Effects of Simulated Sulphuric Acid Deposition On Calluna Vulgaris/Peat Microcosms and Associated Soil Solutions

Calluna vulgaris/peat microcosms have been used in an outdoor simulated acid rain experiment to test a series of hypotheses about sulphuric acid deposition effects upon the growth of Calluna on peat soil, namely: (1) Initially, enhanced acid input will enhance base cation and ammonium concentrations in soil solution. This may enhance uptake of these species, increasing foliar concentrations of base cations and nitrogen, and possibly foliar chlorophyll a and b concentrations. (2) If changes are induced in nutritional status, they may influence plant growth. (3) in the longer term, enhanced ammonium and base cation solubility occurring as a consequence of cation exchange reactions will lead, especially in winter months, to enhanced leaching losses. Hence any positive effects upon plant nutrition will not be sustainable. (4) the peat will acidify significantly over two years, in the shorter term primarily as a consequence of an enhanced mobile anion effect. (5) Acidification may reduce the rate of mineralisation of organic phosphorus and, in a phosphorus-deficient peat soil, this may lead to reduced foliar phosphate concentration and possibly induce phosphorus deficiency.

Most of these hypotheses were supported to some extent by the experimental results. the peat soil solution pH fell immediately in response to the acid treatments, and longer-term acidification continued progressively over the two years of the experiment. in the first year, the treatments significantly influenced the calcium, magnesium, phosphorus and nitrogen status of the leaves from Calluna new shoots, whereas in the second year calcium, potassium and phosphorus were influenced. However, in both years foliar phosphate concentration was enhanced, rather than reduced, in response to increased acid load. Foliar carbon and nitrogen concentrations fell with increasing acidity of     

Economic-based projections of future land use in the conterminous United States under alternative policy scenarios

Land-use change significantly contributes to biodiversity loss, invasive species spread, changes in biogeochemical cycles, and the loss of ecosystem services. Planning for a sustainable future requires a thorough understanding of expected land use at the fine spatial scales relevant for modeling many ecological processes and at dimensions appropriate for regional or national-level policy making. Our goal was to construct and parameterize an econometric model of land-use change to project future land use to the year 2051 at a fine spatial scale across the conterminous United States under several alternative land-use policy scenarios. We parameterized the econometric model of land-use change with the National Resource Inventory (NRI) 1992 and 1997 land-use data for 844 000 sample points. Land-use transitions were estimated for five land-use classes (cropland, pasture, range, forest, and urban). We predicted land-use change under four scenarios: business-as-usual, afforestation, removal of agricultural subsidies, and increased urban rents. Our results for the business-as-usual scenario showed widespread changes in land use, affecting 36% of the land area of the conterminous United States, with large increases in urban land (79%) and forest (7%), and declines in cropland (-16%) and pasture (-13%). Areas with particularly high rates of land-use change included the larger Chicago area, parts of the Pacific Northwest, and the Central Valley of California. However, while land-use change was substantial, differences in results among the four scenarios were relatively minor. The only scenario that was markedly different was the afforestation scenario, which resulted in an increase of forest area that was twice as high as the business-as-usual scenario. Land-use policies can affect trends, but only so much. The basic economic and demographic factors shaping land-use changes in the United States are powerful, and even fairly dramatic policy changes, showed only moderate deviations from the business-as-usual scenario. Given the magnitude of predicted land-use change, any attempts to identify a sustainable future or to predict the effects of climate change will have to take likely land-use changes into account. Econometric models that can simulate land-use change for broad areas with fine resolution are necessary to predict trends in ecosystem service provision and biodiversity persistence.     

Do great tits rely on inadvertent social information from blue tits? A habitat selection experiment

Sympatric species sharing requirements are competitors, but recent evidence suggests that heterospecifics may also be used as a source of information. The heterospecific habitat copying hypothesis proposes that individuals of one species might use information inadvertently produced by the breeding performance of individuals of other species to assess habitat quality whenever the two species share needs. In this study, we provide the first experimental test of this hypothesis by examining whether the manipulated reproductive success of blue tits (Cyanistes caeruleus) is used as heterospecific inadvertent social information (ISI) in breeding-habitat selection by sympatric great tits (Parus major). The reproductive success of blue tits was manipulated 1year at the scale of patches by transferring nestlings from decreased to increased patches. No evidence was found of great tits using the reproductive success of blue tits as a source of heterospecific ISI. However, dispersal decisions by adult great tits correlated with information on con- and heterospecific densities, which constitute other sources of ISI. As density and breeding performance are tightly intertwined forms of information, the difficulty in distinguishing between them might lead great tits to use heterospecific ISI more in the form of density than breeding performance when making dispersal decisions.     

Maternal response to neonatal sibling conflict in the spotted hyena, <Emphasis Type="Italic">Crocuta crocuta</Emphasis>

Among spotted hyenas, Crocuta crocuta, neonatal aggression in twins is a well-known phenomenon and serves to establish intra-litter dominance soon after birth. As the stronger more aggressive cub presumably attains dominance over its twin, intra-litter dominance presents mothers with an ideal opportunity to assess individual cub fitness and, thereafter, to selectively favor one cub over the other. This study quantified maternal response to sibling conflict in 26 sets of twins born to 16 wild-living females to determine whether mothers of different social ranks exhibited favoritism towards sons or daughters, or in the case of same-sex twins, the dominant or subordinate cub. Maternal response to sibling conflict did not vary with litter sex composition, suggesting that mothers do not favor offspring of one sex over the other. All mothers intervened when their cubs fought and sometimes punished their cubs. Higher-ranking mothers more often punished both cubs, while lower-ranking mothers were more selective and punished the dominant cub. Where sibling aggression was most extreme, rather than favor the dominant sibling, mothers of all ranks made concessions to the subordinate cub that included procuring private nursing bouts for the subordinate and temporarily housing twins in separate dens, presumably to decrease sibling conflict. These findings represent a complex example of parent–offspring conflict and support both the insurance cub hypothesis and resource tracking hypothesis that mothers endeavor to keep all offspring alive for as long as possible in the event that the dominant sibling dies or that resources provide for the rearing of twins. This contribution is part of the special issue “Sibling competition and cooperation in mammals” (guest editors: Robyn Hudson and Fritz Trillmich).     

Closed population estimation models and their extensions in Program MARK

Program MARK provides > 65 data types in a common configuration for the estimation of population parameters from mark-encounter data. Encounter information from live captures, live resightings, and dead recoveries can be incorporated to estimate demographic parameters. Available estimates include survival (S or ϕ), rate of population change (λ), transition rates between strata (Ψ), emigration and immigration rates, and population size (N). Although N is the parameter most often desired by biologists, N is one of the most difficult parameters to estimate precisely without bias for a geographically and demographically closed population. The set of closed population estimation models available in Program MARK incorporate time (t) and behavioral (b) variation, and individual heterogeneity (h) in the estimation of capture and recapture probabilities in a likelihood framework. The full range of models from M ₀ (null model with all capture and recapture probabilities equal) to M _tbh are possible, including the ability to include temporal, group, and individual covariates to model capture and recapture probabilities. Both the full likelihood formulation of Otis et al. (1978) and the conditional model formulation of Huggins (1989, 1991) and Alho (1990) are provided in Program MARK, and all of these models are incorporated into the robust design (Kendall et al. 1995, 1997; Kendall and Nichols 1995) and robust-design multistrata (Hestbeck et al. 1991, Brownie et al. 1993) data types. Model selection is performed with AICc (Burnham and Anderson 2002) and model averaging (Burnham and Anderson 2002) is available in Program MARK to provide estimates of N with standard error that reflect model selection uncertainty.     

Blue Tits use fledgling quantity and quality as public information in breeding site choice

Public information (PI), which is the information that can be derived from the behavior and performance of conspecifics, has been demonstrated to be used in many fitness-enhancing decisions. In the context of breeding habitat choice, PI use has been called "habitat copying." We experimentally tested the existence of habitat copying in the Blue Tit (Cyanistes caeruleus), a nonmigratory, short-lived hole-nesting bird. We manipulated the mean number of fledglings raised locally (quantity) and their condition (quality) as components of PI by transferring nestlings from Decreased (D) patches to Increased (I) patches. Our manipulations caused a negative relationship between fledgling quantity and quality that does not exist naturally: I patches had a higher number of fledglings that were in poorer condition, whereas D patches had a lower number in better condition. Control (C) patches, whether manipulated or not, had intermediate levels in terms of fledgling quantity and quality. Adult emigration the following year was higher from D than from C or I patches. Similarly, adult dispersal distance decreased for individuals coming from D to C to I patches. This suggests that resident breeders rely mainly on fledgling quantity to make emigration decisions. Emigration patterns of juveniles did not vary in relation to our patch manipulation. Immigration rates were higher and similar in I and D patches than in C patches. Hence, immigrant Blue Tits seem to rely on one of the manipulated components of PI and are insensitive to the discrepancy between fledgling quantity and quality. This shows that even nonmigratory species, such as Blue Tits, may use PI in their dispersal decisions but weigh its components differently for emigration and immigration. Differences among species in the importance of PI in breeding habitat choices may be explained by differences in life histories.     

Safety in numbers and the spatial scaling of density-dependent mortality in a coral reef fish

In coral reef fishes, density-dependent population regulation is commonly mediated via predation on juveniles that have recently settled from the plankton. All else being equal, strong density-dependent mortality should select against the formation of high-density aggregations, yet the juveniles of many reef fishes aggregate. In light of this apparent contradiction, we hypothesized that the form and intensity of density dependence vary with the spatial scale of measurement. Individual groups might enjoy safety in numbers, but predators could still produce density-dependent mortality at larger spatial scales. We investigated this possibility using recently settled juvenile bluehead wrasse, Thalassoma bifasciatum, a small, aggregating reef fish. An initial caging experiment demonstrated that juvenile bluehead wrasse settlers suffer high predation, and spatial settlement patterns indicated that bluehead wrasse juveniles preferentially settle in groups, although they are also found singly. We then monitored the mortality of recently settled juveniles at two spatial scales: microsites, occupied by individual fish or groups of fish and separated by centimeters, and sites, consisting of approximately 2400-m2 areas of reef and separated by kilometers. At the microsite scale, we measured group size and effective population density independently and found that per capita mortality decreased with group size but was not related to density. At the larger spatial scale, however, per capita mortality increased with settler density. This shift in the form of density dependence with spatial scale could reconcile the existence of small-scale aggregative behavior typical of many reef fishes with the population-scale density dependence that is essential to population stability and persistence.     

Export of manure phosphorus and nitrogen in turfgrass sod

Regulatory mandates have increased demand for best management practices (BMPs) that will reduce nutrient loading on watersheds impaired by excess manure P and N. Export of manure P and N in turfgrass sod harvests is one BMP under consideration. This study quantified amounts and percentages of P and N removed in a sod harvest for different rates of manure and inorganic P and N. Six treatments comprised an unfertilized control, two manure rates with and without supplemental inorganic N, and inorganic P and N only. The treatments were applied to 'Tifway' bermudagrass (Cynodon dactylon L. x C. transvaalensis Burtt-Davey), '609' buffalograss [Buchloe dactyloides (Nutt.) Engelm.], and 'Reveille' bluegrass (Poa arachnifera Torr. x P. pratensis L.) under field conditions. Comparisons among treatments revealed small variations of P and N content in clippings and the plant component of sod, but large variations in the soil component of sod for each turf species. In addition, 2 to 10 times more P and 1.3 to 5 times more N was removed in soil than in plant components of sod for the two manure rates with and without added inorganic N. Percentages of applied P and N in harvested sod were similar for the two manure rates with and without added N for each species, but differed among turf species for each P (46 to 77%) and N (36 to 47%). The large amounts and percentages of manure P and N removed by sod harvest support the feasibility of this BMP in efforts to reduce nutrient loads on watersheds.     

Isochromosome 5p mosaicism at prenatal diagnosis: observations and outcomes in six cases at chorionic villus sampling and one at amniocentesis

We present six cases of 47,+i(5p)/46 mosaicism diagnosed at chorionic villus sampling (CVS), this being the first prospective series to be reported. The clinical indication in each was advanced maternal age. Further prenatal studies in four (amniocentesis, plus fetal blood sampling in one) did not show the isochromosome. In one case, subsequent amniocentesis showed 1/48 in situ colonies with the isochromosome, but fetal blood was karyotypically normal. These five pregnancies resulted in phenotypically normal livebirths; further normal follow-up reports (from age 4 months through 4 years) are noted in four of these. Analysis of placental tissue in one case confirmed the presence of the i(5p) mosaicism. In the remaining case, in which 100% of CVS cultured cells had the i(5p), the pregnancy was terminated. Fetal skin fibroblasts did not show the i(5p). Thus, in none of these six cases was true fetal mosaicism detected, nor an abnormal phenotype noted. We suggest that a 47,+i(5p)/46 karyotype, detected at CVS, may frequently reflect confined placental mosaicism. In addition, we report a case of the primary diagnosis of 47,+i(5p)/46 mosaicism at amniocentesis. The infant appeared normal at birth, but a brain malformation was subsequently identified. Copyright © 2002 John Wiley & Sons, Ltd.