Relationship between topography and the distribution of understory vegetation in a Pinus massoniana forest in Southern China

The poor growth of understory vegetation and the severe losses of soil and water in Pinus massoniana forests have recently become serious concerns in an area in southern China with eroded red soil.The influence of topography on the spatial distribution of vegetation,however,has received little attention.This study combined several multivariate analyses to discern the complicated relationship between understory vegetation and topography.Thirty-six plots(10 m×10 m)were sampled in a field survey of the vegetation and topography in the central red-soil region.The distributions of the understory vegetation differed significantly amongst the topographies.Most plants grew in gullies,and few grew on ridges.The low coverage(25.2%)and number of species(5 per plot)of the vegetation on ridges was due to serious soil erosion.Surface curvature and slope aspect were the first and second most important topographic factors,respectively,affecting the distribution of the vegetation.The relationship between topography and distribution could be described by a linear model.Surface curvature or slope aspect alone,however,could only explain 22.2-59.2%of the variance in distribution.The adaptation of vegetation to specific topographies should be considered for restorations of P.massoniana forests in the study area.The results of this study will be helpful for selecting potential sites for seeding and vegetation restoration to improve the ecology of the study area.Further studies will be needed to identify the mechanism of the distribution of the understory vegetation in these P.massoniana forests.

Spatial patterns of Pinus tabulaeformis and Pinus massoniana forests in Qinling-Daba Mountains and the boundary of subtropical and warm temperate zones

The Qinling Mountains is not only the geographical boundary between North and South China,but also the boundary between subtropical and warm temperate zones.It plays an important role in the geo-ecological pattern of China.However,there is controversy about the specific location of this geographical boundary in academic community due to the complexity,transition and heterogeneity of the transitional zone,as well as the differences in the delimitation indicators and research purposes.To further reveal the characteristics of the North-South transitional zone and clarify the specific location of the geo-ecological boundary between North and South China,combined with SRTM topographic data,temperature and precipitation data,Pinus massoniana forest and Pinus tabulaeformis forest,which represent subtropical coniferous forest in South China and temperate coniferous forest in North China respectively,were chosen to analyze their spatial distributions in the Qinling-Daba Mountains and the climatic conditions at their boundary with the climatic indexes of annual precipitation,the coldest month(January) average temperature,the warmest month(July) average temperature and the annual average temperature.The results show that:(1) Pinus massoniana and Pinus tabulaeformis forests and the climate indicators of their boundary can be used as one of the vegetation-climate indexes for the delimitation of subtropical and warm temperate zones.The boundary between the subtropical coniferous forest(Pinus massoniana forest) and temperate coniferous forest(Pinus tabulaeformis forest) is located along the south slope of Funiu Mountain to the north edge of Hanzhong Basin(the south slope of Qinling Mountains) at an altitude of 1000–1200 m,where the climatic indictors are stable:the annual precipitation is about 750–1000 mm,the annual average temperature is about 12–14℃,the coldest monthly average temperature is 0–4℃,and the warmest monthly average temperature is about 22–26℃.(2) It can be more scientifically to delimitate the boundary of subtropical and warm temperate zones in China by comprehensively considering the vegetation-climate indicators.Additionally,the boundary between subtropical and warm temperate zones in Qinling-Daba Mountains should be a transitional zone consisting of the boundaries of coniferous forests,broad-leaved forests and shrubs between subtropical and warm temperate zones.The results provide a scientific basis for the selection of delimitation index of subtropical and warm temperate zones.

Influences of Post-fires on Subsequent Population of Japanese Pine Sawyer Beetles, Monochamus alternatus Hope (Coleoptera: Cerambycidae) in Masson Pine Forests

[Objective]Both fire and insect outbreaks are considered as important natural disturbance factors in many forest ecosystems,yet few studies have addressed the effects of fires on subsequent insect outbreaks.[Method]In this paper,tree mortality,larval density and vertical distribution were measured through field investigation and sampling method to evaluate the short-term response of Japanese pine sawyer beetle,Monochamus alternatus Hope to Masson pine,Pinus massoniana Lamb.in the second year after the fire in Jiangxi Province,China.[Results]compared with unburned Masson pine forest,burned Masson pine forest suffered from higher tree mortality and more pine trees were attacked by M.alternatus.Burned Masson pine tended to harbor much higher larval density further up along the trunk than unburned pine trees,and most individuals distributed in the middle section and middle-lower section of the trunk.[Significance]The results confirmed that Masson pine forest after being damaged by non-lethal fires were more susceptible to attacks by Japanese pine sawyer beetles,displaying higher population density and higher vertical distribution position.The study will provide an important guideline for the managers of Masson pine forests suffering from fires and pest invaded areas.