Seed Mass Variation And Its Adaptive Significances In Gurbantunggut Desert, China

Desertification is an important issue that affects the environment of human survival,seriously desertification and reduce the available land resources, and cause natural disasters,and the desert vegetation is the contribution of sand desert ecosystem stability and improvethe most direct, as plant continuity, seed size has become the key factor of success of speciescolonization. Seed size affects plant growth process in many biological and ecologicalcharacteristics, so the understanding of composition and distribution in the community ofdifferent seed size species for vegetation protection and restoration has great significance toreduce hazards of desert oasis agriculture and people’s life. The Gurbantunggut Desert in thecenter of Junggar basin, is China’s second largest desert, at the same time is China’s largestfixed semi-fixed desert. In the Gurbantunggut Desert70fixed points we investigated andcollected87species of seed plants, belonging to22families and68genera. By measuring the100-seed weight, analyzes the relationship between seed size variation and systemdevelopment, the character of the plant life history, combined with field survey data analysisof the relative frequency distribution of correlation between seed size and species distributionpattern, describe the objective space total samples in different size of seed type speciesrichness, abundance and seed, in order to reveal reasons and ecological Gurbantunggut Desertseed size variation of the adaptive significance. The results found:1) The masses of seeds of plants of the Gurbantunggut Desert can be divided into fiveclasses: A (0.1~1mg), B (1~10mg), C (10~100mg), D (100~1000mg), E (1000~5000mg).These classes made up1.1%,3.5%,34.5%,47.1%, and13.8%of all species. Class D seedswere the most common among the species examined here. The species were similar to thosefound in Mediterranean deserts, such as those in the northern areas of the Tel Aviv PolegNature Reserve. Most have seeds of medium mass. Because the genera move from theMediterranean region through western and central Asia, the seed mass of desert plants mayhave considerable evolutionary significance.2) The single factor analysis of variance, although genera were similar, families weredifferent. Families containing large numbers of genera, such as Chenopodiaceae, Compositae,and Boraginaceae were significantly better represented than those with few genera. 3) Single factor variance analysis showed differences in seed size significantly amongdifferent life forms. The87species included six kinds of life forms and covered significantdifferences of seed mass. Seed mass, from large to small, was as follows: shrub> ephemeralplant> perennial herb> ephemeroid> subshrub> annual herb.4) We will seed consists of3communication types, including wind-borne plants have40species, accounting for46%of the total number of active communication,45, accountingfor51.7%of the total,2kinds of animal communication, accounting for2.3%of the total.Three type of propagation by seed size from big to small order: wind-borne> activecommunication> animal communication.5) Regression analysis showed that seed mass and plant height have a binomialrelationship.When the plant height in the range of0~0.6m seed mass increased with plantheight increased, the plant height in the range of0.6m~2m with plant height, seed sizedecreases with plant height increased.6) Regression analysis showed that seed size and species distribution relative frequencyhave significant negative correlation, but there are10.3%species have environmentalspecialization phenomenon more obvious.7) Regression analysis showed that the total number of seed in the sample, the B type, Ctype, D type three kinds of seed number increased with altitude, longitude and precipitationand increasing significantly, but decreased significantly with latitude increasing, E type seednumber were contrary. It showed that with the increasing of the Gurbantunggut Desertprecipitation, have a significant impact on plant adapted species B type, C type, D type seed,advantage gradually increased.8) The richness of species with type C, D and E increased significant with increases inaltitude but decreased significant with increases in latitude. It also increased significant withthe increases in longitude and precipitation same as all species in sample area.The abundanceof species with type C and D increased significant with increases in altitude but decreasedsignificant with increases in latitude. It also increased significant with the increases inlongitude and precipitation. This was also true of all species in sample area. However, theopposite was true of type E seeds. Our research shows that different seed type have differentinfluence on the distribution of species, The species with large seeds dominance will reduce with the increase of rainfall. With precipitation increasing, species richness of different seedsize has increased, but the advantage will reduce seed, plant number decreased, the number ofsmall seed plants increased significantly. So in the future the desert plant protection should beintensify for Haloxylon ammodendron, Haloxylon persicum, Calligonum mongolicum suchlarge seed plants.