Functioning of land-water ecotones in relation to nutrient cycling

Preliminary results of the study on the functioning of the littoral zone of the Gooimeer, The Netherlands, are presented. The results comprise data on the chemical composition of the open water and the aquatic littoral zone, the composition of phytoplankton, metaphyton and epiphyton. On the basis of these data, the Gooimeer littoral zone is characterized as an eutrophic land-water ecotone dominated by a few species of primary producers. Some data on characteristic processes concerning the decomposition of organic matter in rooted littoral sediments are also discussed. Enzyme activities, relevant to mineralization of macrophytic polymers, appear to be highly stimulated in the reed belt of the littoral zone. A first impression of the distribution and the efflux of oxygen in the rhizosphere of reed is given.     

Conditions for the development of the Pinus pumila zone of Hokkaido,northern Japan

The development of the Pinus pumila zone of Hokkaido, northern Japan is discussed on the basis of an examination of the Warmth Index (WI). The Pinus pumila zone is developed on deforested areas in the boreal subalpine belt, and is characterized by strong wind and heavy snow accumulation in winter, and by the presence of rocky fields. It is concluded that in Japan, including Hokkaido, this high mountain zone generally is intrazonal, belonging mainly to the subalpine belt, and that such zones are not common in Europe and North America. Its formation is due mainly to present-day wind, snow and substrate conditions and partly to conditions prevailing during the glacial period.     

No general edge effects for invertebrates at Afromontane forest/grassland ecotones

The Afromontane region of South Africa is characterised by numerous small, remnant forests in a grassland matrix. The edges, or ecotones between forests and grasslands are usually sharp (typically just over a few metres) and are mainly maintained by both natural and, more recently, anthropogenic fires. We investigated epigaeic amphipod, carabid and ant distribution patterns across Afromontane forest/grassland ecotones and found little evidence to support the biological edge effect. Five of the fifty-two sampled species however, did increase significantly in abundance at the ecotone. Among these was a very distinct edge species, the amphipod Talistroides africana. Overall, carabids were more abundant and species rich in forests while for ants it was in the grasslands. Ants and carabids were both more abundant and species rich in spring and summer than in autumn and winter. More interestingly, the abundance and species richness patterns across the ecotone did not change with the passing of the seasons. We argue that a conservation strategy for the Afromontane forest patches must also incorporate the surrounding grassland. The grassland habitat is often perceived as less valuable than forest and, as a consequence, is subject to many anthropogenic disturbances such as fragmentation, cattle grazing and afforestation. Protecting grasslands around forest patches not only conserves the rich ant diversity, but also conserves the biota in the forests and at the edges, and would therefore be more meaningful in terms of the overall conservation of Afromontane biodiversity.     

Extremely low fine root biomass in Larix sibirica forests at the southern drought limit of the boreal forest

Mongolia's Larix sibirica forests at the southern fringe of the Eurosiberian boreal forest belt are exposed not only to very low winter temperatures, but also to frequent summer droughts. It is not completely known how Siberian larch adapts to these stressors. We examined whether (i) these forests differ in their fine root bio- and necromass from more humid boreal forests further in the North and (ii) inter-annual fluctuations in fine root biomass are related to tree vitality. In two exceptionally dry summers, we found only 4–5 g DM m^?2 of fine root biomass (in 0–20 cm depth), which is far less than typical conifer fine root biomass figures from boreal forests (c. 200–400 g m^?2) and the lowest forest fine root biomass reported worldwide; in a moist summer, fine root biomass was 20 fold higher. In contrast to fine root biomass, both necromass and non-tree root mass were high in all three years. From the large increase of fine root biomass in the moist summer and the generally high root necromass, we conclude that drought-induced fine root dieback was the likely cause of the very small amount of live root mass in the dry summers. Larch fine roots seem to be more drought-sensitive than shoots, since marked needle loss did not occur under the extreme conditions.     

Predictive factors for flea occurrence in red foxes (Vulpes vulpes) from semi-arid Mediterranean environments

The role of red fox as host for a wide range of parasites, particularly fleas and other arthropods causing vector-borne diseases, in combination with its capability to adapt to anthropized environments, makes this wild canid an epidemiologically remarkable species at the wildlife–domestic–human interface, especially in the present time of rise of emerging and re-emerging diseases. This study evaluated the prevalence and parasite intensity of fleas in 88 foxes from Murcia Region (Southeastern Spain) and determined the geographic distribution of areas with the highest potential risk of flea presence. Pulex irritans, Ctenocephalides felis, Spilopsyllus cuniculi and Nosopsyllus fasciatus were identified. The overall prevalence was 76.13%. This is the first time that N. fasciatus has been reported in foxes from Murcia Region. The predictive model established a certain pattern to determine the areas with the highest risk of acquiring fleas. Positive correlation of daily potential evapotranspiration (ET₀) in winter and the opposite effect occurring for ET₀ in summer were obtained, as well as positive correlations for mean daily temperature (T_mean) in summer and mean precipitation (P_mean) in winter and summer. The model was also found positively correlated in the forest habitat ecotone areas and the anthropized areas.     

Environmental gradients across four rainforest-open forest boundaries in northeastern Queensland

Abstract This paper examines gradients and correlations among nine environmental factors across four contrasting rainforest-open forest boundaries at Skull Pocket in northeastern Queensland. With few exceptions, the environmental factors formed significant gradients across all four boundaries. Gradients were most pronounced for canopy openness, depth of leaf litter, soil pH, soil temperature and understorey solar radiation, and least pronounced or non-existent for total nitrogen and organic carbon. Boundary site location was shown to have some influence on the degree of change in environmental factors across the rainforest-open forest boundary, with depth of leaf litter, organic carbon, soil temperatures in March and June, and understorey solar radiation in June being significantly different among the four boundary sites. The number of significant correlations among the nine environmental factors was also affected by boundary site location.     

Species-specific foraging behavior of birds in a riparian forest

In riparian forest, insectivorous birds are largely dependent on aquatic preys. However, the contribution made by aquatic preys to bird diets varies considerably among bird species. In the present study, bird foraging behaviors were observed in order to examine the relationship between bird foraging method and the variation in the contribution of aquatic preys. The great tit, the black-faced bunting, and the wren are largely dependent on aquatic preys by capturing them on the ground. Sallyers, the brown flycatcher, the pale-legged willow warbler, and the narcissus flycatcher are also largely dependent on aquatic preys and capture them mostly during flight. The narcissus flycatcher frequently utilises aquatic invertebrates dwelling on the ground. The leaf and branch gleaner, the crowned willow warbler, does not depend on aquatic prey as much. Although both the pygmy woodpecker and nuthatch are branch and trunk gleaners, the nuthatch utilises aquatic preys frequently by capturing them on the ground as well as during flight, but the pygmy woodpecker does not depend on aquatic preys. The marsh tit also does not depend on aquatic preys but carefully searches terrestrial prey that hide in the vegetation. The differential dependence on aquatic preys among species can lead to the heterogeneous distribution of birds within a riparian forest, suggesting that the indirect effect of aquatic preys on a forest ecosystem via birds can vary within a forest–stream ecotone.