科研之友
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摘要
The diversity of seed plants in Beiluo River Basin was identified through field investigation and statistical analysis of historical documents. Result: There were 1671 species of seed plants belonging to 581genera and 123 families in this area, accounting for 83.67%, 67.24% and 51.83% of the total seed plants in the Loess Plateau. of all the detected 1671 species, the majority (>65%) belonged to large (>50 species) and larger family (21~50 species), and more than half (~56%) belonged to single species genus and small genus (2~5 species). According to cluster analysis of the plant similarity for the 11main streams, 5groups were obtained, with Huanglong County as the firstly separated category, and the largest category including four geographical units, i.e. Fu County, Heshui County, Yijun County and Huangling County, which were all affected by the connection of Ziwuling mountains. The SD values of floristic richness of Fu County, Heshui County and Huanglong County were highest, while those of Luochuan County, Huachi County and Ganquan County were the lowest. There were 15 areal types and 16forms of geographical elements at the genus level in this area, which were dominated by the temperate distribution and its forms (287genera, accounting for 49.40%) and closely related to the tropical distribution and its forms (115 genera, accounting for 19.79%). There was a significant positive correlation between SD value of plant richness and temperate components. Huangling County, Luochuan County and Huanglong County had the highest R/T value and the strongest tropical property, while Huachi County and Dingbian County had the lowest R/T value and the weakest tropical property. The R/T value was affected by altitude and had a similar distribution pattern with temperature and precipitation decreasing from the southeast to the northwest. It is concluded that the plants in this area are important plant germplasm resources, because they have an ancient origin, a high degree of differentiation, rich species diversity and complex geographical elements. The transition pattern of plant species diversity zone is significant, which reflects the niche demands of these groups. Species of the six dominant families (Asteraceae, Poaceae, Rosaceae, Fabaceae, Lamiaceae and Ranunculaceae) that are suitable for the land and trees and grasses (temperate in nature) can be selected for vegetation restoration and soil erosion control.
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