High Mean Annual Rainfall Research Articles

Habitat Utilization and Behavioral Patterns of the Endemic Sri Lankan Green Pit Viper (Craspedocephalus trigonocephalus) in the Wet Zone of Sri Lanka

Behavioral patterns and habitat utilization of the endemic Green Pit Viper (GPV) Craspedocephalus trigonocephalus were studied in the wet zone of Sri Lanka. The region, which is covered by the wet zone, has no significant dry periods and a moderately high mean annual rainfall of over 2,500 mm. Data collection occurred between April 2021 and March 2022 with a total of 260 hours of standardized sampling effort distributed throughout the collection period. The method used was an active search which consists of a visual search of up to six meters from the central line along each side of the quadrate. Quadrats were placed in habitats, taking each GPV sighting as the center of a quadrate. At each GPV-occupied quadrat, ambient temperature, body surface temperature, prey availability, perch position and perch light level were recorded. The day was divided into six-time periods as; early morning, morning, mid-day, evening, late evening, and night. Activity level was determined considering the number of GPV that could be visually observed. A total of 49 GPV were examined during the study. Focal animal sampling was conducted, and an ethogram was developed. A strong positive relationship was observed between ambient temperature (Ta) and body surface temperature (Ts) of GPVs (Pearson correlation r=0.936). The highest number of individuals preferred filtered sun light (57.14%). C. trigonocephalus mostly preferred distal position on the branches followed by middle and apical. There was a significant difference in the percentage of individuals with different behaviors [ANOVA, F=3.64, p<0.05]. Behavioral pattern of GPV varied in the temporal scale during the day. During the morning time slot, C. trigonocephalus spent most of the time ambushing (16.12%) and basking (6.42%) respectively. During the mid-day they spent most of their time basking (10.57%), followed by resting (7.15%). The evening, late evening, night, and early morning slots were spent mostly on ambushing. The highest average time of 239 min was spent on ambushing behavior. Feeding behavior (9.8 min) had relatively short time on average. Results of this study indicate that C. trigonocephalus is well adapted for the utilization of its preferred habitat in the wet zone, and that, it displayed behavioral patterns that vary within temporal scales, which results in more efficient and effective utilization of resources. Therefore, this study provides important insights for conservation and management of C. trigonocephalus by critically evaluating the requirements of this species. 
 Keywords: Craspedocephalus trigonocephalus, Behavior, Endemic pit viper, Wet zone

Climate, fire, and anthropogenic disturbance determine the current global distribution of tropical forest and savanna

Tropical forest and savanna biomes are pivotal in the functioning of the Earth system. Both are biodiverse and under increasing threat due to land clearing and anthropogenic climate change, and play important roles in the global carbon cycle, through maintenance of a large carbon pool in tropical forests, and exchange in savannas through extensive landscape fires. Reliable mapping of tropical forest and savanna is essential to understand how the current distribution of these vegetation types is controlled by climate land clearing and fire. Using Google Maps satellite imagery, we manually classified 24 239 random points as forest, savanna, or anthropogenic landscapes within the tropics and applied this novel dataset to defining the climatic zone where forest and savanna exist as alternative states. Because fire and climate are correlated, we developed separate geospatial models to rank the importance of climate, topography, and human influence on vegetation present. This modeling confirmed that those areas with more fires had lower probabilities of tropical forest, that forest was most likely in areas with high mean annual rainfall with little seasonal variation in precipitation, and that anthropogenic factors disrupt this environmental predictability. We also identified areas where tropical forest and savanna both co-occur, but these were relatively uncommon. These relationships suggest that future drier climates projected under anthropogenic climate change, combined with clearing and burning that have reduced tropical forest extent to a subset of its theoretical distribution, will lead to irreversible loss of tropical forests. Our modeling provides global mapping that can be used track further changes to distribution of tropical forests.

Effect of Rainfall Regime on Rainwater Harvesting Tank Sizing for Greenhouse Irrigation Use

The use of rainwater harvesting tanks to supply human water needs is an old and sustainable practice. In the case of covering irrigation demand in greenhouse agriculture, the potential is huge. Still, the relative research worldwide is low, while it is nearly absent in Greece. In this study, the rainwater harvesting tank size for irrigation use of greenhouse tomato cultivation was investigated by applying a daily water balance model in three regions of Crete Island (Greece) with significant greenhouse areas. Daily rainfall data from three representative rainfall stations of the study areas characterized by different rainfall regime for a 12-year time series were used. Additionally, the daily irrigation water needs for a tomato crop during an 8-month cultivation period were used. The greenhouse roof was defined as catchment area of the rainwater harvesting system and greenhouse areas of 1000, 5000 and 10,000 m2 were studied. In all areas examined, a tank of 30–100 m3 per 1000 m2 of greenhouse area could reach approximately 80–90% reliability. Higher values of reliability (reaching 100%) could be achieved mainly with covered tanks. Tank size for 100% reliability in covered tanks, ranged from 200 m3 (per 1000 m2 of greenhouse area) in the study area with high mean annual rainfall depth (974.24 mm) and moderate mean longest dry period (87.67 days), to 276 m3 (per 1000 m2 of greenhouse area) in the study area with relatively low mean annual rainfall depth (524.12 mm) and high mean longest dry period (117.42 days). For uncovered tanks, a 100% reliability value could be reached only with a tank size of 520 m3 (per 1000 m2 of greenhouse area) in the study area with high mean annual rainfall depth and moderate mean longest dry period.

Distribución espacial y controles ambientales de las represas (tajamares) en el Chaco Árido

Arid regions are characterized by water shortage throughout the year, which constrains both the vegetation growth and the supply of water for livestock consumption. The Arid Chaco (~10 Mha) hosts extensive and low-investment livestock systems based on rainwater harvesting stored in dams (small impoundments) as the main source of water supply. In this study, we characterized the spatial distribution of dams in the Arid Chaco and analyzed their relationship with biophysical variables (e.g. rainfall, vegetation, roads). For these purposes, we used satellite images, vector information and performed multivariate analysis on a spatial grid of 135 cells of 0.25°x0.25°. In total, 7920 dams were identified (1 dam every 1230 ha), with maximum densities of 1 dam every 185 ha but also cells without dams associated with the presence of mountains, salt flats and dunes. Dam density was higher in cells with higher densities of livestock establishments, roads and cattle stock (r=0.63, r=0.56 and r=0.51, respectively; P<0.01 in all cases), and in cells with higher mean annual rainfall and lower interannual rainfall variability (r=0.62 and r=-0.47, respectively; P<0.01 for both cases). Although the mean annual rainfall was the best-associated variable with the distribution of dams at the regional scale, this relationship weakened towards the extremes of the gradient (arid and sub-humid). This may be due to anthropic factors such as the low profitability of livestock systems, the previous land uses or land-use changes. The results of this study represent a first attempt to assess the importance of impoundments in the Arid Chaco. We believe that this study may be useful not only to understand livestock production, but also for future studies related to the conservation of wildlife and the development of rural towns in the region.

Flood Vulnerability Mapping using Geospatial Techniques: Case Study of Lagos State, Nigeria

Flood is one of the natural disaster known to be part of the earth biophysical processes, which its occurrence can be devastating; due to mostly anthropogenic activities and climatological factors. The aim of the research is to identify and map the extent at which the impact of flood due to intense rainfall and rise in water in the study area using geospatial techniques and the specific objectives are to carry out terrain analysis of the study area and to generate flood indicator maps of the study area. The study analyzed rain fall data;, the drainage system and Shuttle Radar Topographic Mission (SRTM 30m) of the area. ArcGIS 10.8 was to modelled and to generate the contributing factors map of the study area. The drainage system was generated through on-screen digitization of topographic map of scale 1:50,000 of Ondo South-West. The mean annual rainfall of Lagos State was generated in the ArcGIS environment from the rainfall data through spatial analysis tool. The SRTM was used in terrain analysis of the study area. The results generated showed the lowest mean annual rain fall of the area 1,700mm and the highest mean annual rain fall was 2,440mm. Digital elevation model (DEM), slope, flow direction were generated from the SRTM. Drainage density of the area was generated using the drainage system. The slope map of the entire area which are classified into five slope classes of very high (14%-48.5%) to high (7.6%-13.9%) to moderately high (4.2%-7.6%) to low (1.5%-4.2%) and very low (0. % - 1.2%).

Rainfall analysis over Kalyana Karnataka districts for resource planning in agriculture

The study has been made to analyze the rainfall of six districts of Kalyana Karnataka by utilizing the past 50 years (1971-2020) rainfall data. The rainfall data was critically examined and analyzed statistically for annual and seasonal values followed by computation of trend analysis of annual rainfall. The results revealed that, the highest mean annual rainfall was recorded at Bidar (917.8 mm) followed by Yadgir (877.8 mm) and the lowest at Ballari (559.8 mm). The CV varied between 24.0% (Bidar) to 32.6% (Yadgir). From the skewness analysis it was observed that, skewness varied from 0.3 (Bidar and Koppal) to 0.7 (Yadgir and Raichur). The Yadgir district showed zero Kurtosis and the remaining districts were found to be negatively Kurtosis and it varied from -0.1 to -0.6. The Raichur district showed 0.6 positively Kurtosis. From regression analysis, it was found that, the slopes of regression line of annual rainfall are positive at Bidar, Raichur and Koppal. This shows that these districts have increasing annual rainfall trend. However, since the correlation coefficient value (R2) is too low, the increasing trend is not significant. The remaining stations (Kalaburgi, Yadgir and Ballari) showed negative slope of regression line. This indicates these stations have decreasing trend of annual rainfall. The mean monsoon season rainfall varied between 315.3 mm (Ballari) to 705.8 mm (Bidar) and the CV was found to be more than 30% in all the districts which indicate highly erratic rainfall and the rainfall is not much dependable around the mean rainfall. The skewness analysis revealed that, all the stations showed positive skewness and it varied between 0.3 (Raichur and Koppal) to 0.9 (Yadgir).

Comparison of annual maximum and peaks-over-threshold methods with automated threshold selection in flood frequency analysis: a case study for Australia

Flood frequency analysis (FFA) involves fitting of a probability distribution to observed flood data. Two main models, annual maximum (AM) and peaks over threshold (POT), are generally adopted in FFA. The POT model is underemployed due to its complexity and uncertainty associated with threshold selection and meeting independence criteria in selecting POT data series. This study evaluates the POT and AM models using data from 188 gauged stations in southeast Australia. The POT model adopted in this study applies different average numbers of events per year fitted with generalized Pareto (GP) distribution with an automated threshold detection method. For the AM model, the GP distribution is also adopted, and flood quantiles estimated by the two models are compared. It has been found that there are notable differences in design flood estimates between the AM and POT models. The study uses catchment characteristics data to understand the differences in quantile estimates between the AM and POT models. The percentage differences between the AM and POT models can be explained by mean annual rainfall (MAR) and mean annual evapotranspiration (MAE) (ARIs of 1.01–5 years), MAR (10-year ARI), stream density (SDEN) (for 20- and 50-year ARIs) and SDEN, main stream slope (S1085) and MAE (for 100-year ARI). Stations showing smaller % differences have relatively higher MAR and smaller MAE (indicating wetter condition); conversely, stations showing higher % differences have smaller MAR and higher MAE (drier condition).

Evaluating restoration outcomes: trial of a community‐based monitoring protocol

SummaryRestoration planting is undertaken widely in rural landscapes to promote more sustainable land use, such as reforesting agricultural land, and to enhance nature conservation. Land managers and community groups have a key role in delivering these actions and can also contribute to monitoring the outcomes. Here, we describe a monitoring protocol developed to assist practitioners to assess the survival of plant species in restoration plantings and report results of a trial of the protocol from 123 monitored plots at 62 sites across Victoria. On average, 61% of plants per site (all species combined) survived and 77% of the species planted persisted after the first summer post‐planting. Rates of survival varied considerably among plant species, with differences in outcomes evident across bioregions. Overall, the survival of plantings (all species combined) was greater at sites with higher mean annual rainfall and where plants were protected by guards. Widespread adoption of monitoring will assist project managers to better understand how plants survive and grow, and to adaptively manage revegetation programmes under a changing climate. A co‐ordinated monitoring effort will require resources for on‐ground monitoring, as well as an online database for data storage, collation, analysis and reporting.

Natural intraspecific trait variation patterns of the wild soursop Annona senegalensis (Annonaceae) along a climatic gradient in Benin, West Africa

Background and aims – Geographic patterns of phenotypic variability can inform understanding of the resilience potential of plant species to environmental hazards such as climate change. Such understanding provides support for conservation and domestication efforts. Here, we investigated natural morphological variation of the individuals, fruits, seeds, and leaves of the tropical shrub Annona senegalensis Pers. along a climatic gradient. Methods – Morphological data were collected on shrubs, fruits, seeds, and leaves of 150 shrubs from five populations in the three climatic zones of Benin. Linear mixed effects models were used to test the variability of the morphological traits of the species and also to estimate the variance components in order to tease apart the importance of each source of variation. The most important morphological descriptors discriminating climatic zones were identified using a stepwise discriminant analysis. Redundancy analysis was then used to determine the relationships between discriminant morphological traits and bioclimatic variables. Key results – Morphological traits of A. senegalensis varied greatly both within and among climatic zones. A substantial part (42%) of the among-climatic zones phenotypic variability in the species was attributable to climate, mainly rainfall and temperature. Morphological traits such as big shrubs, big fruits, and high number of seeds per fruit were associated with high mean annual rainfall and low mean temperature of the warmest quarter. Conclusions – The findings suggest an important zonal adaptation of the species to climate variability. The phenotypic diversity pattern that we highlighted can be useful when designing conservation policies for the species. However, quantitative genetics through common garden or reciprocal transplantation experiments related to the species’ populations would enable to explore the heritable part of the observed variability to support effective conservation and domestication efforts.

Determination of Empirical Rainfall Thresholds for Shallow Landslides in Slovenia Using an Automatic Tool

Rainfall-triggered shallow landslides represent a major threat to people and infrastructure worldwide. Predicting the possibility of a landslide occurrence accurately means understanding the trigger mechanisms adequately. Rainfall is the main cause of slope failures in Slovenia, and rainfall thresholds are among the most-used tools to predict the possible occurrence of rainfall-triggered landslides. The recent validation of the prototype landslide early system in Slovenia highlighted the need to define new reliable rainfall thresholds. In this study, several empirical thresholds are determined using an automatic tool. The thresholds are represented by a power law curve that links the cumulated event rainfall (E, in mm) with the duration of the rainfall event (D, in h). By eliminating all subjective criteria thanks to the automated calculation, thresholds at diverse non-exceedance probabilities are defined and validated, and the uncertainties associated with their parameters are estimated. Additional thresholds are also calculated for two different environmental classifications. The first classification is based on mean annual rainfall (MAR) with the national territory divided into three classes. The area with the highest MAR has the highest thresholds, which indicates a likely adaptation of the landscape to higher amounts of rainfall. The second classification is based on four lithological units. Two-thirds of the considered landslides occur in the unit of any type of clastic sedimentary rocks, which proves an influence of the lithology on the occurrence of shallow landslides. Sedimentary rocks that are prone to weathering have the lowest thresholds, while magmatic and metamorphic rocks have the highest thresholds. Thresholds obtained for both classifications are far less reliable due to the low number of empirical points and can only be used as indicators of rainfall conditions for each of the classes. Finally, the new national thresholds for Slovenia are also compared with other regional, national, and global thresholds. The thresholds can be used to define probabilistic schemes aiming at the operative prediction of rainfall-induced shallow landslides in Slovenia, in the framework of the Slovenian prototype early warning system.

Could drought constrain woody encroachers in savannas?

Droughts are expected to become more frequent and severe, due to climate change, with uncertain consequences for savanna vegetation. Drought-driven tree mortality has been observed in some savannas, but little is known about how tolerant savanna trees are to drought, or what determines differences among species in drought vulnerability. Here, we examine which characteristics best distinguished tree species that were most negatively affected by a recent drought in Kruger National Park, South Africa. Woody-encroaching, root-suckering species, which tended to have relatively low investments in non-structural carbohydrates, had the highest mortality rates. Of particular interest was Dichrostachys cinerea, a notable contributor to widespread woody encroachment across southern African savannas, which suffered high drought mortality. Using rainfall maps and vegetation survey data, we show that D. cinerea distributions in Kruger National Park are limited to areas with higher mean annual rainfall and lower past drought frequency, and stem densities are lower where droughts have occurred more frequently, suggesting that past droughts have had lasting impacts on the distribution and abundance of this species. Woody encroachers, such as D. cinerea, may face a trade off between traits promoting proliferation vs. drought tolerance, and more frequent and severe droughts could increasingly limit their spread.

Adaptive genetic variation at three loci in South African vervet monkeys (Chlorocebus pygerythrus) and the role of selection within primates.

Vervet monkeys (Chlorocebus pygerythrus) are one of the most widely distributed non-human primate species found in South Africa. They occur across all the South African provinces, inhabiting a large variety of habitats. These habitats vary sufficiently that it can be assumed that various factors such as pathogen diversity could influence populations in different ways. In turn, these factors could lead to varied levels of selection at specific fitness linked loci. The Toll-like receptor (TLR) gene family, which play an integral role in vertebrate innate immunity, is a group of fitness linked loci which has been the focus of much research. In this study, we assessed the level of genetic variation at partial sequences of two TLR loci (TLR4 and 7) and a reproductively linked gene, acrosin (ACR), across the different habitat types within the vervet monkey distribution range. Gene variation and selection estimates were also made among 11–21 primate species. Low levels of genetic variation for all three gene regions were observed within vervet monkeys, with only two polymorphic sites identified for TLR4, three sites for TLR7 and one site for ACR. TLR7 variation was positively correlated with high mean annual rainfall, which was linked to increased pathogen abundance. The observed genetic variation at TLR4 might have been influenced by numerous factors including pathogens and climatic conditions. The ACR exonic regions showed no variation in vervet monkeys, which could point to the occurrence of a selective sweep. The TLR4 and TLR7 results for the among primate analyses was mostly in line with previous studies, indicating a higher rate of evolution for TLR4. Within primates, ACR coding regions also showed signs of positive selection, which was congruent with previous reports on mammals. Important additional information to the already existing vervet monkey knowledge base was gained from this study, which can guide future research projects on this highly researched taxon as well as help conservation agencies with future management planning involving possible translocations of this species.

Effect of catchment properties and flood generation regime on copula selection for bivariate flood frequency analysis

Applying copula-based bivariate flood frequency analysis is advantageous because the results provide information on both the flood peak and volume. More data are, however, required for such an analysis, and it is often the case that only data series with a limited record length are available. To overcome this issue of limited record length, data regarding climatic and geomorphological properties can be used to complement statistical methods. In this paper, we present a study of 27 catchments located throughout Norway, in which we assess whether catchment properties, flood generation processes and flood regime have an effect on the correlation between flood peak and volume and, in turn, on the selection of copulas. To achieve this, the annual maximum flood events were first classified into events generated primarily by rainfall, snowmelt or a combination of these. The catchments were then classified into flood regime, depending on the predominant flood generation process producing the annual maximum flood events. A contingency table and Fisher’s exact test were used to determine the factors that affect the selection of copulas in the study area. The results show that the two-parameter copulas BB1 and BB7 are more commonly selected in catchments with high steepness, high mean annual runoff and rainfall flood regime. These findings suggest that in these types of catchments, the dependence structure between flood peak and volume is more complex and cannot be modeled effectively using a one-parameter copula. The results illustrate that by relating copula types to flood regime and catchment properties, additional information can be supplied for selecting copulas in catchments with limited data.

Assessment of Long-Term Spatio-Temporal Rainfall Variability over Ghana using Wavelet Analysis

Rainfall variability has strong impact on food security, livelihood and socio-economic activities as farming in West Africa is mainly rain-fed. The annual, seasonal and decadal rainfall variability over Ghana has been studied and their periodicities analysed using wavelet analysis. A rainfall time series from 1901–2010 from the Global Precipitation Climatology Center (GPCC) was used in this analysis. It was observed that high mean annual rainfall totals ranging from 900–1900mm are recorded over the entire country. In addition, very high totals between 1500–1900mmare recorded at the South-Western part of the country whereas low totals (900–1200 mm) are recorded in the Savannah and East coast of the country. In general, a decreasing trend was observed for the annual rainfall over all the agro-ecological zones except for the coastal zone, where a slight increasing trend of 0.1600mm per year was seen. The seasonal trend analysis revealed a significant decreasing trend at 0.01 significance level in all the agro-ecological zones except for the Savannah during the DJF season indicating an intensification of the Harmattan. The Coastal zone recorded the lowest mean rainfall values for all seasons with the highest of about 150 mm in MAM. The Forest zone on the other hand recorded very high rainfall values for all seasons with the maximum of about 200 mm in JJA. The Transition zone, however, recorded almost quite stable rainfall amount for all seasons except for DJF. On the decadal time scale, below normal rainfall values were observed between the 1901–1920 and 1980–2010 periods for almost all the agro-ecological zones except for the Savannah which showed above normal rainfall values within the 1901–1940 period. Indicating that, the decreasing trend observed in recent years is not solely due to antropogenic factors but have a strong contribution from a natural climate variability. The wavelet analysis also revealed a strong annual periodicity over all the agro-ecological zones except for the Coastal and Forest zones where the annual periodicity was accompanied by 4–8 months signal. The results of both the 5 year moving average and the decadal anomaly confirm a significant decrease in rainfall amount. This will have negative consequences on agricultural practices, water resource management and food security.

The terrestrial landscapes of tetrapod evolution in earliest Carboniferous seasonal wetlands of SE Scotland

The Lower Mississippian (Tournaisian) Ballagan Formation in SE Scotland yields tetrapod fossils that provide fresh insights into the critical period when these animals first moved onto land. The key to understanding the palaeoenvironments where they lived is a detailed analysis of the sedimentary architecture of this formation, one of the thickest and most completely documented examples of a coastal floodplain and marginal marine succession from this important transitional time anywhere in the world. Palaeosols are abundant, providing a unique insight into the early Carboniferous habitats and climate.More than 200 separate palaeosols are described from three sections through the formation. The palaeosols range in thickness from 0.02 to 1.85m and are diverse: most are Entisols and Inceptisols (63%), indicating relatively brief periods of soil development. Gleyed Inseptisols and Vertisols are less common (37%). Vertisols are the thickest palaeosols (up to 185cm) in the Ballagan Formation and have common vertic cracks. Roots are abundant through all the palaeosols, from shallow mats and thin hair-like traces to sporadic thicker root traces typical of arborescent lycopods.Geochemical, isotope and clay mineralogical analyses of the palaeosols indicate a range in soil alkalinity and amount of water logging. Estimates of mean annual rainfall from palaeosol compositions are 1000–1500mm per year. The high mean annual rainfall and variable soil alkalinities contrast markedly with dry periods that developed deep penetrating cracks and evaporite deposits. It is concluded that during the early Carboniferous, this region experienced a sharply contrasting seasonal climate and that the floodplain hosted a mosaic of closely juxtaposed but distinct habitats in which the tetrapods lived. The diversification of coastal floodplain environments identified here may link to the evolution and movement of tetrapods into the terrestrial realm.

ANALYSIS OF WATER POVERTY FOR IREPODUN LOCAL GOVERNMENT AREA (KWARA STATE , NIGERIA)

In the wake of a growing concern about the unchecked rise of poverty and the consequences of water scarcity, the relationships between water and poverty form an object of a sprawling literature. This research seeks to study access to rural water supply in Irepodun Local Government Area (LGA), Kwara State. Data were sourced from the 11wards in the LGA. Twenty households were sampled per ward; altogether 220 households were sampled in this study. Access to water was estimated using Water poverty index (WPI) computed after Sullivan and Meigh [2006] using household data; based on 5 sub-components: resources, accessibility, capacity, uses and environment. Resources was seen to be high generally, with highest in Omu Aran ward I (93 %), accessibility was highest in Oro I (71 %), capacity was generally weak (highest score was 43 % in Omu Aran II), uses was highest in Omu Aran II and in Oko, environment was highest in Ipetu-Rore-Aran Orin ward (63 %.).Water poverty index (WPI) was least (47 %) in Oko ward, while the highest (62 %) was obtained at Ipetu-Rore-Aran Orin ward. Only 2 LGAs namely: Oko and Arandun wards are water poor, all other wards have above average scores. However, the seemingly high scores are mainly due to the relatively high mean annual rainfall (MA R) and the efforts of Community Based Associations (CBA) which is typical of Kwara south senatorial districts of Kwara state which has long history of CBAs and Town Unions dating back into about 100years. Hence, there is need for government and public-private intervention in water provision; particularly in Oko and Arandun wards in view of their low capacities and few sources of water as locals will have low capacities to explore alternative sources of water. Conclusively, access to water in Irepodun LGA is appreciably high. However, the challenges of increasing population and urbanization suggest needs for expanding water resources infrastructures in the LGA.

Climate and exotic pasture area in landscape determines invasion of forest fragments by two invasive grasses

To date, there has been a focus on biological aspects of invasion rather than landscape-scale processes within human-modified landscapes. Applying a multi-scale approach may improve predictive models of invasion in fragmented landscapes as well as management. We tested a priori models of the relative importance of landscape (10 000 to 30 000 ha), site-scale (<0·3 ha) factors and climate gradients, and their interactions, on the cover of exotic grasses in forest fragments. We tested the models for two exotic pasture grasses Cenchrus ciliaris and Panicum maximum in fragmented agricultural landscapes of subtropical eastern Australia. Mixed-effect models were applied to quantify the multi-scale effects of land use, forest area and fragmentation, vegetation structure, soil and climate attributes and their interactions on the ground cover of the two exotic grasses. We used model averaging to account for model and parameter uncertainty and tested for spatial autocorrelation and the model fit in model residuals. There was strong evidence that the area of exotic pasture grass in the landscape and climate gradients had a strong influence on cover observed at the site scale, but the climate influence was species specific. Cenchrus ciliaris cover was higher in forest sites within landscapes converted to exotic pastures and with high mean minimum temperatures and sites with low canopy cover. In contrast, P. maximum cover was primarily influenced by high mean annual rainfall, with moderate positive effects from area of exotic pasture in the landscape and high minimum temperatures. Synthesis and applications. This study highlights several key issues that need to be considered when prioritizing management of invasive species in fragmented landscapes. First, the propagule supply in the landscape and climate gradients are key factors influencing the spread of exotic grasses into forest fragments. Second, managing canopy cover is critical to enhancing C. ciliaris invasion resistance, but not for P. maximum. We conclude that a multi-scale approach provides the conceptual and applied basis for an improved understanding and management of plant invasions in fragmented landscapes.

Seroprevalence and correlates of Toxoplasma gondii infection in domestic sheep in Michoacán State, Mexico

Toxoplasma gondii infection in sheep is of public health and economic importance. Seroprevalence of T. gondii infection and correlates were determined in 405 sheep from 7 farms in 4 geographical regions in Michoacán State, Mexico using the modified agglutination test (MAT). General sheep and environmental characteristics were obtained by a questionnaire. All sheep were raised in semi-extensive conditions in temperate climate. Antibodies to T. gondii were found in 121 (29.9%) of the 405 sheep with MAT titers of 1:25 in 46, 1:50 in 20, 1:100 in 7, 1:200 in 5, 1:400 in 7, 1:800 in 11, 1:1600 in 5, and 1:3200 or higher in 20. Seropositivity did not vary significantly with age, sex or breed. In contrast, seroprevalence varied among farms, geographic region, municipality, altitude, mean annual temperature, and mean annual rainfall. The median seroprevalence in farms was 32.6% (range 7.1–71.4%). Sheep raised in farms at ≥1900m above sea level had a higher seroprevalence (44.1%) than those in farms at lower sea level (16.3%). Sheep raised in municipalities with ≤17.7°C mean annual temperature had a higher seroprevalence (37.2%) than those in municipalities with higher mean annual temperature (14.1%). Sheep raised in a municipality with 600mm of mean annual rainfall had a higher seroprevalence (71.4%) than municipalities with higher mean annual rainfall (29.1%). This is the first report on the seroprevalence and correlates of T. gondii infection in sheep in Michoacán State, Mexico. The role of environmental characteristics for T. gondii infection in sheep deserves further research.

Terrestrial–marine connectivity: Patterns of terrestrial soil carbon deposition in coastal sediments determined by analysis of glomalin related soil protein

Glomalin, an arbuscular mycorrhizal protein component of soil, can be used as an indicator of terrigenous‐derived carbon. We measured glomalin in sediments using the terrestrial end‐member as a reference in four coastal settings: (1) intertidal seagrass meadows distributed over a rainfall gradient, (2) sediments inshore and offshore from the mouth of a river, (3) coastal coral reefs at various distances from the shore, and (4) intertidal wetlands with varying levels of groundwater influence. Across the rainfall gradient, glomalin in seagrass meadow sediments increased at sites with high mean annual rainfall during the wet season (r2 = 0.27; F1,29 = 5.75; p = 0.029). Glomalin decreased in inshore river sediments (terrestrial) to offshore (marine) sediments (r2 = 0.81; F1,17 = 71.7; p ≤ 0.0001). Furthermore, glomalin in reef sediments decreased with distance from the shore. The high intertidal was rich in glomalin where groundwater flowed directly into the wetland compared with those with little groundwater influences. Our data indicate that rivers and groundwater transport terrestrial material, and that mangroves, salt marsh, seagrass meadows, and coral reefs accumulate it, but the connections vary among sites, within sites, and seasonally. Variations in glomalin concentrations are indicative of links between the terrestrial and marine environment that reflect proximity, filtration services, and the level of subsidies that marine ecosystems derive from terrestrial sources. Assessment of glomalin contributes to evaluating terrestrial–marine connectivity, and thus provides knowledge to improve catchment management for the protection of marine ecosystems.

Rainforest ants of the Tiwi Islands: a remarkable centre of endemism in Australia’s monsoonal tropics

The small and isolated rainforest patches that are embedded in the predominantly savanna landscape of Australia’s monsoonal tropics support a highly distinctive and biogeographically significant ant fauna. This fauna features shade-tolerant taxa of Indo-Malayan origin, in contrast to the arid-adapted, endemic Australian taxa that dominate the surrounding savanna. The Tiwi Islands north of Darwin in the Northern Territory (NT) receive the highest mean annual rainfall (up to 2,000 mm) in monsoonal Australia, and have a particularly extensive rainforest estate that has been poorly surveyed for invertebrates. Here we describe results from intensive ant surveys at 17 sites representing the full range of Tiwi rainforest types, using subterranean traps, Winkler sacs, pitfall traps and arboreal traps, supplemented by opportunistic hand collections. Our surveys yielded a total of 87 species from 37 genera, with the richest genera being Pheidole (9 species collected), Polyrhachis (8), Camponotus (5), Rhytidoponera (5) and Strumigenys (5). The overall structure and diversity of the Tiwi rainforest fauna is comparable to that of rainforest ant faunas on the Australian mainland. However, the species have exceptional biogeographic significance. At least 21 species across 12 genera have apparently never previously been collected, three species from subcoastal northeastern Australia are recorded for the first time in the NT, and the genera Mesoponera and Onychomyrmex are documented for the first time in the NT. There was a very low incidence of exotic species, which further highlights the conservation values of this remarkable fauna.