Hidden Forces of the Landscape: Deer, Rivers, and the Systems That Shape the Land
Landscapes rarely reveal their full story at first glance. What appears simple on the surface is usually shaped by forces operating over long periods of time. Animals follow established routes across the land, rivers support life beneath their currents, and small changes in conditions can influence an entire ecosystem.
Two examples illustrate this clearly across northern landscapes such as Scotland: the movement of deer across glens and the presence - or absence - of migratory fish in rivers.
Red deer are among the most recognisable animals of the Highlands. Herds crossing open ground are familiar across many glens, yet their influence on vegetation is often discussed only in terms of browsing.
Where deer numbers are high, repeated grazing can prevent young trees from establishing. For this reason fencing is frequently used during the early stages of woodland planting or regeneration. Young shoots contain high nutrient levels and are especially attractive to grazing animals.
At the same time, grazing animals also shape vegetation in several ways. As deer move between feeding areas they redistribute nutrients through dung and urine. Seeds can attach to their coats or pass through digestion and be deposited elsewhere. Their hooves disturb the soil surface, creating small patches of exposed ground where new plants can establish.¹
Movement across landscapes is also significant. Rivers that appear large to observers do not necessarily restrict animal movement. Red deer are capable swimmers and will cross substantial stretches of water while travelling between feeding grounds.²
These patterns mean that deer influence vegetation not only where they graze but across entire glens through movement and nutrient transport.
By the mid-twentieth century the condition of Highland landscapes had already been widely discussed. The ecologist Frank Fraser Darling, whose work examined land systems across the Highlands and Islands, described the region in West Highland Survey: An Essay in Human Ecology as “a devastated terrain.”³
Darling’s argument was that grazing pressure, land use, and ecological change had combined over centuries to shape the condition of the Highlands.
Rivers provide another example of how easily hidden processes shape the natural world.
Many Scottish rivers are closely associated with salmon, particularly well-known systems such as the Spey, Tay, and Dee. Yet fish distribution within a river is rarely uniform. One stretch may hold fish while another appears empty, even though the water itself appears similar.
This is because most of the conditions determining fish presence lie beneath the surface. Salmon require clean gravel beds for spawning, where eggs develop within spaces between stones. If those spaces become filled with fine sediment, oxygen flow is reduced and survival rates decline.⁴
River connectivity is also critical. Even relatively small barriers can prevent fish reaching upstream spawning grounds.
Where such barriers are removed or modified, fish sometimes return to sections of river that have been inaccessible for decades. One example occurred on the River Eden in Scotland, where the removal of the Gateside Mills weir reopened more than seventeen kilometres of upstream habitat to migratory fish for the first time in over a century.⁵
Disturbance can also influence river systems in unexpected ways. Floods that initially appear destructive may remove accumulated sediment and restore clean spawning gravel. In later seasons fish populations can increase because the riverbed has effectively been refreshed.
Taken together, these examples reveal a broader ecological pattern. Landscapes are shaped not by a single force acting alone but by many interacting processes. Grazing animals influence vegetation even as they feed on it. Rivers continually reshape themselves through erosion, flood, and sediment movement.
The naturalist Aldo Leopold described this complexity when reflecting on land systems:
“The outstanding scientific discovery of the twentieth century is not television, or radio, but rather the complexity of the land organism.”⁶
Similarly, John Muir observed while writing about wild landscapes:
“When we try to pick out anything by itself, we find it hitched to everything else in the universe.”⁷
Understanding land therefore begins with observation. A hillside that appears unchanged may be shaped by generations of deer movement. A stretch of river that looks empty may contain complex ecosystems beneath the current.
The visible landscape is only a small part of the forces shaping it.
Sources
Putman, R. The Natural History of Deer (Cornell University Press, 1988).
Wildlife Online. “Red Deer Behaviour and Ecology.”
Frank Fraser Darling, West Highland Survey: An Essay in Human Ecology (Oxford University Press, 1955).
Malcolm Greenhalgh, Atlantic Salmon: An Illustrated Natural History (Merlin Unwin Books, 2005).
Dam Removal Europe, “Gateside Mills Weir Removal, River Eden, Scotland.”
Aldo Leopold, A Sand County Almanac (Oxford University Press, 1949).
John Muir, My First Summer in the Sierra (1911).