Weed Ecology in Natural and Agricultural Systems (Cabi)
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Ecology is central to our understanding of how and why weeds invade and yet there are few books that link introductory weed science texts with more advanced ecology books. This textbook introduces ecological principles to students interested in weed science and weed management. It includes examples from the weed and invasive species literature to illustrate the ecological principles discussed. It is suitable reading for final year undergraduates and graduates.
five ageclass distributions to explain population trends of trees (Fig. 3.6). The ‘inverse-J’ curve shows a population with many more juveniles than adults; this population is likely to be relatively constant or increasing. The ‘bimodal’ distribution is a result of pulse recruitment (addition of new individuals) where periods of lower recruitment are followed by periods of higher recruitment. This population will likely be stable or increase as long as recruitment pulses are frequent enough to
allelopathy, rosettes, rapid growth and other means 6 Chapter 1 Impact of weeds Negative effects The harmful impacts of weeds can be classified as land-use effects or as ecosystem effects. Land-use effects are easier to quantify because they can be measured in terms of decreased crop yield or increased control costs. Costs to the ecosystem may be just as great, but are less well understood and the impact is harder to quantify in numerical terms. In managed (agricultural) systems, weeds can
though each individual will experience differential success for the reasons we just mentioned. For example, redroot pigweed and lambsquarters can germinate from April to October. In addition to the early season weather risks, any individuals in agricultural fields likely will be subject to weed man- 94 Chapter 6 agement. Some may escape management and survive to set seed but the chances of success are generally low. However, this may be worth the risk because later germinating weeds (e.g. in
competition. Journal of Applied Ecology 25, 279–296. Wilson, S.D. and Tilman, D. (1995) Competitive responses of eight old-field plant species in four environments. Ecology 76, 1169–1180. Zimdahl, R.L. (1980) Weed–Crop Competition: a Review. International Plant Protection Centre, Corvallis, Oregon. Zimdahl, R.L. (1999) Fundamentals of Weed Science, 2nd edn. Academic Press, San Diego, California. 9 Interactions Among Populations II: Herbivory, Parasitism and Mutualisms Concepts • Herbivory is
in the proportion of each species present. The partial additive design is the simplest type of competition experiment. Here, a ‘target’ species is kept at a constant density and grown in competition with a second species at a range of densities. This design is useful only when looking at the effect of increasing density on some component of plant growth. It is often used in agricultural experiments looking at weed density effects on crop yield (Buchanan et al., 1980). In the replacement series