A killer of the Countryside

Lots of Rhododendron bushes around a still empty Middle Walshaw Dean Reservoir.

This plant is responsible for the destruction of many native habitats and the abandonment of land throughout the British Isles. The reason for this is simple. Where conditions are suitable, Rhododendron will out compete most native plants. It will grow to many times the height of a person, allowing very little light to penetrate through its thick leaf canopy. This effectively eliminates other competing native plant species which are unable to grow due to insufficient light. This in turn leads to the consequent loss of the associated native animals.

Rhododendron thrives in milder, wet climatic conditions, where there are poor, acidic soils. Unless established stands are constantly kept in check, they will expand into adjacent areas, rapidly eliminating the majority of native plant species. The twentieth century demise of many former country estates and the consequent lack of control of remaining Rhododendron has allowed this species to invade large areas of the British countryside.

Rhododendron invades areas both vegetatively and via seed. Established plants spread by lateral horizontal growth of the branches. A single plant may eventually end up covering many metres of ground with thickly interlaced, impenetrable branches. Where the horizontal branches touch the ground, they will root, continually extending the area of Rhododendron cover.

It is worth noting that because of its extremely lateral growth form, Rhododendron plants are capable of extending well into areas which otherwise would not be suitable for their growth. For example Rhododendron is capable of dominating large areas of wetland with its canopy, while the main stem and roots of the plant are well back on suitably dry land.
For the same reason streams can become completely overgrown and shaded out by Rhododendron growing on the banks. This severely affects animal life in the stream. Fish such as trout depend upon invertebrates which fall off native bankside vegetation for 80% of their food.