An evaluation of the predictive performance of distributional models for flora and fauna in north-east New South Wales.

To use models of species distributions effectively in conservation planning, it is important to determine the predictive accuracy of such models. Extensive modelling of the distribution of vascular plant and vertebrate fauna species within north-east New South Wales has been undertaken by linking field survey data to environmental and geographical predictors using logistic regression. These models have been used in the development of a comprehensive and adequate reserve system within the region. We evaluate the predictive accuracy of models for 153 small reptile, arboreal marsupial, diurnal bird and vascular plant species for which independent evaluation data were available. The predictive performance of each model was evaluated using the relative operating characteristic curve to measure discrimination capacity. Good discrimination ability implies that a model's predictions provide an acceptable index of species occurrence. The discrimination capacity of 89% of the models was significantly better than random, with 70% of the models providing high levels of discrimination. Predictions generated by this type of modelling therefore provide a reasonably sound basis for regional conservation planning. The discrimination ability of models was highest for the less mobile biological groups, particularly the vascular plants and small reptiles. In the case of diurnal birds, poor performing models tended to be for species which occur mainly within specific habitats not well sampled by either the model development or evaluation data, highly mobile species, species that are locally nomadic or those that display very broad habitat requirements. Particular care needs to be exercised when employing models for these types of species in conservation planning.     

Mapping wildland-urban interfaces at large scales integrating housing density and vegetation aggregation for fire prevention in the South of France

Every year, more than 50,000 wildland fires affect about 500,000 ha of vegetation in southern European countries, particularly in wildland-urban interfaces (WUI). This paper presents a method to characterize and map WUIs at large scales and over large areas for wildland fire prevention in the South of France. Based on the combination of four types of building configuration and three classes of vegetation structure, 12 interface types were classified. Through spatial analysis, fire ignition density and burned area ratio were linked with the different types of WUI. Among WUI types, isolated WUIs with the lowest housing density represent the highest level of fire risk.     

The composition of rime ice as an indicator of the quality of winter deposition

Rime ice deposition and snow chemistry has been determined over a 4-year period on the summit of Cairngorm Mountain, NE Scotland. The direction of ice deposition reflected the dominant air mass movement over the summit. Sea salt concentrations in the rime ice were approximately 2.5 times greater than in snow deposited over the same period. Excess sulphate concentrations were double, and those of nitrate nearly four times higher. The direction of deposition influenced concentrations of excess sulphate and nitrogen species (nitrate and ammonium) in rime ice. The same directional effect was found in the snow chemistry indicating increased entrapment of pollutants, or a more polluted air mass, when it prevailed from a Southerly or Easterly direction. The potential surface reactions involving gaseous species of S and N may increase the ionic loading to the rime and reflect natural ionic enrichment of the rimed snowpack surface. Because of such phenomena, rime ice is proposed as a further indicator of winter air quality revealing important information on ionic interactions and total deposition flux measurement, especially at high altitudes.     

Will reduced sulphur emissions under the Second Sulphur Protocol lead to recovery of acid sensitive sites in UK?

A conceptual model of the combined effects of acid deposition and land-use, Model of Acidification of Groundwater In Catchments (MAGIC), was applied to 21 upland sites in the UK Acid Waters Monitoring Network (AWMN) to assess the likely future recovery in response to the latest international agreements controlling anthropogenic sulphur emissions throughout Europe. Future estimates of sulphur deposition were generated by the Hull Acid Rain Model (HARM), based on the agreed reductions outlined in the Second Sulphur Protocol. The results indicate only a limited degree of recovery in surface-water chemistry at all sites over the next 50 years; moreover, a continuing decline in soil base status is predicted to occur at 70% of sites, resulting in longer term reacidification of surface-water at 38% of sites. However, compared with a 'business as usual' scenario the recovery is pronounced, although acidified sites will require further reductions in acidic deposition if recovery to pre-industrial chemical conditions are to be achieved. Furthermore, land-use scenarios at afforested sites suggest that replanting of felled forest will lead to a further increase in acidification. This strengthens the argument that plantation forestry should be avoided in areas considered geologically sensitive to acidic deposition.     

A Comparison of Loch Chemistry from 1955 and 1999 in the Cairngorms,N.E. Scotland

The Cairngorms in north-east Scotland is remote from pollutant sources although it currently receives ca. 10 kg ha¹ yr¹ S and ca. 11 kg ha¹ yr¹ N deposition from the atmosphere.In 1955, 15 lochs (lakes) at a range of altitudes were sampled and analysed for major ion concentrations. A new survey of these and an additional 23 lochs and their catchment soils was conducted in 1999 to determine the impact of acid deposition, and the changes in loch chemistry since the 1955 survey. The bedrock geology of this region has a strong influence on the loch chemistry. Surface waters were generally more acidic in high altitude areas due to predominantly poorly buffered, thin alpine soils developed on granitic parent material (mean acid neutralising capacity (ANC) for 23 lochs = 30 eq L¹). At lower altitudes where the geology is dominated by Dalradian metamorphic rocks surface waters are comparatively base rich and have higher ANC (mean ANC for 15 lochs = 157 eq L¹). Surface water nitrate concentrations show a negative relationship with soil C:N status, in that higher nitrate only occurs at low soil C:N ratios. A comparison of data for 1955 and 1999 shows that sulphate concentrations are significantly lower (67.8 and 47.5 eq L¹, respectively), and pH has improved (pH 5.6 and 5.9) in response to decreased S deposition since the mid 1970s. However, mean nitrate concentrations were found to increase from 2.48 >eq L¹ in 1955 to 5.65 eq L¹ in 1999. Differences in the sampling and laboratory methods from 1955 and 1999 are acknowledged in the interpretation of data.