Influence of exotic plant invasions on the structure and functional attributes of native ecosystems has been extensively documented and debated. The complex interactions of invasive species with native ecosystems make invasion ecology an interesting and important area of research. Prosopis julifora native to south and central America was introdouced in India to meet the fuel-wood requirements of the rural poor and to restore degrated lands. Now, it has become an aggressive weed in several parts of the country and poses a serious threat to native biodiversity.

We coordinated biogeographical comparisons of the impacts of an exotic invasive tree in its native and non-native ranges with a congeneric comparison in the non-native range. Prosopis juliflora is taxonomically complicated and with P. pallida forms the P. juliflora complex. Thus we sampled P. juliflora in its native Venezuela, and also located two field sites in Peru, the native range of Prosopis pallida. Canopies of Prosopis juliflora, a native of the New World but an invader in many other regions, had facilitative effects on the diversity of other species in its native Venezuela, and P.

C. Jaishankar
Prosopis juliflora is invading the coastal marine system

Silent invasion: A man trying to cut

Differences in foliage tissue concentration of elements were assessed for Prosopis juliflora, Calotropis gigantia and Ipomoea fistulosa growing on abandoned fly ash and a control soil. In general, plants from the fly ash exhibited reduced concentrations of N, K, Ca, Mg, S and Mn while elevated trace element concentration in comparison to the control.

Mining is generally followed by a revegetation programme carried by the Forest Department. In such programmes, often exotic plant species are also used along with native tree species. Since the last one and half decades an exotic tree species, Prosopis juliflora has gained tremendous popularity among forest officials due to its easy establishment, low mortality rate and fast growth rate on mine spoil, compared to other woody species.

The hot arid regions of India in economically and environmentally disadvantaged part of the country with unique problems. These, ecosystems are highly fragile and large liabilities causing severe impediments in development programmes.

Deforestation for free

J K Tiwari and Asad R Rahmani profile a tree that is changing the face of Kutch

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