Moderate Season Research Articles

Impacts of Human Visitors on Australian Sea Lions (Neophoca cinerea) at Carnac Island, Western Australia: Implications for Tourism Management

This study investigates the effects of human visitation on Australian sea lions (Neophoca cinerea) hauled out at Carnac Island Nature Reserve, near Perth, Western Australia. Male sea lions haul out on Carnac Island's main beach year round, and this is also where recreational boaters and tourists land when visiting from the mainland, thus coming into close contact with the sea lions. There was no significant difference in the rate of return of sea lions to the beach between low–moderate and high human visitation seasons. However, there was a specific profile of sea lion response to human approaches; the level of sea lions' vigilance was mainly a function of age (higher in juveniles than in adults) and time of the day (higher in the early part of the day). Remarkably, vigilance levels did not change with the distance of approach of humans to sea lions nor with the number of humans involved. With regard to spatial competition between sea lions and people on the beach, the section of beach where most people landed was the least often used by sea lions. This last result, however, was inconclusive, as habitat preference could have been involved in where sea lions chose to haul out. Finally, repeated incidental observations were made of direct interference of sea lions by humans, including approaches at very close range of less than 2.5 m, and throwing water and sand at sea lions. Suggested visitor management actions to reduce potential impacts of human presence on sea lions included: limiting the overall numbers of visitors to Carnac Island's main beach at peak visitation times, implementing a visitor interpretation and education program, and establishing a stronger ranger presence at the site.

Water, nitrogen and yield losses for a nonhomogeneous furrow set

Water distribution can be nonuniform along the furrow length under surface irrigation. This “down field” nonuniformity is combined with “inter-row” non-uniformity which is a consequence of differences in infiltration characteristics across the plot. Global nonuniformity of application depth causes variation of yield, drainage and nitrogen leaching. In addition to that, due to year-to-year variability of climate, irrigation depths range significantly (from 0 to 360 mm/season). The objective of this paper is to study the impact of the nonuniformity of irrigation-water distribution within a furrow plot on yield, water and nitrogen losses when climate variation is taken into account. Six maize vegetation seasons on a Chromic Luvisol soil in the Sofia region with varying irrigation requirements are considered. Irrigation water is distributed in relative terms over the plot at different levels of nonuniformity (coefficient of variation Cv ranging from 13 to 66%) by the FURMOD model. Water and nitrogen cycle and crop growth are simulated then compared at 30 representative points in the set with various “climate-irrigation nonuniformity” combinations by the CERES-maize model. It was established that non-uniformity of irrigation is not important in wet vegetation periods. The drier the irrigation season, the higher the yield loss and risk to environment due to nonuniformity of irrigation water distribution. In moderate and dry irrigation seasons it causes yield losses of 2–14%, significant variation (30% < Cv < 200%) of drainage, nitrogen leaching and residual soil nitrate over the furrow set. Surface irrigation performances can be improved by reducing lateral nonuniformity of stream advance.

Organic carbon transport and C/N ratio variations in a large tropical river: Godavari as a case study, India

This study gives an insight into the source of organic carbon and nitrogen in the Godavari river and its tributaries, the yield of organic carbon from the catchment, seasonal variability in their concentration and the ultimate flux of organic and inorganic carbon into the Bay of Bengal. Particulate organic carbon/particulate organic nitrogen (POC/PON or C/N) ratios revealed that the dominant source of organic matter in the high season is from the soil (C/N = 8–14), while in the rest of the seasons, the river-derived (in situ) phytoplankton is the major source (C/N = l–8). Amount of organic materials carried from the lower catchment and flood plains to the oceans during the high season are 3 to 91 times higher than in the moderate and low seasons. Large-scale erosion and deforestation in the catchment has led to higher net yield of organic carbon in the Godavari catchment when compared to other major world rivers. The total flux of POC, and dissolved inorganic carbon (DIC) from the Godavari river to the Bay of Bengal is estimated as 756 × 109 and 2520 × 109 g yr−1, respectively. About 22% of POC is lost in the main channel because of oxidation of labile organic matter, entrapment of organic material behind dams/sedimentation along flood plains and river channel; the DIC fluxes as a function of alkalinity are conservative throughout the river channel. Finally, the C/N ratios (∼12) of the ultimate fluxes of particulate organic carbon suggest the dominance of refractory/stable soil organic matter that could eventually get buried in the coastal sediments on a geological time scale.

GAPS AND ROOT TRENCHING INCREASE TREE SEEDLING GROWTH IN PANAMANIAN SEMI-EVERGREEN FOREST

Although competition between plants is nearly universal in vegetation, we know relatively little about belowground competition and how it interacts with aboveground competition in tropical forests, and almost nothing about such interactions on soils of intermediate fertility in sites with a moderate dry season, despite the fact that such forests are extensive. We investigated this over one year in a Panamanian tropical semi-evergreen rain forest, using tree seedlings (Simarouba amara, Gustavia superba, Tachigali versicolor, and Aspidosperma cruenta; least to most shade tolerant), experimental gaps, and trenching. Gaps increased growth and decreased mortality; growth increases were: Simarouba 684% (increase in height relative growth rate), Gustavia 411%, Aspidosperma 364%, and Tachigali 324%. Trenching in gaps increased growth in three species (Simarouba 49%, Gustavia 63%, and Aspidosperma 38%) but had very small effects in the understory; trenching did not affect mortality. We infer that trenching caused increased growth due to increased nutrients in the wet season, and increased water and/or nutrients in the dry season. Thus, across the tropics, in all but the wettest sites with fertile soils, seedlings of many species will be limited by belowground competition, at least in gaps. This is similar to the pervasive importance of belowground competition in temperate forests.

CERES model application for increasing preparedness to climate variability in agricultural planning – calibration and validation test

The procedure of stepwise calibration and validation of CERES-maize and CERES-wheat models was used for models adjustment in two fields under contrastive soil conditions (Chromic Luvisol and Vertisol) in Sofia region. Both models reflected well the phenomenon of water/nitrogen extraction and retention in the root zone after the calibration. Adjusted CERES wheat was validated over a range of soils, varieties, climate, and management conditions and proved acceptable reliability of model predictions in most of the tested situations. The highest degrees of association ( R 2 > 0.85%) was established between observed and simulated series of potentially extractable soil water (PESW) on fertilised Vertisol and Chromic Luvisol when the error (RMSE) ranged from 8.9 to13.3 mm in moderately wet, moderate and dry wheat vegetation seasons. Detailed observations of the vulnerable “Chromic Luvisol-maize” agroecosystem in lysimeters, including water and nitrogen fluxes at the bottom boundary, enabled to validate integrally the prediction capacity of calibrated CERES-maize model. Simulation outputs after calibration about PESW, water uptake, drainage, soil nitrogen storage, nitrogen leaching and crop dry weights, proved to be accurate enough over a comparatively long period (1.05.1997–1.10.1999). Graphical and statistical test of CERES-maize output characterised the performance of the model as acceptable over the specific conditions of validation lysimeter trial.

Trace elements in South America aerosol during 20th century inferred from a Nevado Illimani ice core, Eastern Bolivian Andes (6350 m asl)

Abstract. A 137 m ice core drilled in 1999 from Eastern Bolivian Andes at the summit of Nevado Illimani (16º 37' S, 67º 46' W, 6350 m asl) was analyzed at high temporal resolution, allowing a characterization of trace elements in Andean aerosol trapped in the ice during the 20th century. The upper 50 m of the ice core were dated by multi-proxy analysis of stable isotopes (d18O and d2H), 137Cs and Ca+2 content, electrical conductivity, and insoluble microparticle content, together with reference historical horizons from atmospheric nuclear tests and known volcanic eruptions. This 50 m section corresponds to a record of environmental variations spanning about 80 years from 1919 to 1999. It was cut in 744 sub-samples under laminar flow in a clean bench, which were analyzed by Ion Chromatography for major ionic concentration, by a particle counter for insoluble aerosol content, and by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for the concentration of 45 chemical species from Li to U. This paper focuses on results of trace element concentrations measured by ICP-MS. The high temporal resolution used in the analyses allowed classifying samples as belonging to dry or wet seasons. During wet season elemental concentrations are low and samples show high crustal enrichment factors. During dry seasons the situation is opposite, with high elemental concentrations and low crustal enrichments. For example, with salt lakes as main sources in the region, average Li concentration during the 20th century is 0.035 and 0.90 ng g-1 for wet and dry seasons, respectively. Illimani average seasonal concentration ranges cover the spectrum of elemental concentration measurements at another Andean ice core site (Sajama) for most soil-related elements. Regional crustal dust load in the deposits was found to be overwhelming during dry season, obfuscating the contribution of biomass burning material. Marked temporal trends from the onset of 20th century to more recent years were identified for the concentrations of several trace species of anthropic origin, especially for Cu, As, Zn, Cd, Co, Ni and Cr. Among these elements, Cu shows average wet season crustal enrichment factors above 103, while the others range between 102 to about 5x102. P and K show moderate average wet season enrichment factors, suggesting an impact of natural biogenic emissions from the Amazon Basin. Pb has multiple anthropic sources in the region, from mining activities in the beginning of 20th century to automotive fuel after 1950s. From the large number of samples analyzed from Illimani, it was possible to derive an effective chemical characterization of the deposited background Andean soil dust aerosol during 20th century.

Analysis of the benefits to wheat yield from assimilates stored prior to grain filling in a range of environments*

Grain yields of rainfed agriculture in Australia are often low and vary substantially from season to season. Assimilates stored prior to grain filling have been identified as important contributors to grain yield in such environments, but quantifying their benefit has been hampered by inadequate methods and large seasonal variability. APSIM-Nwheat is a crop system simulation model, consisting of modules that incorporate aspects of soil water, nitrogen (N), crop residues, crop growth and development. Model outputs were compared with detailed measurements of N fertilizer experiments on loamy soils at three locations in southern New South Wales, Australia. The field measurements allowed the routine for remobilization of assimilates stored prior to grain filling in the model to be tested for the first time and simulations showed close agreement with observed data. Analysing system components indicated that with increasing yield, both the observed and simulated absolute amount of remobilization generally increased while the relative contribution to grain yield decreased. The simulated relative contribution of assimilates stored prior to grain filling to grain yield also decreased with increasing availability of water after anthesis. The model, linked to long-term historical weather records was used to analyse yield benefits from assimilates stored prior to grain filling under rainfed conditions at a range of locations in the main wheat growing areas of Australia. Simulation results highlighted that in each of these locations assimilates stored prior to grain filling often contributed a significant proportion to grain yield. The simulated contribution of assimilates stored prior to grain filling to grain yield can amount to several tonnes per hectare, however, it varied substantially from 5–90% of grain yield depending on seasonal rainfall amount and distribution, N supply, crop growth and seasonal water use. High N application often reduced the proportion of water available after anthesis and decreased the relative contribution of remobilization to grain yield as long as grain yields increased, particularly on soils with greater water-holding capacity. Increasing the capacity or potential to accumulate pre-grain filling assimilates for later remobilization by 20% increased yields by a maximum of 12% in moderate seasons with terminal droughts, but had little effect in poor or very good seasons in which factors that affect the amount of carbohydrates stored rather than the storage capacity itself appeared to limit grain yield. These factors were, little growth due to water or N deficit in the weeks prior to and shortly after anthesis (when most of the assimilates accumulate for later remobilization), poor sink demand of grains due to low grain number as a result of little pre-anthesis growth or high photosynthetic rate during grain filling. Increasing the potential storage capacity for remobilization is expected to increase grain yield especially under conditions of terminal drought.

Spatial Distribution of Sheep, Feral Goats and Kangaroos in Woody Rangeland Paddocks.

The densities and distributions of sheep, kangaroos and feral goats were assessed from extensive dung surveys following dry, moderate and green seasons in three large paddocks in the wooded rangelands of north-westem New South Wales. Densities of sheep (21 9nanimals/km2) were around the long-term district average. Densities of goats (24 animals/km2) were often higher than sheep. Densities of kangaroos (1 1 animals/km2) were usually much lower than either sheep or goats. Animal density was usually related to vegetative cover (ground cover for sheep and kangaroos, shrub and tree cover for goats), but there were also differences among paddocks. Distribution of kangaroos showed the most differentiation according to vegetation type, with densities being consistently high on a small area of alluvial grassland and very low in the paddock with no alluvial plains and the lowest levels of ground cover. The distributions of sheep and goats were correlated in the dry season and both species showed similar ranges in preferences for different vegetation types. Of the large herbivores present in these woody rangelands, kangaroos were the most selective in terms of the vegetation types they grazed, and goats were the least selective. Because their grazing activities are focussed on alluvial grasslands, kangaroos have potential to degrade this locally uncommon vegetation type. However, the densities of kangaroos in other, more widespread, vegetation types were uniformly low. Goats were frequently the most abundant large herbivores present and were also the least selective. Therefore goats probably have the greatest potential for causing widespread grazing impacts across much of these woody rangelands.

Seasonal fluctuations of aquatic fungi recovered from Egyptian soil (Delta Region)

AbstractOne hundred and eleven identified and seven unidentified species in addition to 5 varieties belonging to forty‐three aquatic fungal genera were recovered from 452 soil samples collected randomly from different localities in Nile Delta and Suez canal regions including eleven governorates. The investigated soil samples were collected seasonally during the period from autumn 1990 to summer 1991 (113 samples each season). The richest season (85 identified and 5 unidentified species in addition to 2 varieties) in aquatic fungi was the winter season (10.0‐15.5°C) whereas the poorest (32 identified and 5 unidentified species in addition to one variety) was summer (24.0‐27.5°C). The richest soil samples in aquatic fungi were those of low or moderate temperature seasons, high contents of organic matter and considerably poor in total soluble salts. The pH value did not show any regular seasonal variation and did not exhibit any considerable influence on fungal populations. Some aquatic fungal genera and species were disappeared completely in certain seasons and vice versa.The most dominant aquatic fungal genera were Pythium, Allomyces, Aqualinderella and Nowa‐kowskiella. The commonest aquatic fungal species were Allomyces anomalus, Aqualinderella fermentans, Nowakowskiella elegans, Blastocladiopsis parva and Dictyuchus sterilis.

Corn (Zea mays) Injury Following Use of Clomazone, Chlorimuron, Imazaquin, and Imazethapyr

This study examined the response of corn to clomazone, chlorimuron, imazaquin, and imazethapyr the year following their application to soybeans. Herbicides were surface-applied from one-half to three times the labeled application rates. Soybeans were planted the year of application and crop tolerance was evaluated. Corn was planted in rotation the following season. Soybeans were tolerant of all four herbicides. The highest rates of clomazone, chlorimuron, and imazaquin injured the corn early in the season. Imazethapyr did not influence corn growth. Visual estimates of clomazone injury were as high as 39% chlorosis. Seedling dry weight reductions at the highest chlorimuron and imazaquin rates were 32% and 24%, respectively. Although corn was injured by higher rates of clomazone, imazaquin, and chlorimuron at the 3-leaf stage, none of the herbicides significantly reduced grain yield. This study suggests that these herbicides can carry over and injure corn, especially if labeled application rates are exceeded. However, low to moderate early season injury to corn may not affect grain yield.

A transition matrix model of European red mite (Panonychus ulmi) population dynamics in a managed apple orchard

Abstract A transition matrix model is developed for changes in the abundance of a population of Panonychus ulmi, the European red mite, in a managed apple orchard. Thee population is divided into two age classes, eggs and motile mites. This is a single-species model that considers transitions among four states (defined in terms of high/low egg and mite abundance on a tree) over two summer seasons. Transition probabilities vary through time as functions of temperature and mite abundance. The effects of miticide application are incorporated. The model provides an excellent fit to the data and is capable of predicting abundance changes in a second orchard. There is a strong tendency for the population to attain high abundance, especially given moderate early season abundance and warm temperatures. The model can indicate likely outbreaks of this commercially important pest species.

Studies on aquatic fungi in delta region (Egypt)

117 species and 2 varieties related to 2,712 colonies in addition to 991 unidentified colonies of the genera Achlya, Saprolegnia, Pythium and Phytophthora were recovered in this investigation. The richest season (94 species, 1,018 colonies) was autumn and the poorest (58 species, 720 colonies) was summer. The richest samples were generally characterized by comperatively high amounts of organic matter, high oxygen content, low contents of salts and low to moderate temperature. The pH value did not show any regular seasonal variation and did not exhibit any considerable influence on fungal population. The fungal species which possess centric or subcentric oospores prevailed in low or moderate temperature season and those which possess eccentric oospores prevailed in summer season. 12 species disappeared completely in summer and 7 in winter. Some species appeared only in spring and autumn and others appeared althrough the year. In estuarine sites of both Nile branches, no Saprolegniaceae appeared in salinity exceeding 1.5% whereas some species which belong to Peronosporales and Chytridiales appeared but only in a limited occurrence. In den vorliegenden Untersuchungen wurden aus Wasserproben 2712 Kolonien isoliert, die 117 Arten aus 2 Varietäten zugeordnet wurden. 991 Kolonien konnten nicht näher identifiziert werden, sie gehören den Gattungen Achlya, Saprolegnia, Pythium und Phytophthora an. Im Herbst war die Pilzpopulation mit 94 Arten bzw. 1018 Kolonien größer als im Sommer mit nur 58 Arten bzw. 720 Kolonien. Die artenreichsten Wasserproben zeichneten sich im allgemeinen durch hohe Gehalte an organischem Material und O2, geringen Salzgehalten und niedrige bis mittlere Temperaturen aus. Der pH zeigte keine saisonbedingten Schwankungen und auch keinen Einfluß auf die Pilzpopulation. Die Pilzarten mit zentralen und subzentralen Oosporen herrschten bei niedrigen und mittleren Temperaturen vor, während die mit exzentrischen Oosporen insbesondere im Sommer vorkamen. 12 Arten traten nicht im Sommer und 7 nicht im Winter auf. Andere Arten kamen nur im Frühjahr und Herbst vor und wieder andere waren ganzjährig vertreten. In den Meeresbuchten beider Nilarme, wo der Salzgehalt 1,5% übersteigt, kamen keine Saprolegniaceae vor, während einige Peronosporales- und Chytridiales-Arten, jedoch nur mit geringer Häufigkeit, anzutreffen waren.

Transaminases in cattle and buffalo ( Bubalus bubalis) semen in relation to fertility and seminal characteristics during moderate and colder seasons

Semen from eight (four cattle and four buffalo) bulls was collected and analysed for physical characteristics and transaminase activity. The values of glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) activity were 1567±63 and 368±25 SF units 1 1 SF unit=amount of transaminase required to produce 1 μg of pyruvic acid per ml of semen per hour of incubation at 37°C. in the whole semen and 807±31 and 121±11 SF units in the seminal plasma for cattle and 1359±48 and 279±29 in the whole semen and 635±28 and 94±11 in the seminal plasma for buffalo. Cattle semen had significantly ( P<0.01) higher mass motility, sperm concentration and transaminase activity than did buffalo semen. The enzyme activity was positively correlated with mass motility, sperm concentration and fertility, while only GOT activity was inversely related to the ambient temperature.

Cattle Use of Riparian Meadows in the Blue Mountains of Northeastern Oregon

Cattle Use of Riparian Meadows in the Blue Mountains of Northeastern Oregon

Yield Response of Major Pod-bearing Nodes in Bush Snap Beans to Irrigation and Plant Population

Abstract Yield variables of mainstem nodes 6 (terminal) and 2 (that of the first trifoliate leaf) of ‘Oregon 1604’(Phaseolus vulgaris L.) were evaluated at 2 irrigation regimes × 2 plant populations in a warm (1978) and a moderate (1979) season. A single inflorescence formed at node 6, whereas up to 4 inflorescences were borne on branches at node 2. After emergence, crops were irrigated either when the soil water potential reached −0.06 MPa (high) or −0.25 MPa (low). High and low plant populations were, respectively, 45 vs. 18 plants/m2 in 1978 and 54 vs. 33 plants/m2 in 1979. Yield per unit area was increased significantly from 38–54% by high plant population and 40–120% by high irrigation. On a per plant basis, plant population failed to have a significant effect on total yield or yield variables at node 6. At node 2, however, high plant population reduced the number of inflorescences in 1978 and decreased the number of flowers, number of pods formed and harvested, and percentage set and reduced pod yield by about 50% in both years. Per unit area yields of node 2 at high and low plant population differed by less than 13–18%. Since the productivity of node 6 was not influenced by density, per unit area yields at this node more directly reflected plant population. Nodes 2 and 6 responded similarly to the low irrigation regime, which in 1978 significantly decreased the number of pods formed, percentage set, and pod yield at both nodes. Irrigation effects on individual yield parameters at each node generally were less in the cooler 1979 season. No significant irrigation–plant population interactions occurred for any measured yield variable in either season.

The influence of mist irrigation on the potato: II. Growth and development

The influence of irrigation method on potato growth and development was assessed during three years. Low volume “mist” irrigation (M), furrow irrigation (F), mist plus furrow (MF) and no irrigation (NI) were compared. During a high and moderate stress season misting maintained the haulm later into the season and increased the proportion of small and medium size tubers. Further during the high stress season misted plots (M and MF) yielded more than NI plots.

Effects of soil cultivation on the growth and yield of winter wheat. I.—soil cultivation and winter survivals

Abstract1. The effects of three types of soil preparation—ploughing to 8 in., use of a cultivator 3 to 4 in. deep or more, shallow cultivation to 1 1/2‐2 in.—on the winter survivals of wheat were examined on six farms and during three seasons.2. The effects varied with the type of soil and with the season; open‐textured and light soils were the chief types in which winter survivals were affected by cultivation. In ploughed and 4‐in.‐cultivated soils winter survival was superior to that in shallow‐cultivated soils in mild seasons; the reverse was true in the severe winter of 1946–47.3. In the moderate seasons of 1945–46 and 1947–48, early frost caused higher mortality after shallow cultivation as a result of the shallower placement of seed. In the severe winter, with deeper ground‐frost, of 1946–47, the relative depth of penetration of frost into the soil in the arable layer was the factor primarily concerned in producing greater frostinjury to the plants in the ploughed and deep‐cultivated plots, as compared with the shallow‐cultivated. The seed‐bed left after shallow cultivation was more compact than that after ploughing or deep cultivation and seemed to be associated with the effects of different types of cultivation on winter survivals in 1946–47.4. It is suggested that early sowing of the crop with shallow cultivation to about 2 in. would reduce the risk of frost injury in the open‐textured and light soils during moderate as well as severe winters. Sowing must be early enough to ensure good establishment of the plants before the frosty periods.5. Varietal differences in susceptibility to winter killing were of the same order under the three types of cultivation treatments and in all soils. Neither cultivation nor varietal selection alone could give a normal stand in a severely affected soil such as Burdiehouse. In such soil, shallow cultivation (2 in.) and use of a frost‐resistant variety would probably give a stand of plants equal to that in a soil in which no frost injury occurred.

Some Ecological Characters and Application of Joint-to-Joint Analysis in Sorgo Plant

Some ecological characters of yield of sorgo were examined and it was found that the joint-to-joint analysis is recommended as a method for ecological studies in this crop just as in sugar cane. The results obtained in this experiment are summarized as follows: 1. April (early) planting may be recommendable for twice-reaping system when sorgo is used as a forage crop, though it is not suitable for grain sorgo because it may be seriously damaged by birds. A moderate planting season for using it as both green and grain sorgo seemed to be in June (late planting), when the advance of the date of heading may be brought about. 2. Varieties suitable for early planting may surely be distinguished from those for late planting by deciding the relative position of the heaviest internode which is determined by joint-to-joint analysis of the stem; the variety whose heaviest internode locates at a low positoin in a standing stem is adapted for early planting, and the one with the heaviest node at a high position for late planting. 3. Rind harness is remarkably high at the lowest intermode and it gradually decreases upwards along the stem. 4. An even transition of brix throughout the successive internodes from the base to the top can be observed at flowering time, but later, brix begins to increase, as grains mature, in the middle and uper portions of the stem, leaving brix in the lower portion almost as it is. The course of maturing as mentioned above may greatly be affected by yield of grains and mechanical damages in green leaves. The maximum mean brix is expected at full maturing stage of grains, and the persistence of high brix varies with either variety or planting season. 5. Windbreakage of the stem caused by stem borers, deterioration of the content of internode tissue and damages in grains by birds all vary widely with the plant variety as well as season.