Biodiversity Monitoring
Species observations, surveys, monitoring sites and indicators.
Biodiversity Indicators
Biodiversity assessments are carried out by several mandated institutions: KWS for wildlife, NMK for biodiversity hotspots, and research and academic institutions. Because trees are a significant indicator of forest biodiversity, the NFMS bases its biodiversity assessment on the NFI design: species, size, form, health and location of trees in each plot.
| Biodiversity indicator | purpose for monitoring | Methodology for monitoring |
|---|---|---|
| Abundance by numbers | Identifies the number of trees identified in a forest. Noting the uneven distribution of trees in forests, a forest with more trees is better stocked compared to one with less trees | Abundance is derived from the total number of individuals recorded in a forest |
| Species richness | Identifies how many species are found in a forest. A forest with more species is richer and has a wider variety | Species richness is calculated from total number of species in a forest |
| Relative abundance | Identifies the contribution of a species to the total population of a forest. A species with more numbers in the population has a higher relative abundance. Such a species may not be threatened by overuse in that forest | Calculated from the total number of individuals of each species as a fraction of the total population |
| Relative frequency | Identifies the distribution of a species among sample sites. A species that is recorded in most sample sites is well distributed and can be described as adaptable to different ecological conditions or different levels of anthropological/natural stress | Calculated from the total number of samples a species is recorded as a proportion of the total number of sample sites |
| Relative dominance | Identifies the contribution of a species to the total basal area of a forest. Large trees with more basal area normally form the dominant trees in the forest and may comprise emergent/top canopy trees, mother trees for seed production. They may also influence water catchment and are major hosts of biodiversity. | Calculated from the total basal area of a species as a proportion of the total forest biomass |
| Importance Value Index | This is a combined index that caters for relative abundance, relative frequency and relative dominance and indicates the overall dominance of a species based on several indicators | Calculated as the sum of relative abundance + relative frequency + relative dominance per species[^7] |
| Species similarity | Forests exists as associations where certain group of species grow together. A forest with a wide variety of associations deviates from monoculture characteristics and therefore host more biodiversity | Calculated from a variety of similarity indices e.g. Sorenson’s[^8] or Jacard’s[^9] indices |
| Diversity | Diversity of species in a forest explain the variety of roles the forest has. This variety includes the opportunities for hosting flora and fauna as well as microorganisms | The most commonly used index for species diversity is the Shannon- wiener diversity index[^10]. it takes into account the number of species present, as well as the relative abundance of each species |
| Species evenness | Describes how homogenous or evenly distributed the species described in the diversity index occur | Is calculated form the diversity index and the species richness of the forest |
Source: Ministry of Environment and Forestry, National Forest Monitoring System in the Republic of Kenya, Version 1 (Draft), February 2021. Chapter 5.5, Biodiversity.