Predicting plant invasiveness from native range size: clues from the Kashmir Himalaya

Aims In view of the growing interest in modelling the potential spread of invasive species,prediction of plant invasiveness on the basis of native range size holds considerable promise.Our objective was to use a simple model to evaluate whether a wider native range predisposes plant species to become invasive in non-native regions and to easily identify potential invaders on this basis.The Kashmir Himalayan alien flora,of which a large proportion is native to Europe,was used to test this model.Methods The Kashmir Himalayan alien flora comprises 436 species of vascular plants at different stages of invasion.We focussed on plant species at two critical invasion stages(sensu Colautti and MacIsaac 2004),i.e.Stage II(species that are just at the earliest phase of introduction)and Stage V(species that are widespread and dominant in the invaded region and are thus considered invasive).We used the territorial distribution in Europe(number of countries)as a surrogate for the native range size of plants of European origin.Important Findings Using a subset of 88 species,for which information on the native European range was available,we showed that a large proportion(68%)of Stage II species growing in the Kashmir Valley had a relatively restricted European range(present in<20 countries);on the other hand,77%of Stage V species had an extensive native range(present in>20 countries).We consequently hypothesized that 14 Kashmir Himalayan Stage II species of European origin that are distributed in>20 European countries are at risk of becoming future invaders in Kashmir.On the other hand,those Kashmir Himalayan Stage II species of European origin distributed in<20 European countries are less likely to become invasive.Although this analysis is quite simple,the data suggest that a wider native range is a good predictor of plant invasiveness and could be used as a simple and low-cost early warning tool in predicting potential invasive species.

Invasion by Conyza sumatrensis alters soil microbial community structure in urban ecosystems

Introduction:Whether invasive plants stimulate or inhibit the soil microbial diversity is still an open question.Despite large-scale invasion by Conyza sumatrensis(Retz.)E.Walker in the urban ecosystems of the Srinagar city of the Kashmir Himalayan region,limited information exists on its impact,particularly,on the belowground microbial diversity.The present study was thus conducted to compare the soil microbial(bacterial and ascomycetous fungal)diversity between the sites invaded by C.sumatrensis and un-invaded(control)sites.Methods:Soil metagenome was extracted from C.sumatrensis invaded and un-invaded plots at the three study sites.A total of six plots(5×5 m each in size),including three invaded by C.sumatrensis and three un-invaded plots were nested within each study site.DNA after amplification was subject to denaturing gradient gel electrophoresis(DGGE);the bands were extracted from the DGGE gel,re-amplified,and sequenced for identification of the species.Results:The number of bacterial species was reduced in the invaded plots at two out of the three sites while as it was relatively higher in the un-invaded plots with many species exclusively found in these plots.Fungal species richness was higher in the invaded plots compared to the un-invaded plots at all the three sites.Also,more fungal species were found to occur exclusively in the invaded plots without being represented in the un-invaded plots.Conclusions:Invasion by C.sumatrensis alters soil microbial community structure in the urban ecosystems in the Kashmir Himalaya.How this species does so and what benefits does it draw from such alteration promise to be an interesting future discourse.