C7. Plants of the wider countryside
a. Arable field margins
b. Bog and wet heath
c. Broadleaved woodland and hedges
d. Lowland grassland
Official statistics in development – indicator under development: The UK biodiversity indicators project team would welcome feedback on the novel methods used in the development of this indicator. For example, does this new indicator measure something readers feel should be measured, and how well does it measure plant abundance? As this is an official statistic in development, it has not been assessed.
Type: State indicator
This indicator was updated in 2023.
Introduction
This indicator measures, in small plots, change in the abundance of plant species considered indicative of good habitat condition in the UK, using modelled abundance data from the National Plant Monitoring Scheme (NPMS). Plant populations form the environment in which most other species exist, as well as providing numerous ecosystem services. Drivers of change are well-understood for many UK habitats.
This indicator is presented for four UK broad habitat types: Arable field margins; Broadleaved woodlands and hedges; Bog and wet heath; and Lowland grassland. Within each habitat, plant species abundance trends are averaged to provide an indication of the habitat's current state. Positive average trends in abundance are indicative of good condition.
Key results
This indicator was not updated in either the 2021 or the 2022 (reduced set) biodiversity indicator publications. The collection of 2020 data (for the 2021 publication) was affected by the COVID-19 pandemic, and the 2022 (reduced set) publication was affected by the need to perform a thorough review of the Biodiversity Indicators in line with new global and domestic strategies.
In 2022, average indicator plant abundance for three of the four habitat types presented are above the 2015 level. The habitat ‘Bog and wet heath’ is lower than its 2015 level (Figure C7i):
- arable field margins, while fluctuating annually, shows an overall increase of 14% between 2015 and 2022;
- bog and wet heath after an initial decline of 33% in 2016, shows a rise to 89% of the baseline;
- broadleaved woodland and hedges shows an increase of 2%; and
- lowland grassland shows a decline followed by a rise and is 9% higher than its 2015 level.
Figure C7i. Abundance of plant species in four UK broad habitat types, 2015 to 2022
Notes about Figure C7i:
- The line graphs show the unsmoothed trends (dashed line); the variation around the lines shown (the shaded area) is the standard deviation of 1,000 simulated trend indices calculated according to the method of Soldaat, L.L., Pannekoek J., Verweij, R.J.T., Van Turnhout, C.A.M. and Van Strien, A.J. (2017). A Monte Carlo method to account for sampling error in multi-species indicators. Ecological Indicators, 81: 340–347 doi:10.1016/j.ecolind.2017.05.033.
- Abundance is measured by the percentage area covered by a species within a plot.
- The figures in brackets indicate the number of species or species aggregates included in the composite index for that particular habitat type.
Source: Botanical Society of Britain & Ireland; Joint Nature Conservation Committee; National Plant Monitoring Scheme; Plantlife; UK Centre for Ecology & Hydrology.
Indicator description
The National Plant Monitoring Scheme (NPMS) was designed to monitor UK habitats of conservation importance. This is achieved through the establishment of small plots in areas of habitats targeted by the scheme. The abundances of plant species, measured as the percentage area covered by a species within a plot, are recorded each year. Surveyors record from different lists of indicator species depending on their level of experience and the habitat within which a plot is located. Both the placement of plots, and the selection of 1 km national grid squares within which the plots are located, are subject to statistical methodologies designed to minimise bias (Pescott et al. 2019a).
The design of the NPMS included the definition of a set of 11 broad habitat types, within which 28 finer habitat types are nested. These fine-scale habitats are linked to existing classifications such as the British National Vegetation Classification. Surveyors can choose, based on their knowledge of a habitat, whether to record a plot at the broader or finer level.
The current indicator summarises species’ percentage cover (abundance) data at the broad habitat level. This is done using a model that is able to account for both the range of percentage covers that a species may exhibit in a habitat when present, and the fact that species may often be absent from any given plot (Pescott et al. 2019b). Such data are often described as “zero-inflated”. This model is applied across years for each species/habitat combination, and the indicators presented here for each broad habitat are the result of combining the resulting species/habitat time trends across the relevant set of NPMS habitat indicator species. The four broad habitat measures presented in this indicator (Arable field margins; Lowland grassland; Broadleaved woodlands and hedges; and Bog and wet heath) are those for which the largest numbers of NPMS plots currently exist. See the technical background document for more detail.
As this is an official statistic in development it has not been assessed.
Relevance
Plants are a large part of the fundamental fabric of which habitats are made and directly indicate changes to environmental conditions and habitat management. Plants provide essential habitats and food for wildlife, and essential ecosystem services for humans, such as reduced erosion, nutrient cycling, oxygen production, and climate regulation. Furthermore, many plants, such as bluebells (Hyacinthoides non-scripta), horse chestnut (Aesculus hippocastanum) fruits (conkers), heather (Calluna vulgaris), oaks (Quercus spp.) and brambles (Rubus spp.) have deep cultural significance and are valued in their own right by the public.
Background
The creation of the NPMS allowed for the estimation of annual trends in the abundance of plants in habitats of conservation importance. Following five years of development, the scheme was launched by a partnership consisting of the Botanical Society of Britain and Ireland (BSBI), the Joint Nature Conservation Committee (JNCC), Plantlife, and the UK Centre for Ecology & Hydrology (UKCEH) in 2015. This indicator uses species selected by the NPMS as indicative of good condition in those habitat types considered to be of most importance for the conservation of UK biodiversity – see the technical background document for a full list of species included. These species are monitored in small sample plots (between 25 and 100 m2 in area) according to a methodology that was designed to minimise biases in data collection.
Since 2018, UKCEH, with input from all partners, have been developing a method of using NPMS data to indicate annual changes in habitat condition. The method is based on a hierarchical model, formulated in a Bayesian framework, that integrates information on a species’ abundance and occupancy; the occupancy estimates also take advantage of the fact that most plots are surveyed twice a year, allowing adjustments for false negatives (i.e. species that are overlooked during surveys). Simulation tests and applications to real data suggest that the method produces ecologically sensible metrics.
The 1 km squares of the NPMS were selected according to a weighted-random algorithm designed to introduce a known bias towards semi-natural habitats. However, within this design, a sampling bias exists in that, in common with other UK structured monitoring schemes based on volunteer participation, squares located within lowland areas are more likely to be sampled. Further work will focus on additional adjustment for bias (Pescott et al. 2019b; Boyd et al. 2023).
Until 2013, this indicator was based on analysis of the change in plant species richness in the wider countryside. Data were taken from the UK Countryside Survey. This survey provides a random sample of vegetation plots located in arable and horticultural fields, agricultural grasslands, woodlands and associated boundary habitats in Great Britain. Key messages from the previous indicator are presented here; although now archived, the indicator can also be viewed in full.
The indicator presented the change in plant species richness in survey plots across Great Britain between 1990 and 2007 for a range of widely occurring habitats. The results from seven habitat types were grouped into three measures for the assessment: arable and horticultural land; woodland and grassland; and boundary habitats. The indicator compared species richness per plot for the exact same plots surveyed in 1990, 1998 and 2007. For each broad habitat type, the data were converted to an index (on a scale of 0 to 100) to compensate for the difference in plot size between habitats. In the long term (1990 to 2007) and short term (1998 to 2007), the change in plant diversity of arable and horticultural land was assessed as improving; whilst for woodland and grassland and boundary habitats the assessment in both the long and short term was declining (see Figure C7ii).
Figure C7ii. Plant species richness in the wider countryside, 1990 to 2007
Notes about Figure C7ii:
- * A statistically significant change between 1990 and 2007.
- ~ A statistically significant change between 1998 and 2007.
Source: UK Centre for Ecology & Hydrology; Countryside Survey.
Goals and Targets
The UK and England Biodiversity Indicators are currently being assessed alongside the Environment Improvement Plan Targets, and the new Kunming-Montreal Global Biodiversity Framework Targets, when this work has been completed the references to Biodiversity 2020 and the Aichi Global Biodiversity Framework Targets will be updated.
Aichi Targets for which this is a primary indicator
Strategic Goal C. To improve the status of biodiversity by safeguarding ecosystems, species and genetic diversity.
Target 12: By 2020 the extinction of known threatened species has been prevented and their conservation status, particularly of those most in decline, has been improved and sustained.
Aichi Targets for which this is a relevant indicator
Strategic Goal B. Reduce the direct pressures on biodiversity and promote sustainable use.
Target 5: By 2020, the rate of loss of all natural habitats, including forests, is at least halved and where feasible brought close to zero, and degradation and fragmentation is significantly reduced.
Target 7: By 2020 areas under agriculture, aquaculture and forestry are managed sustainably, ensuring conservation of biodiversity.
Strategic Goal C. To improve the status of biodiversity by safeguarding ecosystems, species and genetic diversity.
Target 11: By 2020, at least 17 per cent of terrestrial and inland water, and 10 per cent of coastal and marine areas, especially areas of particular importance for biodiversity and ecosystem services, are conserved through effectively and equitably managed, ecologically representative and well connected systems of protected areas and other effective area-based conservation measures, and integrated into the wider landscape and seascapes.
Web links for further information
- Botanical Society of Britain & Ireland
- Countryside Survey
- Joint Nature Conservation Committee
- National Plant Monitoring Scheme
- Plantlife
- UK Centre for Ecology & Hydrology
References
Boyd, R.J., Stewart, G.B. and Pescott, O.L. (2023). Descriptive inference using large, unrepresentative nonprobability samples: An introduction for ecologists. EcoEvoRxiv, https://doi.org/10.32942/X2359P
Pescott, O.L., Walker, K.J., Harris, F., New, H., Cheffings, C.M., Newton, N., Jitlal, M., Redhead, J., Smart, S.M. and Roy, D.B. (2019a). The design, launch and assessment of a new volunteer-based plant monitoring scheme for the United Kingdom. PLoS ONE, 14(4): e0215891.
Pescott, O.L, Powney, G.P. and Walker, K.J. (2019b). Developing a Bayesian species occupancy/abundance indicator for the UK National Plant Monitoring Scheme. Wallingford, NERC/Centre for Ecology & Hydrology and BSBI, 29pp. DOI:10.13140/RG.2.2.23795.48161
Soldaat, L.L., Pannekoek J., Verweij, R.J.T., Van Turnhout, C.A.M. and Van Strien, A.J. (2017). A Monte Carlo method to account for sampling error in multi-species indicators. Ecological Indicators, 81: 340–347 DOI:10.1016/j.ecolind.2017.05.033
Downloads
Download the Datasheet and Technical background document from JNCC's Resource Hub.
Last updated: November 2023
Latest data: 2022
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