科尔沁沙地丘间低地不同生活型物种格局与共存机制

Spatial pattern and coexistence of plants with different life forms in inter-dune low land of Horqin Sandy Land

植物种群格局与不同生活型之间物种共存的研究有助于理解物种的生态适应性。丘间低地是科尔沁沙地生态系统发育的一个关键阶段,在此生境中存在多种生活型的植物。采用样线法调查了科尔沁沙地丘间低地100个1 m×1 m样方,根据调查结果选取了分属于4个科3个生活型的15种植物为对象进行格局和共存机制的研究。经格局指数以及Poisson分布的t检验和χ2检验表明:15个物种的种群分布均为聚集分布,但聚集强度差别很大,这可能由种子扩散、物种形态、植物发育时期以及土壤养分条件差异导致;聚集指数DI、CI、m*、GI之间呈极显著正相关关系,表明它们表征共同的生态学意义,相互之间可以替代;多年生草本这一生活型内的物种相互共存较多,多年生草本与其他两个生活型共存较少,这可能与相同生活型物种生态位重叠度大有关。Spearman秩相关和Pearson相关对物种对的检验结果均表明:部分豆科植物与其他科的多年生草本共存机会较大,这可能与豆科植物对改良土壤和减少病虫害有关。物种聚集分布以及不同生活型内几个物种对正相关显著是物种适应环境的结果,对结果显著的部分植物进一步研究可以为沙地植被恢复提供理论指导。

Plant spatial pattern and coexistence between different life forms have contributed to understanding species adaptation. Inter-dune low land is a key stage of Horqin Sandy Land eco- system, with different life forms. Line-transect method was applied for vegetation investigation on 100 quadrats with a size of 1 mx 1 m. Then, we chose fifteen species, which belong to three life forms and four families as research objects, to study their pattern and coexistence mechanism. Pattern indexes, t-test andX2-test showed that the spatial patterns of fifteen species were of aggre- gation; but there was much discrepancy in the intensity of aggregation, which may be related to seed dispersal, plant morphology and development and soil condition. The correlations among DI, CI, m ＊ , and GI were significantly positive, indicating that these indexes had same ecological meaning and could replace each other. The perennial species had more coexistence within the pe- rennial life form but had less coexistence with other life forms, which might be due to the reason that the same life forms have more ecological niche overlap. Both Spearman correlation analysis and Pearson correlation analysis showed that a few leguminous plants had more coexistence with other families of perennial, which may benefit from the soil improvement and plant disease de- cline by legume. The species aggregation and species coexistence in different life forms resultedfrom the species＇ adaptation to the environment. Further research on significant correlation of species could provide a support for sandy vegetation restoration.