黄土丘陵沟壑区80种植物繁殖体形态特征及其物种分布

Research on diaspore morphology and species distribution of 80 plants in the hill-gully Loess Plateau

植物繁殖体的形态特征及其物种分布是植物长期适应环境的结果,对退化生态系统的更新与恢复具有重要的理论与实践指导意义。研究了80种植物的繁殖体形态特征及与其物种分布的关系,结果表明:1)繁殖体重量差别较大(0.020—357.428mg),主要集中在1—9.999 mg(占52.5%)。2)繁殖体的形状指数FI变化范围较大(1.06—12.93),61.3%的植物繁殖体的形状近圆球形。3)33种植物繁殖体具有明显的附属物,包括毛、翅、芒和刺等。4)87.5%的植物繁殖体表面具有各种纹饰(棱、被毛、纹和颗粒状等);繁殖体颜色以褐色和黑色为主,少数繁殖体颜色鲜艳;6种植物繁殖体具有吸水分泌粘液的特性。5)黄土丘陵沟壑区繁殖体重量小或形状近圆球形的植物分布数量多、范围广。6)繁殖体具有毛、翅和芒附属物或吸湿分泌粘液的植物在黄土丘陵沟壑区较繁殖体无附属物的植物能够分布更多、更广。繁殖体这些有利于物种分布的形态特征对于植物适应该区干旱与土壤侵蚀干扰具有重要的生态学意义,而且可用于指导该区人工补播促进植被恢复的物种选择。

Soil erosion is a natural geomorphic process on slopes in semiarid region, which influences the soil water holding capacity, nutrients stored and the plant species distribution. The hill-gully Loess Plateau is located in the forest-steppe region and has a semiarid climate with severe soil erosion. Vegetation is identified as the essential and available approach to control soil erosion and to recover degraded ecosystem. Diaspore is the base of vegetation regeneration and recovery after disturbance. Unfortunately, in the degraded ecosystem, diaspore is always regarded as a limited factor of vegetation regeneration. Especially, in eroded environments, seed limitation is caused not only by seed production reducing due to the soil degradation, but also by other seed ecological process. Diaspore morphology is one of the most important functional characteristics of plant, which influences seed production, seed dispersal, seed longevity, seed germination, seedling establishment, then influences species distribution and community composition. Many ecologists have studied seed mass,seed shape, and the corresponding ecological function. However, there are few studies on diaspore morphology and ecological function carried out in the hill-gully Loess Plateau region. 80 species were chose to investigate their diaspore morphology and distribution characteristics, in order to better understand the influence of diversity and adaptation of diaspores on plant restoration. Diaspores of the 80 species were collected from three small watersheds of Xinzihe watershed. To determine species distribution （ species density and frequency） on eroded slopes in the study area, 304 quadrats of 69 sample plots from 16 eroded slopes were investigated. The results showed the mean seed mass varied widely （0. 020-- 357. 428 mg）, with the mean mass of the heaviest diaspore （Ziziphus jujuba） was 17870 times higher than the smallest diaspore （Artemisia scoparia）. The mean diaspore mass of most plant species were varied from 1.000 to 9.999 mg, occupied 52.5% of the study species. The Flatness Index of diaspore ranged from a value of 1.06 for spherical shape to greater value of 12.93 for spindle shape, with most of diaspores had the approximate spherical shape （61.3%）. Diaspores of 33 species had appendages, such as pappus, awn, wing, spine, etc. About 87.5% species had emblazonry on the surface of diaspore. The main colours of diaspores among these species were brown and black. The diaspores of six species had the ability to secrete mucilage in contact with water. The relationship between diaspore mass and species density and frequency were negative, as well as the relationship between diaspore shape （FI） and species density and frequency were negative. The species with small diaspore, or the approximate spherical diaspore, or with the appendages such as awn, wing and pappus on the diaspore, or with the diaspore that can secrete mucilage distribute widely in the study region. These morphological traits of the diaspore have important role in the distance dispersal, adhering to the soil and persisting in the eroded habitat. And then help the species to adapt the drought and erosion. Diaspore morphological characteristics of adapting the drought and erosion are useful to guide the species selection of revegetation by seed addition.