THE EFFECT OF COMPLETE REMOVAL OF HIPPOPOTAMUS ON GRASSLAND IN THE QUEEN ELIZABETH NATIONAL PARK, UGANDA

Coincident with the shooting out of hippopotamus in May 1958 20 permanent 30.46 m line intercept transects were established on the denuded grassland of the Mweya Peninsula, Queen Elizabeth National Park, western Uganda, to assess botanical changes in basal cover, species composition and frequency. Between May 1958 and May 1959, grass basal cover (GBC) decreased from 14.7% to 5.3% and bare ground increased from 78.3% to 83.6%. After four years total ground cover was 10.9% GBC, 27.2% litter, 1.3% dicotyledons and 60.6% bare ground. Changes occurred in grass species composition. The perennial carpet grass, Chrysochloa orientalis, declined from 37.7% GBC (transect frequency 100%) to 6.6% (87%) by May 1962. Bunch grasses showed marked recovery: Sporobolus pyramidalis increased from 8.0% GBC (60%) to 27.6% (100% frequency). Cynodon dactylon, initially prominent in two lakeside transects only, declined from 9.2% GBC to 2.1%, then became re-established in inland localities and recovered to 11.7% GBC. The variable rainfall (714 mm annual average) and its influence on plant growth is discussed and the advantage of mechanically increasing effective rainfall mentioned. Authorities for plant names are given in Table 3.     

IDENTIFYING PREDATORS AT NORTHERN BOBWHITE NESTS

Abstract: We identified nest predators of northern bobwhites (Colinus virginianus) on private lands in northern Florida and southern Georgia, USA, using continuous infrared micro-video cameras, 1999–2001, and compared these results to predictions based on diagnostic sign at nests. Mammals (59%), snakes (29%), and ants (12%) accounted for known bobwhite nest depredations. Mammalian predators, in order of importance, were the raccoon (Procyon lotor), nine-banded armadillo (Dasypus novemcinctus), Virginia opossum (Didelphis virginiana), bobcat (Lynx rufus), hispid cotton rat (Sigmodon hispidus), and coyote (Canis latrans). Using diagnostic sign, technicians correctly classified 30% of mammalian depredations to species and overestimated nest depredations by snakes. A classification tree model correctly classified 75% of the test sample (n = 33) into “mammal” or “snake” categories, but still overestimated depredations by snakes. We documented a broader predator community upon bobwhite eggs than previously known for northern Florida and southern Georgia and confirmed that snakes were significant nest predators in some years. We conclude that diagnostic sign at depredated nests was unreliable for identifying nest predators of northern bobwhites.     

The Infection of Pine stumps by Fomes annosus and other fungi

A study of the infection biology of stump-colonizing fungi hasshown that certain species, for instance Fomes annosus, Peniophoragigantea, Stereum sanguinolentum, and several causing blue-stain,initiate infection of fresh stumps by means of air-borne sporeswhich colonize the cut surface. The incidence of natural infectionis reduced considerably by applying creosote to the surfaceimmediately after felling. High resin content of stumps is correlatedwith increased resistance to infection. Marked seasonal variationin the incidence of stump infection by F. annosus and P. giganteawas observed. The spore content of the air, and competitionbetween fungi in stumps, are considered to be important factorsaffecting this variation. Initial colonization of stump roots usually proceeds from thebody of the stump. Invasion of roots by saprophytes presentin the soil or litter also occurs but only many months afterfelling. Crowns of plantation pines may bear many spores of stump-colonizingfungi, including F. annosus. Under the conditions described,the proportion of stump infections ascribable to rain-splash-bornespores was small compared with that caused by wind-borne spores.     

Does flooding affect spatiotemporal variation of fish assemblages in temperate floodplain wetlands?

1. Floodplain wetlands are productive components of lowland rivers and are thought to be important habitat and nurseries for many fish species. Fish assemblages inhabiting floodplain wetlands vary considerably through space and time and are largely shaped by wetting/drying cycles, although there is little understanding how many aspects of flooding (e.g. magnitude, timing, duration, frequency) influence the fish assemblages. As a consequence, decisions on flooding of wetlands by managers aimed at restoring native fish assemblages are often based on limited knowledge. 2. This study examined the importance of total duration of flooding on the temporal and spatial dynamics of wetland fish assemblages in the Murray River, in south‐eastern Australia. The study examined: (i) how the abundance of 0+ and 1+ fish varied with wetland, season and the duration of wetland filling; (ii) how environmental parameters, including food production changed in relation to the duration of wetland filling; (iii) changes in condition indices for the most abundant species and (iv) changes in species richness and total abundance over time. 3. The 0+ fish assemblage varied more through space and time than the 1+ assemblage. Longer cumulative river–wetland filling was associated with greater total abundances of newly recruited (0+) fish; this was particularly true for common carp (Cyprinus carpio, alien) and carp gudgeon (Hypseleotris spp., native). The body condition of carp gudgeon also increased with the duration of filling, even though static measures of food production declined. The small flooding events that occurred as part of this study did not translate into measurable improvements in the fish assemblage over the longer term (3 years), but did prevent wetlands from drying and thus maintained these habitats as refuges.     

Indirect Compartmental Analysis of Copper in Live Ryegrass Roots; Comparison with Model Systems

The technique of indirect compartmental analysis of ⁶⁴Cu elutionmeasurements was applied to cellulose discs, a ryegrass (Loliumperenne L. cv. Premo) root cell wall isolate and live and deadroots of whole ryegrass seedlings. Curves of logarithm countsremaining in the material versus time resolved into four phasesin each case. The half-time of exchange of the slowest compartmentranged from 3.6 to 66.1 h for cellulose discs and live ryegrassroots, respectively. Plots of logarithm efflux versus time againresolved into four phases for cellulose discs, isolated rootcell wall, and dead ryegrass roots; the efflux of these materialsobeyed first order kinetics. In live ryegrass roots the plotof logarithm efflux versus time could not be resolved beyondthe initial curve; efflux from live ryegrass roots did not obeyfirst order kinetics. A full compartmental analysis of copperin live ryegrass roots could not be performed. It is suggestedthat, in live ryegrass roots, cell wall adsorption sites areresponsible for a wide continuous range of half-time of exchangevalues which overlie the elution curves of the vacuolar andcytoplasmic compartments. The technique of indirect compartmentalanalysis artificially splits the total elution curve into fourdiscrete compartments, the slowest of which has contributionsfrom both the vacuole and cell wall. Key words: Copper efflux, cell wall, ryegrass     

Mortality and survival of African Penguins Spheniscus demersusinvolved in the Apollo Seaoil spill: an evaluation of rehabilitation efforts

The bulk ore carrier Apollo Sea sank near Dassen Island, South Africa, on 20 June 1994 during a period of winter storms. Approximately 10 000 African (Jackass) Penguins Spheniscus demersus were oiled, collected and transported to the SANCCOB rescue centre; 5213 were released after cleaning, 4076 with flipper bands. We believe that most of the penguins oiled during this incident reached an island or the mainland alive, and that there was no mass mortality in the wild at the time of the oil spill. Birds from all parts of the breeding range were oiled, but most were from Robben and Dassen Islands. The overwhelming majority of released birds made the transition from the rescue centre to the wild successfully; 2652 had been resighted at breeding colonies within two years of their release; the cumulative number of birds was increasing steadily and an asymptote had not been reached by August 1996. There was a wide dispersal of released penguins, with recoveries and resightings over 1800 km of coastline between Algoa Bay and Walvis Bay.