Threatened conifers of the world

Conifers which become stressed following habitat disturbance are often out-competed by better adapted native plant species.  For example, in Bosnia and Herzegovina regeneration in some populations of Picea omorika is being supressed by native Fagus sylvatica because of being better adapted to colonising disturbed forest areas. In Western USA fire-supression has reduced the ability of Cupressus bakeri (which is fire-dependent) to regenerate, hence it is gradually being replaced by Abies magnifica and A. concolor.  Native mistletoes species of the genera Arceuthobium, Phoradendron and Psittacanthus can have a deterimental affect on conifers in North America and Mexico. These shrubby, aerial parasites, which are bird dispersed or have explosive fruits, cause deformation of the infected stems, growth loss, increased susceptibility to other disease agents or insects, and reduced longevity. Species of Abies, Cupressus and Juniperus are particularly susceptable to infestation especially if stressed by habitat disturbance.