National Vegitation Classification
The standard technique for Phase 2 vegetation survey uses the technique developed for the National Vegetation Classification (NVC) project. The NVC is a classification of terrestrial and freshwater vegetation and is more detailed than a Phase 1 habitat survey.
An initial walkover of the survey area is undertaken to determine the variation in the vegetation. For each homogenous stand identified, samples are taken using quadrats. Within each stand selected for analysis a random sample location strategy is adopted. As a general rule, quadrats of 2m x 2m are used for short, herbaceous vegetation, 4m x 4m for taller or more open herb communities and low woodland field layers, 10m x 10m for species-poor or very tall herbaceous vegetation or woodland field layers and dense scrub, and 50m x 50m for sparse scrub and woodland canopy and understory. Within each quadrat, all species of higher plant are identified and the frequency of each species is recorded as a 1-10 Domin value. Finally, the NVC community type is determined, as far as possible, by comparing the results from the field survey with the published accounts and floristic tables of vegetation communities given in British Plant Communities (Rodwell, et al, 1992).
Hedgerow Surveys
Hedgerow surveys can be undertaken to ascertain the condition, and the species richness of a hedge. The surveys are often tailored for one particular species, for example the dormouse (Muscardinus avellanarius), or the brown hairstreak (Thecla betulae) butterfly. 9 hedgerows should be collected in every 1km square. A 30m section of the selected hedgerow should then be selected and the hedgerow type, features and vegetation identified. The average number of woody species per 30m length can assist in dating the hedgerow (in broad terms), as well as determining whether a hedgerow is defined as species-rich. Species that count towards species-richness are structural species, not climbers (other than roses) or bramble. They are also limited to woody species either native in the UK, or which are ‘archaeophytes’ (have been recorded as naturalised in the wild before 1500 AD, (DEFRA, 2007).
Invasive plant species
Invasive Non-Native Species are one of the main causes of biodiversity loss. They pose a threat to many native species, can carry disease and cause economic and environmental harm. This means that they can have a major impact on terrestrial, freshwater and marine environments throughout England and can seriously damage our biodiversity, landscape, access and ecosystems (Natural England, 2009). These plants include Japanese knotweed, giant hogweed and Himalayan balsam. These plants need to be managed in very specific ways in order to control their spread.
