Two introduced carnivores, the European red fox Vulpes vulpes and domestic cat Felis catus, have had extensive impacts on Australian biodiversity. In this study, we collate information on consumption of Australian birds by the fox, paralleling a recent study reporting on birds consumed by cats. We found records of consumption by foxes on 128 native bird species (18% of the non-vagrant bird fauna and 25% of those species within the fox’s range), a smaller tally than for cats (343 species, including 297 within the fox’s Australian range, a subset of that of the cat). Most (81%) bird species eaten by foxes are also eaten by cats, suggesting that predation impacts are compounded. As with consumption by cats, birds that nest or forage on the ground are most likely to be consumed by foxes. However, there is also some partitioning, with records of consumption by foxes but not cats for 25 bird species, indicating that impacts of the two predators may also be complementary. Bird species ≥3.4 kg were more likely to be eaten by foxes, and those <3.4 kg by cats. Our compilation provides an inventory and describes characteristics of Australian bird species known to be consumed by foxes, but we acknowledge that records of predation do not imply population-level impacts. Nonetheless, there is sufficient information from other studies to demonstrate that fox predation has significant impacts on the population viability of some Australian birds, especially larger birds, and those that nest or forage on the ground.

In the early 1830s and 1840s, a British colonial official by the name of Colonel James Low uncovered evidence for an early culture with Indic traits in a river system known as the Bujang Valley. On the west coast of the Thai-Malay peninsula, the Bujang Valley is today located in the Malaysian state of Kedah. However, it wasn't until just before World War II that excavations took place, conducted by H. G. Quaritch Wales and his wife Dorothy. Their discoveries and subsequent publications led to the first real attempts to explain the origins and extent of this civilisation and its place within the larger South and Southeast Asian world. In the intervening years between Quaritch Wales's excavations and the present day, considerably more research has taken place within the Bujang Valley, though this has not been without controversy. Recently claims and counter-claims regarding the antiquity of Hinduism and Buddhism at the site have arisen in some quarters within Malaysia. It therefore seems pertinent that this material be re-evaluated in light of new scholarship and discoveries as well as the prevailing paradigms of interactions between South and Southeast Asia. This paper presents an updated reading of this material and argues that the Bujang Valley should be seen as a cosmopolitan trading port with substantive evidence for the presence of Hinduism and Buddhism.

Weed seed return and seedbank composition, with particular reference to common lambsquarters, were studied in four tillage systems established on a site near Fingal, Ontario. The tillage treatments were moldboard plow, chisel plow, ridge-till, and no-till. The cropping system was a cornsoybean rotation. Tillage effects on weed population composition were assessed after all weed control measures had been implemented. More than 60% of the weed seedbank was concentrated in the upper 5 cm of soil in chisel plow and no-till. The seedbank of the moldboard plow system was more uniformly distributed over depth and larger than the other systems. Common lambsquarters comprised more than 50% of the seedbank in all systems except ridge-till, but only dominated the aboveground weed population in chisel plow. Seedbank populations of common lambsquarters with moldboard plowing were greater than those with ridge-till and no-till, and chisel plow seedbank populations were greater than those in ridge-till. Chisel and moldboard plow systems generally had higher aboveground plant populations of common lambsquarters than the other two systems. Seed production per plant by common lambsquarters was equivalent among the four systems, but estimated seed production per unit area was higher in moldboard plow and chisel plow systems than in the other systems. Populations of common lambsquarters and similar species may produce more seeds and persist in moldboard plow and chisel plow systems; these weeds may produce fewer seeds per unit area and be easier to manage in no-till and ridge-till systems.

DPX-79406 was evaluated for POST annual grass weed control in both controlled environment and field experiments. In controlled environment experiments, green foxtail was most susceptible to DPX-79406; whereas yellow foxtail was least susceptible of the species evaluated. DPX-79406 at 12 g/ha completely controlled six leaf black-seeded proso millet, yellow foxtail, green foxtail, and barnyardgrass. In the field, DPX-79406 at 3.0 to 25.0 g/ha effectively controlled annual grass weeds without injury to three- to six-leaf corn. There was more variation in the effectiveness of DPX-79406 applied in the field. Early POST applications provided less weed control than the late application, especially for barnyardgrass, because of weeds emerging after application. As a result, higher doses were sometimes needed for effective control. In weed-free field trials at two sites in 1990 and 1991, corn tolerated doses up to 75 g/ha of DPX-79406 applied at the three- to six-leaf growth stage. However, doses as low as 18.8 g/ha applied at the six- to nine-leaf growth stage reduced grain yield. In 1991, corn tillering increases and height and yield reductions were related linearly to the dose of DPX-79406 applied during later growth stages. DPX-79406 should be applied early POST in order to avoid crop injury while providing effective weed control.

To predict weed emergence and help farmers make weed management decisions, we constructed a mathematical model of seed germination for green and redroot pigweed based on temperature and water potential (moisture) and expressing cumulative germination in terms of thermal time (degree days). Empirical observations indicated green pigweed germinated at a lower base temperature than redroot pigweed but the germination rate of redroot pigweed is much faster as mean temperature increases. Moisture limitation delayed seed germination until 23.8 C (green pigweed) or 27.9 (redroot pigweed); thereafter, germination was independent of water potential as mean temperatures approached germination optima. Our germination model, based on a cumulative normal distribution function, accounted for 80 to 95% of the variation in seed germination and accurately predicted that redroot pigweed would have a faster germination rate than green pigweed. However, the model predicted that redroot pigweed would germinate before green pigweed (in thermal time) and was generally less accurate during the early period of seed germination. The model also predicted that moisture limitation would increase, rather than delay, seed germination. These errors were related to the mathematical function chosen and analyses used, but an explicit interaction term for water potential and temperature is also needed to produce an accurate model. We also tested the effect of mean temperature on shoot elongation (emergence) and described the relationship by a linear model. Base temperatures for shoot elongation were higher than for seed germination. Shoot elongation began at 15.6 and 14.4 C for green and redroot pigweed, respectively; they increased linearly with temperature until the optimum of 27.9 C was reached. Elongation was dependent on completion of the rate-limiting step of radicle emergence and was sensitive to temperature but not moisture; hence, elongation was sensitive to a much smaller temperature range. Beyond mathematical changes, we are testing our model in the field and need to link it to ecophysiological, genetic, and spatially explicit population processes for it to be useful in decision support for weed management.

We studied the effect of no-till, chisel, and moldboard plow and the presence or absence of corn on soil temperature, moisture and, subsequently, the emergence phenology and density of pigweed seedlings at 2 sites from 1993 to 1995 inclusively. Tillage significantly affected the phenology of pigweed seedling emergence only during a June drought at one site in 1994. Soil temperature and moisture, measured at 2.5-cm depths, also were unaffected by tillage. Weed phenology is usually earlier in no-till because more seeds are located closer to the surface (< 5 cm deep) in no-till, thereby reducing the delay in penetrating through the soil, and because soil temperatures and moisture are nearer the germination and emergence optima. However, pigweed seedlings are already physiologically restricted to germination depths of less than 2.5 cm regardless of tillage; therefore, this prior constraint eliminated any potential differences in emergence phenologies caused by tillage. The presence or absence of corn also did not affect soil temperatures, soil moisture, or pigweed seedling emergence phenologies. Pigweed seedling density was significantly higher in no-till; this may have been caused by increased numbers of seeds near the soil surface in no-till. The presence or absence of corn did not affect pigweed seedling density; the lack of a significant effect probably reflects high variances in density. Although necessary for most weed species, tillage may be a less important factor to consider in predicting pigweed population dynamics and subsequent management recommendations.

On-farm implementation of IWM includes the biological and economic rationalization of weed management decisions. This, in turn, requires the ability to predict how weed populations and pressures will change with farm management options such as tillage method. We have developed a set of algorithms that simulate seedling emergence of mixed populations of green and redroot pigweed on the basis of the ecophysiological responses of seed germination and shoot elongation to temperature and, for germination, to moisture. The algorithms were calibrated using field data from 1993 and evaluated with data from two locations in 1994 and 1995. Over both sites and years, for four tillage systems, cumulative emergence was predicted with an overall root mean square error of 1.7%. Overprediction in one year was attributed to moisture shortage. Errors were greater for moldboard plowed plots than for those no-tilled. This decreased ability to predict emergence with increased tillage (soil disturbance) suggests that the algorithms should be modified to account for increased heterogeneity in weed seed distribution and soil moisture within disturbed soil. The algorithms, which were explicitly designed for incorporation within a crop growth model (e.g., CROPSIM), could become a useful part of a decision support system to rationalize weed management. Importantly, they could help predict changes in weed populations as farm management is adjusted, thereby reducing economic and environmental risk in agroecosystems.

The ability to predict time of weed seedling emergence relative to the crop is an important component of a mechanistic model describing weed and crop competition. In this paper, we hypothesized that the process of germination could be described by the interaction of temperature and water potential and that the rate of seedling shoot and radicle elongation vary as a function of temperature. To test these hypotheses, incubator studies were conducted using seeds and seedlings of common lambsquarters. Probit analysis was used to account for variation in cardinal temperatures and base water potentials and to develop parameters for a new mathematical model that describes seed germination and shoot and radicle elongation in terms of hydrothermal time and temperature, respectively. This hydrothermal time model describes the phenology of seed germination using a single curve, generated from the relationship of temperature and water potential.

We studied the effect of tillage systems (no-till, chisel, and moldboard plow) and the presence or absence of Zea mays L. (corn) on soil temperature, moisture, and, subsequently, the emergence phenology and density of Chenopodium album L. (common lambsquarters) at two sites (Elora and Woodstock) from 1993 to 1995. The tillage system affected the phenology of C. album seedling emergence only in 1995. In that year, more days were required to reach 80% cumulative seedling emergence in no-till than in the chisel or moldboard plow treatments. The delay in obtaining 80% cumulative emergence was attributed to a dry period from days 159 to 177 at Elora and from days 155 and 176 at Woodstock. The presence or absence of Z. mays did not affect soil temperatures, soil moisture, or C. album seedling emergence phenologies. Chenopodium album seedling density was influenced by tillage and environmental conditions. Large variations in seedling density were attributed to environmental conditions. The presence or absence of Z. mays did not affect C. album seedling density.

Integrated weed management (IWM) research has focused on how crop yields and weed interference are affected by changes in management, e.g., tillage, herbicide application timing and rates, cover crops, and planting patterns. Acceptance of IWM will depend on recommendation of specific strategies that manage weeds and maintain crop productivity; such research will and should continue. However, IWM needs to move from a descriptive to a predictive phase if long-term strategies are to be adopted. Linking management changes with crop-weed modeling that includes such components as weed population dynamics and the ecophysiological basis of competition will help predict future weed problems and solutions and the economic risks and benefits of intervention. Predictive approaches would help incorporate IWM into models of the processes that occur in agricultural systems at wider spatial and temporal scales, i.e., in agroecosystems comprised of the interactions among organisms (including humans) and the environment. It is at these larger scales that decisions about management are initiated and where questions about the long-term consequences and constraints of IWM and agriculture are often asked. These questions can be addressed by agroecosystem health, an approach that integrates biophysical, social, and economic concerns and recognizes that agriculture is part of a world with many complex subsystems and interactions. Indicators are used to examine the status of an agroecosystem, e.g., whether or not it contains all that is necessary to continue functioning. Indicators include soil quality, crop productivity, and water quality; all of these are related to the rationale of IWM, hence IWM can be linked to agroecosystem health. Ancillary effects of using IWM relate to other indicators such as diversity and energy efficiency. Linking IWM to agroecosystem health has at least two benefits: (1) predictive models within IWM can be incorporated into larger agroecosystem models to explore hitherto unforseen problems or benefits of IWM, and (2) the relevance and benefits of IWM should become clearer to the public and government agencies who otherwise might not examine how IWM promotes many of the larger social, economic and environmental goals being promulgated.

Field studies were conducted during two soybean-corn rotations to evaluate the effect of tillage systems on quackgrass growth and control with and without glyphosate. In the final year of the study, tillage alone (compared to no-till) resulted in 88%, 78%, 64%, and 31% control of quackgrass with fall moldboard plow, spring moldboard plow, fall soil-saver, and spring soil-saver tillage, respectively. When glyphosate was used to control quackgrass, crop yields increased as tillage was reduced and excellent control of quackgrass in no-till was achieved. Increased shoot growth (in moldboard plowed and fall soil-saver tillage plots), exposure of rhizomes in winter (in fall tilled plots), and increased depth of rhizome burial (in spring tilled plots) increased quackgrass control. In general, the total biomass of quackgrass was reduced in drier years. Nonetheless, drought increased crop yield losses caused by quackgrass interference.

Field experiments were conducted from 1995 to 1997 in southern Ontario to determine the influence of tillage and ground cover on the quantity of postdispersal seed predation of common lambsquarters and barnyardgrass. Ground-dwelling invertebrates were the dominant seed predators and were responsible for 80 to 90% of all seeds consumed. Predation was highest in no-till and moldboard-plowed environments (averaging 32% in both) and lowest in chisel-plowed environments (averaging 24%). This indicates that the relationship between the level of disturbance and predation is nonlinear and that other factors, such as the mobility of invertebrates and food availability, may also play important roles in determining the quantity of seed predation. In no-till, the type of crop residue also influenced the quantity of predation, with highest seed predation found in plots with corn residue (averaging 31%) and lowest in those with soybean and wheat residue (24 and 21%, respectively). It is apparent that there is an optimum combination of residue quantity and quality that maximizes the quantity of seed predation. Based on the experimental design used in this study, no feeding preference by seed predators was detected between common lambsquarters and barnyardgrass. Density-dependent feeding, however, was evident for both species. Most biological control efforts have centered around predators with specific feeding habits. We contend that invertebrates with opportunistic feeding strategies that feed on weed seeds may be the most significant broad spectrum and natural form of biological weed control affecting weed population dynamics. Populations of beneficial arthropods should be conserved, and management strategies that augment the size of their natural populations should be encouraged.