The bark of trees: thermal properties, microclimate and fauna

Abstract

The thermal properties of four different types of bark were investigated on twentyfour central European tree species using thermocouples. Tree species with white bark avoid overheating of their surface by reflection of the radiation. Species with fissured and scaly barks shade inner parts of their bark. Some tree species with fissured barks show high insulation across the bark. Smooth and thin barks show no adaptation to avoid overheating. These tree species (in central Europe e.g. Fagus sylvatica) have to form closed stands and are not able to occur in open stands as tree species with structured or white bark types.The arthropod fauna of the same bark types was studied on six tree species using three collecting methods. The microclimate on the bark determines the number per cm of some species, some are active during winter, and other tend to aptery and reproduce parthenogenetically. On smooth bark one species dominates, whereas a highly diverse fauna lives on fissured barks. The occurrence of species on bark is determined by the microstructure, microclimate and consistence of the epiphyts. If tree species alter within forest ecosystems the dominant species on bark will persist. Specialists of fissured barks will die out if tree species with smooth bark (Fagus sylvatica) form the central European forest.

Properties of dissolved and total organic matter in throughfall, stemflow and forest floor leachate of central European forests

“…Interspecific differences in bark traits and cortisphere properties, e.g. bark texture and colour, influence the microclimate and arthropod fauna (Nicolai, 1986), the plant epiphyte (Wyse and Burns, 2011) and microbial community (Andrews and Harris, 2000) consequently affecting the amount and composition of OM as well. For example, enhanced bark microrelief increases the contact time of stemflow solutions with bark surfaces leading to an enrichment of aromatic hydrocarbons likely due to the enhanced degradation and release of soluble lignin compounds .…”

An overview of proximate factors affecting the nesting behavior of solitary wasps and bees (Hymenoptera: Aculeata) in preexisting cavities in wood

“…Cavities in live trees are preferred for nesting than those in dead trees; this can be partially explained by the microclimate inside cavities (Mccomb & Noble 1982, Nicolai 1986, Parker 1986, Tepedino & Parker 1986). The maintenance of a suitable microclimate is important for the development of Aculeate offspring nesting in wood cavities (Frankie et al 1988).…”

Rainforest air-conditioning: the moderating influence of epiphytes on the microclimate in tropical tree crowns

“…For small and poikilothermic animals like arthropods, the microclimatic conditions of their habitat must be crucial determinants of their distribution and behavior (Almquist 1970;Nicolai 1986;Kaspari 1993;Tobin 1995;Rodgers and Kitching 1998). In the canopy, where the bulk of arthropod diversity is expected (Erwin 1983;Nadkarni 1994;Stork et al 1997), the climatic conditions are often extremely harsh and characterized by sudden changes in temperature and relative humidity.…”

“…In contrast, little is known about the adaptations of arboreal arthropods to these hostile conditions. It is often assumed that a primary adaptation may be behavioral, in that arthropods search for sites with more favorable microclimate where desiccation and overheating can be avoided (Lowrie 1948;Almquist 1970;Riechert and Tracy 1975;Nicolai 1986;Kaspari 1993;Didham et al 1998).…”

“…The primary focus is on counting the species (Leigh 1999), and little has been done to unravel details of the biology of particular taxa, let alone their responses and adaptations to canopy climate. However -although experimental evidence is rare -a number of studies have attributed distribution patterns of arthropods in tropical forests to microclimatic parameters (Nicolai 1986;Nadkarni and Longino 1990;Kaspari 1993;Didham et al 1998;Rodgers and Kitching 1998). For small animals like most arthropods, microclimatic conditions in their environment can be extremely limiting factors, e.g.…”