Agroecosystems Site | Biology Department | Dalhousie University


Class description for 2000/2001*



*This class was last offered in 2001, and will not be reoffered.
The description remains posted for archival purposes.


Summary Description

(from Dalhousie Calendar)

Agroecosystems, which are defined spatially as individual crops or farms, occupy approximately 35% of the ice-free land area. Biodiversity varies from enhanced to impoverished in comparison to the pristine systems that were converted to agriculture. Agroecosystems have significant impacts on adjacent ecosystems and on global ecological processes. In this class we examine: domestication of crops and livestock; classification of agroecosystems; relationships between climate, crops and soils; foodwebs and energy flows; nutrient cycling; biotic interactions affecting weeds, pests and diseases; impacts of agroecosystems on other ecosystems; human nutritional needs, population growth and agricultural production; conservation of biodiversity in agroecosystems. Numerical problem solving is emphasized. Students select specific agroecosystems and topical issues for individual and small group study, according to their interests. The class employs a computer assisted, web-linked, collaborative learning approach.

INSTRUCTOR: D. Patriquin
FORMAT: Lecture/Group work/Labs 5 hours
PREREQUISITE: BIOL 2060.03 or permission of instructor

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Skills Transcript Class

This is a skills transcript class and you may opt to have it included in your skills transcript under the headings of
  1. IT/Computer Literacy
  2. Problem-Solving
  3. Team Work

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Schedule for 2000/2001

The class is offered in the second semester for which classes begin on Jan 3 and finish on April 6. We meet twice weekly: Mondays 4-6 p.m. in LSC 220, and Wednesday evenings, 6:30-9:30 p.m. in LSC 200 (a Computer Learning Lab).

Text for 2000/2001:

(i) Selected readings, distributed in class
(ii) Elizabeth Castro. 2000. HTML4 for the World Wide Web. Peachpit Press. $24.95

You can purchase the Casto book at Rosswells or at most stores that carry a substantive section of computer books. Purchase the latest 4th edition (2000). Let me know if you have any difficulties and I will ask Rosswells to get some in. Ask for a Dal discount at Rosswells. ( Rosswell Books 1587 Brunswick Street, phone 4233161). Turn left on Brunswick street just before the public library, and it is in the little complex of shops on the corner of Brunswick and Sackville.

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More Details



  1. To become familiar with the basic structures and processes of agriculture, e.g. the spread of weeds, domestication of crops, feeding of livestock, tillage of soil, viewed from an ecological perspective.

    After this class, you should be able to recognize major types of farming systems, crops and livestock in a variety of landscapes, and have some understanding of how they evolved, function today, and how farming systems interact with neighboring ecosystems.

    Click on images below for examples of some of the agricultural landscapes and processes that you will be familiar with after this class:

    rice seedlings wheat
    Rice transplants
    in NE Thailand
    Winter wheat
    in Nova Scotia
    Alley cropping Cattle on dykeland
    Alley cropping
    in Nigeria
    Cattle on
    N.S. dykeland

  2. To hone skills in solving quantitative problems related to the practice of agriculture in an ecosystem context.

    For example, we might want to estimate how much carbon is stored in a hectare of wheat and its turnover time. We will develop sound methodologies for making 'back of the envelop' calculations, and for converting units to different scales of space and time. We also want to gain some sense of where to find and how to evaluate, different databases. These sorts of calculations have practical use in agriculture and are increasingly important in every day life, as we consider the environmental consequences of almost everything we do.

  3. To develop some particular expertise related to agroecosystems.

    The Special Topics assignments will provide an opportunity to do so. In the 2001 class, the topics will explore relationships (positive and negative) between production of food and fiber in agriculture, and the provision of "ecosystem services" by agriculture.

  4. To experience working in groups to conceptualize, solve problems, peer review group members' work and to share knowledge, insights and perspectives.

    In today's complex global community, no individual can 'know it all'. Employers cite ability to work in groups as a critical skill, and one that is often poorly developed amongst science graduates. There is a lot to gain by contributing our skills and experience to a group of individuals who have a common goal, and from interacting synergistically with other members of the group so that its output is more than the sum of the parts.

  5. To develop "Web Literacy".

    The Web has become a major mode of communication in modern society. This class provides training in the core technical skills for "Web Literacy", and an opportunity to develop a good Web Writing Style through assignments written for the Web.

    (You might like to view some examples from the previous class).

  6. Others (yours) _________

    Please forward these to me (

  7. Others (the Instructor' s): to test and further develop a Collaborative, Problem Based, Web Linked learning approach in a Science class.

    This class is conducted almost entirely using non-lecture methodologies. My hope is that you will find it more stimulating than the traditional lecture-only format, and that it will help us all (your instructor included) to become more conversant in new modes of communication, as well as learning the material covered in more traditional formats.

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Format: an Active Learning approach

This class employs a combination of collaborative learning, problem-based learning and Web-linked collaboration and learning.

It works as follows.

Working Groups of 4-6 students (ideally 5) are formed in the first week.
Students are assigned to groups in a way that distributes critical skills and background knowledge more or less evenly between groups. These groups are retained through the semester. Because the group based activities are critical in this class, attendance of classes and labs is compulsory.

A common concern expressed by students about group work is disparity between individuals in their contributions to group efforts. The disparity problem is addressed by use of a Peer Assessment Technique - at the end of the semester, each person's contribution is evaluated by other members of the group, and a factor is calculated that is used adjust group marks accordingly.

A second concern students often cite is difficulty in scheduling time to get together outside of class. In this class, individuals interact directly within their groups during scheduled classtime, and we make use of the Web to facilitate interaction outside of class time.

Classroom sessions are held on Monday afternoons from 4-6. In one week we focus on factual material, and in the alternate weeks, on quantitative problem-solving.

For the factual sessions, reading assignments are given two weeks ahead of time; each assignment is accompanied by a set of Guided Questions, which help the student to know which details and concepts are most important to recall or understand for class tests. In class, a short answer quiz on the reading is given first to individuals; answer sheets are handed in, and then the quiz is discussed within each group, and the group submits a set of answers. The material is discussed by the class as a whole, and finally, the Instructor introduces the next set of reading. Topics of the reading assignments are:
  1. Global Ecosystems/Farming Systems
  2. Soils and climate
  3. Landscape and Biodiversity
  4. Crops
  5. Livestock

Factual learning also takes place during other class activities. We make regular use of images and video in class. Demonstration materials can be examined outside of class. There will be a a voluntary field trip.

For the problem-solving sessions, a quantitative problem related to agroecosystems is presented at the beginning of the class. Each group works on the problem, and then the solutions are handed in; they are discussed by the class as a whole, and we select a "best approach". Some of these exercises will extend into the Computer Learning Lab sessions. In the final week of class, a problem-solving test, based on the classroom exercises, is written by individuals.
Above: Students working in groups during a problem-solving session. See class in action on streaming video

We meet on Wednesday evenings 6:30-9:30 in a Computer Learning Lab. There we develop basic skills in "Web Literacy" and apply them to Special Topics (the equivalent of term papers, but prepared for the Web medium), and to facilitating communication within groups outside of class

Students must attend for at least 1.5 h.

Over the course of the labs, you will acquire basic skills in "Web Literacy", by which I mean the tools and concepts that are essential for effective communication on the Web.

You will make use of the Web Literacy skills to prepare a Web site on a Special Topic (this is the equivalent of a term paper). Incentives are given for individuals to assist and provide feedback to other group members on their pages. Topics that achieve an A grade will be published on the class site.

(see The Agroecosystems site for the topics pursued by the previous class).

The class as whole collaborates to a revision of the existing site.

In the final two weeks, individuals present and discuss their Special Topics Web Pages. We draw some conclusions relating to the theme for this year (Food and Ecosystem services).


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Assessment is based on 7 categories of endeavor. Students can choose, within broad limits, how to distribute marks between the different categories.

We use an Individually Weighted Marking Scheme. You must do assignments in each of the 7 categories (listed below) but you can weight the different categories of assignments to accommodate your own strengths and interests. The minimum values add up to 70%; you decide by the end of the third week of classes how to distribute the other 30% within the limits given below. There will also be a mark given according the default weighting: you will receive the highest of the two.

The 7 categories, range of possible weightings and the default weightings:

  1. Tests (5) on printed factual material (10-30%), default: 15%
  2. Tests (2) on factual materials preseented as images (5-10%) default: 5%
  3. Tests on Web Literacy skills (5-15%), default: 10%
  4. Submissions to class resources: (5-15%), default, 12.5%
  5. Special topic* (Web site) report - individual mark (20-40%), default: 25%
    and Peer Adjusted Group mark:** (5-20%), default: 10%
  6. Problem-solving: Peer adjusted Group Mark: (5-10%), default: 7.5%
    Final Quiz, individual mark: (10-15%), default: 10%
  7. Attendance: 5%

This means, for example, that if you achieve an average of 8/10 for 5 tests in category 1, by default this category counts for 20% of your total mark, and you would be awarded 8/10*20=16% for that category according to the default scheme

*The Special Topics Assignments are marked by 10 peers (values are averaged to give one peer value), the Instructor and an external examiner; the mark is the average of the three values.

**Peer Adjusted Group Marks are derived as follows: For each group, the unadjusted mark is the average of the group members' marks. At the end of the semester, each individual apportions (n-1) *10 marks between the other group members. The PAF (Peer Assessment Factor is the average of these values for each individual; the adjusted mark is calculated by multiplying the unadjusted mark by the PAF/10. It sounds complicated but it works!

Office Hours

Office hours will be posted at the Class Web Site (URL to be given in class). If you wish to talk to me about the class before January 2001, please e-mail me: to set up an appointment.

-David Patriquin

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Agroecosystems Site | Biology Department | Dalhousie University