løvfall

Lövfall, or leaf fall, is the seasonal shedding of leaves by deciduous plants, mainly in temperate and boreal regions. It typically occurs in autumn, as day length shortens and temperatures cool, though drought, damage, or stress can hasten the process. The shedding helps the plant conserve water and energy during winter when conditions are adverse.

The physiological process involves the development of an abscission zone at the base of the leaf petiole. Changes in hormone levels, particularly a decline in auxin and an increase in ethylene, trigger cell wall breakdown in this zone. As a result, a separation layer forms, and leaves detach from the tree, often aided by wind or gravity. While leaves are detached, the tree limits resource loss by closing stomata and reducing photosynthesis in leaves that have not yet dropped.

Autumn coloration accompanies lövfall in many species, as chlorophyll breaks down and reveals carotenoids and, in some cases, anthocyanins, producing yellows, oranges, and reds. The timing and intensity of color vary by species, climate, and soil conditions.

Ecologically, leaf fall contributes to nutrient cycling through leaf litter, supporting soil organisms and affecting forest floor habitats. The timing of the drop influences understory light and microclimate. Some evergreen species retain foliage year-round, while others shed older leaves gradually or under stress. In human contexts, lövfall affects forestry, gardening, and urban maintenance, with seasonal cleanup and leaf disposal considerations.