Biodiversity and Conservation

Diatoms are abundant and diverse in many Antarctic freshwaters, with a general trend of decreasing diversity moving southwards. They form an important component of many benthic algal communities in streams and standing waters but are generally less common in the phytoplankton. Diatoms are excellent ecological indicator species and, because their remains are preserved in many sedimentary environments, there appears to be a great potential for palaeoenvironmental reconstruction and the examination of past diversity. A lack of taxonomic precision and consistency, coupled with the insufficient collection from some geographical areas, makes the estimation of the number of Antarctic diatom species problematic.

This paper analyzes the diversity of dung and carrion beetles (Scarabaeinae and Silphidae) in four human-induced habitats of a disturbed tropical montane cloud forest: polyspecific shade coffee plantations, monospecific shade coffee plantations, tropical montane cloud forest fragments, and clear cuts. The four habitats had similar richness, species composition, and assemblage structure of dung and carrion beetles. Differences were found in abundance and biomass levels for the four dominant species in the landscape. Dung beetles were more abundant than carrion beetles, but the biomass was higher for the latter. Carrion beetles were seasonal, while dung beetles were clearly not. When forest fragments and shade coffee plantations were compared to other similar habitats in the region, the same general pattern was observed. However, forests with high disturbance and monospecific shade coffee plantations had lower species richness than forests with low and medium disturbance and polyspecific shade coffee plantations. Thus shade coffee plantations maintain connectivity between patches of cloud forest in a landscape that is strongly affected by human activities. Protecting landscape diversity appears to ensure high species richness.

Some urbanising rural (i.e. ‘amenity’) landscapes have seen an increase in forest cover over recent decades. Small-acreage landowners are key stakeholders in this forest recovery and its future ecological trajectory. Using 17 qualitative case-studies of small-acreage properties located in the Noosa hinterland in south-east Queensland, this study explores the types and condition of forests on these properties, the landholder’s differing forest management perspectives, practices and outcomes, and the implications for local biodiversity conservation. The properties contained a diverse mix of managed and un-managed natural and planted forests. Invasive weed species were a common component. Protecting and enhancing the ecological values of amenity landscapes will require an increase in active, best-practice forest management on small-acreage properties. Small-acreage landowners will require greater access to labour support and other subsidised resources to implement recommended practices. Such practices include controlling and reducing the spread of invasive weeds and soil erosion, reducing fire hazards, and positively influencing the rate and pathway of succession in regrowth forests. Peer-mentoring programs incorporating guided tours of ‘model’ small-acreage forests, and supporting landowners to establish their own small native plant nurseries and engage with local community nurseries (i.e. supplying seeds, volunteering labour), could help to increase small-acreage landowners’ forest management interests, knowledge, skills and activity. Long-term cooperative, cross-boundary forest management projects with on-going monitoring and adaptive management guided or implemented by skilled professionals are needed in amenity landscapes, particularly to increase the success of restoration interventions in weed-dominated regrowth forests. There is also a need for long-term socio-ecological analyses of amenity landscapes’ diverse and evolving small-acreage forests to better inform their future management.

Very old trees harbour a diverse fauna of saproxylic insects, many of which are classified as threatened due to the scarcity of this kind of habitat. Parks, which often contain many old trees, are therefore considered to be important sites for this fauna. However parks are intensively managed and dead wood is often removed. Therefore this study compares if the saproxylic beetle fauna in parks is as diverse as it is in more natural stands. Eight ‘Park’ sites at manor houses around lake Mälaren, Sweden were compared with trees in wooded meadows: eight grazed sites, here termed ‘Open’, and 11 sites regrown with younger trees, termed ‘Re-grown’. The comparison was made on lime trees (Tilia spp.): one of the most frequent tree species in old parks which host a diverse beetle fauna. Beetles were sampled with window traps, which in total caught 14,460 saproxylic beetles belonging to 323 species, of which 50 were red-listed. When comparing all saproxylic species, ‘Park’ sites had significantly fewer species than ‘Open’ sites. However, for beetles in hollow trees and for red-listed species there was no significant difference, the number in ‘Park’ being intermediate between ‘Open’ and ‘Re-grown’. Species composition differed between sites, but only marginally so. Therefore, the conclusion is that old park trees on average are as valuable for faunal diversity as trees in more natural sites. Large conservation benefits can be obtained by combining cultural and conservational values in the management of park habitats.

In fragmented landscapes, agroforest woodlots can potentially act as stepping stones facilitating movement between forest fragments. We assessed the influence of agroforest woodlots on bird distribution and diversity in the Atlantic forest region (SE Brazil), and also tested which categories of species can use different types of connection elements, and whether this use is influenced by the distance to large forest patches. We studied two fragmented landscapes, with and without stepping stones linking large fragments, and one forested landscape. Using a point count, a bird survey was undertaken in the fragmented landscapes in five different elements: large remnants (>400 ha), agroforest woodlots (0.4–1.1 ha), small patches (0.5–7 ha), riparian corridor, and pasture areas (the main matrix). Generalist and open-area species were commonly observed in the agroforest system or other connection elements, whereas only a few forest species were present in these connections. For the latter species, the distance of woodlots to large patches was essential to determine their richness and abundance. Based on our results and data from literature, we suggest that there is an optimal relationship between the permeability of the matrix and the efficiency of stepping stones, which occurs at intermediate degrees of matrix resistance, and is species-dependent. Because the presence of agroforest system favors a higher richness of generalist species, they appeared to be more advantageous for conservation than the monoculture system; for this reason, they should be considered as a management alternative, particularly when the matrix permeability requirement is met.