Influence of Gap Size on Regeneration, Structure and Species Diversity of Woody Vegetation in a Secondary Montane Forest Reserve, Kenya

Jemimah Achieng Ocholla *

Department of Natural Resources, Faculty of Environment and Resource Development, Egerton University, P.O.Box 536-20115, Kenya.

Gilbert Obati Obwoyere

Department of Natural Resources, Faculty of Environment and Resource Development, Egerton University, P.O.Box 536-20115, Kenya.

Shadrack Kinyua Inoti

Department of Natural Resources, Faculty of Environment and Resource Development, Egerton University, P.O.Box 536-20115, Kenya.

*Author to whom correspondence should be addressed.


South-Western (SW) Mau forest reserve has been experiencing anthropogenic and natural disturbances creating canopy openings in the forest. The objective of this study was to determine how these canopy openings influence regeneration, forest structure and species diversity. The study employed nested sampling design in disturbed sites of the forest reserve. Plots of 500 by 500 m were laid once at 100 m inwards from the forest edge in the three blocks of SW Mau; Ndoinet, Maramara and Itare. Gaps were randomly identified in the plots and gap area calculated using Ellipse Method (EM). Gap sizes were categorized based on area (m2). Woody species surrounding the gaps were identified and names inventoried. To determine regeneration, two quadrats of 5 by 5 m and 1 by 1 m were randomly delineated in every gap size four times and eight times for saplings (1-3 m high) and seedlings (<1 m high), respectively. Tree heights surrounding the gaps were measured using suunto clinometer. Diameter at breast height (dbh) was measured using diameter caliper (65 cm for small trees) and diameter tape for large trees (dbh> 65 cm). A total of 41 gaps were identified with small gap sizes dominating (23). Kruskal-Wallis rank sum test indicated non-significant differences in regeneration, forest structure and species diversity in the three gap sizes.

This was attributed to Piper capensis which invaded medium and large gap sizes creating a closed canopy. It was, therefore, concluded that canopy cover from the invasive species influenced woody vegetation parameters in the gap sizes. It is, therefore, recommended to clear the dense ground cover to allow better natural regeneration and also enrichment planting in the gaps.

Keywords: Canopy cover, canopy openings, disturbed sites, ellipse method, piper capensis, vegetation parameters

How to Cite

Ocholla, J. A., Obwoyere, G. O., & Inoti, S. K. (2022). Influence of Gap Size on Regeneration, Structure and Species Diversity of Woody Vegetation in a Secondary Montane Forest Reserve, Kenya. Asian Journal of Environment & Ecology, 19(3), 20–31.


Download data is not yet available.


Bewernick T. Mapping forest degradation in the Mau Forest Complex using NDFI time series. MSc Thesis Dissertation Wagening Univ Res Cent Neth. 2016;9–26.

Kimutai DK, Watanabe T. Forest-cover change and participatory forest management of the lembus forest, Kenya. Environments. 2016;3(3):20.

Chaudhry S. Politics of land excisions and climate change in the Mau Forest Complex: A case study of the SouthWestern Mau Forest. J Sustain Environ Peace. 2019;1(2):52–62.

Černecká L, Mihál I, Gajdoš P, Jarčuška B. The effect of canopy openness of European beech (Fagus sylvatica) forests on ground-dwelling spider communities. Insect Conserv Divers. 2020;13(3):250–61.

Cerqueira AF, Rocha-Santos L, Benchimol M, Mielke MS. Habitat loss and canopy openness mediate leaf trait plasticity of an endangered palm in the Brazilian Atlantic Forest. Oecologia. 2021;196(3):619–31.

Mutugi M, Kiiru W. Biodiversity, Local Resource, National Heritage, Regional Concern and Global Impact: The Case of Mau Forest, Kenya. Eur Sci J. 2015; 1:681–91.

Ronoh DK, Sirmah PK, Hitimana J, Mullah CJA. Variation in Regeneration Density and Population Structure of Prunus africana Across Human Disturbance Gradient in South West Mau Forest, Kenya. Int J Nat Resour Ecol Manag. 2018;3(1):1–8.

Johnson DJ, Magee L, Pandit K, Bourdon J, Broadbent EN, Glenn K. Canopy tree density and species influence tree regeneration patterns and woody species diversity in a longleaf pine forest. For Ecol Manag. 2021; 490:1–10.

Przepióra F, Loch J, Ciach M. Bark beetle infestation spots as biodiversity hotspots: Canopy gaps resulting from insect outbreaks enhance the species richness, diversity and abundance of birds breeding in coniferous forests. For Ecol Manag. 2020; 473:1–11.

Feldmann E, Drößler L, Hauck M, Kucbel S, Pichler V, Leuschner C. Canopy gap dynamics and tree understory release in a virgin beech forest, Slovakian Carpathians. For Ecol Manag. 2018; 415:38–46.

Diaci J, Rozman J, Rozman A. Regeneration gap and microsite niche partitioning in a high alpine forest: Are Norway spruce seedlings more droughttolerant than beech seedlings? For Ecol Manag. 2020; 455:21–30.

Hammond ME, Pokornỳ R. Diversity of Tree Species in Gap Regeneration under Tropical Moist Semi-Deciduous Forest: An Example from Bia Tano Forest Reserve. Diversity. 2020;12(8):301.

Zhu J jun, Matsuzaki T, Lee F Qin, Gonda Y. Effect of gap size created by thinning on seedling emergency, survival and establishment in a coastal pine forest. For Ecol Manag. 2003;182(1–3): 339–54.

Kinjanjui JM, Karachi M, Ondimu KN. Natural regeneration and ecological recovery in Mau Forest complex, Kenya. Open J Ecol. 2013;3(6):417–21.

Wanyama I, Pelster DE, Arias-Navarro C, Butterbach-Bahl K, Verchot LV, Rufino MC. Management intensity controls soil N2O fluxes in an Afromontane ecosystem. Sci Total Environ. 2018; 624:769–80.

Butynski TM, De Jong YA. South Western Mau Forest Reserve Game-Proof Barrier Feasibility Study. Nairobi Initiat Sustain Landsc ISLA. 2016;172–6.

Githumbi EN, Courtney Mustaphi CJ, Marchant R. Late Pleistocene and Holocene Afromontane vegetation and headwater wetland dynamics within the Eastern Mau Forest, Kenya. J Quat Sci. 2021;36(2):239–54.

De Lima RAF. Gap size measurement: the proposal of a new field method. For Ecol Manag. 2005;214(1–3):413–9.

Holdridge LR, Grenke WC. Forest environments in tropical life zones: a pilot study. For Environ Trop Life Zones Pilot Study. 1971;739–47.

Shannon CE. A mathematical theory of communication. Bell Syst Tech J. 1948;27(3):379–423.

Xia Y. Correlation and association analyses in microbiome study integrating multiomics in health and disease. Chapter Eleven. In: Sun J, editor. Progress in Molecular Biology and Translational Science [Internet]. Academic Press; 2020; 171: 309–491. [cited 2022 Aug 29].

Devagiri GM, Khaple AK, Mohan S, Venkateshamurthy P, Tomar S, Arunkumar AN. Species diversity, regeneration and dominance as influenced by canopy gaps and their characteristics in tropical evergreen forests of Western Ghats, India. J For Res. 2016;27(4):799–810.

Guo Y, Zhao P, Yue M. Canopy disturbance and gap partitioning promote the persistence of a pioneer tree population in a near-climax temperate forest of the Qinling Mountains, China. Ecol Evol. 2019;9(13):7676–87.

Song X, Hogan JA, Lin L, Wen H, Cao M, Yang J. Canopy openness and topographic habitat drive tree seedling recruitment after snow damage in an oldgrowth subtropical forest. For Ecol Manag. 2018; 429:493–502.

Tinya F, Márialigeti S, Bidló A, Ódor P. Environmental drivers of the forest regeneration in temperate mixed forests. For Ecol Manag. 2019; 433:720–8.

Velázquez E, Wiegand T. Competition for light and persistence of rare lightdemanding species within tree-fall gaps in a moist tropical forest. Ecology. 2020;101(7):1–11.

Zhang M, Yi X. Seedling recruitment in response to artificial gaps: predicting the ecological consequence of forest disturbance. Plant Ecol. 2021;222(1): 81–92.

Zhang T, Yan Q, Wang J, Zhu J. Restoring temperate secondary forests by promoting sprout regeneration: effects of gap size and within-gap position on the photosynthesis and growth of stump sprouts with contrasting shade tolerance. For Ecol Manag. 2018; 429:267–77.

Kovács B, Tinya F, Németh C, Ódor P. Unfolding the effects of different forestry treatments on microclimate in oak forests: results of a 4-yr experiment. Ecol Appl. 2020;30(2):1–14.

Fotis AT, Morin TH, Fahey RT, Hardiman BS, Bohrer G, Curtis PS. Forest structure in space and time: Biotic and abiotic determinants of canopy complexity and their effects on net primary productivity. Agric For Meteorol. 2018; 250:181–91.

Kovács B, Tinya F, Guba E, Németh C, Sass V, Bidló A. The short-term effects of experimental forestry treatments on site conditions in an oak–hornbeam forest. Forests. 2018;9(7):1–17.

Lu D, Zhang G, Zhu J, Wang GG, Zhu C, Yan Q. Early natural regeneration patterns of woody species within gaps in a temperate secondary forest. Eur J For Res. 2019;138(6):991–1003.

Edwards RB, Naylor RL, Higgins MM, Falcon WP. Causes of Indonesia’s forest fires. World Dev. 2020; 127:1–12.