Distributions of lizard species across edges delimiting open‐forest and sand‐mined areas

Abstract The distributions of lizards across habitat edges delimiting open‐forest and regenerating sand‐mined areas as a function of distance from the edge were studied at Tomago, New South Wales, Australia. Pitfall‐trapping was used to survey lizards across the northern edges of four forest fragments, to determine if lizards displayed characteristic responses across the edge, and whether these could be explained by the different habitat conditions. At each site, 11 equally spaced drift fences (each parallel to the edge) were arranged in a transect running perpendicular to the edge, and stretching 50 m into each habitat type. Captures of Amphibolurus muricatus (Agamidae) decreased substantially across the edge from the mine‐path to the forest so that it was identified as a mine‐path specialist lizard species. Captures of two skink species decreased across the mine‐path before reaching the edge, and were not caught (Ctenotus taeniolatus) or were seldom caught (Ctenotus robustus) in the forest, so they were identified as mine‐path specialist, edge avoiding, lizard species. Captures of Lampropholis delicata (Scincidae) increased across edges into the forest, consistent with the expectation for a forest specialist. Regression analyses indicated the responses to edges of three lizard species (A. muricatus, C. robustus and C. taeniolatus) were negatively correlated with canopy cover (probably due to its influence on temperature, as captures of A. muricatus and C. robustus were also correlated positively with mean daily temperature). In addition, the response of C. robustus correlated negatively with a vegetation factor (dense, even vegetation in the first 50 cm from ground level). The response of L. delicata correlated positively with understorey height. We have identified edge response strategies for four species of lizards across edges delimiting temperate open‐forest and mined areas, and identified habitat and microclimate variables that may have driven these responses.     

Conserving Waste Rice for Wintering Waterfowl in the Mississippi Alluvial Valley

Abstract: Rice lost before or during harvest operations (hereafter waste rice) provides important food for waterfowl in the Mississippi Alluvial Valley, USA, but >70% of waste rice is lost during autumn. We conducted experiments in 19 production rice fields in Arkansas and Mississippi during autumns 2003 and 2004 to evaluate the ability of common postharvest practices (i.e., burn, mow, roll, disk, or standing stubble) to conserve waste rice. We detected a postharvest treatment effect and a positive effect of initial abundance of waste rice on late-autumn abundance of waste rice (P ≤ 0.022). Standing stubble contained the greatest abundance of waste rice followed by burned, mowed, rolled, and disked stubble. We recommend standing stubble or burning to maximize waste rice abundance for wintering waterfowl.     

The utility of leaf flavonoids as taxonomic markers for some Malaysian species of the tribe Shoreae (Dipterocarpaceae)

A flavonoid survey was carried out on 45 taxa from the genera Shorea, Hopea, Parashorea, Neobalanocarpus, and Dryobalanops of the tribe Shoreae in the Dipterocarpaceae. The study showed significant chemotaxonomic differences in leaf flavonoid aglycone patterns and the presence of tannins in these taxa. The flavonoid patterns are useful in the delimitation of some taxa. For example, the genus Parashorea is distinguished by the universal presence of kaempferol 3‐methyl ether, and the monotypic genus Neobalanocarpus is unique in not producing ellagic and gallo tannins. The presence of chalcones and flavone C‐glycosides supports the separation of the genus Hopea into two sections, section Dryobalanoides and section Hopea in Ashton's classification, which is based on the type of venation. The flavonoid distributions in this study show that they can be very useful for differentiating between the Balau group in the genus Shorea and some scaly barked Hopea species, particularly H. helferi (lintah bukit), H. nutans (giam), and H. ferrea (malut). © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157 , 755–762.     

Phylogeny of South American Bufo (Anura: Bufonidae) inferred from combined evidence

Despite the considerable research that has focused on the evolutionary relationships and biogeography of the genus Bufo, an evolutionary synthesis of the entire group has not yet emerged. In the present study, almost 4 kb of DNA sequence data from mitochondrial (12S, tRNA^Val, and 16S) and nuclear (POMC; Rag-1) genes, and 83 characters from morphology were analysed to infer a phylogeny of South American toads. Phylogenies were reconstructed with parsimony and maximum likelihood and Bayesian model-based methods. The results of the analysis of morphological data support the hypothesis that within Bufo , some skull characters (e.g. frontoparietal width), correlated with the amount of cranial ossification, are prone to homoplasy. Unique and unreversed morphological synapomorphies are presented that can be used to diagnose recognized species groups of South American toads. The results of all phylogenetic analyses support the monophyly of most species groups of South American Bufo . In most DNA-only and combined analyses, the South American (minus the B. guttatus and part of the ' B. spinulosus ' groups), North American, Central American, and African lineages form generally well-supported clades: ((((((((South America) (North America + Central America)) Eurasia) Africa) Eurasia) South America) West Indies) South America). This result confirms and extends prior studies recovering South American Bufo as polyphyletic. The biogeographical results indicate that: (1) The origin of Bufo predates the fragmentation of Gondwana; (2) Central and North American species compose the sister group to a large, 'derived' clade of South American Bufo ; and (3) Eurasian species form the sister group to the New World clade.  © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society , 2006, 146 , 407–452.     

Nutrient uptake in streams draining agricultural catchments of the midwestern United States

1. Agriculture is a major contributor of non‐point source pollution to surface waters in the midwestern United States, resulting in eutrophication of freshwater aquatic ecosystems and development of hypoxia in the Gulf of Mexico. Agriculturally influenced streams are diverse in morphology and have variable nutrient concentrations. Understanding how nutrients are transformed and retained within agricultural streams may aid in mitigating increased nutrient export to downstream ecosystems. 2. We studied six agriculturally influenced streams in Indiana and Michigan to develop a more comprehensive understanding of the factors controlling nutrient retention and export in agricultural streams using nutrient addition and isotopic tracer studies. 3. Metrics of nutrient uptake indicated that nitrate uptake was saturated in these streams whereas ammonium and phosphorus uptake increased with higher concentrations. Phosphorus uptake was likely approaching saturation as evidenced by decreasing uptake velocities with concentration; ammonium uptake velocity also declined with concentration, though not significantly. 4. Higher whole‐stream uptake rates of phosphorus and ammonium were associated with the observed presence of stream autotrophs (e.g. algae and macrophytes). However, there was no significant relationship between measures of nutrient uptake and stream metabolism. Water‐column nutrient concentrations were positively correlated with gross primary production but not community respiration. 5. Overall, nutrient uptake and metabolism were affected by nutrient concentrations in these agriculturally influenced streams. Biological uptake of ammonium and phosphorus was not saturated, although nitrate uptake did appear to be saturated in these ecosystems. Biological activity in agriculturally influenced streams is higher relative to more pristine streams and this increased biological activity likely influences nutrient retention and transport to downstream ecosystems.     

Differences in the utilization of water vapour and free water in two co‐occurring foliose lichens from semi‐arid southern Australia

Hydration and dehydration kinetics were investigated in two xerophytic lichens with contrasting thallus morphologies, Chondropsis semiviridis (F.Muell. ex Nyl.) Nyl. and Xanthoparmelia convoluta (Krempehl.) Hale. Pulse‐modulated chlorophyll fluorescence was used to measure photosynthetic activity in thalli hydrated with either liquid water or water vapour in the laboratory and in the field. Water content (WC) and photosynthetic activity of thalli in both species increased rapidly on contact with liquid water. When exposed to water vapour, C. semiviridis hydrated more rapidly and achieved higher WC than X. convoluta. Both lichens achieved maximum Fv/Fm at low WC, regardless of hydration source. Rates of water loss were slower, and Fv/Fm remained high for longer, in X. convoluta than in C. semiviridis. Light saturated electron transport rates of both lichens were low compared with a homoiohydric plant from the same environment. Our results suggest that X. convoluta, which has a more complex morphology, retains water and remains photosynthetically active for significantly longer periods than C. semiviridis, providing X. convoluta with a potential advantage in the semi‐arid environment in which both species are found.     

Development and characterization of microsatellite loci in the endangered oyster mussel Epioblasma capsaeformis (Bivalvia: Unionidae)

Primers for 10 polymorphic microsatellite loci were developed and characterized for the endangered oyster mussel Epioblasma capsaeformis from the Clinch River, Tennessee. Microsatellite loci also were tested in four other populations or species. Amplification was successful for most loci in these closely related endangered species or populations; therefore, a high level of flanking sequence similarity was inferred for this group of species and populations. Allelic diversity ranged from nine to 20 alleles/locus, and averaged 13.6/locus. This study demonstrated the feasibility of using polymerase chain reaction (PCR) primers to amplify microsatellite loci across freshwater mussel species to conduct population genetics studies.     

Release rates and potential fates of nitrogen and phosphorus from sediments in a eutrophic reservoir

1. Nutrients released from lake sediments can influence water column nutrient concentrations and planktonic productivity. We examined sediment nutrient release [soluble reactive phosphorus (SRP) and ammonia (NH)] at two sites in a eutrophic reservoir (Acton Lake, OH, U.S.A.) that differed in physical mixing conditions (a thermally stratified and an unstratified site). 2. Sediment nutrient release rates were estimated with three methods: sediment core incubations, seasonal in situ hypolimnetic accumulation and a published regression model that predicted sediment phosphorous (P) release rate from sediment P concentration. All three methods were applied to the deeper stratified site in the reservoir; however, we used only sediment core incubations to estimate SRP and NH release rates at the shallow unstratified site because of the lack of thermal stratification. We also compared the total P concentration (TP_S) of sediments and the concentration of P in various sediment fractions at both sites. 3. Anoxic sediments at the stratified site released SRP at rates more than an order of magnitude greater than oxic sediments at the shallow unstratified site. However, P accumulated in the hypolimnion at much lower rates than predicted by sediment core incubations. In contrast, NH was released at similar rates at both sites and accumulated in the hypolimnion at close to the expected rate, indicating that P was ‘lost’ from the hypolimnion through biogeochemical pathways for P, such as precipitation with inorganic material or biological uptake and sedimentation. 4. TP_S was significantly greater at the deeper stratified site and organically bound P accounted for >50% of TP_S at both sites. 5. We examined the magnitude of SRP fluxes into the study reservoir in 1996 by comparing the mean summer daily SRP fluxes from anaerobic sediments, aerobic sediments, stream inflows and gizzard shad excretion. While the SRP release from anaerobic sediments was high, we hypothesise that little of this SRP gained access to the epilimnion in mid‐summer. SRP flux to the reservoir from aerobic sediments was less than from gizzard shad excretion and streams. Large interannual variability in thermocline stability, gizzard shad biomass and stream discharge volumes, will affect SRP loading rates from different sources in different years. Therefore, construction of P budgets for different years should account for interannual variation in these parameters.     

Comparison of regeneration following burning,clearing or mineral sand mining at Tomago,NSW: I. Structure and growth of the vegetation

Abstract We have begun a long-term ecological research project to address questions about the impact of multiple disturbances on the species richness of communities and whether multiple disturbances are additive or interactive. A protected water catchment area was chosen, which is subjected to fires, sand mining and clearing, and for which detailed records are available. The study area, at Tomago (32°52′S, 151°45′E), has forest, woodland, shrubland and swamp on a sand substrate, with the vegetated dunes forming part of a coastal embayment. Forty-four sites were located in forested areas that had undergone disturbance by either fire, sand mining or clearing. Sites of each disturbance type were grouped into four age classes: less than 1 year since disturbance, nominally 1991; 5 years, nominally 1986; 11 years, nominally 1980; and 17 years, nominally 1974. A set of burned sites, with the time of the last fire matched to the times of the other disturbances, was used as the control response. In this paper we describe the study area and sites, then examine the effects of each single disturbance on vegetation structure. Canopy cover increased with time and type of disturbance, with 17 year old cleared or mined sites similar to the cover of 11 year old burned sites. In the first two years after disturbance, burned sites had significantly more understorey vegetation than cleared or mined sites, but by 5 years all three were similar. The data presented here show that regeneration of mined sites at Tomago is substantially slower than regeneration following disturbance by fire, with the regeneration of cleared sites intermediate but closer to mining than fire. After 17 years regeneration, cleared and sand mined sites had not returned to the vegetation structure of the pre-disturbance state. Understorey height and the amount of vegetation on cleared or mined sites have not achieved the levels in the original forest, although canopy cover did seem to have reached pre-disturbance levels. Current rehabilitation techniques are more sophisticated than those used 17 years ago and continued monitoring of sites currently being rehabilitated may show a faster return to pre-disturbance states. Having established the hierarchy and nature of the response to each single disturbance here, we are now in a position to investigate the impact of multiple disturbances.