Study On Root Sucker Process And Herbaceous Characteristics Of Populus Hopeiensis In Northern Shaanxi Loess Area

Populus hopeiensis is an important native tree species in northern Shaanxi loess area. Research on the process of Populus hopeiensis root sucker has theoretical and practical significance to the establishment of plantation which is stable and sustainable in this area. This research obtained tree age composition of Populus hopeiensis by establishing the relation model between tree age and diameter of Populus hopeiensis natural forest in northern Shaanxi loess area, and calculated the speed, range and direction of root sucker process of Populus hopeiensis. In addition, this research also compared the differences of root sucker process and herbaceous biomass, species composition, diversity in different Populus hopeiensis stand age and different slope aspect, then grasped the pattern of Populus hopeiensis root sucker. The results showed that:(1) The root sucker of Populus hopeiensis in Northern shaanxi loess area was in a vigorous period in development process. In 30 years after the begining of root sucker, the quantity of individuals in natural forest increase exponentially with the growing of Populus hopeiensis stand age, and the total root sucker range can be 20 m or so. In the aspect of root sucker direction, we found that the quantity of individuals which developed downward along the slope was 1.7 times of the quantity of individuals which developed upward.(2) The development of Populus hopeiensis root sucker in Northern shaanxi loess area will slowing down with the growing of Populus hopeiensis stand age, and the composition of Populus hopeiensis forest will tend to be stable. In aspect of site conditions, the root sucker degree of Populus hopeiensis on half-sunny slope was faster and stronger than Populus hopeiensis forest on shady slope and half shaded slope, but growth and development of the individuals were slowly.(3) The dominant families of herbaceous plant under Populus hopeiensis natural forest in Northern shaanxi loess area was Asteraceae, Grass, Legume and so on. The dominant species of herbaceous plant under Populus hopeiensis includes Artemisia sacrorum, Cyperus rotundus, Carex rigescens, Glycyrrhiza uralensis, Potentilla acaulis, Leymus secalinus and so on. The stable community in process of succession under Populus hopeiensis natural forest is a community mainly composed by perennial herbaceous of Legume and Asteraceae with length and higher biomass. With the growing of Populus hopeiensis stand age, community diversity and evenness of herbaceous plant under Populus hopeiensis will be reduced. In aspect of site conditions, community diversity and evenness of herbaceous plant under Populus hopeiensis forest on half-sunny slope was higher than that is on shady slope and half shaded slope.