Species Rich Grassland Mapping in the Cairngorms - new survey methodology

{{DigitalResource
 * Type=Blog
 * Resource=Report by Dr Susan Watt Habitat Specialist for NatureScot on new methodology developed by NatureScot to map habitats - this example species rich grasslands in the Cairngorms
 * Description=The project is mapping Species Rich Grassland within the Cairngorms National Park and is a partnership between Cairngorms National Park Authority and NatureScot. The new methodology uses image segmentation software to create habitat polygons that are populated by surveyors in the field
 * Blog====Introduction and results for Glen Livet 2020===

What is the project?
The project is mapping Species Rich Grassland within the Cairngorms National Park and is a partnership between Cairngorms National Park Authority and NatureScot.

Overall, the aim is to produce a complete and up-to-date map of species-rich grassland (SRG) sites for enclosed lowland areas across the whole of the Cairngorms National Park using a combination of remote sensing and targeted field survey.

We have been approaching this stepwise by catchment, completing Glenlivet, Glen Avon and part of Deeside so far.

Though we do not have data for overall loss of SRG in Scotland one report noted 16% of Priority lowland grassland habitat surveyed in 1983 was lost by 2011 (Dadds and Averis 2014). In a recent comparative study of SRG in the Badenoch and StrathSpey area of the CNPA (Bourne 2020) ca.19 % of SRG was lost since 2005 and 60 % of fields were affected by under-management.

Alongside the new map of species-rich grasslands we are also collecting information on the quality and condition of SRG stands which can be used to better understand the resource, and work with land managers to target future management.

What is Species Rich Grassland?
Species Rich Grasslands are naturally occurring, unimproved (or semi-improved) grasslands that support a diverse range of wildflowers such as Harebells, Yellow Rattle, Orchids, Fairy Flax, Field Gentian and Ragged Robin. They can be found on acid, neutral or calcareous soils and can be dry, mesic or wet grasslands. Most will be maintained by some type of management such as mowing or grazing.

What are we mapping?
In terms of National Vegetation Classification we are mapping species-rich examples of

Lowland dry acid grassland (U1d, U4c, U5c) Lowland calcareous grassland (CG1*, CG2*, CG7*, CG10* *noting if orchid-rich and/or on limestone]) Neutral hay meadow and floodplain grasslands (MG2, MG3, MG5, MG8) Wet meadow and mires (M23a, M25c, M26, M27, M28)

How are we mapping it?
We are using a combination of remote sensing and targeted field survey, a methodology previously applied to uplands (Scobie 2018). The approach involves the production of an aerial photography segmentation and subsequent classification of the output.

A set of survey polygons representing a search map containing fields, or sections of fields, most likely to contain species-rich grassland (SRG) and other habitats of conservation interest was supplied to the contractors to then visit. For each polygon, all NVC communities present were identified and their cover proportions estimated and data entered into the mobile GIS app Collector. In addition, when target SRG communities were encountered, attributes were collected describing their quality and condition.

Glen Livet 2020
708 search map polygons were surveyed on 15 days between 17 August and 7 September 2020 in the Glen Livet Catchment area within Cairngorms National Park. 16% were found to contain at least some species-rich grassland (SRG) with U4c being the most widespread vegetation type. MG5 and U5c were also frequent but species-rich wetland types such as M23a, MG8 and M27 were uncommon, even though species-poor rush pasture and wet grassland was widespread and abundant with a presence in 58% of polygons.

While the percentage of SRG found was fairly low, most other polygons did contain unimproved grassland and wetland types. Only 7% consisted entirely of improved or poor semi-improved grassland. The method was considered to be better than traditional approach in targeting field survey time and reducing the number of polygon discards Many of the SRG stands found were rank, and undergrazing was often considered to be a problem, especially for U4c and U5c stands. Even a slight increase in grazing in SRG areas could be beneficial for species diversity.

The NVC survey has been converted to EUNIS for further use and display in HabMoS. We are hoping to make the 2020/2021 data available very soon via the Habitat Map of Scotland and further disseminated by the Cairngorms National Park.

The methodology used is a combination of remote sensing and targeted field survey developed by NatureScot and previously applied to the uplands (Scobie 2018). We hope it can be expanded for other habitat surveys in the future.

Dr Susan Watt Environmental Data and Innovative Technologies Team - Habitats }}