Journal Articles

Asuk, SA, Matthews, TJ, Sadler, JP, Pugh, TAM, Ebu, VT, Ifebueme, NM, Kettridge, N (2023) Impact of human foraging on tree diversity, composition, and abundance in a tropical rainforest, Biotropica, 55(1), pp.232-245, ISSN: 0006-3606. DOI: 10.1111/btp.13180.

Nchor, AA and Asuk, SA (2018) Perception of the Status of Iko-Esai Community Forest, Akamkpa Local Government, Cross River State, Nigeria, Advances in Research, 17(5), pp.1-10, DOI: 10.9734/air/2018/42604.

Asuk, S and Nchor, A (2018) Challenges of Community-based Ecotourism Development in Southern Eastern Nigeria: Case Study of Iko Esai Community, Journal of Scientific Research and Reports, 20(1), pp.1-10, DOI: 10.9734/jsrr/2018/42603.

Asuk, SA, Etim Offiong, E, Ifebueme, NM, Okokon Akpaso, E (2018) Species composition and diversity of mangrove swamp forest in southern Nigeria, International International Journal of Avian & Wildlife Biology, 3(2), DOI: 10.15406/ijawb.2018.03.00078.

(2017) Array, 5(1), DOI: 10.15739/ijapr.17.002.

Bukie, J, Ebu, V, Asuk, S (2017) Effects of Farming Activities on the Population of Three Sympatric Species of Guenons in Afi Mountain Wildlife Sanctuary, Cross River State, Nigeria, Journal of Agriculture and Ecology Research International, 10(3), pp.1-8, DOI: 10.9734/jaeri/2017/30524.

Ogogo, AU, Asuk, SA, Ikpeme, RV (2014) Evaluation of the Anti-Poaching Programme of the Cross River National Park Okwango Division, Nigeria 2002 to 2013, Open Journal of Forestry, 04(05), pp.507-511, ISSN: 2163-0429. DOI: 10.4236/ojf.2014.45054.

Other

Meyer, BF, Darela-Filho, J, Gu, Q, Gregor, K, Krause, A, Papastefanou, P, Buras, A, Hesse, B, Asuk, SA, Liu, D, Grams, TEE, Zang, CS, Rammig, A (2024) Leaf conductance, isohydric strategy, and Ѱ50 shape drought responses of European tree species in a dynamic vegetation model, Increasingly frequent and intense drought events can jeopardize the current and future productivity and health of forests. Consequently, the ability of dynamic vegetation models (DVMs) to simulate drought impacts is paramount to improving their representation of the carbon cycle. To capture the physiological damage inflicted by drought, many state-of-the-art DVMs have implemented representations of plant hydraulic architecture in recent years. Although the understanding of the underlying processes governing hydrodynamic behavior in plants has steadily increased, the parameterization of hydraulic traits for different plant functional types (PFTs) remains a source of uncertainty in model output – in part due to limited data availability.    Here, we use LPJ-GUESS-HYD, an extension of LPJ-GUESS with new parameters and processes to simulate plant hydraulic architecture, isohydrodynamic water-potential regulation, and hydraulic failure mortality. Using latin hypercube sampling we create 6000 sets of hydraulic parameter combinations based on values found in the literature. Based on these parameter sets, we conduct a comprehensive variance-based sensitivity analysis for a set of 12 common European tree species across 37 sites from the FLUXNET 2020 warm winter dataset, encompassing a wide range of European ecosystems. Subsequently, we determine which parameters and parameter interactions contribute the most to variations in model outputs.    Our results indicate that of the seven parameters used in the hydraulic architecture model of LPJ-GUESS-HYD, only a few have a significant effect on the model outcomes. More specifically, Ѱ50, the water potential at which 50 percent of conductance is lost, and maximum specific leaf conductance had the largest impact on simulated processes. Parameters related with the isohydric strategy of plants, had a lesser but still substantial role in shaping the model output.    These results suggest that certain hydraulic parameters – and combinations thereof –  play a disproportionate role in modulating simulated forest fluxes and states in LPJ-GUESS-HYD. Specific parameterization choices can drastically alter model performance, including whether PFTs can survive in a given climate or not. Aside from encouraging careful consideration of the available trait data when parameterizing new PFTs, our results may guide future experiments in choosing which hydraulic traits to focus on.. DOI: 10.5194/egusphere-egu24-8421.

Asuk, S, Kettridge, N, Sadler, J, Pugh, T, Matthews, T, Ebu, V, Ifebueme, N (2021) Does foraging impact tropical forest composition?, <p>Growing evidence suggests that low-intensity anthropogenic activities affect ecological communities. The resultant changes in the forest structure and composition can also be influenced by elevational gradients. During foraging for food collection, humans can cover a wider spatially and elevational range compared to other high-intensity activities. These foraging activities can alter the species richness and evenness patterns either through preferential planting or intentionally or inadvertently influence the propagule pool. This study investigated the impact of foraging on forest composition and structure along an elevation gradient in Cross River National Park in the tropical rainforest zone of Nigeria. Fifteen permanent 40 x 40 m sample plots, covering an area of 2.4 hectares, were established in the forest located in the park along an elevational gradient of 120m to 460m. All trees of 10cm diameter at breast height (dbh) and above in all the plots were measured for dbh and identified to species level. Structured questionnaires on tree species utilization amongst forest-dependent rural communities were used to create edible and inedible tree species categories. Species abundance distributions were calculated at community level. Pairwise beta diversity between all plots along the elevational gradient was calculated using Sorensen’s dissimilarity index (β<sub>sor</sub>) and the turnover component of β<sub>sor</sub> using Simpson’s dissimilarity index (β<sub>sim</sub>). A total of 35 edible species with a density of 128 stems/hectare and basal area of 11.99 m<sup>2</sup>/ha and 109 inedible species with a density of 364 stems/hectare and basal area of 22.42 m<sup>2</sup>/hectare were encountered. A reversed j-shaped function characteristic of a ‘natural’ uneven-aged tropical forest stand was observed in the diameter size distribution for all species categories. The pairwise beta diversity trend of inedible species showed that there was a positive trend between beta diversity and elevation, and this was driven by turnover; the replacement of species in the species pool along the elevational gradient. In comparison, edible species differed significantly from inedible species and showed a negligible trend indicating that the species turnover was not enough to cause a change in beta diversity with increase in elevation. These results suggest that low-impact activities such as foraging may be subtly but notably altering the composition of tropical forest, perhaps by preferential planting, or influencing the propagule pool along elevational gradients. Further tests across a wider range of sites are required to assess if this is a widespread phenomenon and to identify the driving mechanisms.</p>. DOI: 10.5194/egusphere-egu21-8867.