Lab Topic 5: Coastal Forest Ecology 2

BI-165C LAB REPORT #5 NAME ______EXERCISE 5 Coastal Forest Ecology Introduction

In this lab exercise, you will investigate Coastal Forests and their ecology by completing a variety of exercises including answering questions based on your notes and handouts, completing exercises based on field trips, and searching internet if needed for added information. You will need to hand-in journal notes taken on one or more field trips describing the forest we explored to complete this lab.

EXERCISE 5.1 Forest Succession: Pioneers to Old Growth

In the past, an old growth forest eventually succumbed to rare disasters such as forest fires, landslides, windstorms, and insect epidemics. In its place a "natural young growth" forest slowly emerged after a preliminary succession of herb and shrub communities. Now days human disturbances predominate (highways, development complexes, clearcutting), and their more-or-less permanent nature bodes ill for both old growth and natural young growth. Clearcutting usually involves removal of woody debris, slash burning, spraying of herbicides and insecticides, replanting of the desired species of tree seedlings, and periodic thinning. So the forests that emerge on a clearcut site are not natural, but "managed" and generally poorer in habitats, nutrients, and biotic diversity than natural young growth. Nevertheless both types of young forests are interesting because of the dynamic changes ongoing in function, structure, and composition as they progress (usually theoretically) to old growth.

As succession advances from grassland to shrub to young forest, several trends in forest function (i.e. in energy and nutrient flow) can be seen. As the plants grow they add biomass to the forest. Nutrient uptake from the soil is typically high to support this quick growth in biomass. Since photosynthesis occurs only in the leaves and green stems, the slow rise in foliage biomass mirrors a slow rise in gross productivity. These both peak at about 50 years (in the young forest stage), and then level off. Meanwhile, wood biomass continues to rise with the growing branches, trunks, and roots, and levels off only after 400-600 years. So though gross productivity stays constant, net productivity actually drops because the trees burn more and more sugars simply to keep the enlarging trunks and branches alive. Net productivity reaches a minimum when the wood biomass levels off. Lab Topic 5: Coastal Forest Ecology 2

Look at the trends in the following figure to answer questions on a western hemlock forest.

1. Looking at the Nitrogen Uptake figure, at what community stage is Nitrogen uptake at the greatest?

2. Looking at foliage nutrient accumulation, how do the peaks in accumulation of Nitrogen, Calcium, and potassium compare?

3. At what community stage does the understory biomass peak? Why is it lower in the Old growth forest? Lab Topic 5: Coastal Forest Ecology 3

4. At what community stage does the total biomass accumulation peak? In what form is it found?

5. Why does the net annual production (a measure of photosynthesis) decrease in old growth forests?

6. Why does the erosion and landslide potential decrease with the age of a forest?

EXERCISE 5.2 Forest Succession Compared to Dune Succession

Using your Lab Report #4 on Sand Dunes, lecture notes, handouts, internet sites and field trip experiences, answer these questions comparing forest succession to dune succession.

1. Compare secondary succession seen in our coastal forests to the secondary succession seen in sand dunes. Which is quicker? Why?

2. The transitional stages seen in the coastal forests differ from those seen on sand dunes. Compare how they differ using both abiotic and biotic (specific plant examples) factors. (think of the soil that seeds must germinate in)

Coastal Forest Trasitional Sand Dune Transitional Stages Stages

Abiotic Factors

Biotic Examples Lab Topic 5: Coastal Forest Ecology 4

EXERCISE 5.3 Identifying Stages of Succession

Using your lecture notes, handouts, internet, other sources and field trip experience, complete the following comparisons to the succession stages of the forest. Don't forget: Notes taken on fieldtrips will be handed in with this lab!

1. How would you know if you are in a transitional forest? Give examples of plant species seen on field trips.

2. How would you know if you are in a climax (old growth) forest? Give examples of plant species seen on field trips.

EXERCISE 5.4 Symbiotic Relationships

Using your lecture notes, handouts, internet and field trip experience, complete the following comparisons of symbiotic relationships seen in our Coastal Forests.

1. Define the term “symbiotic”.

2. What is a Mutualistic Relationship? Give an example seen on our field trips. Name both species involved in the relationship.

3. What is a Competitive Relationship? Give an example seen on our field trips. Name both species involved in the relationship. Lab Topic 5: Coastal Forest Ecology 5

4. What is a Commensalism Relationship? Give an example seen on our field trips. Name both species involved in the relationship.

5. What is a Commensalism Relationship? Give an example seen on our field trips. Name both species involved in the relationship.

6. To summarize these types of Symbiotic Relationships, scientists often use a scoring table to quickly illustrate the interactions. Complete the following table by placing a + (if the species benefits from the interaction), a – (if the relationship is harmful in any way to the species) or a 0 (if no harm or benefit occurs)

Type of ORGANISM A ORGANISM B Relationship

Competition

Predation

Mutualism

Commensalism

Checklist to Turn in: Lab Topic 5: Coastal Forest Ecology 6

____ Answers to questions in all the Exercises ____ Detailed notes in Field Trip Journal to coastal forests visited