科尔沁草原区火电厂储灰池植被恢复过程中白草种群分蘖株的年龄结构

Abstract

植被恢复过程中优势植物种群的年龄结构对于演替动态的预测具有重要的作用。通过对科尔沁草原区火电厂不同恢复年限储灰池植被恢复过程中白草种群分蘖株年龄结构、分蘖节芽年龄结构、分蘖株的物质生产力及营养繁殖力的比较研究，分析了不同恢复年限（1区：1992-1993年恢复；2区：1996-1997年恢复：3区：1999-2000年恢复）和家畜干扰条件下（2005年开始）白草分蘖株结构的变化。结果表明：2003年围栏时，随着恢复年限的增长，3个储灰池中白草分蘖株数量和生物量的龄级构成以增长型为主；2007年时，两年不同程度的家畜干扰后，3个储灰池中白草分蘖株数量和生物量均为稳定型结构。2007年各龄级白草分蘖节芽及其总量均显著高于2003年。2003年围栏时，3个储灰池中白草分蘖株的物质生产力在同一龄级间均无显著差异；2007年家畜干扰后，2区和3区中1a分蘖株和总体均值的物质生产力均显著低于2003年。2003年围栏时，3区中1a分蘖株和总体均值的营养繁殖力均显著高于1区和2区；2007年家畜干扰后，3区中1a、3a分蘖株和总体均值的营养繁殖力均显著低于1区和2区；2007年各龄级分蘖株及总体均值的营养繁殖力均高于2003年，各恢复区1a、1区2a和各区分蘖株营养繁殖力的均值在两个取样年间的差异均达到显著水平。继续围栏保护对于本研究中火电厂储灰池的植被恢复是切实可行而有效的管理措施。;Age structure of dominant plant populations is vital to forecast community dynamics during vegetation restoration. <em>Pennisetum flaccidum</em>, a perennial grass with long rhizomes, is widely distributed in the northeast and western regions as well as the Inner Mongolian Plateau of China. In the Kerqin grassland region, <em>P. flaccidum </em>is one of several native plant species that are used to restore coal ash storage pools generated by Coal Power Plants. In 2003, we located three ash storage pools (from here on referred to as‘plots’) that differed in age (12, 8, and 5 years old) and contained <em>P. flaccidum</em>. We found that natural colonization had successfully restored these plots, with the average herbaceous cover for all three plots reaching 85%-90%. We sampled the <em>P. flaccidum</em> population. Due to relaxed oversight at the storage pools following a change in the managing entity in 2005, the plots were grazed by livestock. In 2007, we resampled the same plots and found that the total vegetation coverage had decreased to 30%-50%.<br>In late August of 2003 and 2007, three to five replicate quadrats (each 0.25 x 0.25 m in area and 50 cm deep) in each plot were sampled by taking soil cores, including all aboveground shoots and belowground rhizomes, to maintain the inherent links among tillers and rhizomes. Age classes of tillers and tillering buds were classified according to vegetative propagation generations of tillering nodes and their numbers were counted. Age structure of tillers, tiller buds, tiller matter productivity and tiller vegetative propagation capability of <em>P. flaccidum</em> populations were studied during different vegetation restoration years in the coal ash storage plots of Coal Power Plant in the Kerqin grassland region. Structure changes of <em>P. flaccidum</em> tillers were analyzed under different restoration years (spot 1: 1992-1993; spot 2: 1996-1997; spot 3: 1999-2000) and livestock disturbance (the beginning of 2005). Number and biomass of <em>P. flaccidum</em> tillers showed expanding age structures in both spot 1 and spot 2 and it was stable in spot 3 in 2003. After two years livestock disturbed with different intensities since 2005, <em>P. flaccidum</em> tillers showed stable age structures in all three spots. Every age class and total tiller buds were significantly higher in 2007 after disturbing than those in 2003 as enclosed. Dry matter productivity of same age class tillers was not significantly different among three spots in 2003. Dry matter productivity of 1a tillers and average of each age class in spot 2 and spot 3 in 2007 were significantly fewer than those in 2003. Vegetative propagation capability of tillers of both 1a and average of all age classes were all higher in spot 3 than those in spot 1 and spot 2 in 2003 (<em>P</em>< 0.05). Vegetative propagation capability of tillers of 1a, 3a and average of all age classes in spot 3 were all significantly fewer than those in spot 1 and spot 2 in 2007 after livestock disturbance. Vegetative propagation capability of every age class tillers and their average value in 2007 was higher than those in 2003. There were significant differences between 2003 and 2007 at vegetative propagation capability of 1a age class tillers in every spot, 2a age class tillers in spot 1 and average vegetative propagation capability. Sustaining fence to coal ash storage pools of Coal Power Plant is an effective way to vegetation restoration in the arid Kerqin grassland region.