The effects of climate change on landscape diversity: an example in Ontario forests

The predicted increase in climate warming will have profound impacts on forest ecosystems and landscapes in Canada because of increased temperature, and altered disturbance regimes. Climate change is predicted to be variable within Canada, and to cause considerable weather variability among years. Under a 2 × CO₂ scenario, fire weather index (FWI) is predicted to rise over much of Ontario by 1.5 to 2 times. FWI may actually fall slightly, compared to current values, in central eastern Ontario (Abitibi), but for central-south Ontario it is expected to rise sharply by as much as 5 times current values. We predict that the combination of temperature rise and greater than average fire occurrence will result in a shrinkage of area covered by boreal forest towards the north and east; that some form of Great Lakes forest type will occupy most of central Ontario following the 5 C isotherm north; that pyrophilic species will become most common, especially jack pine and aspen; that patch sizes will initially decrease then expand resulting in considerable homogenization of forest landscapes; that there will be little 'old-growth' forest; and that landscape disequilibrium will be enhanced. If climate change occurs as rapidly as is predicted, then some species particularly those with heavy seeds may not be able to respond to the rapid changes and local extinctions are expected. Anthropogenically-altered species compositions in current forests, coupled with fire suppression over the past 50 years, may lead to forest landscapes that are different then were seen in the Holocene period, as described by paleoecological reconstructions. In particular, forests dominated by white pine in the south and black spruce in the middle north may not be common. Wildlife species that respond at the landscape level, i.e., those with body sizes >1 kg, will be most affected by changes in landscape structure. In particular we expect moose and caribou populations to decline significantly, while white-tailed deer will likely become abundant across Ontario and Quebec.     

Effect of the appetite stimulant cyproheptadine on deoxynivalenol ‐ induced reductions in feed consumption and weight gain in the mouse 1

Abstract

Deoxynivalenol (DON, vomitoxin), a Fusarium mycotoxin, is suspected of inducing its anorectic/feed refusal activity through a serotoninergic (5HT) mechanism, possible via 5HT₂‐receptors. In this study the efficiency of cyproheptadine (CYP), a serotonin antagonist and known appetite stimulant, to attenuate the adverse effect of DON was investigated in mice. CYP was administered in the feed for two days before animals began receiving the DON, which was also added to the feed. Both agents were administered concurrently thereafter for a 12‐day period. Dosing levels included various combinations of the two compounds, ranging from 0–16 ppm DON and 0–20 ppm CYP.

Results showed that CYP could effectively offset the reduction in feed intake caused by dietary DON, but only when dose levels were optimized (CYP appeared to have a narrow effective dose range, which was also dependent on the DON concentration). In fact, optimum CYP doses were able to enhance feed intake in DON‐fed mice above control levels, indicating that more than just a direct block of the toxin's effect was occurring. Conversely though, the effect of CYP on weight gain (WG) was ambiguous. At the lower CYP doses (≤ 5 ppm), alone or in combination with the lowest DON level tested (4 ppm), a modest positive effect was noted, but at the higher DON concentrations (≥ 8 ppm) the overall WG generally remained depressed, and tended to be reduced further by increasing doses of CYP.

These results provide additional support that serotoninergic mechanisms probably play a role in mediating DON‐induced reduction in feed intake. Where and how DON actually initiates its anorectic effect, however, has not been resolved.     

Recording the Response of Plants to Various Air Pollutants

A discussion of the methods used to determine the most economic design of chimney for a new thermal power station or large industrial plant is presented, with the objective that ground level concentration of pollutants will be kept at a minimum. Attention is paid to the geography and climatology of the site, with special reference to the frequency and height of inversions and the prevailing wind direction and speed.

A method is illustrated in using a large thermal power station as an example. The maximum sulfur dioxide concentrations at ground level are computed for several chimney heights and gas exit velocities. The values of these sulfur dioxide concentrations, the capital cost of the chimney, the pumping costs, and the gas pressures within the chimney are considered in selecting a suitable chimney height and a gas exit velocity which will meet most economically the stated objective.

The paper deals primarily with chimneys for industrial or power boiler plant of maximum continuous rating greater than 450 million Btu/hr (about 450,000 lbs of steam/hr), or to chimneys serving furnaces burning fuel at a maximum rate greater than 50,000 lbs/hr of coal, or 80,000 lbs/hr of oil. For chimneys serving plant with smaller heat inputs, chimney selection by reference to Clean Air Act 1956, Memorandum on Chimney Heights is suggested.     

Abundance,population structure and claw morphology of the semi-terrestrial crab <Emphasis Type="Italic">Pachygrapsus marmoratus</Emphasis> (Fabricius, 1787) on shores of differing wave exposure

Wave action is known to influence the abundance and distribution of intertidal organisms. Wave action will also determine the duration and suitability of various foraging windows (high-tide and low-tide, day and night) for predation and can also affect predator behaviour, both directly by impeding prey handling and indirectly by influencing prey abundance. It remains uncertain whether semi-terrestrial mobile predators such as crabs which can access intertidal prey during emersion when the effects of wave action are minimal, are influenced by exposure. Here, we assessed the effect of wave action on the abundance and population structure (size and gender) of the semi-terrestrial intertidal crab Pachygrapsus marmoratus on rocky shores in Portugal. The activity of P. marmoratus with the tidal cycle on sheltered and exposed shores was established using baited pots at high-tide to examine whether there was activity during intertidal immersion and by low-tide searches. Because prey abundance varies along a wave exposure gradient on most Portuguese shores and because morphology of crab chelipeds are known to be related to diet composition, we further tested the hypothesis that predator stomach contents reflected differences in prey abundance along the horizontal gradient in wave exposure and that this would be correlated with the crab cheliped morphology. Thus, we examined phenotypic variation in P. marmoratus chelipeds across shores of differing exposure to wave action. P. marmoratus was only active during low-tide. Patterns of abundance and population structure of crabs did not vary with exposure to wave action. Stomach contents, however, varied significantly between shores of differing exposure with a higher consumption of hard-shelled prey (mussels) on exposed locations, where this type of prey is more abundant, and a higher consumption of barnacles on sheltered shores. Multivariate geometric analysis of crab claws showed that claws were significantly larger on exposed shores. There was a significant correlation between animals with larger claws and the abundance of mussels in their stomach. Variation in cheliped size may have resulted from differing food availability on sheltered and exposed shores.     

Riding the storm: the response of Plantago lanceolata to simulated tidal flooding

Supra-tidal plant communities fulfil a vital role in coastal protection and conservation but despite an increased likelihood of salt-water inundation from storm surges, we understand remarkably little on how salinity affects habitats like coastal grasslands or their component species. We quantified the survival and growth of a common coastal grassland plant, Plantago lanceolata when exposed to short-duration (1-, 2-, 4-, or 8-h) immersion in sea water. We also calculated root:shoot ratios (R:SR) and specific leaf area (SLA) to examine how salinity stress affects above- and below-ground resource allocation patterns and likely interactions with other trophic levels. Immersion in sea water reduced Plantago survival particularly at longer durations of 4- and 8 h, and for surviving plants, growth was also much reduced. Contrary to studies with crop plants however, we found reduced allocation to root biomass (R:SR) and increased SLA. The fact that Plantago displayed opposite ecophysiological responses to those consistently reported in the literature highlights that the response of coastal grassland plants to storm surge events cannot be assumed from conventional wisdom. In order to better protect and conserve these internationally important ecosystems from the effects of anthropogenically induced sea-level rise, a systematic exploration of the effects of sea water flooding on coastal grasslands is required.     

Lipid composition of eggs and adductor muscle in giant scallops (Placopecten magellanicus) from different habitats

Scallops (Placopecten magellanicus Gmelin) were collected during August 1989 from shallow water (10 m) and deep water (31 m) habitats at Sunnyside, Trinity Bay, Newfoundland, to compare the lipid composition of eggs and adductor muscle tissue. Less favorable food levels and lower temperature conditions associated with deeper water have previously been shown to produce slower growth and reduced fecundity in individuals from this habitat. Triacylglycerol reserves consistently accounted for 60% of the total lipids present in both groups. The total lipid content of the eggs and the composition of their triacylglycerol fatty acid pools were similar in shallow water and deep water scallops, indicating very little if any nutritional difference between the two groups. Relative to their counterparts from shallow water, individuals from deeper water contained higher proportions of docosahexaenoic acid [22:6(n-3)] in the egg phospholipids and higher levels of 24-methylenecholesterol (a phytosterol commonly found in diatoms) in the adductor muscle. Differences in fatty acid composition are interpreted as biochemical adjustments of cell membranes to increase membrane fluidity, thereby compensating for the lower temperatures prevailing at the greater depth.     

Wildlife Association with Human-Altered Water Sources in Semiarid Vegetation Communities

Based on common use in wildlife management, we hypothesized that human-constructed water sources influence faunal communities detectably compared to similar habitats that lack water. We examined 20 wildlife water units and 20 paired comparison sites without water from April to August 1992 in semiarid southern New Mexico to assess animal species associations. We sampled sites by using small-mammal live traps, herpetofaunal and invertebrate pitfall arrays, and 30-minute time-area counts. We compared animal species richness and species concordance among water units (rain catchments, earthen tanks, and windmills) and comparison sites in three vegetation communities (mixed scrub, grassland, and pinyon-juniper). We detected 134 animal taxa during field sampling. Animal species richness did not differ between water units and comparison sites among vegetation communities. Amphibians were found only at water units but occur far from units during seasonal wet periods. Greater numbers of individual small mammals and herpetofauna at water units versus comparison sites likely related to debris and disturbed soil present near water units. Taxa detected at water units and comparison sites were 65% concordant overall; discordant taxa were those rarely detected. Our data implied that definitive effects of artificial water sources on native wildlife species were not detectable. Providing water sources may be a strategic management tool but must be viewed critically regarding effect on distribution of native, feral, and exotic animals. Water units should be developed only when and where clear objectives have been stated, natural water sources have been quantified, commitment exists to ensure continued function, and feral and exotic animals will not benefit to the detriment of native species.     

What Food is “Good” for You? Toward a Pragmatic Consideration of Multiple Values Domains

What makes a food good, for you? With respect to food, the expression “good for you” usually refers to the effect of the food on the nutritional health of the eater, but it can also pertain more broadly. The expression is often used by a person who is concerned with another person’s well-being, as part of an exhortation. But when framed as a question and addressed to you, as an individual, the question can require a response, calling for accountability beyond the realm of nutrition or other material qualities of the food. Economic value may be considered as a ratio: goodness/price. In this paper, we examine the numerator, exploring a broad range of values domains related to food, attempting to obtain a more comprehensive understanding of the meaning of goodness of food. We present a typology of values domains with respect to food, divided into three main categories: (1) material considerations, (2) psychological, psychosocial, and spiritual health, and (3) the well-being of society. This understanding that results from comprehensive consideration of these values domains has important implications for an individual for use in considering the question “what food is good for you?” in order to guide his or her future actions, helping to distinguish between what Dewey termed immediate good and reasonable good. A pragmatic approach to a fuller consideration of food-related values domains by individuals also has broad social, political, and economic implications. If, according to the FAO, food security involves both needs and preferences, consideration of what preferences are appropriate is fundamental to achieving food security. The questions about what is considered to be good food are central to questions about the sorts of food and agricultural systems human societies will seek to sustain. The approach to resolving this important aspect of sustainability might help inform a more general question as to appropriate limitations on preferences, a question fundamental to achieving sustainability in general.     

Armed sibling rivalry among suckling piglets

Summary A piglet's most precious possession Is the teat that he fattens his flesh on. He fights for his teat with tenacity Against any sibling's audacity. The piglet, to arm for this mission, Is born with a warlike dentition Of eight tiny tusks, sharp as sabres, Which help in impressing the neighbors; But to render these weapons less harrowing, Most farmers remove them at farrowing. We studied pig sisters and brothers When some had their teeth, but not others. We found that when siblings aren't many, The weapons help little if any, But when there are many per litter, The teeth help their owners grow fitter. But how did selection begin To make weapons to use against kin? Offprint requests to: D. Fraser