sporophyte production or not, but sporophyte production limited the increscent rate of height and increased the variation level of height of ramets in different age classes.(5) On the two hands of growth of biomass and height, the three bryophytes showed an equal velocity growth. The two dwarf shrubs populations showed allometry, and emphasized particularly on biomass growth.(6) On the two hands of growth of biomass and length in rhizomes of C. middendorffii populations, no allometry was found. There were no significant difference in mean biomass per unit length of rhizomes in C. middendorffii population in July and August, but 1 a rhizomes showed a role to increase length to expand spatial niche by using limited dry material accmulation.(7) The two dwarf shrubs populations showed high ecological plasticity in height and biomass. Mean height and biomass in the margin of the mire was significantly higher.(8) Except that arbor only grew in the margin of mires, dwarf shrubs showed a strong tolerant capacity in low pH and low nutrient conditions, and could be seen both in open area and margin of mires. The coverage of dwarf shrubs, but Dasiphora fruticosa and Oxycoccus quadripetalus, was significantly higher in the margin of mires(9) In Hani mire, no difference between coverage of S. acutifolium in the margin and that in the open area. S. magellanicum, S. papillosum and S subsecundum are dominant Sphagna. The coverage of S. magellanicum and S. papillosum are higher in the open area, while by contraries, other Sphagna and P. juniperum with a higher coverage in the margin of the mire.(10) All the dwarf shr...