Spatial and temporal deforestation dynamics in protected and unprotected dry forests: a case study from Myanmar (Burma)

Tropical dry forests are more threatened, less protected and especially susceptible to deforestation. However, most deforestation research focuses on tropical rain forests. We analyzed spatial and temporal changes in land cover from 1972 through 2005 at Chatthin Wildlife Sanctuary (CWS), a tropical dry forest in Myanmar (Burma). CWS is one of the largest protected patches of tropical dry forest in Southeast Asia and supports over half the remaining wild population of the endangered Eld’s deer. Between 1973 and 2005, 62% of forest was lost at an annual rate of 1.86% in the area, while forest loss inside CWS was only 16% (0.45% annually). Based on trends found during our study period, dry forests outside CWS would not persist beyond 2019, while forests inside CWS would persist for at least another 100 years. Analysis of temporal deforestation patterns indicates the highest rate of loss occurred between 1992 and 2001. Conversion to agriculture, shifting agriculture, and flooding from a hydro-electric development were the main deforestation drivers. Fragmentation was also severe, halving the area of suitable Eld’s deer habitat between 1973 and 2001, and increasing its isolation. CWS protection efforts were effective in reducing deforestation rates, although deforestation effects extended up to 2 km into the sanctuary. Establishing new protected areas for dry forests and finding ways to mitigate human impacts on existing forests are both needed to protect remaining dry forests and the species they support.     

Projected climate changes threaten ancient refugia of kelp forests in the North Atlantic

Intraspecific genetic variability is critical for species adaptation and evolution and yet it is generally overlooked in projections of the biological consequences of climate change. We ask whether ongoing climate changes can cause the loss of important gene pools from North Atlantic relict kelp forests that persisted over glacial–interglacial cycles. We use ecological niche modelling to predict genetic diversity hotspots for eight species of large brown algae with different thermal tolerances (Arctic to warm temperate), estimated as regions of persistence throughout the Last Glacial Maximum (20,000 YBP), the warmer Mid‐Holocene (6,000 YBP), and the present. Changes in the genetic diversity within ancient refugia were projected for the future (year 2100) under two contrasting climate change scenarios (RCP2.6 and RCP8.5). Models predicted distributions that matched empirical distributions in cross‐validation, and identified distinct refugia at the low latitude ranges, which largely coincide among species with similar ecological niches. Transferred models into the future projected polewards expansions and substantial range losses in lower latitudes, where richer gene pools are expected (in Nova Scotia and Iberia for cold affinity species and Gibraltar, Alboran, and Morocco for warm‐temperate species). These effects were projected for both scenarios but were intensified under the extreme RCP8.5 scenario, with the complete borealization (circum‐Arctic colonization) of kelp forests, the redistribution of the biogeographical transitional zones of the North Atlantic, and the erosion of global gene pools across all species. As the geographic distribution of genetic variability is unknown for most marine species, our results represent a baseline for identification of locations potentially rich in unique phylogeographic lineages that are also climatic relics in threat of disappearing.     

Land use and biodiversity patterns of the herpetofauna: The role of olive groves

The intensification of agriculture has significant environmental consequences. This intensification entails the simplification and homogenisation of the landscape, which leads to strong negative impacts at ecosystem level, including declines in animal biodiversity. The purpose of this study was to assess the effect of different land uses on reptilian and amphibian biodiversity patterns at a regional scale by analysing a large database on the presence of amphibians and reptiles in Andalusia (southern Spain). GIS techniques and the Ecological-Niche Factor Analysis (ENFA) were applied in order to assess whether the habitat was suitable for each reptilian and amphibian species, when the land use variables were excluded. The incongruence between the potential and the observed species richness was then correlated with the main types of land use in Andalusia. Our results showed that irrigated and unirrigated olive groves were associated with a biodiversity deficit of amphibians and reptiles respectively, whereas natural forests and pastures, along with more heterogeneous crops areas, were more suitable. A clustering analysis showed that generalist species were related to olive groves whereas rare and specialist species were related to land uses related to natural vegetation. In summary, our results indicate that large areas covered by olives groves harbour less amphibian and reptilian diversity, thus suggesting that agro-environmental schemes should be carried to promote the species richness in these crops.     

Liana diversity and distribution in four tropical dry evergreen forests on the Coromandel coast of south India

Liana diversity was inventoried in four tropical dry evergreen forest sites that are characterized by numerous trees, of short stature and small diameter, and a varying degree of anthropogenic disturbance, on the Coromandel coast of south India. A 1-ha plot was established in each of the four sites and was subdivided into 100 quadrats of 10 m× 10 m. All lianas 1 cm diameter at breast height (dbh) rooted within the plot were enumerated. The species richness and density of lianas, with respect to site disturbance and forest stature, varied across the sites. Liana density totaled 3307 individuals (range 497–1163 individuals ha^–1) and species richness totaled 39 species (range 24–29 species ha^–1) representing 34 genera and 24 families. Combretaceae, Asclepiadaceae, Capparaceae and Vitaceae were the well-represented families. The top five species Strychnos minor, Combretum albidum, Derris ovalifolia, Jasminum angustifolium and Reissantia indica contributed 55% of total density. The slopes of the species–area curves were different for each of the four sites and the curve stabilized in only one site. Of the four climbing modes recognized among the total 39 species, 18 were twiners (56% of the total density). Eight species (24% of density) were tendril climbers and 12 species (16% of density) were scramblers. Hugonia mystax was the only hook climber. All the 39 species and 88% of liana density were encountered within a category of 6 cm dbh or less, and a similar pattern prevailed in the individual sites. Of the three diaspore dispersal modes found among the 39 liana species, animal (64%) and wind (23%) dispersal were predominant over the autochorous mode (13%). Liana diversity and distribution in dry forest communities appear to be influenced by forest stature and site disturbance levels. In the light of the extent of liana diversity and sacred grove status of the study sites, the need for forest conservation, involving local people, is emphasized.     

Range reshuffling: Climate change,invasive species,and the case of Nothofagus forests in Aotearoa New Zealand

Aim

The impact of climate change on forest biodiversity and ecosystem services will be partly determined by the relative fortunes of invasive and native forest trees under future conditions. Aotearoa New Zealand has high conservation value native forests and one of the world's worst invasive tree problems. We assess the relative effects of habitat redistribution on native Nothofagus and invasive conifer (Pinaceae) species in New Zealand as a case study on the compounding impacts of climate change and tree invasions.

Location

Aotearoa New Zealand.

Methods

We use species distribution models (SDMs) to predict the current and future distribution of habitat for five native Nothofagus species and 13 invasive conifer species under two 2070 climate scenarios. We calculate habitat loss/gain for all species and examine overlap between the invasive and native species now and in future.

Results

Most species will lose habitat overall. The native species saw large changes in the distribution of habitat with extensive losses in North Island and gains mostly in South Island. Concerningly, we found that most new habitat for Nothofagus was also suitable for at least one invasive species. However, there were refugia for the native species in the wetter parts of the climate space.

Main Conclusion

If the predicted changes in habitat distribution translate to shifts in forest distribution, it would cause widespread ecological disruption. We discuss how acclimation, adaptation and biotic interactions may prevent/delay some changes. But we also highlight that the poor establishment capacity of Nothofagus, and the contrasting ability of the conifers to invade, will present persistent conservation challenges in areas of both new habitat and forest retreat. Pinaceae are problematic invaders globally, and our results highlight that control of invasions and active native forest restoration will likely be key to managing forest biodiversity under future climates.     

The Contribution of Tropical Secondary Forest Fragments to the Conservation of Fruit-feeding Butterflies: Effects of Isolation and Age

Concomitant with the rapid loss of tropical mature forests, the relative abundance of secondary forests is increasing steadily and the latter are therefore of growing interest for conservation. We analysed species richness of fruit-feeding nymphalid butterflies in secondary forest fragments of different age and isolation and in mature forest at the eastern margin of the Lore Lindu National Park in Central Sulawesi, Indonesia. From April to August 2001 we collected 2322 individuals of fruit-feeding butterflies, belonging to 33 species. Butterfly species richness increased with succession, but was significantly higher in mature forests than in all types of secondary forest. Isolation of the forest fragments did not have a significant effect on butterfly species richness in the range of distances (up to 1700 m) studied. Rather it appeared to affect only a few species. Species richness of endemic species was higher than of non-endemic species. Although endemic species were most diverse in mature forests, many species captured were restricted to secondary forests. Our results show that mature forest is essential for the conservation of nymphalid butterflies and for the endemic species in this area. However, considering the relatively large number of species found in these rather small habitat islands, secondary forest fragments, especially older successional stages, can be taken into account in conservation efforts and thus contribute to the preservation of tropical biodiversity on a landscape scale.     

Biogeography of the Amazon molly: ecological niche and range limits of an asexual hybrid species

Aim To understand the relative contributions of environmental factors, dispersal limitations and the presence of sperm donors in determining the distribution of the Amazon molly (Poecilia formosa), a sperm‐dependent unisexual fish species of hybrid origin. To explore niche similarities and/or differences between the hybrid and parental species. To evaluate whether large‐scale abiotic factors can explain a successful introduction of both P. formosa and Poecilia latipinna. Location South‐east United States, Mexico and Central America. Methods We used abiotic variables in ecological niche modelling (ENM) to identify regions with suitable conditions for the presence of the Amazon molly and its two parental species (P. latipinna and Poecilia mexicana). We also used a recently developed metric to calculate the degree of niche overlap between the hybrid and its parental species. Results ENM produced highly significant models [all area under the curve (AUC) > 0.99 for the three species]. Annual mean temperature and minimum temperature of the coldest month were the variables that best explained the distribution of the Amazon molly. With the exception of south Florida, few areas beyond the known distribution of the species were predicted to have suitable environmental conditions. The hybrid species niche overlaps partially with the parental species. However, given the available data, it is neither more similar nor more different than expected by chance. Main conclusions Two different processes are acting to limit the distribution of P. formosa. At the northern limit, although a sperm donor species is present further north, suitable environmental conditions are absent from nearby locations. At the southern limit, a sperm donor species is present and areas with good environmental conditions are present at nearby locations, suggesting that dispersal ability is the limiting factor. We found that the hybrid species overlaps in a similar way with both parental species while still having its own niche identity. This result may be explained by the fact that hybrid species inherit characteristics of two ecologically divergent species, which can result in intermediate or even transgressive phenotypes. These results support recent work on the role of hybridization in diversification.