Double sampling to assess the accuracy of ground‐based surveys of tree hollows in eucalypt woodlands

Ground‐based surveys of tree hollows often give poor estimates of hollow abundance in forests. Woodlands have shorter trees and a more open structure than forests, which may make hollows easier to detect. Therefore, one would expect ground‐based surveys of tree hollows to be more accurate in woodlands than in forests. We compared hollow counts from ground‐based and climbing surveys (double sampling) for four species of Eucalyptus trees in woodlands of central‐western New South Wales, Australia: E. camaldulensis Dehnh, E. melliodora A. Cunn. ex Schauer, E. microcarpa Maiden and E. populnea F. Muell. ssp. bimbil L.A.S. Johnson & K.D. Hill and E. melliodora A. Cunn. ex Schauer. Overall, 83% of hollow‐bearing trees and 93% of trees without hollows were correctly classified by ground‐based surveys. Mean difference in hollow counts of ground‐based surveys to climbed surveys was 1.7 hollows ± 0.2 SE (all species combined) with 91% of ground‐based hollow counts being within five of the actual number of hollows. The error in ground‐based counts of hollows in E. microcarpa was larger than for the other three species. Errors in all species resulted from both overestimation and underestimation of hollow abundance by ground‐based surveys. A larger error was associated with the detection of hollows located in branches compared with hollows located in the main trunk(s). Total number of hollows in the tree (based on climbing surveys), crown area or maximum trunk diameter were significant predictors of ground‐based survey accuracy. Overall, the accuracy associated with ground surveys was relatively high and generally error rates were lower than those published for forests.     

A generic method of pesticide dose expression: Application to broadcast spraying of apple trees

The recommended dose for many pesticides is expressed as a constant mass or volume per unit ground area covered by the crop. This method of dose expression is well suited to boom spraying where a reasonably uniform horizontal distribution of deposit can be achieved with a well‐adjusted sprayer. However, in many practical situations (e.g. broadcast spraying of apple trees or other row structures where the spray application is made from within the canopy) the horizontal deposit distribution is strongly influenced by the crop area density and other crop structural parameters. This paper describes a generic method of pesticide dose expression to investigate these effects. The method incorporates a model of the spray volume deposition process. The model assumes that the pesticide deposit is proportional to the tank‐mix concentration of pesticide. The model also assumes that spray volume deposit is proportional to the applied spray volume per unit row length and is inversely proportional to a crop length scaling function L (i.e. a parameter with the units of length that is expressed as a generic function of different crop parameters). The useful working range of this model is bounded by the condition for high spray volume where target losses become significant due to saturation and the condition for very low volume where evaporative transport losses become significant. Within this framework, four different models are formulated using first‐order approximations for the length‐scale as functions of the following crop parameters: tree row spacing, tree row height, tree area density and tree row volume to ground area ratio. Published measurements of crop structure and spray volume deposit on apple trees are compared with the output from these models. Light detection and range (LIDAR) measurements of apple orchards are presented and used in conjunction with the different models to predict pesticide use associated with different methods of dose expression. The results demonstrate the relative potential for varying the pesticide application rate according to the different crop parameters. The results enable the identification of reference orchards that could be used to establish worst‐case pesticide application rates for registration purposes. The results also enable the identification of other orchards and growth stages where pesticide application rate might be reduced by up to a factor of five and give the same pesticide deposit as the reference structure.     

The first British record and a new species of the superfamily Terrestricytheroidea (Crustacea, Ostracoda): morphology, ontogeny, lifestyle and phylogeny

Terrestricythere elisabethae sp. nov. is described from a semiterrestrial coastal habitat at two sites in Hampshire, southern England. It is the first record of a living population of the genus outside the Far East (north-west Pacific). Based on extensive collections and from observations of cultures, its morphology is described (including a formal definition of the unique 'visordont' hinge), as well as its ontogeny and lifestyle (encompassing habitat, life cycle, mode of life and locomotion). A further new species from Somerset, south-west England is also recorded on the basis of a single specimen but left in open nomenclature. The affinities of the Terrestricytheroidea are discussed in the context of a tentative phylogeny of podocopan Ostracoda. Both carapace and appendage characters are such as to warrant maintaining it as a separate superfamily, which is more closely related to the Cytheroidea and Darwinuloidea than to the Cypridoidea.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 142 , 253–288.     

Comparative Studies of Acid Glycosidases from Three Legumes

The major isoenzymes of -mannosidase (EC 3.2.1.24 [EC] ) and ß-galactosidase(ECf 3.2.1.23 [EC] ) have been separated from cotyledons of gardenpea, Pisum sativum L. (Vicieae), chick pea, Cicer arietinumL. (Cicereae), and cowpea, Vigna unguiculata (L.) Walp. (Phaseoleae).Some of their properties have been determined, including pHoptima, K_m values for p-nitrophenyl glycosidc substrates, andthe effects of several inhibitors. Swainsonine, an indolizidinealkaloid, was the most effective inhibitor of mannosidase 1,with I₃₀ values of 5.6 x 10^–8 M (cowpea), 1x 10^–7M (chick pea) and 2.9 x 19^–7 M (pea). The most effectiveinhibitor of ß-galactosidase 2 from all sources wasD-galactonic acid-1,4-lactonwe (-lactone), with K_i values rangingbetween 3.0 and 3.9x 10^–3 M. An inhibitor of the E. coliß-galactosidose, p-aminophenyl thio-ß-D-galactopyranoside,did not inhibit any of the legume ß-galctosidases;rather it enhanced the activites of the enzymes from chick peaand cowpea cotyledons. Etiolated hull and seed tissues frompea pods developing in darkness contained similar acid glycosidaseactivities to normal green tissues, thus the chloroplast isan unlikely location for ß-galactosidase 2. The majorß-galactosidasesdetected with an indigogenic substrate (5-bromo-4-chloro-3-indoxyl-ß-D-galactopyranoside)following gel electrophoresis of extracts from pea hull, seedcoats and cotyledons appeared to be different from ß-galactosidase2. Acid glycosidase, cotyledon, isoenzyme, -lactone, legume, swainsonine     

Shock Pulse Effects on Wheat Growth

Wheat seedlings (Triticum aestivum cv. Pacific Blue Stem) grown under continuous low-level illumination were used to study the effects of pressure variation and its duration. Growth was determined by dry weights, leaf length, and types of secondary roots produced. Two sublethal shock pulses (1.41 and 2.82 kg cm ^?2) and three pressure duration intervals (0.1, 1.0 and 10.0 seconds) were studied. The results indicated a general overall reduction in growth associated with the shock pulse and that the pressure duration interval influenced the shock- growth response. The long pressure duration interval was found to be the most influential on shock pulse response. Present knowledge indicates that a pulse rise-time of 1 ms and a pressure duration interval of at least 1.0 second affect plant growth at sublethal shock pulses, such that the growth response is linear or bi-directional, depending on the magnitude of the shock pulses, and either linear or complex with respect to pressure duration interval for any shock pulse level.     

Visual fields in Blue Ducks Hymenolaimus malacorhynchos and Pink-eared Ducks Malacorhynchus membranaceus: visual and tactile foraging

Blue Ducks Hymenolaimus malacorhynchos (Anatidae), an IUCN Red Listed Endangered species, reside in headwaters of New Zealand rivers and feed primarily on aquatic invertebrates. However, whether such food items are detected by tactile or visual cues is unknown. That Blue Ducks may use tactile cues when foraging is suggested by the presence of specialized flaps of thickened, keratinized epidermis containing Herbst's corpuscles along the ventral margins of the upper mandibles near the bill tip. Similar bill flaps are found only in one other duck species, Pink-eared Ducks Malacorhynchus membranaceus , that surface filter-feed on a range of planktonic organisms. Using an ophthalmoscopic reflex technique we determined the visual fields of both species. In Blue Ducks the eyes are frontally placed resulting in a relatively wide binocular field into which the narrow tapering bill intrudes. There is a large blind area to the rear of the head. This visual field topography is similar to that of other visually guided foragers including those that take mobile prey from the water column, e.g. penguins (Spheniscidae). By contrast, Pink-eared Duck visual fields show features found in other tactile feeding ducks: a narrow frontal binocular field with the bill falling at the periphery, and comprehensive visual coverage of the celestial hemisphere. We conclude that although Blue Ducks may take prey from rock surfaces they are primarily visual feeders of the water column and we suggest therefore that their foraging may be significantly disrupted by changes in water clarity. This introduces a previously unconsidered factor into the selection of sites for population enhancement or re-introductions, a current conservation focus.     

Periphyton biomass dynamics in gravel bed rivers: the relative effects of flows and nutrients

SUMMARY. 1. Periphyton chlorophyll a and ash free dry weight (AFDW) were monitored in nine rivers to examine the relative importance of flows and nutrients for regulating periphyton biomass in gravel bed rivers. 2. Mean annual flows in the rivers ranged from 0.94 to 169 m³ s^?1, mean dissolved reactive phophorus (DRP) from 1.3 to 68 μ g 1^?1, periphytic chlorophyll a from 4.6 to 73 mg m ^?2. and AFDW from 2.8 to 16 g m^?2. 3. For eight of the nine rivers NH₄-N. DRP, total Kjeldahl nitrogen, total phosphorus and total suspended solids were correlated (P<0.01) with flow, and for seven rivers conductivity was inversely correlated (P<0.05) with flow. 4. There was a hyperbolic relationship between flows and biomass, with chlorophyll a >100 mg m ^?2 and AFDW >20 g m^?2 occurring most frequently in flows of <20 m³ s^?1. 5. Floods prevented the development of medium term (i.e. up to 2 months) maxima in biomass in five of the rivers, but maxima occurred over summer-autumn and winter-spring in the three rivers where floods were absent. 6. Chlorophyll a biomass was more resistant to flooding than AFDW. Only 5993 of the forty-six recorded floods caused chlorophyll a scouring, whereas 74% of the floods caused AFDW scouring. The efficiency of scour was more influenced by the pre-flood biomass than the magnitude of the event. 7. Biomass maxima were significantly correlated (P<0.01) with mean DRP concentration during the accrual period. Overall, up to 53% of the mean annual biomass difference between rivers was explained by the mean annual DRP concentrations. However, the high correlations between nutrient concentrations and flow indicated that the nutrient data were also carrying hydrological information and that simple causal relationships between nutrients and biomass are difficult to establish in rivers. 8. It is concluded that hydrological factors contribute at least equally with nutrients to the differences in periphyton biomass between the gravel-bed study rivers. They combined to explain up to 63.3% of the variance in biomass, compared with 57.6% for nutrients. It is recommended that periphyton data from gravel-bed rivers should always be viewed within the context of the flow history of the site, and not just as a function of nutrient concentrations.