Browsing by Author "Harris, DJ"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item Open Access From town to national park: Understanding the long-term effects of hunting and logging on tree communities in Central Africa(Forest Ecology and Management, 2021-11-01) Maicher, V; Clark, CJ; Harris, DJ; Medjibe, VP; Poulsen, JRAnthropogenic disturbances are changing the structure and composition of tropical forests worldwide. Multiple disturbances often occur simultaneously in forests. Hunting and logging, for example, are within-forest disturbances that impact vast areas of seemingly intact rainforests. Despite recent work on the individual effects of these disturbances, our understanding of how they interact to influence tree communities is still limited. In northern Republic of Congo, we explored the effects of hunting and logging on tree communities. Over an 8-year period, we monitored 12,552 tree stems (≥10 cm diameter-at-breast height) spread over 30 1-ha plots along a gradient of human disturbance to compare the tree diversity between hunted and logged forest, once-logged forest, and protected forest free of both disturbances. Tree density, species richness, and community composition were affected by both hunting and logging. Forest close to human settlements was richer, more heterogenous, and more dynamic in species composition across censuses. In hunted and logged forest, fast-growing secondary species with low shade tolerance replaced old growth species. Comparatively, the once-logged forest had the greatest stem density and intermediate species richness with an increased density of shade-bearing species over time. Both tree species spatial turnover and tree recruitment were greatly affected by proximity to human settlements. A shift towards abiotically dispersed trees and increasing seed predation by rodents near villages can partly explain the differences in tree recruitment across the forest types. The combination of hunting and logging seems to have a greater impact on tree communities than either single disturbance, especially with nearness to villages.Item Open Access The global abundance of tree palms(Global Ecology and Biogeography, 2020-09-01) Muscarella, R; Emilio, T; Phillips, OL; Lewis, SL; Slik, F; Baker, WJ; Couvreur, TLP; Eiserhardt, WL; Svenning, JC; Affum-Baffoe, K; Aiba, SI; de Almeida, EC; de Almeida, SS; de Oliveira, EA; Álvarez-Dávila, E; Alves, LF; Alvez-Valles, CM; Carvalho, FA; Guarin, FA; Andrade, A; Aragão, LEOC; Murakami, AA; Arroyo, L; Ashton, PS; Corredor, GAA; Baker, TR; de Camargo, PB; Barlow, J; Bastin, JF; Bengone, NN; Berenguer, E; Berry, N; Blanc, L; Böhning-Gaese, K; Bonal, D; Bongers, F; Bradford, M; Brambach, F; Brearley, FQ; Brewer, SW; Camargo, JLC; Campbell, DG; Castilho, CV; Castro, W; Catchpole, D; Cerón Martínez, CE; Chen, S; Chhang, P; Cho, P; Chutipong, W; Clark, C; Collins, M; Comiskey, JA; Medina, MNC; Costa, FRC; Culmsee, H; David-Higuita, H; Davidar, P; del Aguila-Pasquel, J; Derroire, G; Di Fiore, A; Van Do, T; Doucet, JL; Dourdain, A; Drake, DR; Ensslin, A; Erwin, T; Ewango, CEN; Ewers, RM; Fauset, S; Feldpausch, TR; Ferreira, J; Ferreira, LV; Fischer, M; Franklin, J; Fredriksson, GM; Gillespie, TW; Gilpin, M; Gonmadje, C; Gunatilleke, AUN; Hakeem, KR; Hall, JS; Hamer, KC; Harris, DJ; Harrison, RD; Hector, A; Hemp, A; Herault, B; Pizango, CGH; Coronado, ENH; Hubau, W; Hussain, MS; Ibrahim, FH; Imai, N; Joly, CA; Joseph, S; Anitha, K; Kartawinata, K; Kassi, J; Killeen, TJAim: Palms are an iconic, diverse and often abundant component of tropical ecosystems that provide many ecosystem services. Being monocots, tree palms are evolutionarily, morphologically and physiologically distinct from other trees, and these differences have important consequences for ecosystem services (e.g., carbon sequestration and storage) and in terms of responses to climate change. We quantified global patterns of tree palm relative abundance to help improve understanding of tropical forests and reduce uncertainty about these ecosystems under climate change. Location: Tropical and subtropical moist forests. Time period: Current. Major taxa studied: Palms (Arecaceae). Methods: We assembled a pantropical dataset of 2,548 forest plots (covering 1,191 ha) and quantified tree palm (i.e., ≥10 cm diameter at breast height) abundance relative to co-occurring non-palm trees. We compared the relative abundance of tree palms across biogeographical realms and tested for associations with palaeoclimate stability, current climate, edaphic conditions and metrics of forest structure. Results: On average, the relative abundance of tree palms was more than five times larger between Neotropical locations and other biogeographical realms. Tree palms were absent in most locations outside the Neotropics but present in >80% of Neotropical locations. The relative abundance of tree palms was more strongly associated with local conditions (e.g., higher mean annual precipitation, lower soil fertility, shallower water table and lower plot mean wood density) than metrics of long-term climate stability. Life-form diversity also influenced the patterns; palm assemblages outside the Neotropics comprise many non-tree (e.g., climbing) palms. Finally, we show that tree palms can influence estimates of above-ground biomass, but the magnitude and direction of the effect require additional work. Conclusions: Tree palms are not only quintessentially tropical, but they are also overwhelmingly Neotropical. Future work to understand the contributions of tree palms to biomass estimates and carbon cycling will be particularly crucial in Neotropical forests.