No abstract

Questions: How has the composition and diversity of canopy tree species in a riparian woodland changed over time? How are the compositional changes related to impact of elephants? Does the composition of juvenile plants indicate that the woodland retains the potential to recover its former composition? Location: Northern Botswana adjoining the Linyanti River. Methods: We assessed the species composition of the riparian woodland in 2007/2008 along belt transects, recording living and dead individuals in different size classes plus signs of elephant damage and the presence of juvenile plants. We related this current composition to the composition recorded in a previous survey in 1991/1992 and reconstructed the earlier composition by combining living and dead trees recorded in 1991/1992. We established the association between mortality and impact agent, severity, year and size class using model selection statistics. Changes in species diversity were assessed using the Shannon diversity index. Results:The composition of canopy trees changed from the initial dominance of two Acacia spp. towards the current situation with these two species forming <5% of the woodland canopy. Dead trees were strongly associated with severe damage inflicted by elephants, including bark stripping and felling. As the acacia trees declined, elephant impacts shifted onto other canopy tree species. The woodland canopy became progressively more open because recruitment from juvenile and sapling stages to replace trees that had died was also suppressed. Nevertheless, the tree species that had decreased in abundance in the canopy remained abundant as juvenile plants. Conclusion: Substantial changes in woodland composition can occur in the presence of high elephant concentrations because of the selective damage that elephants impose on particular tree species and size classes. The loss of functionally important species may not be reflected by changes in compositional diversity measures. K E Y W O R D S Acacia, Chobe National Park, Colophospermum mopane, debarking, demographic bottleneck, disturbance, diversity, elephant impact, non-equilibrium, regeneration, wind throw 586 | Journal of Vegetation Science TEREN ET al.

Fynbos is a unique endemic vegetation type belonging to the Cape Floral Kingdom in the Western Cape Province of South Africa, representing the smallest of the six floral kingdoms in the world. Nowadays, only a few game reserves in this region support populations of African elephants (Loxodonta africana), and thus, little information exists regarding the suitability of the nutritionally poor Fynbos vegetation for these megaherbivores. Using already established non-invasive methods, the monitoring of individual body conditions and fecal glucocorticoid metabolite (fGCM) concentrations, as a measure of physiological stress, was performed to examine a herd of 13 elephants in a Western Cape Province Private Game Reserve, during two monitoring periods (April and June 2018), following a severe drought. The results indicate that overall median body condition scores (April and June: 3.0, range 2.0–3.0) and fGCM concentrations (April: 0.46 µg/g dry weight (DW), range 0.35–0.66 µg/g DW; June: 0.61 µg/g DW, range 0.22–1.06 µg/g DW) were comparable to those of other elephant populations previously studied utilizing the same techniques. These findings indicate that the individuals obtain sufficient nutrients from the surrounding Fynbos vegetation during the months monitored. However, a frequent assessment of body conditions and stress-associated fGCM concentrations in these animals would assist conservation management authorities and animal welfare practitioners in determining ways to manage this species in environments with comparably poorer nutritional vegetation.