Alterations to biological soil crusts with alpine meadow retrogressive succession affect seeds germination of three plant species

Biological soil crusts(BSCs) are the important components of alpine meadow ecosystems.The extent and morphology of BSCs vary greatly with alpine meadow retrogressive succession due to grazing pressure.There is significant interest in impacts of crust composition on plant seed germination,especial l y in(semi-) arid environments.However,little is known about the influences of BSCs,and their associations with alpine meadow succession,on germination of typical alpine meadow vascular plant species.In a full factorial common-gardenexperiment,we studied effects of:(1) crust type,(2) seed position,and(3) surface texture on seed germination.We chose three typical alpine meadow plant species(i.e.Poa pratensis,Tibetia himalaica and Potentillen nivea),which belonged to different functional groups(graminoids,legumes,and forbs) and play important roles in all alpine meadow succession stages.Crust type and seed position influenced seed germination,and the inhibitory effects of BSCs depended on the crust type and seed species tested.The major factors influencing seed germination were BSC type,seed position,soil texture,and the interactions between BSC type and seed position; species and seed position; species andsurface texture; and species,crust type,and surface texture.Cyanobacteria crust significantly inhibited germination of all seeds.Seed position also had a significant effect on seed germination(p < 0.001).Fewer seedlings germinated on the surface than below the surface,this was especially true for P.nivea.seeds within cyanobacteria and lichen crusts.Only germination rates of T.himalaica on the soil surface were significantly correlated with plant occurrence frequency within the alpine meadow community.The poor correlation for the other two species is possibly that they are perennials.Our results clearly demonstrated that BSCs can be biological filters during seed germination,depending on the BSC succession stage.Through their influences on seed germination,BSCs can strongly influence community assemblages throughout alpine meadow retrogressive succession.

Discovery of ferromanganese crust boundary and its genetic and ore prospecting significance

Evidences for the existence of ferromanganese crust boundary were found for the first time during the survey of the “DA YANG YI HAO” Vessel 2003. Some typical characteristics of the boundary are summarized and the significances of the finding of the boundary are included in the genesis discussion. Ore prospecting and assessment of the crust resources are described in this paper. The morphologic and extending characteristics of the crust boundary led to the recognition of two types of crust boundary： interpenetration crust boundary and closed crust boundary. According to the distribution and types of the crust, however, the boundaries are classified into three types： the boundary between ferromanganese crust and detrital sediment, the boundary between tabular crust and seamount nodules, and the boundary between tabular crust and rudaceous crust. This study revealed that the boundary between tabular crust and nodules was not formed under different regional environments but formed under different nucleation potential barriers between different initial growth （nucleation and germination） processes and between solid rocks and loose sediments. The rudaceous crusts are controlled spatially by fracture zones and the crusts＇ boundaries are controlled by the seamount structure and landform. The discovery of the crust boundaries reveals the crust＇s ‘negative growth’ phenomena （especially for some seamount nodules）. The boundary investigation can be helpful in identifying the existence of tabular crust covered by detrital sediments and in calculating the area covered by the crust. The resource calculation error and the resource quality as well as resource exploration degree can be assessed through the survey of crust boundary.

Historical-Dynamic Integrative Classification of Basinogenesis and Ore-Forming Basins

Interesting classifications of basinogenesis and basins were proposed by many scientists. They classified basinogenesis and basins mainly from a single angle, either from a historical angle or from a dynamic angle . In order to more comprehensively understand them for more effectively guiding prospecting and exploration, the author integrates the two methods of analysis with each other and proposes an integrative classification .According to the historical - dynamic integrative classification,basinogenesis and basins can be.di-vided into three types :oceanic crust type ,embryo-continental (transitional )crust type and continental crust type .Oceanic crust type can be subdivided into mobile region type (mainly tenskmal )and stable region type . Embryo-continental type includes pre-geosynclinal type (divisible into several mobile region types and stable region types with tensional type predominating among mobile region types ) and ear ly-geosynclinal type (mainly tenskmal ) .Continental crust type includes late- geosynclinal (fold belt)type (compressional or tenskmal ),platform type (mainly sinking and rarely tenskmal subsidence-aulacogen)and geodepression (diwa )type (compressional , tenskmal or compresskmal-tenskmal ).