Impacts of bark and foliage harvest on Khaya senegalensis (Meliaceae) reproductive performance in Benin

Published source details Gaoue O.G. & Ticktin T. (2008) Impacts of bark and foliage harvest on Khaya senegalensis (Meliaceae) reproductive performance in Benin. Journal of Applied Ecology, 45, 34-40.
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Summary

In the Saharan region, African mahogany Khaya senegalensis (Meliaceae) bark is an important local medicine for malaria and the foliage is cut by herders for livestock fodder. In order to assist conservation plans by determining sustainable non-timber forest product (NTFP) harvesting levels, this study assessed the impacts of combined bark and foliage harvests (at reduced and high harvest intensities) on K.senegalensis reproductive performance in Benin, West Africa.

Data was collected from 12 K.senegalensis populations spread across the Sudanian and (wetter) Sudano-Guinean ecological regions of Benin. Six had a history of high harvest intensity (>50% of trees pruned and >10% of trees debarked), six were subject to low/no harvest (<5% of trees pruned and <10% debarked). Harvesting categories were selected based on the intensities observed; no populations with intermediate harvest intensities were found, and only one non-harvested population was located (in the Sudano-Guinean region).

In each population, two 0.5-ha plots were established within which K.senegalensis trees with diameter at breast height (dbh) greater than 5 cm were sampled: dbh, height, trunk height, bark thickness, percentage of trunk debarked, number of branches, number of branches pruned and year since last pruning were recorded.

Estimates of i) fruit productivity (3-18 fruiting trees/population sampled, n = 94 trees; and average of 83% fruiting trees sampled/population); ii) seed productivity (for trees that had more than 10 fruits, 10 fruits were selected and the number of seeds/fruit counted); and iii) seed weight (average of 100 seeds), were made.

Fruit production: In the study years, trees produced more fruit and began fruiting at a smaller size in the Sudanian region than in the Sudano-Guinean region regardless of harvest intensity. High intensity pruning decreased fruit production significantly in the Sudanian region (c.210 fruit/tree low intensity; c.55/tree high intensity) but no such trend was apparent in the Sudano-Guinean region (c.45/tree low intensity; c.70/tree high intensity). Pruning also had a greater impact on fruit production in larger trees.

Seed production: In the Sudano-Guinean region, high harvest populations had more seed per individual fruit (50/fruit) than low harvest (43/fruit) populations. In the Sudanian region, seed produced per fruit appeared unaffected by harvest intensity (44/fruit low; 45/fruit high intensity).

Seed weight: There was a trend for the average weight of 100 seeds to be heavier in high harvest populations (Sudanian low - 14 g; high - 18 g; Sudano-Guinean low - 17 g; high - 20 g).

There were no significant effects of debarking or combined debarking and pruning on reproductive performance.

Note: The compilation and addition of this summary was funded by the Journal of Applied Ecology (BES). If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://www3.interscience.wiley.com/cgi-bin/fulltext/119392040/PDFSTART