Section One Introduction 1.2 Ecological Methods 1.3 Spatial Scale

2003 生態學 Ecological methods Example: Study of Locust Outbreaks –What causes outbreaks of locusts, which destroys crops and other vegetation? –Development of study plan. –Interaction web (Figure 1.8)

2003 生態學 3 NATURAL ENEMIES Bacterial parasites Bird predator Insect parasites COMPETITORS Vertebrate herbivores Other insects PHYSICAL ENVIRONMENT Physical extremes, such as temperature and moisture. Host plant quality Host plant quantity FOOD AVAILABILITY Fig.1.8 interaction web of the factors that could influence locust population size.

2003 生態學 4 Interaction web Natural enemies –Birds or other vertebrates –Insect parasites –Bacterial parasites Competitors –Other insects –Larger vertebrate grazers Host Plants –Host plant quality –Host plant quantity Physical factors –Temperature –Rainfall

2003 生態學 5 Where to begin Observations and Interpretations (Figure 1.9a, Figure 1.9b and Figure 1.9c). Locusts numbers per m % predation (a)(b) (c) Fig. 1.9 How locust numbers might be correlated with predation.

2003 生態學 6 Observations and Interpretations Statistical tests to determine significance of relationships. Causation vs. correlation. Experimentation – Predator study Hypothesis: Increased predators will decrease locust population.

2003 生態學 7 Experimentation Two study groups –Treatment Group: Locusts with predators removed –Control Group: Locusts with nothing done – predators present. Measurements Replications (Figure 1.10)

2003 生態學 8 Mean values Predators removed Predators still present Locusts numbers per m 2 Fig a predator removal experiment

2003 生態學 9 Experimentation Statistical Tests – ANOVA and t-tests. –Means and Standard error Types of Experimentation –Laboratory –Field –Natural

2003 生態學 10 Laboratory Experiments Most exact regulation of abiotic and biotic factors. Vary only the factor of interest. Disadvantage: Oversimplification of the biotic community. Best uses: Physiological responses of individuals.

2003 生態學 11 Field Experiments Conducted outdoors. Manipulation of abiotic or biotic factors (eg. Elimination of a competitor). Disadvantage: Methods of exclusion are unlikely to be generated by nature.

2003 生態學 12 Natural Experiments Uses natural perturbations to disrupt biotic community. Used to follow the trajectory of the perturbation over time. Results can be extrapolated to other communities.

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2003 生態學 14 Experimental Problems Logistic problems lead to low replication Which leads to a Type I error; declaring that a hypothesis is false when in fact it is true. ( 否定 null 假說，但事實上是「 null 假 說是成立的」 ) Low replications lead to greater standard error (SE) values.

2003 生態學 15 two types of error in measurement type I error — the conclusion that there is an effect when in fact there is none, ( 否定 null 假說，但事實是「假說是成立的」 ) type II error — when an impact exists but is not detected. ( 接受 null 假說，但事實是 「假說是錯誤的」 )

2003 生態學 16 two types of error 自然現象的研究，盡量的下降 type I error 。 – 盡量避免否定 null 假說。 – 如此可以避免研究方向的錯誤。 然而，對於自然資源 ( 災害 ) 的研究，則需要 選擇下降 type 2 error – 譬如：漁業資源的耗減

2003 生態學 17 declining fish stocks Current management focuses on reducing type I errors because maximizing fish catch is of primary economic importance (Paully et al., 1998; Williams, 1998). However, scientific advice should be explicit about type II errors also, because the environmental consequences from type II errors are much more serious and take longer to recover from. Type I errors usually result in only short-term economic costs.

2003 生態學 18 Experimental Problems Difficulty in combining studies with differences in statistical power. Meta-analysis –a technique for combining studies. –Meta-analysis weights different studies primarily on the basis of their sample size. –Starts by estimating the size of the effect of a treatment from every experiment and then pooling all the effects together to get one overall effect size, usually called d.

2003 生態學 19 Mathematical Models Experiments may not be possible. Give valuable signposts on how natural systems might work. Indicate need for further data Indicate need for further observations.

2003 生態學 Spatial scale A space occupied by an individual (behavior ecology) A local patch occupied by many individuals (a population) A large enough space to comprise multiple populations (a community) A biogeographic scale large enough to encompass a community, and its nutrients and energy cycles (an ecosystem).

2003 生態學 21 Fig Determining the correct spatial scale

2003 生態學 22 Temporal Scale Proper choice of scale, depends on phenomenon and species studied. Short time scale studies for behavioral responses. Longer time scales studies for population dynamics and ecosystem processes.

2003 生態學 23 Discussion Question In a local park, forest, or even in your backyard think about five ecological questions you could ask and the information you would need to answer them. Do your questions relate to behavioral, population, community, or ecosystems ecology or do they cross categories?

2003 生態學 24 網路資源 The tools that you'll find on our site include: CHAPTER OUTLINES: help summarize all of the key information in the chapter. CHAPTER QUIZZES: self-grading quizzes for each chapter to help you reinforce your understanding CASE STUDIES: concise reviews and analysis of important ecological research DESTINATIONS: accurate, dependable Web sites

2003 生態學 25  問題與討論！ Ayo 台南站：