How has climate change changed the way our gardens grow and what can be done to alleviate its effects? Professor Geoff Dixon tells us more.
Climate has changed on Earth ever since it solidified and organic life first emerged. Indeed, the first photosynthesising microbes changed the atmosphere from carbon dioxide rich to oxygen rich over millions of years. What we now face is very rapid changes brought about by a single organism, mankind, through industrialisation.
The effects of change are very evident in gardens. Over a generation, leaf bud breaking and flowering by early spring bulbs, herbaceous plants, shrubs and trees has advanced by at least four weeks (see main image of Cyclamen hederifolium).
Latter spring displays have advanced by at least two weeks. This is caused by milder, wetter winter weather, encouraging growth. The danger lies in the increasing frequency of short sharp spells of severe frost and snow. These kill off precocious flowers and leaves which trees especially cannot replace.
Desiccated, cracked soil.
Increasingly, the summer climate is becoming hotter and drier. Since the Millennium there has been a succession of hot droughts. These seriously limit scope for growing vegetables, fruit and ornamentals unless irrigation is regularly available. Drought also damages soil structure especially where there is a high clay content by causing cracking and the loss of plant cover (see image of desiccated, cracked soil above).
Cracking disrupts and destroys the root systems of trees and shrubs in particular. The effects of root damage may not become evident until these plants die in the following years.
Climate change is apparently advantageous for microbes. Detailed surveys show that fungal life cycles are speeding up, increasing the opportunities for diseases to cause damage. Even normally quite resilient crops such as quince are being invaded during milder, damper autumns (See image of brown rot on quince fruit below). Throughout gardens, the range and aggressiveness of pests and disease is increasing.
Brown rot (Monilia laxa) on quince fruit.
However, each individual garden or allotment, no matter its size, can contribute to reducing the rate of climate change. Simple actions include the removal of hard landscaping, and planting trees and shrubs reduces carbon emissions.
Using electric-powered tools and machinery in place of petrol or diesel has similar advantages. Tumbling down parts of a garden into native flora, and perhaps encouraging rarer plants such as wild orchids or fritillarias, mitigates climate change. Such areas may also form habitats for hedgehogs or slow worms, increase populations of bees, butterflies and moths and encourage bird life.
Written by Professor Geoff Dixon, author of Garden practices and their science, published by Routledge 2019.
All images from Professor Geoff Dixon.