扎龙湿地不同生境芦苇种群根茎数量特征及动态

采用单位土体取样,计测长度和生物量的调查与统计方法,对扎龙湿地保护区4个生境芦苇种群根茎数量特征进行比较分析。结果表明,芦苇5月10日左右返青后进入营养生长期,根茎长度6—8月份缓慢增加,8—10月份显著增加,后期是前期的3.5—10.3倍,生长季中后期是种群新根茎补充和生长的主要时期,不仅实现了种群空间扩展,并为营养繁殖储备更多繁殖芽;根茎生物量和干物质贮量6—8月份逐渐减少,8—10月份又逐渐增加,均以生长季末期的10月份最大,并均显著地(P0.05)高于其他月份,种群根茎养分的消耗主要供给根茎芽的萌发和幼株生长,根茎养分的储藏又为翌年种群的更新及扩展提供物质保障,种群对地下根茎存在明显的养分"超补偿性"贮藏现象。种群根茎长度和生物量均以湿生生境最大,依次为旱生生境、水生生境,盐碱生境最小,根茎干物质贮量以旱生生境最大,依次为湿生生境、水生生境,盐碱生境最小。种群根茎长度与返青后实际生长时间之间均较好地符合直线函数关系,种群根茎生物量和干物质贮量与生长时间之间较好地符合二次曲线函数关系,R2在0.804—0.997之间,拟合方程均达到了显著或极显著(P0.01)水平。4个生境芦苇种群在根茎长度、生物量、干物质贮量等数量特征均表现出由遗传因素控制的比较稳定的季节动态规律,在生境间的差异及其差异序位又均基本稳定,均表现出明显的土壤因子环境效应,其中土壤含水量、有机质、速效氮为正向驱动,p H、速效磷为负向驱动,土壤含水量、p H对根茎数量特征的驱动作用更突出。

Quantitative characteristics and dynamics of the rhizome of Phragmites australis populations in heterogeneous habitats in the Zhalong Wetland

A comparative study of the quantitative characteristics of the rhizome of Phragmites australis populations in four habitats in the Zhalong Wetland was performed by sampling a unit volume of soil and measuring biomass and rhizome length. The results showed that P. australis returned green around May 10 and began to enter the vegetative growth period. There was a slow increasing trend in rhizome length from June to August, but a significantly increasing trend was observed from August to October. Moreover, rhizome length in the late period was 3.5-10.3 times higher than that in the early period. The middle and late growth seasons were the main periods of new rhizome supplement and growth of the population, during which time the spatial expansion of the population was achieved and more breeding buds were reserved for nutritional reproduction. Rhizome biomass and dry matter storage decreased gradually from June to August, but increased gradually from August to October, with the largest biomass observed in October, the end of the growth season, and was significantly higher than in other months(P < 0.05). The consumption of rhizome nutrients in the population mainly contributed to the germination of rhizome buds and the growth of young plants. The storage of rhizome nutrients also provided material support for the renewal and expansion of the population in the next year. The phenomenon of "super compensatory" storage in the rhizomes of the population was obvious. The length and biomass of rhizomes were the largest in the wet habitat, followed by the xeric, and aquatic habitats, however, they were the lowest in the saline-alkali habitat. The dry matter storage of rhizomes was the largest in the xeric habitat, followed by the wet and aquatic habitats, it was the lowest in the saline-alkali habitat. There was a significant, linear correlation between rhizome length of P. australis and the actual growth time after returning green. However, there was a significant, logarithmic correlation between rhizome biomass, dry matter storage, and the actual growth time after returning green, the goodness of fit of equation was 0.804-0.997, and the fitting equation reached a significant level of P < 0.01. The length, biomass, and dry matter storage of P. australis rhizomes in the four habitats showed relatively stable seasonal dynamics controlled by genetic factors during the growing period. The differences between the habitats and their differential orders were basically stable, showing significant environmental effects of soil factors, among which, the soil water content, organic matter, and available nitrogen were the positive drivers, while pH and available phosphorus were the negative drivers. The driving effects of soil water content and pH were the most prominent.