Study On Spore Ecology Of Sphagnum Squarrosum In Hani Peatland

Sexual reproduction plays an important role in Sphagnum populations persistence and regeneration,but the ecological significance of sexual reproduction has not been taken seriously account.In the peatlands,many Sphagnum can produce large numbers of spores in the midsummer.The size,production,and vitality of the sporophyte will all affect the sexual reproduction capacity of Sphagnum.But there are very few studies on this aspect.In this study,Sphagnum squarrosum in Hani Peatland of the Changbai Mountains,northeastern China,were selected as study specie.Under indoor conditions,observing morphology of capsules and spores,and the size of capsules and spores.According to the size of capsules,capsules were sorted by size to measure spores vitality in order to study the relationship between the size of capsules and the spore vitality.In field conditions,we survey quadrat's microhabitat and the take S.squarrosum and swampwater back to the laboratory to measure.In that way,we aim to figure out the effect of microhabitat condition on capsules production,spore vitality and capsules cracking,and to clarify the importance of microhabitat conditions for sexual reproduction in Hani Peatland of the Changbai Mountains.The main results and conclusions are as follows:?1?Mean height of S.squarrosum capsule is 2.21±0.11 mm,and mean diameter is1.98±0.08 mm.In capsule Morphology,height and diameter has prominent positive correlation.Smaller compare with other Sphagnum capsules,obey the normal distribution on the diameter of the spores,mean diameter length is 25.28±2.31?m.There was a significant negative correlation between the capsules morphological size and spore morphology size,and the correlation between capsule and spore diameter was more significant by correlation analysis,indicated that the size of the spore can affect the size of capsule morphology.The capsule size and spore size affect the spore yield,which is directly related to the spore's sexual reproduction ability.?2?In this study,the average of capsule diameter was used as the boundary.The capsules were divided into large capsules and small capsules.On the 10th day of spore cultivation,the size of capsule significantly affected germination percentage,and the large capsule,the lower the spore germination percentage.At day 20 of culture,although there was a trend of higher spore germination percentage in the capsule,it did not reach a significant level.Larger capsule also tend to be larger spore,Small spore only increased germination percentage in a short time,and the effect disappeared after a long time,indicated that the significance of small spore is to shorten germination time rather than increase germination percentage.The high incidence of germination may represent the early germination and even settlement of small spore rather than the higher activity,so the significance and contribution of small spore in the persistent spore bank of Sphagnum may be smaller.?3?There was correlation between the environmental factors of the sample,especially,the hydrochemical indexes of marsh are more prominent,all factors are related to at least one of the other hydrochemical indexes.In addition,the water table depth is negatively correlated with tree density.Complex correlation between habitat factors,indicates that the geographical environment is holistic,independent of each other,unified and has a relationship of restriction,promotion and balance among them.?4?There was no significant relationship between the capsule production and the factors in the habitat during the spore maturation of Sphagnum.By the linear regression analysis,the factors such as degree of depression,pH,concentration of Na⁺,concentration of K⁺and conductivity were obtained.The distribution of coarse-leaved Sphagnum is only found in the low-lying areas of the understory habitat,so the water table depth is no longer a limited factor,rather a significant factor in the distribution of nutrients in marsh water.Lack of nutrients and excesses will inhibit the sexual reproduction of Sphagnum.?5?In the period of spores maturity,the capsules cracking percentage was positively correlated with illumination intensity and water table depth in the habitat.By progressive linear regression analysis,concluded that the illumination intensity,water table depth,TP,TN,pH,Fe²⁺concentration and Mg²⁺concentration were important factors,indicated that water table depth and light plays an important role in the cracking of capsules.Under humid and shading conditions,sporophytes grow for a long time,are not easy to erupt,and are well developed.?6?In the period of spore maturity,the spore germination percentage was negatively correlated with the total nitrogen content in marsh water and positively correlated with water table depth.By progressive linear regression analysis,It was concluded that the illumination intensity,water table depth,TN,conductivity,Fe²⁺concentration and K⁺concentration were important factors,indicated that the water nutrients in the marsh had great influence on spore activity.The experiment of indoor germination results showed that the germination percentage of newly mature spores was99.52%,the lowest was 92.96%,the average germination percentage was 97.72%,and the spore germination percentage of 78.89%was between 96.5%and 98.6%,belonging to a kind of Sphagnum with strong spore activity.Spores have long lifespan and form a long-lasting spore bank,which plays an important role in the continuation and renewal of Sphagnum population.