Quantitative delimitation of warm-temperate deciduous forest areas

Abstract

The zonal vegetation of [humid] warm-temperate regions is normally considered to be evergreen broad-leaved forest, as in East Asia, southern Brazil, and much of New Zealand. Kira, however, proposed the term ‘warm-temperate deciduous’ for forests composed of deciduous trees that do not occur in the adjacent cool–temperate or subtropical zones in Japan but do occur in parts of the otherwise warm-temperate zone that have colder winters. This concept also fits some deciduous forests on other continents, and some such forests are described in other chapters of this book. In addition, in the Overview chapter of this book, an attempt was made to delimit such forest areas quantitatively, using climatic data. In this chapter an attempt is made to identify these and other potential temperate forest areas geographically, based on their climatic envelopes, and to map them worldwide. Limiting values for the envelopes are based on the “breaks” in climatic response identified in the Overview chapter, but with a compromise threshold for summer temperatures, in order to show European areas that occur at lower summer temperatures than on continental east sides. The resulting map shows the expected three main regions, plus some additional smaller areas, thus suggesting that warm-temperate deciduous does represent a consistent sub-zonal climatic and potential forest type. The regions shown, though, are too large in eastern North America and East Asia, in order to show some areas in Europe.