Ecological succession (Focus - May)

Farmers deal with issues of succession as part of their job. Lately, it is the Family Farming Tax which has threatened a lot of family-owned businesses (not just farming) with unaffordable tax bills.

Another succession which we farmers deal with (and anyone with a garden) is Ecological Succession, which can be defined as ‘the gradual, often predictable process by which the structure of a biological community changes over time, replacing one group of species with another.’ It begins with pioneer species colonizing a new area and progresses through stages, often culminating in a stable "climax" community. Ponds are an obvious example, where a newly created pond with purely open water quickly gets colonised by aquatic plants which grow quickly to cover the surface with foliage and drop leaves, which eventually reduce the pond to a bog. The time it takes to go through these stages can be lengthened by human intervention, birds and fish (thinking Carp here).

Similarly, farmed grassland is prevented from rapid succession by regular cutting or grazing. Chalk downland, for example, has been maintained by grazing in a relatively stable shape for thousands of years, leading to a specialised rich plant and animal community. Cease or relax grazing and very quickly succession leads to long grass, over-competing specialist plants and, before long, scrub and trees take over. We need all these succession states to have the richest variety of wildlife. On either side of the Shaston Drove, we not only have variety of succession in abundance but we have extra variety of wildlife on either side; for example, on the colder north side we have Duke of Burgundy fritillary butterflies, and on the warmer south side, Adonis Blue butterflies.

At Chicksgrove, I have a species-rich hay meadow (created 25 years ago from a former arable field). This field has been kept in a stable state all that time by cutting it once at the end of each summer. The flora has increased in richness as new species, such as three types of orchids, have colonised. The drawback of cutting the whole field at one time is the decimation of animal life, so starting two years ago I left a strip uncut down the centre of the field. Straight away, succession kicked off with tussocky grass, suppression of the more delicate flower species and spread of scabious. On the positive side, the new habitat was perfect for rare and declining Marsh Fritillary butterflies, and a female found it straight away - probably flying from one of the Shaston ridge colonies - and laid hundreds of eggs on the scabious, the food plant of its caterpillars. As a result, in the course of two years, this spring there is a thriving caterpillar population.
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Peter Shallcross