Can species richness be maintained in logged endemic Acacia Heterophylla forests (Reunion Island, Indian Ocean) ?

It is assumed that forests can serve multiple uses, including wood production and maintenance of high biodiversity level. We tested this hypothesis by studying eradication methods of invasive plants currently implemented in exploited endemic Acacia heterophylla forests located in a tropical highland forest region on the island of Réunion. We also compared species richness in logged (over time) and natural forests. Our results show that all individuals of the widespread alien invasive plant Rubus alceifolius were generated from cuttings. We quantifi ed the high growth capability of this species by comparing with those of Acacia heterophylla along with Rubus apetalus var. apetalus, a close non-invasive congener. The substantial multiplicative and vegetative growth ability of R. alceifolius enabled it to form monospecific patches in only 2.5 years. The species richness of the exploited Acacia heterophylla forest was thus very affected. Although the species richness increased over time after logging, the extent of the resulting richness was not as great as that in natural forests which, moreover, included numerous exotic plants. The authors assess the impact of highly disturbing logging operations and, based on the results of the comparisons, are very pessimistic about the possibility of maintaining species richness in logged forests. Nevertheless, the results indicate that the situation is not beyond hope and an eradication program specifi cally tailored to this kind of forest is proposed if exploitation will stop

Morphometric variation of leaves of Aphloia theiformis along an altitudinal gradient on La Réunion Island

The variation in length (L), width (l), shape index (L/l) and estimated area (2/3 L × l) of leaves of Aphloia theiformis (Flacourtiacées) has been analysed on a sample of 200 individuals along an altitudinal gradient on La Réunion Island (Mascarene archipelago). Leaf area and altitude are not correlated, but the former slightly decreases with the height of the vegetation (R = 0.254 ; P < 0.001). Leaf shape index decreases more acutely with the altitude (R = 0.579 ; P < 0.001). At this specifi c level, the altitude does not determine the variation of the leaf area, which remains partially linked with the vegetation structure. On the other hand, the altitude seems to determine more strongly the variation of the leaf shape inde

La Possession, Saint-Paul – Rivière des Galets, paléoforêt

La paléoforêt de la Rivière des Galets est localisée dans le lit du cours d’eau du même nom, un kilomètre en amont des Deux Bras, aux portes du cirque de Mafate. Il s’agit d’un ensemble remarquable de troncs d’arbres morts, conservés dans les sédiments de la rivière à l’état de bois organique, c’est pourquoi l’on parle de « paléoforêt » et non de «forêt fossile», la matière n’étant pas minéralisée. Le site a été remis au jour par une crue exceptionnelle, à la suite d’un événement cyclonique r..