Differences in arthropod communities between island and inland Masson pine forests infested by pine wilt disease in Zhejiang Province

The invasion of Bursaphelenchus xylophilus （pine wood nematode, PWN） carried by Monochamus alternatus predominately attacks Masson pine （Pinus massoniana） forests and causes great economic losses in China. In this study, we assessed whether the effect of the invasion of PWN is different between island and inland forests. Arthropods were sampled in Fuyang （inland） and Zhoushan （island） counties in Zhejiang Province with sweep netting and light traps at four plots. During two field periods （May to June 2004 and September to October 2005） a total of 21,916 insects, representing 384 species belonging to 99 families and 15 orders, were collected in the sample plots from the island, whereas, from the inland forest a total of 29,262 insects, representing 308 species belonging to 96 families and 13 orders, were found. A hierarchical cluster analysis （HCA） and one-way ANOVA, based on the composition of different arthropod guilds, were performed. The results showed that there was no significant difference in the composition of arthropod communities at the family level between inland and island. But these two habitats had a significant effect on the composition of species, individuals, sub-communities and energy class levels. Statistically, the composition of the two orders, Lepidoptera and Diptera, in the two habitats were significantly different.

Demographic mechanisms of disturbance and plant diversity promoting the establishment of invasive Lupinus polyphyllus

Aims Community characteristics,such as disturbances and interspecific competition that affect the availability of microsites and resources,contribute to the success or failure of the establishment of exotic plant species.In particular,these two community characteristics may have adverse effects on plant emergence and survival,which are particularly important for population establishment and there-fore it may be necessary to consider both these vital rates simul-taneously when assessing demographic mechanisms.Here,we investigated the impacts of disturbance and interspecific compe-tition on the establishment of a perennial invasive herb,Lupinus polyphyllus Lindl.Methods Over the course of 2 years,we conducted an experiment in 10 populations of this species in Finland in which we manipulated the levels of soil disturbance.We recorded community charac-teristics(i.e.the number of vascular plant species,vegetation height,and the proportions of bare ground,litter and moss),and observed the emergence and survival of L.polyphyllus individuals in study plots.Important Findings A mild disturbance(breaking the soil surface mechanically)slightly increased seedling emergence but did not affect plant survival.Instead,an intense disturbance(vegetation and litter removal)had no effect on seedling emergence,although it significantly increased the proportion of bare ground and,consequently,seedling survival.Survival was not affected by the height of the surrounding vegetation,but both seedling emergence and plant survival increased with an increasing number of plant species in the study plots.These find-ings demonstrate that single disturbance events may considerably promote the establishment of invasive herbs,although the overall effect and demographic mechanisms behind the increased establish-ment are likely to vary depending on disturbance type.Moreover,our results suggest that species diversity per se may not be a crucial mechanism for locally preventing the establishment of exotic plants.