Book review: Headwaters in the clouds

Abstract

news and update book review Headwaters in the clouds Tropical Montane Cloud Forests, by L. A. Bruijnzeel, F. N. Scatena & L. S. Hamilton (editors), 2011, Cambridge University Press, 768 pp. £65 (Hardback) ISBN: 9780521760355; http:// www.cambridge.org/ Tropical Montane Cloud Forests (TMCFs) are gaining in scientific popularity since a first international symposium on this ecosystem was held in Puerto Rico in 1993. The promotion of the meeting by the UNESCO International Hydrological Programme illustrates a far-reaching effect of cloud forests: they act as water collectors for tropical forelands. TMCFs also harbour extraordinarily many plant species, contributing to outstanding positions in each of the five hottest spots of plant diversity. Why edit yet another comprehensive opus on TMCFs, after several previous fundamental works, despite their encompassing under 0.15% of the global terrestrial surface? The answer is clear to those who know this biome: there hardly exists a more fascinating environment than exuberant, moss-covered cloud forests, often called elfin forests due to their mystical appearance. They form highly complex ecosystems, which on different continents show divergent biocœnoses because of their fragmentation and isolated position within distinct tropical mountains in the Neotropics and, to a lesser degree, in the Paleotropics, and in a few cases even on Pacific islands. This book deals with general features of TMCFs (12 chapters) and contains examples from Middle America (21), South America (19), Southeast Asia (10), Africa (5) and Oceania / Australia (5). Most contributions result from a conference in Hawaii in 2004. A first glance reveals a nearly complete thematic spectrum. The book is subdivided into seven sections with a total of 72 chapters. The first part contains general features of TMCFs. Altitudinal distributions are presented in an introductory chapter, though integrative references to surrounding belts are missing. A useful GIS-based modelling approach provides instructive data on TMCF resources and losses including tables on their dimensions and distributions. Interestingly, Indonesia and Congo rank first in national extent, with neotropical countries falling lower down. A climate chapter is based on a dataset of 477 weather stations in cloud forest sites. Many graphs present vast dot clouds of data from stations between 200 and 5,000 m asl, which raises the confusing suspicion that TMCFs occur in regions of extremely dissimilar climates. A short but informative chapter on changes in fog precipitation should have been part of a later section, as also applies to one on epiphytism. Comments on global and local soil variations, as well as on nutrient cycling and limitation in TMCFs, provide convincing and compact estimations. Coloured maps of TMCF distribution highlight their restricted extent and natural fragmentation on a global scale. The subsequent and sadly brief section on regional aspects of floristic and faunistic diversity contains fascinating information from all TMCF- bearing continents. The range extends from research on epiphyte-diversity on solitary trees (up to 4,806 individuals of 114 vascular plant species on one single fig tree!) to potential and actual distribution patterns of the mountain tapir and Andean bear. The only point of criticism is that in a book on a biological realm this section could have been broader. The third section on hydrometeorology covers a broad remit since fog, rain and their interception are decisive triggers for the formation of TMCFs. Several parts display the importance of potential evaporation and irradiation as driving forces for the variable character of forests. Additionally, the degrees of litter mineraliation and soil acidity become crucial causes of ecological peculiarities. The contributions vary from rather specialist methodical content (e.g. measuring interception, usage of stable isotopes for diagnoses of precipitation origins) to comments on the water frontiers of biogeography 4.1, 2012 — © 2012 the authors; journal compilation © 2012 The International Biogeography Society