Thailand’s catastrophic flood: Bangkok tree mortality as a function of taxa,habitat, and tree size

Urban areas have unique environments such as high air temperature, soil compaction and disturbance, and air and water pollution often impose plant stresses. Natural disasters can impose even greater stresses on plants in such areas. In 2011 Bangkok, Thailand experienced its worst flooding in over two decades, inundated up to a meter for a month. Here we report on tree tolerance to submerged, anoxic soils based on mortality. We identified over 6500 trees by taxa: 395 species in 219 genera within 60 families, which were categorized into three groups: susceptible (>50% mortality), tolerant (<50% mortality), and highly tolerant (no mortality). Among all the species, 18% were categorized as flood susceptible, 75% as tolerant, and 7% as highly tolerant. The floods resulted in decreased overall species richness by 18%, particularly in the Magnoliaceae and Lauraceae families, for which the mortality was 100% and 66%, respectively. Flood susceptible species were mostly from high rainfall habitats such as the hill evergreen forest. As expected, highly flood tolerant species were from the mangrove forests, beach/strand forests, and swamp plant communities, where the root zones are persistently saturated with lower quality water. Unexpectedly, many species native to higher temperature, drier, often deciduous lowland habitats were found to be flood tolerant, and were from the cultivated fruit and ornamental species. The results also indicated that smaller and younger trees suffered more mortality than larger and more mature trees. Therefore, during the tree selection process for planting in urban environments that may be at risk of frequent flooding, species from a wide spectrum of ecological habitats should be considered; particularly those characterized by one or more environmental stresses, such as drought, salt, heat, or saturated soils.     

Seasonal and temporal changes in species use of the landscape: how do they impact the inferences from multi-scale habitat modeling?

Context

Multi-scale approaches to habitat modeling have been shown to provide more accurate understanding and predictions of species-habitat associations. It remains however unexplored how spatial and temporal variations in habitat use may affect multi-scale habitat modeling.

Objectives

We aimed at assessing how seasonal and temporal differences in species habitat use and distribution impact operational scales, variable influence, habitat suitability spatial patterns, and performance of multi-scale models.

Methods

We evaluated the environmental factors driving brown bear habitat relationships in the Cantabrian Range (Spain) based on species presence records (ground observations) for the period 2000–2010, LiDAR data on forest structure, and seasonal estimates of foraging resources. We separately developed multi-scale habitat models for (i) each season (spring, summer, fall and winter) (ii) two sub-periods with different population status: 2000–2004 (with brown bear distribution restricted to the main population nuclei) and 2005–2010 (with expanding bear population and range); and (iii) the entire 2000–2010 period.

Results

Scales of effect remained considerably stable across seasonal and temporal variations, but not the influence of certain environmental variables. The predictive ability of multi-scale models was lower in the seasons or periods in which populations used larger areas and a broader variety of environmental conditions. Seasonal estimates of foraging resources, together with LiDAR data, appeared to improve the performance of multi-scale habitat models.

Conclusions

We highlight that the understanding of multi-scale behavioral responses of species to spatial patterns that continually shift over time may be essential to unravel habitat relationships and produce reliable estimates of species distributions.

     

Mini-review: The effects of apples on plasma cholesterol levels and cardiovascular risk – a review of the evidence

Summary

Evidence suggests that a high intake of fruits is associated with a reduced risk of cardiovascular disease (CVD) and lowered plasma cholesterol, but the specific effects of individual types of fruit, fruit fractions, and processed fruit are less well-studied. Apples are among the most frequently consumed fruits, and human and animal studies on apple may help to clarify the effect of this fruit on CVD risk markers. The aim of this mini-review is to summarise current evidence for a lowering effect of apple on the risk of CVD and plasma cholesterol levels, and to investigate whether such an effect is influenced by fruit processing or the form of intake. Possible mechanisms behind the cholesterol-lowering effect of apples are also considered. All relevant published experimental studies in humans and animals were identified within the open literature. Nine human studies were identified, of which four concerned the effects of whole apples, two the effects of dried apples, and three the effects of filtered apple juice. Additional studies considered specific apple components. In general, there was a cholesterol-lowering effect, in the range of 5 – 8%, after the intake of approx. three whole apples, whereas the consumption of apple juice (375 – 720 ml) had no effect on plasma cholesterol levels and may result in adverse effects on plasma triglyceride levels. Limitations in the study designs did not allow us to draw conclusions on the effect of the intake of whole, dried apples (15 – 52 g). We also identified a total of nine experimental studies in animal models. Feeding with apple products resulted in decreased levels of plasma (11 – 43%) and liver (23 – 67%) cholesterol in the majority of studies. There was an increased excretion of bile acids (3 – 56%) and cholesterol (5 – 41%) in rats fed with apple products. Based on the current evidence from human observational and intervention studies, it seems likely that a reduction in plasma total and LDL cholesterol occurs after a dietary intake of apples, which could lead to a decreased risk of CVD. On average, a daily intake of approx. three apples resulted in a decrease in total cholesterol of 5 – 8% (approx. 0.5 mmol l^?1). The consumption of filtered apple juice may result in adverse effects on plasma triglyceride levels. Evidence from animal studies suggests that the major mechanism behind the cholesterol-lowering effect of apples involves an increased clearance of plasma cholesterol due to enhanced faecal excretion of bile acids and cholesterol.     

Residential runoff – The role of spatial density and surface cover,with a case study in the Höjeå river catchment,southern Sweden

Depending on the spatial density of built cover and location within a catchment, residential areas make varying contributions to surface runoff throughout different rainfall events. This study examined these contributions and the associated effect of different surface covers and sustainable drainage systems on runoff generation. The Soil Conservation Service curve number (SCS-CN) method was applied to analyse urban development in the Höjeå river catchment in southern Sweden.The results indicated that identical amounts of surface runoff are generated by low-density residential areas on heavy clay soils and high-density residential areas on sandy soils. However, increasing the density of built-up areas on sandy soils is likely to be more disruptive to the hydrological balance and to generate a greatly increasing difference in runoff as building density and impermeable surface area increase. A similar pattern is likely to occur if rainfall intensity increases. It may therefore be appropriate to apply different planning considerations to residential developments depending on the existing soil group, e.g. conserving existing vegetated surfaces on sandy soil and incorporating permeable paving materials and sub-surface infiltration beds in development on clayey soils. Increased area of impermeable surface cover will increase surface runoff in all residential areas, irrespective of building density, soil group and rainfall intensity. However, adapting a systems approach in combining vegetative structures and permeable paving materials with subsurface infiltration beds can help mitigate the impact of surface runoff, particularly in urban developments on clay-rich soils.     

Forest recovery in a tropical landscape: what is the relative importance of biophysical,socioeconomic, and landscape variables?

Socioeconomic changes in many areas in the tropics have led to increasing urbanization, abandonment of agriculture, and forest re-growth. Although these patterns are well documented, few studies have examined the drivers leading to landscape-level forest recovery and the resulting spatial structure of secondary forests. Land cover transitions from agricultural lands to secondary forest in the island of Puerto Rico have been ongoing since the 1940s. This study is a glimpse into this landscape level trend from 1991 to 2000. First, we relied on Landsat images to characterize changes in the landscape structure for forest, urban, and agricultural land classes. We found that although forest cover has increased in this period, forest has become increasingly fragmented while the area of urban cover has spread faster and become more clustered. Second, we used logistic regression to assess the relationship between the transition to forest and 21 biophysical, socioeconomic, and landscape variables. We found that the percentage of forest cover within a 100 m radius of a point, distance to primary roads and nature reserves, slope, and aspect are the most important predictors of forest recovery. The resulting model predicts the spatial pattern of forest recovery with accuracy (AUC-ROC = 0.798). Together, our results suggest that forest recovery in Puerto Rico has slowed down and that increasing pressure from urbanization may be critical in determining future landscape level forest recovery. These results are relevant to other areas in the tropics that are undergoing rapid economic development.     

The long-term effects of pre-planting soil fumigation on the growth and cropping of cvs Laxton’s Fortune and Cox’s Orange Pippin on M.2 rootstock,planted on land affected with a replant disease of apple

Soil fumigation of land affected by apple replant disease, using chloropicrin at 281 1 ha^-1 before planting-out, caused increases in shoot numbers, trunk girth and of 35% in total crop accumulated over 10 years for cv Cox’s Orange Pippin on M.2 rootstock. Chloropicrin at 1121 ha^-1 gave rise to a smaller response, and DD at 5621 ha^-1 was ineffective. Cv Laxton’s Fortune on M.2 showed little response to any treatment.