For native plants, three similar species of rush are causing a lot of trouble: they are invading uplands, swamping other vegetation, and ruining pasture and the nesting sites of rare birds.
The varieties are known as soft, hard and compact rushes and have the Latin names Juncus effusus, J inflexus and J conglomerates respectively. Exactly why they are spreading so fast is uncertain although changing farming practices and a warmer and wetter climate are suspected.
Research shows that on the West Pennine moors, a site of special scientific interest, the presence of these rushes in fields has increased by between 81% and 174% in 12 years, in some cases almost eliminating the grass. This invasion is typical of many upland parts of Europe.
The rushes are formidable. They grow to 1 metre tall, spread through rhizomes but also produce up to 4m seeds per sq metre, which can germinate decades later. They like poor, badly drained acid grassland, which is made into more suitable habitat by farmers using heavy machinery that crushes the drains installed by Victorian farmers.
Sheep compact the land further and the ponies and cattle that used to eat rushes are gone. Lime and burning were once effective treatments but efforts stopped through lack of humanpower. The rushes march on.
