Changes in epiphyte diversity in declining forests: implications for conservation and restoration

Abstract

Biodiversity degradation is a serious global problem, and conservation or restoration has been conducted in various ecosystems. The objective of this study was to examine effective conservation measures and restoration goals for epiphytes on the basis of changes in epiphyte flora during the past 30 years on Mt. Odaigahara, Japan. Comparison of epiphyte diversity between 1983 and 2008 indicated that species richness and cover in plots surveyed in 1983 had declined significantly by 2008. The results of nonmetric multidimensional scaling showed that the dominance of hygrophilous species decreased on trees surveyed in 2008 accompanied with forest decline. In addition, total species richness decreased with increasing coverage of wire mesh installed for protection against debarking by deer. We conclude that severe drought stress caused by forest decline after the 1980s and the toxic effects of wire mesh on epiphytes have led to a dramatic decrease in epiphyte diversity during the past 30 years. To conserve epiphyte diversity, first, tree protection without wire mesh should be adopted. In addition, intensive conservation of undamaged forest patches may be necessary to prevent loss of remaining hygrophilous species from this region. The results also indicate that epiphyte diversity can be strongly affected by slight changes in forest structure, and by site-specific environmental factors. Considering that these changes or environmental factors are often not easy to evaluate, comparison of epiphyte diversity before and after disturbance can be an important means of determining appropriate restoration objectives.