How MOTH is designed

Objectives

The objective of the project is to develop an entire system for the monitoring of terrestrial habitats. This is important for the implementation of the EU directive on the conservation of natural habitats and of wild fauna and flora. Every sex years, member states shall draw up a report on the conservation status of the habitat types specified in the directive. This was done during the first semester of 2013, and MOTH was then able to provide data for the Swedish report.

MOTH is developed in cooperation with existing Swedish monitoring programs, especially the National Inventory of Landscapes in Sweden (NILS) and the Swedish national forest inventory. NILS uses a sampling grid consisting of 631 5x5 km landscape units all over Sweden. Since forests are thoroughly monitored through the Swedish national forest inventory, NILS focuses on other types of habitat.The goal is to adapt the system to the needs of other member states as well.

In each landscape unit, data is collected from small sampling plots. But the grid is not dense enough for monitoring less common habitat types. A mere increase of the sample size within the existing surveys would not be cost-efficient, since data from the sparsely occurring habitat types would still be too limited. 

MOTH will provide methods for the monotoring of these sparsely occurring habitats. Two methods are under development: point grid and line-intersect.

Point grid method

In the point grid method, a large number of points are allocated in a regular grid on a back-ground of aerial infra-red photos. In each 5x5 km landscape unit, there will be 200 grid points. An experienced interpretor scrutinizes a circular plot with a radius of 10 meters around every point. Among the variables analyzed are tree coverage, percentage of deciduous trees and conifers, tree height and ground vegetation. A rough classification of habitat types is also made according to the EU habitat directive.

Some of the plots are then selected for field survey. Most of them will be plots where interesting habitat types are likely to be found, but as a control some other plots will be surveyed as well. The selected plots are surveyed during the NILS inventory, when detailed data is sampled on the different habitat types. During the field seasons of 2012 and 2013, MOTH will also survey 60 own plots per year in addition to the NILS plots, These extra plots will mostly be located in the southern parts of Sweden, in the boreal and continental regions.

Habitat types which can be monitored through this method are, for example, inland dunes, mineral-rich springfens and deciduous slope forests.

The field season starts in the beginning of May with two weeks of training, which in 2012 will take place in Västergötland. During the season, the field staff works two by two in teams, and collect large quantities of data from the plots in field computers. Data and photographs from the plots are transferred to the office every day. In parts of the country were there are many MOTH plots, for example in the mountains, a third member can temporarily join the team. The work can sometimes be demanding, and good physical condition is necessary. The field work is to a large extent based on the registration of species from different plant groups, which means that field workers must know or be able to learn quite a number of plant ant moss species. Through exercises and excursions, the field staff is trained to make standardized assessments.

Line-intersect method

When monitoring habitats located along linear landscape structures, such as the sea-shore, the point-grid method is not efficient. Therefore, these habitat types will be surveyed using a line-intercept method. A layer with line segments, organized in hexagones, is superposed on the aerial photo. All intersections between line segments and shorelines are marked manually. The habitat types at the intersections are analyzed in the same way as in the point-grid method, and some of the intersections are selected for field survey.

This method will be especially important for the monitoring of coastal habitats. From the later part of June till September 2012, the method will be used to survey 40 areas on the Swedish coast. It might be an advantage for the field staff envolved in this part of the project to be have sea-going experience, although we are mainly interested in terrestrial habitats!