Population structure and dynamic characteristics of five wild Viburnum plants in Southwest Hubei, China

To explore the population quantitative characteristics and regional distribution of wild Viburnum plants in Southwest Hubei, and reveal the survival status and development trend of the following five Viburnum species: V. erosum, V. betulifolium, V. sympodiale, V. setigerum and V. dilatatum. A total of 27 hm2 dynamic monitoring stands were set up in Jinzi Mountains National Forest Farm, Mulinzi National Nature Reserve and Qizimei Mountains National Nature Reserve in Southwest Hubei. The age structure, dynamic quantitative analysis and static life table of five Viburnum species were used to explore the population structure, dynamic characteristics and future development potential of Viburnum plants. The results were as follows: (1) The distribution area and population size of Viburnum plants in Southwest Hubei were significantly different. (2) The age structure of the five Viburnum species displayed as the pyramidal type summarized from population structure and dynamic analysis. The number of individuals of each population was large at the young stage (89.48% of V. erosum in Jinzi Mountains, 76.38% of V. betulifolium, 67.24% of V. erosum in Mulinzi, 62.11% of V. dilatatum, 56.53% of V. sympodiale, 58.44% of V. setigerum), and only a small proportion of individuals (0.18% of V. erosum in Jinzi Mountains, 0.85% of V. betulifolium, 3.29% of V. erosum in Mulinzi, 3.97% of V. dilatatum, 8.37% of V. sympodiale, 2.79% of V. setigerum) at the old stage. The young stage plants of five Viburnum species all had strong growth potentials but were sensitive to external disturbances. (3) The survival quantity of the five Viburnum species was decreasing monotonically with increasing age class presented by static life tables. Except for V. setigerum, the life expectancy reached peak at the young age, all the other Viburnum species populations reached the peak at the middle age. The change trend of mortality rate and vanish rate were similar, but the fluctuation of vanish rate and mortality rate curves were different among different species. The survival curves were tended to be Deevey-Ⅱ type. (4) The four survival function curves showed that all five Viburnum species populations exhibited a substantial decrease at the early stage, stabilization at the middle stage, and decline at the late stage. To sum up, plant resources of Viburnum species are abundant in Southwest Hubei. Therefore, it is scientific and feasible to exploit Viburnum plants rationally. At the young stage, artificial thinning can be carried out appropriately to improve the preserving rate. During the stable middle stage, the dominant species which have good ornamental characters can be selected for appropriate development and utilization. However, some species need to be protected to maintain biodiversity in this area.