Modelling the effect of environmental disturbance on community structure and diversity of wetland vegetation in Northern Region of Ghana

Abstract

The substantial variations in the anatomy, physiology and life-history trait of wetland plants tend to limit their ability to tolerate environmental stressors and can consequently affect their community composition and distribution. Comparative studies of wetland plants among water bodies of varying limnological characteristics are useful in understanding the different wetland plant communities’ responses to different environmental drivers. This study examined how community structural assemblages in six different tropical wetlands responded to environmental disturbances over a 1-year period (January–December 2017). They included three standing marshes (Kukobila, Tugu and Wuntori marshlands); two riparian systems (Adayili and Nabogo); and one artificial wetland (Bunglung). The prevalence index method was used to categorize plants as wetland or non-wetland species. Geometric series, individual-based rarefaction and Renyi diversity ordering models were applied to quantify community structural assemblages, while a direct ordination technique (CCA) was used to determine the how they respond to the influence of environmental factors. A total of 3034 individuals, belonging to 46 species from 18 families, were registered across the six wetlands. Grasses, herbs and woody species constituted 42.2%, 42.2% and 15.5%, respectively. Obligate species constituted 30.4%, while facultative wetland and obligate upland species were 47.8% and 26.1%, respectively. Wuntori marshland (n = 768) recorded the highest species per plot (18.73 ± 2.49), while Adayili riparian wetland (n = 260) was the least recorded (6.34 ± 1.80). Chrysopogon zizanioides, Echinochloa stagnina and Pennisetum polystachion were the most abundant species. Species assemblages were influenced by grazing, farming, fire, phosphorus, potassium and soil pH. These variables explained 61.29% of total variances in species abundance distribution, richness and diversity. The results highlight the threats on the wetlands and the need to protect them from further degradation.