Black Forest, Silent Forest

By Bruce G. Marcot, Ecology Picture of the Week:

Covering nearly 160 km (100 miles) across southwest Germany is the Black Forest, the country's largest national park.  This forest has been used for centuries as a source of timber and fuel wood, for hunting of animals, as watersheds for clean water, and for recreation.  

Much of its forestry and forest research is legendary.  And for many decades, the Black Forest has been intensively managed for even-age stands of commercially valuable spruce (Picea abies), fir (Abies alba), and other tree species.  

However, the ages-old application of classic, intensive silviculture there has more recently been known to reduce the biodiversity of the forest in favor of well-pruned, well-spaced commercially-valuable trees.  This has greatly reduced the structural diversity of the forest and old-growth forest conditions.  The Black Forest has become a silent forest, as much of the wildlife depending on old forest conditions has vanished or has become far less common.

In natural old-growth forests, trees are spaced more randomly and there occur large old legacy trees, large standing dead trees (snags), standing and down hollow trees, deep tree canopies, and usually a dense and variable understory of shrubs and young tree patches.  Each of these features are important habitat for many wildlife and even some plant species.  But none of these features occurs in today's even-age managed forests, as shown in this week's featured photo.  

Such intensive forest management also has led to a decline in overall tree growth rate, soil productivity, and forest health.  This is because not nearly as much organic matter, such as from falling trees and branches, is available to become incorporated into the forest soils, and outbreaks of forest insect pests and pathogens occur more frequently and spread rapidly.  

In recent years, a more ecosystem-based and ecologically focused form of forest management has been attempted, in large part to restore soil productivity and overall forest ecosystem biodiversity.  This new form of management has been named "forest transformation" and entails converting these structurally simple even-age stands into more structurally diverse forests with more tree and shrub species.   Along with a change in forest management has been wildlife restoration activities, such as reintroduction of the lynx, previously extirpated from Germany.  

  --Bruce G. Marcot

Image and text © Bruce G. Marcot, Ph.D. Research Wildlife Ecologist,
who produces the Ecology Picture of the Week website.