If you’re putting a lot of time and money into habitat management work, you want to know that it’s working. But what does that mean? You might be able to measure things like the area of land over which trees have established, or the number of drains that have been blocked as part of a peatland restoration project. This management might look great to us, but does nature really respond in the way we hope it will?
Ecological monitoring measures how plants and animals are responding to our restoration work, checking that our restoration really is delivering for nature. Ecological monitoring is very important as there could be unexpected processes at play, preventing the habitat management from having the intended consequences for plants and animals. Monitoring is also vital if we are to learn from our experience and develop better ways of managing and restoring habitats in large scale projects like Cairngorms Connect.
Monitoring the effects of habitat restoration on the wildlife of a 600 km2 area over 200 years is no small task! For such a large-scale, long-term project as Cairngorms Connect, where multiple types of habitat management are being employed, comprehensive ecological monitoring is required for our own needs and for our major funders. Within the Cairngorms Connect, we are monitoring four main ecological indicators: Floodplain Restoration, Woodland Expansion, Species (Songbirds, Moths and Shrubs) and Ecological Function (using deadwood beetles).
Although regarded as one of the most naturally functioning floodplains in the UK, the River Spey within Cairngorms Connect area, including the Insh Marshes floodplain, retains historic features from attempts to reclaim land for agriculture. The series of embankments, bank protection, drainage ditches and river straightening have reduced the natural processes and disconnected the River Spey and its tributaries from the floodplain. We are monitoring the impact of the ongoing restoration work to improve this connection between the river and floodplain.
How Do We Monitor Floodplain Restoration?
Image (above): Spider's webs on scots pine saplings backlit at dawn, in an area of woodland expansion through natural regeneration.
A key objective of restoration work within the Cairngorms Connect is to allow the expansion of native woodlands to their natural limits, high in the mountains.
Our main approach is “assisted regeneration” – we largely allow woodlands to regenerate naturally but, in some areas where natural regeneration is unlikely due to remoteness, or for rarer tree species, then tree planting is used. Controlling deer numbers is a particularly important way in which we encourage natural spread of woodland, and deer stalking staff are a key part of our woodland expansion work. To check whether deer control is working well, we need to monitor where and how rapidly regeneration expands, including trees that are quite good at resisting deer browsing, like Scots pine (Pinus sylvestris), and others that are not, like Rowan (Sorbus aucuparia). To monitor our progress, we’re using the following methods to monitor woodland expansion.
How do we monitor woodland expansion?
Image (above): Identifying moths, which are used as one of our ecological indicators of how nature is responding to our restoration work.
It is impossible to monitor every species, but it is also risky to just pick one species or group and hope that it reflects the responses of everything else. This is why, for Cairngorms Connect, we have picked three broad species groups that are relatively straightforward to monitor objectively, and which offer a good indication of how biodiversity is responding to habitat restoration. These groups are songbirds, macro-moths (i.e. the larger species of moth, which are easier to identify) and ericaceous shrubs (heathers and close relatives).
How do we monitor songbirds, moths and shrubs?
We are using two complementary approaches to monitor songbirds, macro-moths and ericaceous shrubs across the project area. The first is a “longitudinal” study (measuring change through time): sites are monitored every year, to track changes in the wildlife community in real time. The second is a “chronosequence” approach (simultaneously comparing different areas that are at different stages of restoration). This allows us to measure how fast (and what) changes might take place, without having to wait decades for changes to happen at a specific site. Hence, we can understand slow processes, such as the development of mature woodland, within a short timescale.
We also monitor comparison sites in Norway and in the eastern Cairngorms to give us an idea how species assemblages in the Cairngorms Connect area compare to areas of geographically and climatically similar habitat in places under contrasting management regimes. Norwegian comparison areas are more heavily wooded than Cairngorms Connect, while the eastern Cairngorms contain more extensive areas of open moorland.
Image (above): Beetle monitoring in area of restructured pine plantation, as part of our work to understand how deadwood creation helps restore a key element of ecological function, found in more natural forests.
Deadwood is an essential part of a healthy forest, home to a huge diversity of flora and fauna. Unfortunately, in plantation forests the amount and variety of deadwood is often far lower than that present in more natural woodland. Restoring former plantations and woodland that have been managed for timber production to healthy and ecologically rich forests therefore often involves increasing the deadwood resource, both by actively killing trees and by simply leaving trees in situ when they die naturally. Such deadwood creation methods are being used across the Cairngorms Connect area. We are carrying out two separate research projects to quantify the effects of this management on one important element of the forest biodiversity, namely deadwood-dwelling beetles.
One project – the one described here - is a larger scale study comparing forest stands with and without active deadwood creation, and asking the question, “how does deadwood creation, by whatever method, change beetle communities?” Another project (see under Testing Interventions) is an experiment testing different methods of deadwood creation, addressing the question “Which techniques of deadwood creation work best for deadwood beetles?”
How do we monitor deadwood beetles?
We are measuring the abundance and diversity of deadwood beetles in former plantation forests where new deadwood is being actively created, and comparing this with the beetle abundance and diversity in areas where no active deadwood creation is taking place.
In both types of forest, naturally arising deadwood is being left in situ, so we will also be monitoring the natural accumulation of deadwood over the course of the study. In addition, we are repeating the monitoring in nearby areas of semi-natural forest, to help us understand how successful habitat restoration work in former plantation forests is proving, in restoring the deadwood beetle community and associated ecosystem function.
We are using flight interception traps, which are a common way of monitoring flying insects in forests, as they enable objective comparison of different trees or habitat patches and are relatively cheap and straightforward to use. These traps work by insects accidentally flying into a clear plastic panel and then falling down into a collecting fluid below. Traps can then be emptied, and the collected insects taken to a lab to identify.
