Bio171-F10-Lec 11 - Biology 171 Monday October 4, 2010...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
Biology 171 Monday October 4, 2010 Announcements This Week’s Discussion: Indirect effects Essay I assignment on Ctools Text Reading: Lecture 11: 4 th : Chapter 53 (1073-1080), Ch. 54 (1088-1089) 3 rd : Chapter 53 (1213-1219) Lecture 12: 4 th : Chapter 51 (1019-1031) 3 rd : Chapter 51 (1149-1167) Community Dynamics Disturbance: Importance of Fire Biomagni±cation Endocrine Disrupters & Human Sex Ratios Avian Botulism 1
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Community Structure Through Time Research on species interactions usually focuses on just two species at a time, but biological communities contain many thousands of species. To understand how communities work, biologists explore how combinations of many species interact. One of the most interesting questions concerns how species diversity is maintained - how are dominant players restrained from forming monocultures? 2
Background image of page 2
Disturbance and Change in Ecological Communities Disturbance is an event that removes some individuals or biomass from a community. The important feature of disturbance is that it alters some aspect of resource availability. Each community experiences a characteristic type, frequency, and severity of disturbance, known as a disturbance regime . Disturbances, such as fre, storms and Foods , play pivotal roles in structuring many biological communities. Ecologists use two approaches to determine the pattern of disturbance in a community: (1) inference of long-term patterns from data obtained in short-term analysis, and (2) reconstruction of the history of a particular site. 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Disturbance history in a fre-prone community such as giant sequoia groves can be determined From tree rings. 4 ±ig. 53.21 ±ig. 53.20
Background image of page 4
This study established that fres are extremely Frequent in the community examined; but look at the 19th and 20th centuries. Why the plunge in Frequency? 5 ±ig. 53.21
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Patchiness and recovery following a large–scale disturbance. The 1988 Yellowstone National Park fire destroyed large areas of forests dominated by lodgepole pines. 6
Background image of page 6
A few years later - young lodgepole pines are growing back among the dead trees, reestablishing dominance. This tree species produces pine cones that are glued shut with resin and require fire to release the seeds . Biologists are now better aware of the importance Fre in forest communities and are able to better manage these forests by allowing, monitoring, and controlling burns in them. 7
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Pinus banksiana , dominated community in northern lower Michigan. Young jack pine
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/13/2012 for the course BIO 171 taught by Professor Josephinekurdziel during the Fall '08 term at University of Michigan.

Page1 / 42

Bio171-F10-Lec 11 - Biology 171 Monday October 4, 2010...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online