{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Bio171-F08-lec12 - Biology 162 Lecture 12 Monday Todays...

Info icon This preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Lecture 12: Monday September 29, 2008 Biology 162 Today’s Topic: Communities: Structure & Patterns Announcements 1st Exam Tonight 6-8 pm Format: answer all 30 MC questions and 4/5 SA questions Bring #2 pencil! Discussion this week: Ecology simulations Text Reading: Lecture 12: 2 nd ed: Ch. 53 (1232-41) 3 rd ed: Ch. 53 (1213-19) Lecture 13: 2 nd ed: Chapter 51 (1166-1190) 3 rd ed: Chapter 51 (1149-1170) Disturbance: Importance of Fire Succession: Primary & Secondary Clements & Gleason Models Area Effects & Latitudinal Gradients Bioaccumulation review Endocrine Disrupters & Human Sex Ratios
Image of page 1

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

View Full Document Right Arrow Icon
1st Exam: Monday Sep. 29, 6-8pm Exam 1 Locations: Aud B Angell Hall Sections: 009, 034, 013, 031, 044, 045, 012, 021, 041 GSIs: Katie, Hannah, Andres Aud D Angell Hall Sections: 005, 010, 014, 033, 039 GSIs: Laury, Dana 1210 Chemistry Sections: 011, 017, 029, 030, 037, 043 GSIs: Susan, Gyorgy MLB AUD 3 Sections: 008, 025, 028, 019, 035, 040, 015, 020, 038, 007, 016, 042 GSIs: Keith, Ed, Devon, Dieter NS AUD Sections: 023, 026, 032, 006, 022, 036, 018, 024, 027 GSIs: Sean, Senay, Peter Covers 1 st 10 lectures & 3 discussion topics
Image of page 2
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?
Image of page 3

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

View Full Document Right Arrow Icon
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 fire, storms and floods , 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.
Image of page 4
Figure 53.20 shows the results of a study to determine the history of disturbance in a fire-prone community from tree rings.
Image of page 5

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

View Full Document Right Arrow Icon
This study established that fires are extremely frequent in the community examined; but look at the 19th and 20th centuries. Why the plunge in frequency?
Image of page 6
Patchiness and recovery following a large–scale disturbance. The 1988 Yellowstone National Park fire destroyed large areas of forests dominated by lodgepole pines.
Image of page 7

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

View Full Document Right Arrow Icon
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 fire in forest communities and are able to better manage these forests by allowing, monitoring, and controlling burns in them.
Image of page 8
A similar community naturally subject to periodic fire is the jack pine, Pinus banksiana , dominated community in northern lower Michigan.
Image of page 9

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

View Full Document Right Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern