The understory also contains a wide variety of herbaceous and shrub species. Temperate conifer forests sustain the highest levels of biomass in any terrestrial ecosystem and are notable for trees of massive proportions in temperate rainforest regions.
Structurally, these forests are rather simple, consisting of 2 layers generally: an overstory and understory. However, some forests may support a layer of shrubs. Pine forests support an herbaceous groundlayer that may be dominated by grasses and forbs that lend themselves to ecologically important wildfires. In contrast, the moist conditions found in temperate rain forests favor the dominance by ferns and some forbs.
Temperate rain forests only occur in 7 regions around the world - the Pacific Northwest, the Validivian forests of southwestern South America, the rain forests of New Zealand and Tasmania, the Northeastern Atlantic (small, isolated pockets in Ireland, Scotland, and Iceland), southwestern Japan, and those of the eastern Black Sea1).
Forest communities dominated by huge trees (e.g., giant sequoia, Sequoiadendron gigantea; redwood, Sequoia sempervirens; mountain ash, Eucalyptus regnans), an unusual ecological phenomena, occur in western North America, southwestern South America, as well as in the Australasian region in such areas as southeastern Australia and northern New Zealand.
The Klamath-Siskiyou ecoregion of western North America harbors diverse and unusual assemblages and displays notable endemism for a number of plant and animal taxa.
Most tree species and larger vertebrates have relatively widespread distributions; considerable local endemism and beta diversity occurs in some ecoregions in invertebrates, understory plants, and lichens, particularly in rain forests or on unusual soils; may have extremely diverse invertebrate faunas or herbaceous floras; altitudinal specialization occurs but is less pronounced than in the tropics.
Disturbance regimes such as fire, windthrow, and epizootics can vary considerably within this major habitat type, but the extremes are typically of sufficient size and frequency as to make small patches of natural forest have only limited conservation value; many species highly specialized on late-successional forests; larger carnivores very wide-ranging with large home ranges; some species track resources that vary widely in space in time (e.g., epizootic outbreaks, fire events, cone production) requiring large natural landscapes.
Sensitivity to Disturbance
Larger carnivores highly sensitive to human activities including low intensity hunting; large number of species highly sensitive to logging and fragmentation of natural forests, particularly late-successional species; late-successional species and features typically regenerate slowly; many temperate forests require periodic fires to maintain successional processes and many species; exotic species can have extensive and significant impacts on natural forest communities.
In this habitat are the following ecoregions:
(76) Valdivian Temperate Rainforests / Juan Fernandez Islands