Forests and cultivated fields continue to represent fundamental human conditions: wildness and civilization. Some locations remain in a perpetual state of transition due to unique soil characteristics and historical factors. Progress in farming is short-lived as the land reverts back to a pre-human state. The Burren in County Clare, Ireland, is characterized by a variety of ragged grassland and hazel thickets. The movie at the information center in Kilfenora that informs tourists to this changing environment starts with: At the westernmost frontier of the Old World.

These words convey more than just a sense of direction based on geography. Observing the vast area of broken limestone rock near the Atlantic, one gets the impression that it may be indicating a timeline, as if this ancient environment is not yet complete, or has drifted over Galway Bay from another location. Alpine flowers are neatly interspersed inside a Celtic garrigue, which consists of a dense mixture of blackthorn, burnet rose, and creeping madder. The landscape is characterized by mature trees and a dominant shrub, the hazel, which creates black patches in the hollows of the white rock, covers the gentler slopes, and pushes against crumbling walls. The horizon consists of glaciated slopes that are curved, shelved, and terraced.

The low sun highlights pink ribbons on these ridges, which are always visible. Auden referred to limestone landscapes as areas characterized by ‘short distances and distinct spots’. The Burren, derived from the Irish word boireann meaning a stony region, is characterized for being compact, close, and sincere. Hazel is the cohesive element.

I have visited that location six times, and each visit intensifies the feeling of it being a tangible place but from a different era. My initial journey took place in the early summer of the 1970s. Four of us, all passionate about flowers, spent the week exploring wild rock gardens and enjoying the captivating blend of Celtic and southern influences. We gathered mussels and collected sea-salt crystals from the lichen-covered limestone that sloped into the sea. We relaxed under palm trees in the spa town of Lisdoonvarna, where the hotelier allowed us to boil the mussels in his kitchen, and saw the twilight stroll of the visiting nuns. We mostly wandered around, finding it hard to look away from the ground only a few inches ahead of us and the abundant variety of plants growing without any concern for ecological guidelines.

Mediterranean orchids, arctic avens, cobalt blue gentians, and common primroses were growing together in the shadow of dwarf hazel copses. We had the peculiar experience of walking through 200-year-old floral woods that reached no higher than our chests, reminiscent of Gulliver’s travels. The hazel woods maintain a rhythmic pace, with a diverse mix of flora and small-scale features that evoke a landscape from the period following the last ice age.

The Burren’s impressive illusion is created by the haphazard combination of plants that do not naturally thrive together in a contemporary environment. As the glaciers receded from the area that would later become the British Isles 14,000 years ago, they created a landscape of shattered rock, fractured by prolonged winter frosts and summer meltwaters. The ice had removed all humus from the rock, eliminating any chances for plants that relied on it. As the climate warmed, many species accustomed to open and infertile habitats moved north.

They traveled from their strongholds in the ice-free southern regions by crossing the land bridges that connected Britain to the continent. In the arid alpine summers, species often found in specialized habitats flourished harmoniously next to each other on unoccupied ground without shade competition. Bellflowers, bedstraws, gentians, and globe flowers originated from central Europe and the Mediterranean region. Rock roses grew vigorously on both chalky outcrops and any dry piece of land. Cornflowers blossomed in the cornless field. Sea pinks thrived in distant interior areas whereas mountain avens flourished at sea level. Some species, like the strawberry tree and several rare heathers, likely moved along the continuous western European seaboard from Portugal to Ireland. The two streams met in the Burren, benefited from a gentle Atlantic climate, and remained together.

Plant remains accumulated, forming a thin layer of soil as temperatures increased. The first trees, birch and pine, appeared around 9000 BC, followed by hazel, a crucial species in the Burren. The large forest trees, including oak, elm, and ash, appeared shortly thereafter. By 6000 BC, the majority of the lowlands were covered by a sporadic layer of mixed deciduous woods, with the exception of the Burren region where the large trees did not grow very tall or last very long due to the weak soils. When the first farmers arrived around 4000 BC, the obstacles were readily overcome as the increasing sea had already broken through the land bridges connecting Britain and Ireland to the mainland over 1,000 years earlier.

The new pastoralists implemented a herding system that differed from the traditional transhumance practiced in their European homelands. During summer, they moved the cattle to the grassy lowlands, and during winter, they brought them back up to the rocky uplands. The animals grazed on the remnants of the previous season’s vegetation, helping to maintain the ground open for the next year’s variety of blooms.

Hazel flourishes and produces fruit most effectively in open, well-lit environments. It can also live as an undershrub in dense woodland. In the Burren region, hazel plants persisted under the shade of oak and elm trees. It then saw an unforeseen increase. By 3800 BC, there was an abrupt and enigmatic decline in the elm population throughout Britain. Initial hypotheses regarding the ‘Elm Decline’ suggested that early Neolithic farmers utilized elm leaf as feed for their livestock, a tradition that continues in some regions of Europe.

This would have minimized the pollen deposition on the ground. Pollen grains are distinctive characteristics of the species that create them and can endure for an extended period in the low-oxygen and preservative environments of peat and silt. Pollen relics are the most reliable evidence for identifying and dating the vegetation of a location at a specific point in history, as layers of soil can be dated by geological features.

Pollen cores extracted from Diss Mere, located near my residence in Norfolk, indicate that prior to the Decline, elm pollen accounted for approximately 7% and hazel pollen for roughly 15%. In subsequent layers, hazel pollen accounts for around 50% while elm pollen is minimal. After a few centuries, elm pollen has started to reappear. The rapid and significant Decline suggests it is highly improbable that the little Neolithic farming community was accountable. Oliver Rackham argues convincingly that the sudden and early breakout of elm disease was the cause.

In Ireland, a similar pattern was observed, with the exception that in the Burren region, large trees never fully recovered. The settlers easily controlled the hazel vegetation on the sparse soils, although the less prominent hazel tree remained the dominant woody plant in the area. It showed early settlers the concept of natural regeneration more vividly than any other animal. Trees may have robust structures resembling mammals, but they are resistant to harm, possibly even to mortality. Leaves were shed annually in autumn and regrown in spring. Limb loss was remedied by replacement.

When a tree is knocked over by the wind, it may grow a new trunk next to the vertical root plate. The vertical growth and branching of trees remained consistent independent of their position. Even when entire trees were cut down with labor-intensive stone axes, fresh shoots would arise from growth nodes at the top of the damaged stump. Once these reached a sufficient size for cutting, the tree would continue to grow. The technique is commonly referred to as “the constant spring.”