Lecture 3: Sampling Diversity in Tropical Forests

Question 1

problems with sampling in the tropics:

Answer 1

• double counting- overlap of sampling area, or missing out individuals to avoid this
• hard to concentrate on all species at once
• difficulties in identification -miss species or separate 1 as many
• difficulties in spotting things -hard to see & background sounds
• did we sample enough to get species richness?

Question 2

Designing a point count study:

Answer 2

1) how many landscapes (sites) should u sample?
- -at least 2 widely spaced sample landscapes
2) how many points sample within a site? (30-40)
3) how far apart should each point count be?
- not indépendant if too close together
- need to make sure effective sample zone samples unique community
4) what time of day and order to visit points?
- early for birds & mammals (butterflies use a honey & beer trap so midday?)
- change order that u visit a set of counts

Question 3

species accumulation curve axis:

Answer 3

x = cumulative number of individuals

y= cumulative number of species

Question 4

species accumulation curve: if curve reaches an asymptote what does this mean?

Answer 4

yes = sampled effectively
(if u were to continue sampling u would probs not find more species)
-NO ? need to sample more

Question 5

species accumulation curve: is it a smooth curve?

Answer 5

if not, randomise the order of ur sample points = 1000 times

Question 6

positives of species richness?

Answer 6

• shows that you have sampled effectively when your accumulation curve levels off
• good at showing big differences in numbers of species between groups or habitats

Question 7

Negatives of species richness?

Answer 7

• does not show how abundance changed within a species
• does not show whether species present are same or different
• –10 species vs 10 different species
• total species richness is misleading if sampling effort is not equal between groups
• –more species because sampled more
• use in conjunction with species composition