古尔班通古特沙漠植物种子大小变异的空间格局

Variations and spatial distribution pattern of seed mass in the Gurbantunggut Desert

在古尔班通古特沙漠70个固定样地中采集了87种植物种子,通过测量种子百粒重,分析了种子大小在不同分类群中的变异规律,并调查了样地中不同类型种子总数目的空间格局。结果发现:1)古尔班通古特沙漠植物种子大小可分为:A(0.1—1 mg)、B(1—10 mg)、C(10—100 mg)、D(100—1000 mg)、E(1000—5000 mg)5种类型。拥有不同类型物种数量差异较大,其中D型种子物种最多,含41种占总物种数目的 47.1%,其次C型种子30种占总物种数目的 34.5%,E型种子占总物种数的13.8%,B型种子总物种数的3.5%,A型种子占总物种数的1.1%。沙漠植物中中等种子大小物种占多数,与以色列特拉维夫以北的Poleg自然保护区地中海沿岸沙漠地区相似。由于本地属、种为地中海区、西亚至中亚分布,所以认为本沙漠种子大小主要受系统演化影响。2)科间种子大小存在极显著差异,百粒重最大科是蓼科(29315 mg)、最小的是列当科(0.3 mg)。藜科,菊科,紫草科的属间种子大小差异显著。3)生活型间种子大小差异显著,种子大小从大到小排序为:灌木>类短命植物>多年生草本>短命植物>半灌木>1年生草本。4)种子大小与物种相对分布频度相关性不显著,但将相对分布频度小于1.4%的环境特化物种去除后,种子大小与物种相对分布频度呈指数型极显著负相关。5)B型、C型、D型三类种子在样地中的总数目随海拔、经度和降水的增加而极显著增加,随纬度的增加而极显著降低,E型种子则与之相反。表明古尔班通古特沙漠未来随着降水的增加,B型、C型、D型种子的植物优势性逐渐增加,而E型种子的灌木类等物种优势性逐渐减少,注意加以保护。

Gurbantunggut Desert is a famous temperate desert with plant diversity is more special than the same latitude desert in the world. It is an important desert from the viewpoint of drought resistance,heat resistance,and saline plant germplasm resources. Samples were collected from 70 permanent plots( 100 m × 10 m) in the desert,and the total number of different types of seeds and spatial patterns were investigated. Variations in seed mass and seed projected area among 87 species in different taxa were analyzed by measuring the 100-seed weight. The results were as follows: 1) The seed mass of plants can be divided into five classes: A( 0.1—1 mg),B( 1—10 mg),C( 10—100 mg),D( 100—1000 mg),and E( 1000—5000 mg). These classes comprised 1.1%,3.5%,34.5%,47.1%,and 13.8% of all species,respectively. Class D seeds were the most commonly examined species. The species were similar to those found in Mediterranean deserts,such as those in the northern areas of the Tel Aviv Poleg Nature Reserve. Most possess seeds of medium mass. Because the genera move from the Mediterranean region through western and central Asia,the seed mass of the desert plants may be determinedby phylogenetic evolution. 2) There was a significant difference in seed size among the family,maximum family of 100 grain weight is Polygonaceae( 29315 mg),the smallest is Redanko( 0. 3 mg). There was significant difference in seed size among genera such as Chenopodiaceae,Compositae,and Boraginaceae. 3) The 87 species included six life forms and covered significant differences in seed mass as follows: shrub > ephemeral plant > perennial herb > ephemeroid > subshrub> annual herb. A great deal of shrub seed mass belonged to type E( 1000—5000 mg). 4) There was no significant correlation between seed size and species relative distribution frequency. However,removed the environmental specialization species,which relative distribution frequency <1.4%. A negative correlation was observed between the exponential growth model of seed size and species distribution relative frequency. 5) The total number of species with type B,C,and D seeds increased with significant increase in altitude,but decreased with significant increase in latitude. It also increased with significant increase in longitude and precipitation. This was also true of the total number of seeds in the sample area.However,the opposite of this was true for type E seeds. This indicates that more precipitation gradually offered an advantage to plants with type B,C,and D seeds in the area but disadvantage to plants with type E. In future,efforts should be taken to protect the shrub belonging to type E in the Gurbantunggut Desert. The results of this study may facilitate the understanding of seed mass in the life history strategy of plants in arid desert areas and lay the foundation for further studies of plant biology in the Gurbantunggut Desert.