Many ecological theories or principals have been developed after observing species and their interactions with the environment over many years and at many different locations around the world. For instance, the principles of plant succession, niches, the river continuum concept, species-area relationship, and many others were developed through synthesizing knowledge, manipulating systems, and careful observation. Because ecology is a scientific discipline, we treat all of these principles as hypotheses that can be supported or rejected. Thus, it is important that we continue to collect data and test these hypotheses.

Although many ecological principles are well established, others have only been recently developed. One recently developed principle, based upon the Ecosystem Stress Hypothesis, is the rural-urban gradient. The rural-urban (or sometimes called the pristine to human-dominated) principle describes how species, communities, and habitats change over the landscape from areas of little or no human influence to areas of high human influence (see Figure 2 in McKinney 2002) and arose out of the urbanizing gradient research of the 1970s (for good reviews of urbanizing gradients see Pickett et al. 2001 and McKinney 2002). This gradient can be defined by such aspects as the amount of impervious surface, anthropogenic noise, automobile traffic, human population size, and building density, to name a few (Table 1). In essence, different studies have used different measures of human influence to investigate how species respond as the human influence measure increases. Notably, some gradient studies have also investigated how species within a specific type of habitat (e.g., a forest) change as the surrounding landscape becomes increasingly urban.

Table 1. Examples of some commonly measured human influence parameters and the range over which they are considered low to high.
Human Influence Parameter Measured Range of Values
(Low to High)
Human population density (#/km 2) 0 – 1000 Balmford et al. 2001
Amount of impervious surface <20% - >50% McKinney 2002
Percent area covered in pavement 0% - ~40% Blair 1996
Percent area covered by buildings 0% - ~45% Blair 1996
# Moving vehicles passing per 15 min 0 - 150 Blair 1996
Percent area covered by trees and shrubs 82% - 12% Blair 1996

Along this continuum ecologists have hypothesized a number of relationships.  These relationships include the decrease of native species richness (i.e., the number of unique types of species that are native to those habitats) and the increase in exotic species richness (i.e., the number of species that have invaded these habitats after European settlement) and the change in community composition (evenness, dominance, etc.) of plant and animal species. Other possible relationships include changes in biomass, ecosystem services (i.e. services provided by nature, such as water or air purification, pollination), and functional groups (i.e. how a species functions within an ecosystem, such as a nitrogen fixer). However, while these relationships have been found in several locations around the world, the pattern is not agreed upon.  For instance, two other hypotheses also have been proposed that describe how species change along gradients of human influence. The first is the Productivity Hypothesis, in which species richness increases with human influence (e.g., the size of the human population). The second is the Intermediate Disturbance Hypothesis, which postulates that the greatest species richness is found at an intermediate level of human influence. 

Before you begin the experiment, take a moment to answer three basic questions, which will be fruitful in your work over the course of the semester and help guide your research (both in the field and in the library):

The overall goal of this semester long laboratory exercise is to collect data from various positions along the human influence gradient and synthesize it in order to provide support for one of the three hypotheses. To achieve this goal, we will:


Materials and Methods

Study Site(s):

The study sites for this semester will be at five different points along the human influence gradient.  These five points are: the UW-Milwaukee field station, Lake Park Golf Course, Riverside Park/Urban Ecology Center, the UWM campus, and neighborhoods around UWM. At each study site individual tree plots and bird point count locations will be randomly determined. Data on human influence is also collected at each location (e.g., percent impervious surface, number of buildings, presence of people, etc.).

Overview of Data Collection and Analysis Methods:
Week Topic Assignment
1 Field Trip: Tour of an urban ecosystem  
2 Project overview and literature searches Literature review exercise (optional)
3 Field Trip: Riverside Park & UEC Basic bibliography due (optional)
4 Data entry and analysis  
5 All day field trip Field notebook due
6 Field Trip: TBA Literature Report Due
7 Sample Processing  
8 Field Trip: TBA Introduction section of report due
9 Data entry and graphical analysis  
10 Basic statistics Methods section of lab report due
11 Mapping and GIS Field notebook due (second review)
13 Poster and report preparation  
14 Presentation of research poster Final lab report due

Week 1:  Touring the local ecosystem (generally urban or human-influenced if near a college or university) to acquaint students with ecological relationships, plants, animals, and the environment in which they live. This is used to get students outdoors and thinking about nature.

Week 2:  The semester-long project guidelines are handed out to students and gone over during lab. The rest of the session is dedicated to literature, literature review, and using database search tools in a computer laboratory. Specific aspects include discussing the difference between peer-reviewed literature and gray literature, searching databases using Boolean operators, and where to find both electronic and hard copy journal content. This lab can also be run at a library or by a librarian.  A literature exercise was developed as a separate component for grading for this week.

Weeks 2-8:  During this four to six week period, students visit different plots along the gradient to conduct biological inventories and record environmental aspects that they can use to assess a human influence gradient. If enough time permits after the inventories in a given lab session, then the data collected can be entered into spreadsheets.  Sometime during this six week period (e.g., when inclement weather is present) a lab session is devoted to data entry, quality control and assurance (QA/QC), metadata, and data synthesis in a computer lab. With regard to QA/QC and metadata, there are a number of useful journal articles (e.g., Michener et al. 1997, Michener 2006), numerous books (Michener and Brunt 2000), and several ecological websites related to ecoinformatics that contain detailed descriptions that can be translated into lectures. In addition, when students enter the data, they also add in natural history information, including scientific nomenclature, body mass (animals) or biomass (trees), native or exotic/invasive, etc. that they have obtained through field guides or reputable on-line documents.  Reputable sources of on-line documents for natural history or basic biological information included museums, federal agencies, state agencies, and on-line field guides. [see attached document labeled Field Lab 1.doc, which contains the first lab session explanation of biological inventories and types of data to keep in a field notebook]

Weeks 9-10/11:  This two week period is devoted to a basic statistical lab (which can also be broken out for a separate exercise if desired) and graphical interpretations. Statistical information includes a short lecture on what the statistics are testing, why they are useful, and how to interpret them. Depending upon the institution and time a third week and component also can be included on integrating GIS into the exercise. Furthermore, if a course is more advanced then the students can work on incorporating additional ecological metrics or data in the database.

Weeks 10/11-13:  Lab sessions are devoted to data synthesis and analysis, poster presentations and report preparation.  Students tour the science building where many different examples of posters were on hand.

Week 14:  Students give oral presentations (in groups) of their posters, and then have one final week to complete their final lab paper.


Questions for Further Thought and Discussion

The following set of questions can be considered prior to or while conducting the laboratory. In answering the questions, students can be asked to review the literature or seek out additional information. Furthermore, if using these questions early on in the semester they can be graded as a separate component of the laboratory.  

  1. Why do some species benefit from human influence and others do not?
  2. What are the primary metrics ecologists use to define a human-influence gradient?
  3. Which species do we know the most about in regards to how they relate to human influence?
  4. Which species do we know the least about in regards to how they relate to human influence?
  5. What are important biases to consider in the study?

The remaining questions can all be considered after the data have been collected or when the final paper is written.


References and Links


Tools for Assessment of Student Learning Outcomes

Assessment Components

The overall lab project will be graded based on three separate components: the field notebook, a poster, and a research paper. 

Field Notebook
The notebook will be graded twice in order to assess your understanding and progress.  Details to be included in the notebook include: a table of contents, page numbers, location of the plots where data is collected, environmental data (e.g., temperature, time of day, sky), and biological inventory information following the examples given in Field Lab 1 (see Field Lab 1 in PDF format attached to this exercise for further details). The field notebook is worth 25 points, with 10 possible points allocated for the first round of grading and 15 possible points for the second round of grading.

A formal rubric for the Field Notebook was not developed.  However, the main components that I looked for in evaluating the students were: clarity and legibility of the material (i.e., penmanship; could other individuals read the field notebook clearly?), date, environmental data (temperature, Beaufort scale wind index, time of day, cloudiness, etc.), beginning and ending times of surveys, accurate recording of species, table of contents, page numbers, locations of the laboratories, and information describing the human influence at a given site (e.g., percent impervious surface, presence of traffic, pedestrians, etc.).

Poster Presentation
In conjunction with the final lab research report, each lab group will prepare a poster presentation of their lab research project.  This poster will be the responsibility of the entire group and the grade will reflect the input of all members.  There are a number of styles and formats for designing a poster and they will be discussed in detail in coming weeks.  The research poster portion of the project will be worth 50 points and will be graded independently of the research paper.  The total points awarded to each student will be an average of the instructor’s grades, and the group members’ grade of a student.

While posters can be crafted following a number of approaches, several useful websites that have important guidelines on posters are:


Extension Activities for Advanced Students

Guidelines for Poster and Group Project Evaluation
The total points a student receives (out of a possible 50 points), is based upon the average of two major assessments: the student’s group members and the instructors.

Student Assessment
Over the course of the semester you and your group have worked together on the lab research project.  In order to evaluate your own work and that of the other students, please take a moment to grade everyone in the group, including yourself.  A total of 50 points can be given to each student using the general guidelines for grading that follow:
Participation—Did the student actively participate in the work over the course of the semester and with the poster? —15 points

Attendance—Did the student regularly attend lab or meetings outside of lab? —15 points

Ability to work with group—Did the student work well with the group? —10 points

Skills and Contribution—Did the student have important ideas or skills to contribute to the project or throughout the semester? —10 points

Students receive a “Group Project Grade Form,” that serves as their rubric for grade disbursement to each member of the group (see attached document labeled Student Grading Sheet for Semester Project Poster).

Instructor Assessment
Each poster was assessed based upon the following items:

1.  Content—25 points
a. Title
b. Main question/idea/hypothesis
c. Basic methods/approach/instructions
d. Results and Conclusions
2.  Use of Figures and/or Tables—10 points
3.  Creativity—10 points
4.  Spelling/Grammar/Clarity of writing—5 points

Both the professor and the teaching assistant for the laboratory evaluated each poster product independently with the final “Instructor Grade” being an average of both. Hence, the final student grade for the poster is the average of all of his/her group members and both lab instructors (see attached document labeled Group Project Grade Form for the formal rubric laid out above).

 [Note to instructors—posters can be projected on screen without printing them off if time or resources are limited, thereby not allowing students’ access to poster printers]

Research Paper. The research paper follows the format of a standard scientific article such as the journal Ecology, the guidelines for which can be found on the link below. Specifically, the paper will include a title, abstract, introduction, methods, results, discussion, and literature cited.  Draft sections of the Introduction and Methods are required and will be evaluated for feedback to students.

The research paper will be done individually and should reflect your own work. Thus, while you can work with members of your group on the project and analyses, you will need to write the paper on your own. The research paper portion of the project will be worth 100 points. Thus, the two major elements of the semester research project will be worth 150 points, equivalent to one exam or approximately one quarter of your grade.
Guidelines for Writing the Research Paper
Preparation of Manuscripts for Ecology is as follows, but can also be located at http://esapubs.org/esapubs/preparation.htm

Rubric for the Scientific Paper
(see attached file Rubric for Final Semester Lab Paper for a copy in Word format)
Following the General Guidelines—10 points

Title page—2 points

Abstract—8 points (2 points each section)
     Background or reason
     Main question or hypothesis
     Results and discussion

Introduction—10 points (subdivided as follows)
     General background—3 points
     Main question or hypothesis and brief description of what we did—4 points
     Citations or references—3 points

Methods—30 points (7.5 points each section)
    Study Sites or Field Sites
    Field Surveys or Data Collection
    Data Processing or Data Editing
    Data Analysis or Statistical Analysis

Results—20 points (subdivided as follows)
     Main findings—8 points
     Tables and figures—12 points

Discussion—10 points

Literature Cited—10 points

Total___________________(out of 100 possible points)