Woodpeckers as reliable indicators of bird richness, forest health and harvest

Woodpeckers (family Picidae) show promise as indicators of avian diversity in forests because their populations can be reliably monitored, and their foraging and nesting activities can positively influence the abundance and richness of other forest birds. A correlation between woodpecker richness and richness of forest birds is known to exist at the landscape scale, but uncertainty remains whether this correlation occurs at the smaller stand-level spatial scales where forest management activities take place. We used data collected under a diverse range of forest types, harvest treatments, and forest health conditions during a long-term study of bird communities in interior British Columbia, Canada, to examine two basic questions: (1) at the level of individual forest stands, is woodpecker richness correlated with bird richness (measured as richness of all other bird species)? and (2) do woodpecker richness and bird richness have similar habitat correlates? Bird richness was positively correlated with woodpecker richness (β = 0.59, SE = 0.22, 95% CI = [0.14 1.03]). Richness of both woodpeckers and all other birds were positively correlated with tree species richness and negatively correlated with density of pines, and the effect for forest harvest type was similar for both measures of avian richness (uncut < partial harvest < clearcut with reserves). The effect of density of lodgepole pines killed by mountain pine beetles differed between the two richness measures, being positive for woodpecker richness and negative for forest bird richness. We conclude that the richness of woodpeckers is indeed correlated with the richness of other birds at the stand-level, and can serve as a reliable indicator of overall bird richness in most forest stands and conditions, except during insect outbreaks when differential responses by woodpeckers and the rest of the avian community may decouple the relationship between bird richness and woodpecker richness.     

The challenge of maintaining Atlantic forest biodiversity: A multi-taxa conservation assessment of specialist and generalist species in an agro-forestry mosaic in southern Bahia

Recent developments have highlighted the importance of forest amount at large spatial scales and of matrix quality for ecological processes in remnants. These developments, in turn, suggest the potential for reducing biodiversity loss through the maintenance of a high percentage of forest combined with sensitive management of anthropogenic areas. We conducted a multi-taxa survey to evaluate the potential for biodiversity maintenance in an Atlantic forest landscape that presented a favorable context from a theoretical perspective (high proportion of mature forest partly surrounded by structurally complex matrices). We sampled ferns, butterflies, frogs, lizards, bats, small mammals and birds in interiors and edges of large and small mature forest remnants and two matrices (second-growth forests and shade cacao plantations), as well as trees in interiors of small and large remnants. By considering richness, abundance and composition of forest specialists and generalists, we investigated the biodiversity value of matrix habitats (comparing them with interiors of large remnants for all groups except tree), and evaluated area (for all groups) and edge effects (for all groups except trees) in mature forest remnants. Our results suggest that in landscapes comprising high amounts of mature forest and low contrasting matrices: (1) shade cacao plantations and second-growth forests harbor an appreciable number of forest specialists; (2) most forest specialist assemblages are not affected by area or edge effects, while most generalist assemblages proliferate at edges of small remnants. Nevertheless, differences in tree assemblages, especially among smaller trees, suggest that observed patterns are unlikely to be stable over time.     

Carabid beetles (Coleoptera,Carabidae) as bioindicators in biological and conventional farming in Austrian potato fields

Summary Carabid beetles were sampled in 1980 and 1981 by pitfall trapping in two biologically and two conventionally farmed potato fields in B. Zell, Upper Austria. The cultivation differences consisted mainly of a herbicide application to one conventional field in 1980 and higher fertilization levels in both conventional fields in both years. The total carabid catch was 7428 beetles, representing 48 species. In both years the numbers of total carabids and numbers of species were higher in the biologically farmed fields. Of 16 dominant species (representing 96% of all carabids) only 5 (e.g., Platynus dorsalis, Poecilus cupreus) showed similar activity densities under both types of cultivation. Five species (e.g., Carabus spp., Amara consularis, Harpalus rufipes) were frequent only in one field. Pterostichus melanarius was the only species more numerous in the conventional fields, whereas five species occurred either more frequently or exclusively in the biological fields. Of these five species, Poecilus versicolor, Dyschirius globosus, Calathus fuscipes and, only regionally, Harpalus aeneus are considered to be bioindicators for biologically farmed agroecosystems. The frequencies of Amara consularis and Harpalus rufipes are apparently related to weed vegetation.Dedicated to the late Prof. Dr. W. Kühnelt     

Conservation of beetles in boreal pine forests: the effects of forest age and naturalness on species assemblages

The effort of boreal forest conservation has emphasised the preservation of old-growth forests while the role of young successional stages in maintaining biodiversity has remained largely unstudied. We compared the richness of beetle species and composition of species assemblages between managed and seminatural forests in five stages of forest succession. The sites were in boreal sub-xeric pine-dominated forests in eastern Finland. Seminatural study sites, especially the recently burned sites, were important habitats for threatened and near-threatened species. We propose that young stages of natural succession should be included in the network of protected forest areas. On the other hand, the composition of saproxylic species assemblages in seminatural forests differed from the assemblages in managed forests, indicating also the need to improve the forest management guidelines so that they better address the requirements of species protection. Regeneration methods applied should resemble or mimic the natural disturbances more closely.     

Assessing landscapes: a case study of tree and shrub diversity in the seasonally dry tropical forests of Oaxaca, Mexico and southern Honduras

Tropical dry forests, with their distinct and economically important diversity, are acknowledged conservation priorities because of alarming rates of forest conversion. Whilst it is realised that terrestrial conservation requires an understanding of landscape level patterns of diversity, forests are rarely assessed accordingly. Here we demonstrate that, in the case of the seasonally dry tropical forests of the Pacific watershed of Mesoamerica, landscape level assessment of woody diversity can inform decision making relevant to both between-landscape and within-landscape prioritisation. We report floristic surveys of dry forest landscapes in Oaxaca, Mexico and southern Honduras. It is noted that these forests are floristically similar to other seasonally dry tropical forests in the neotropics. By calculation of Genetic Heat Indices, a relative measure of the concentration of restricted range species in a sample, we determine that the conservation of the tree diversity of the coastal lowlands of Oaxaca should be prioritised over that of southern Honduras. The current conservation status of forested areas in Oaxaca is briefly described. We suggest that the greater degree of anthropogenic disturbance in southern Honduras may explain the relative lack of restricted range species there. We argue that some forest fallows can act as analogues of mature forest and therefore landscape elements other than mature forest need to be included in forest conservation assessments. We conclude that diversity sampling of any forest type should not be limited to mature forests, but extended to other elements of forested landscapes.     

Changes in food resources and conservation of scarab beetles: from sheep to dog dung in a green urban area of Rome (Coleoptera, Scarabaeoidea)

The aim of the research was to show how a change in land use influences the structure of a dung beetle assemblage and affect its conservation. In the Pineto Urban Regional Park (Rome), dog dung is the sole food resource currently available for scarab dung beetles, after the recent removal of wild and domestic herbivores. A one-year sampling was conducted to study the scarab assemblage in dog scats (1999) and to compare it with the previous assemblage associated with sheep droppings (1986). Richness, evenness and similarity parameters were compared between the two allochronic assemblages. From sheep to dog dung, an impoverishment of the total richness was observed (from 19 to 9 species) together with an increase of individuals (by 7 times). Dog dung harboured 20% of the current scarab dung beetle fauna of Rome, probably as a consequence of the dog mixed diet, rich in cellulose. Both the communities showed a high percentage of tunnellers, probably because of the food shortage and, for dog scats, of the high dehydration rate. A comparison with other Roman scarab communities enhanced that: (1) the change in food resource determined a higher difference in species composition respect to other parameters (size and habitat diversity); (2) dog dung provided a temporary refuge for species that otherwise may encounter local extinction in urban environments.     

Openness in management: Hands-off vs partial cutting in conservation forests, and the response of beetles

The appropriate management of forest reserves is debated; two major alternatives are succession to ‘wild’ state, or management to produce semi-open stands. For temperate conservation stands, there are no strong experiments replicated at landscape level. In each of 22 forests rich in oaks (Quercus spp.) in Sweden, we set up a closed-canopy wild plot (1 ha), and a cutting plot (1 ha) to produce semi-open conditions, studying them before and after cutting. About 25% of the tree basal area was cut (large trees and dead wood retained) and harvested as bio-fuel, a CO₂ - neutral energy source. We examined the response of beetles and trapped 59,000 individuals (1174 species; 100 red-listed species). For both the guild of herbivorous beetles (222 species) and of saproxylic beetles connected to oak wood (267 species), species richness increased by about 35% in the harvested plots, relative to the wild reference plots. Species composition within the groups changed, though not strongly. Thirteen saproxylic species of 50 analysed, and three herbivores of 12 increased in cutting plots. For red-listed saproxylic beetles, species richness did not change significantly. Regression analyses suggest that more open cutting plots disfavour the red-listed beetles of this forest type. Thus, partial cutting increased species diversity of two beetle groups, probably due to changed microclimate and increase in herbaceous plants, but some red-listed saproxylic beetles may be disfavoured. A hands-off alternative may through storms and other disturbances produce open patches, more dead wood, and favour some species. Combinations of these alternatives, carefully planned at the landscape level, need to be considered.     

Habitat modelling for the conservation of the rare ground beetle species Carabus variolosus (Coleoptera, Carabidae) in the riparian zones of headwaters

Carabus variolosus is a highly endangered insect which is listed in the EC Habitats and Species Directive. Detailed knowledge of the habitat requirements of this semi-aquatic woodland carabid beetle is needed if effective conservation and management strategies are to be developed. Previous habitat models have proved to be a successful analytical and predictive tool for the conservation of species. We conducted an intensive study over a two year period on two extant C. variolosus populations in Westphalia (Germany) using live capture pitfall traps. We analysed the distribution of the beetles over their main activity period in relation to a large number of edaphic and vegetation variables in order to estimate habitat suitability models and describe optimum ranges. C. variolosus is restricted to the fringes of water bodies and to areas of high soil moisture that display patches of bare soil, shows a slight preference for sparse tree vegetation, and avoids acidic soil. Temporal and spatial transferability of the statistically significant habitat models indicates their robustness and validity. Based on the results of our study, we suggest management measures for the conservation of C. variolosus, which promote the rehabilitation of natural flood plains of headwater areas.     

Influence of contrasting urban edges on the abundance of arboreal mammals: A study of squirrel gliders (Petaurus norfolcensis) in southeast Queensland, Australia

The primary impacts of urban development on biodiversity are loss and fragmentation of habitat, and changes in the structure, composition and function of remnant native ecosystems. Forest dependent species, including arboreal mammals, are particularly sensitive to these changes due to their highly specific habitat requirements and inability or reluctance to cross the urban matrix. We addressed this problem using a case study of the squirrel glider (Petaurus norfolcensis) in fragmented urban landscapes of southeast Queensland, Australia. We applied a mixed effect modeling approach clustered by patch to quantify the importance of site-level habitat factors relative to edge contrast and habitat patch size on squirrel glider abundance. Analysis of variance was used to test for differences in glider age and sex in interior habitats compared to road and residential edges. We found that edge contrast had a strong negative effect on the abundance of squirrel gliders but is conditional on the presence of a low numbers of unreliable flowering overstorey trees and the availability of critical resources such as nest hollows at a site. We also found that older male gliders prefer forest fragment interiors over road and residential edge habitats. We conclude that although interior habitats are ideal to maintain large stable populations, the conservation value of low contrast edges containing key site-level resources should not be underestimated for arboreal mammals such as the squirrel glider.     

Soil ciliates (Protozoa: Ciliophora) from evergreen rain forests of Australia, South America and Costa Rica: diversity and description of new species

This paper provides, for the first time, comprehensive data on alpha diversity of soil ciliates from evergreen tropical and temperate rain forests. Thirty-three samples were collected in Australia, Tasmania, Amazonia and Costa Rica and analysed with the non-flooded Petri dish method, which reactivates the ciliates’ resting cysts from air-dried samples. The 175 taxa found contained 34 new species, 4 of which are described in this paper, viz. Platyophrya paoletti n. sp., Lamtostyla abdita n. sp., L. granulifera n. sp., and Apoamphisiella tihanyiensis (Gellért and Tamás 1958) n. gen., n. comb. Although this is a considerable number, it is much lower than one would expect. The data would be even more perplexing if the four rich samples (up to 90 species/sample) from the Manaus floodplain were excluded. We then would be confronted with about 90 taxa in 29 samples, of which 13 contained fewer than ten species. A hypothesis is put forward that the non-flooded Petri dish method is inappropriate for studying soil ciliate diversity in evergreen rain forests because most species have a reduced capacity to produce dry-resistant (protective) resting cysts due to the permanent wetness of their habitats. This view is supported by a comparative analysis of a fresh (containing 40 species) and air-dried/rewetted (2 species only) sample from a cloud rain forest near Merida (Venezuela), and the observation that the capacity of soil ciliates to produce resting cysts often dramatically decreases after prolonged laboratory cultivation in liquid media. Direct microscopy of fresh samples seems to be an appropriate alternative because specimens can be easily collected due to their considerable abundance (≥1000 individuals/g wet mass of litter). Received: 8 April 1997     

Parasitoids (Hymenoptera, Ichneumonoidea) of Saproxylic beetles are affected by forest successional stage and dead wood characteristics in boreal spruce forest

The habitat requirements and effects of forest management on insects belonging to higher trophic levels are relatively unknown in forest ecosystems. We tested the effect of forest successional stage and dead wood characteristics on the saproxylic parasitoid (Hymenoptera, Ichneumonoidea) assemblage in boreal spruce-dominated forests in northern Sweden. Within each of nine areas, we selected three sites with different management histories: (1) a clear-cut (2) a mature managed forest and (3) an old-growth forest. Parasitoids were collected in 2003 using eclector traps mounted on fresh logs, which were either untreated (control), burned, inoculated with fungi, or naturally shaded, and on artificially-created snags.Both forest type and dead wood characteristics had a significant effect on parasitoid assemblages. Grouped idiobionts and some species, such as Bracon obscurator and Ontsira antica, preferred clear-cuts, while others, such as Cosmophorus regius (Hym., Braconidae) and other koinobionts, were associated with older successional forest stages. No single dead wood substrate was sufficient to support the entire community of parasitoids in any forest type, even when the regular host was present. In particular, snags hosted a different assemblage of species from other types of dead wood, with parasitoids of Tetropium spp. such as Rhimphoctona spp. (Hym., Ichneumonidae) and Helconidea dentator (Hym., Braconidae) being abundant. These results indicate that a diversity of dead wood habitats is necessary to support complete assemblages of beetle-associated parasitoids from early successional stages of dead wood and that parasitoids may be more sensitive to habitat change than their hosts.     

Effects of litter (beech and stinging nettle) and earthworms (Octolasion lacteum) on carbon and nutrient cycling in beech forests on a basalt-limestone gradient: A laboratory experiment

Effects of leaf litter of beech (Fagus sylvatica L.) and stinging nettles (Urtica dioica L.) and of the endogeic earthworm species Octolasion lacteum (Örley) on carbon turnover and nutrient dynamics in soil of three beechwood sites on a basalt hill (Hesse, Germany) were investigated in a laboratory experiment lasting for about 1 year. The sites were located along a gradient from basalt (upper part of the hill) to limestone (lower part of the hill) with an intermediate site in between (transition zone). At the intermediate site U. dioica dominated in the understory whereas at the other sites Mercurialis perennis L. was most abundant. The amount and composition of organic matter was similar in soil of the basalt (carbon content 5.9%, C/N ratio 13.8) and intermediate site (carbon content 5.6%, C/N ratio 14.3) but the soil of the intermediate site produced more CO₂ (in total +17.5%) and more nitrogen (as nitrate) was leached from this soil (in total +55.6%). It is concluded that the soil of the intermediate site contains a large mobile carbon and nitrogen pool and the formation of this pool is ascribed to the input of U. dioica litter. Leaf litter of U. dioica strongly increased NO₃ ^–-N leaching immediately after the litter had been added, whereas nitrogen was immobilized due to addition of beech litter. Despite the very fast initial decomposition of nettle litter, the increase in CO₂ production due to this litter material was only equivalent to 20.1% of the amount of carbon added with the nettle litter; the respective value for beech litter was 34.8%. Earthworms altered the time course of carbon and nitrogen mineralization in each of the treatments. In general, earthworms strongly increased mineralization of nitrogen but this effect was less pronounced in soil of the intermediate site (treatments without litter), which is ascribed to a depleted physically protected nitrogen and carbon pool. In contrast, their effect on the total amount of nitrogen mobilized from nettle litter was small. Earthworms significantly reduced CO₂ production from soil of the intermediate site (treatments without litter) and it is concluded that earthworm activity contributes to the restoration of the depleted physically protected carbon pool at this site.     

Elephant- and human-induced changes to dung beetle (Coleoptera: Scarabaeidae) assemblages in the Maputaland Centre of Endemism

High African elephant stocking rates in nature reserves in southern Africa have been shown to have significant impacts on vegetation structure and diversity. However, the direct and indirect effects of elephants on fauna, particularly invertebrates, remain poorly known. The Maputaland Centre of Endemism, an area of southern Mozambique and northern KwaZulu-Natal in South Africa, is undergoing rapid rates of habitat conversion. Sand Forest, the rarest vegetation type in the Centre, is threatened by human disturbance outside of protected areas and by elephant browsing pressure in Tembe Elephant Park, one of the few protected areas for Sand Forest. Here we examine the effects of elephant- and human-induced disturbance to Sand Forest on a functionally important component of invertebrate diversity, i.e. the dung beetle fauna. The dung beetle assemblage associated with elephant-disturbed Sand Forest was transitional between undisturbed Sand Forest and Mixed Woodland, whereas that associated with human disturbance was markedly different to either habitat type. Differences are attributed to a change in habitat structure under both disturbance types, as well as to changes in the quality and distribution of dung under human disturbance. Therefore, grazing impacts by elephant not only affect plant diversity, but also implement changes in invertebrate fauna. The maintenance of the integrity of the Sand Forest–Mixed Woodland matrix is considered critical for biodiversity conservation in the Maputaland Centre of Endemism. Management of elephant populations, as well as the protection of sufficient Sand Forest inside conservation areas must, therefore, necessarily form part of the conservation strategy for the Centre.     

Golden bowerbird (Prionodura newtonia) habitat in past, present and future climates: predicted extinction of a vertebrate in tropical highlands due to global warming

A generalised linear model was used to predict climatically suitable habitat for the golden bowerbird (Prionodura newtonia De Vis), an endemic species of the Wet Tropics of North Queensland. Mean temperature of the coldest quarter and mean precipitation of the wettest quarter were found to be the best habitat predictors. For independent validation data, accuracy was 67% (Kappa statistic, n=30). Past, and future habitats suitable to the golden bowerbird were mapped by altering the temperature and precipitation input to the model. In the current climate, total potential habitat is estimated to be 1564 km², occurring as a number of separate patches with distinct bowerbird subpopulations. Past habitat was most limiting, 406 km², during the Holocene climatic optimum (c. 5000-3600 YBP, +2 °C and +50% rainfall relative to today). With future warming, assuming a 10% decrease in rainfall, potential habitat is reduced to 582 km² (1 °C warming), 163 km² (2 °C warming) and 37 km² (3 °C warming). Thus, global warming in the coming decades is likely to be a significant threat to the survival of this and similar upland and highland species in the tropics.     

Agronomic Evaluation of Manure Ashes: Changes in Soil Phosphorus Fractions,Maize (Zea mays) Yield,and Phosphorus Uptake

ABSTRACT

In order to reduce bulkiness and concentrate its nutrients, manures were burnt to ashes, and the effect of manures and their ashes on soil phosphorus fractions and maize performance in laboratory incubation, screenhouse, and field experiments was evaluated. Treatments were control, dried poultry manure (DPM), poultry manure ash, dried cattle manure (DCM), cattle manure ash (CMA), dried goat manure, goat manure ash and NPK 15-15-15, each applied at 120 kg P ha^?1. Periodic data were taken from soil P fractions, maize yield, and P uptake. Results showed that manures and their ashes increased soil P fractions in incubation, screenhouse, and field experiments. Available P and Ca-P increased with application of DPM while CMA only increased labile P, Al-P, and Fe-P at later weeks. Dry matter yield and P uptake increased with the application of manures and ashes while available P was positively correlated with P uptake. The impact of manure ashes was comparable to manures, hence recommended for use as alternatives, thereby getting rid of the problems of manure bulkiness and offensive odors.