Understanding the inner workings of ecosystems is key for ecologists and naturalists in order for them to do their jobs. Whether this is to assess the impact of a reintroduced species on an area or to protect a site due to the presence of a local, regional, or national rarities, knowing what you are looking at is highly important.
Of course, all naturalists have varying degree of field identification skills. For example, some will have an aptitude for spotting nesting raptors on high cliff faces, others will be able to identify the trees they are seeing along the banks of a river, and somewhat fewer people will be able to identify the moss that is growing in the crevices of a sea cliff. Some will be able to do all three of these and more, whereas others will be specialist and have a specific taxon that they focus on.
But, what do all these species mean? Why does an Alder Alnus glutinosa grow here? Why is there so much Heather Calluna vulgaris there? Why are there Crested Tits Lophophanes cristatus over there but not over here? Knowing the relationships between some species and their respective habitats can help an ecologist understand the ecology of the area they are in.
Almost every habitat has a particular set of species that allow people to easily classify it. Some of the most obvious and easiest to observe are plants. Woodland habitats are typically made up of mainly one or two tree species. Beech Fagus sylvatica wood, for example, is easy to spot as the dominant species is beech; a tall, smooth-barked, deciduous tree. But look down and you will also see a characteristic bare understory, as the thick foliage above shades out the light, only allowing for some ferns, mosses and rare saprophytic orchids to prevail.
Some habitats are a little less clear cut. Comparing two patches of grassland from a distance can have the mind thinking they are the same, but look closer and it may become clearer that they are not as similar as first thought. Grasslands in the UK can be split into many different types including upland and lowland, acidic and calcareous and rushes and grasses. Knowing even a handful of key species will make grasslands go from one habitat to many different habitats, opening opportunities to find rarities that prefer one habitat over another.
The same rule applies for all habitats. Knowing key species allows the wandering ecologist to divide the landscape up into the parcels of ecologically distinct ground that occur across the country.
Check vital signs…
Just as doctors use symptoms to assess the health of patients, it is possible to look at species present (or not present) in an area in order to assess the condition of the ecosystem. A healthy ecosystem will hold a range of species that fill different niches and have varying abundance.
When walking through agricultural land it can be very clear how healthy the ecosystem is. Species richness is affected greatly by the activities of man, whether for the better or the worse and farmland is a good place to see the evidence for this. If walking through wildlife-friendly farmland you may come across species such as Grey Partridge Perdix perdix or Corn Bunting Emberiza calandra that rear their young on insects found in the fields and thrive on the seeds that are produced from the arable crops later in the season.
However, in farmland that has been stripped of its hedgerows and grassy margins perfect for nesting, and that has been sprayed with pesticides that kill off the vital supply of insects, you are less likely to find such species thriving if existent at all.
Grey partridge Perdix perdix in arable farmland
Following the clues
Certain species act as clues to human presence or human activity. Knowing these species and how they react to disturbance, pollution, etcetera, can give an insight into how people are impacting the landscape on a localised scale. An example would be the presence of Reed Canary-grass Phalaris arundinacea; this species grows well on eutrophicated (nutrient enriched) soils, associated with run-off from intensively farmed areas and so can be a good sign of nutrient enrichment. Of course, it grows naturally in areas such as at Loch Leven, where the soils are naturally eutrophic as a result of being next to a large, naturally eutrophic loch.
Heather Calluna vulgaris is a plant that can be easily seen in woodlands, on heathlands, and areas that are managed specifically for this species are very easy to see. It is possible to read heather like a book in order to find out how grazing pressures have changed: a short carpet means heavy grazing pressure, tall with lots of flowers means lightly or un-grazed, and a topiaried look means the heather was once lightly grazed but has recently become heavily grazed.
What’s in it for you?
A greater appreciation of indicator species, and therefore a better understanding of the landscapes you spend time in, is an asset that employers will likely look for in someone who is applying for a job in the ecology sector. The ability to read habitats and explain why a species grows or lives in one place but not another is well sought after as it demonstrates a sound level of understanding of ecosystems.
On top of this, it can make it a lot easier to find those target species that you’ve always wanted to see! If driving past damp, marshy areas in the north of Scotland you may notice that the habitat is ideal for rare breeding waders such as Wood Sandpiper Tringa glareola, or whilst traipsing over hummocks of heather you may think to check beneath for Lesser Twayblades Listera cordata. It is very rewarding when suspicion turns out to be truth, and when rewarded with something as exciting as breeding wood sandpiper is there any reason not to start learning those indicator species?