Studying Ecosystems (SL IB Environmental Systems & Societies (ESS))

Identifying an ecosystem

• The study of an ecosystem first requires that it be named and located to provide a specific and clear reference point for the ecosystem being studied
• Naming an ecosystem can include the identification of its physical characteristics, such as vegetation type, climate, and location
  
  • Location is important because it provides a specific geographic area for the ecosystem being studied, allowing for more accurate comparisons with other similar ecosystems

• Examples of named ecosystems and their geographical locations include:
  • Amazon Rainforest, South America:
    
    • The Amazon rainforest is located in South America, covering approximately 2.7 million square miles
    • It is the largest rainforest in the world and is home to a diverse range of plant and animal species
    • Characteristic vegetation: dense evergreen trees, such as mahogany, Brazil nut, and rubber trees, and understory vegetation, such as ferns, palms, and lianas

Photo by Kai Pütter on Unsplash

The Serengeti is well known for its herds of wildebeest

• • Serengeti, Tanzania:
    
    • The Serengeti National Park is located in Tanzania, covering an area of over 5,700 square miles
    • It is known for its large herds of wildebeest, zebras, and gazelles, as well as predators such as lions and cheetahs
    • Characteristic vegetation: grasslands dominated by perennial grasses, with scattered trees, such as acacia and baobab

• Naming and locating ecosystems not only provides a clear reference point for research, but it also helps to raise awareness about the unique characteristics and value of each ecosystem, encouraging conservation efforts

Identifying organisms in an ecosystem

• Organisms in an ecosystem can be identified using various tools and techniques
• These tools are important for understanding the biodiversity and ecological interactions within the ecosystem
• By accurately identifying organisms, scientists can better understand the roles they play in the ecosystem and how they contribute to its functioning
• Examples of these tools and techniques include:

    1. Comparison to herbarium or specimen collections

• • Herbariums and specimen collections are archives of pressed and preserved plants, animals, and other organisms
    These collections can be used to compare the characteristics of the organisms in question with the archived specimens to identify them

    2. Technologies such as DNA profiling

• • DNA profiling involves the extraction of DNA from an organism, which is then amplified and sequenced
  • The resulting sequence can be compared to known sequences in databases to identify the organism

    3. Scientific expertise

• • Scientists with specialised knowledge of a particular group of organisms can identify them based on their morphology, anatomy, and behaviour

    4. Dichotomous keys

• • Dichotomous keys are tools used to identify organisms based on their characteristics
  • The keys consist of a series of questions with two possible answers, leading to the identification of the organism

Dichotomous Keys

A dichotomous key for animals in the Serengeti

• Below is an example of a dichotomous identification key for eight named species in the Serengeti ecosystem:

1	a	Animal covered in black and white stripes	Zebra (Equus quagga)
	b	Animal not covered in black and white stripes	go to 2
2	a	Animal is a large cat	go to 3
	b	Animal is not a large cat	go to 4
3	a	Animal covered in spots	Cheetah (Acinonyx jubatus)
	b	Animal not covered in spots	Lion (Panthera leo)
4	a	Animal has horns	go to 5
	b	Animal does not have horns	go to 7
5	a	Horns meet in middle of head	Cape buffalo (Syncerus caffer)
	b	Horns do not meet in middle of head	go to 6
6	a	Horns are long and curved	Grant's gazelle (Nanger granti)
	b	Horns are not long and curved	Oribi (Ourebia ourebi)
7	a	Animal has a long neck	Giraffe (Giraffa camelopardalis)
	b	Animal does not have a long neck	African elephant (Loxodonta africana)

• There are several limitations of using a dichotomous identification key for identifying organisms:

1. Limited scope

• • Dichotomous keys are typically designed to identify a limited number of species and may not be comprehensive enough to identify all organisms in a given ecosystem

2. Inaccuracies

• • Dichotomous keys are only as accurate as the information provided
    If the key is not designed properly or lacks important distinguishing characteristics, the identification may be inaccurate

3. Variability

• • Organisms can exhibit variability in their physical characteristics, which can make it difficult to accurately identify them using a dichotomous key

4. Time-consuming

• • Using a dichotomous key can be a time-consuming process, especially for beginners who are not familiar with the organisms in question

5. Expertise required

• • Dichotomous keys require a certain level of expertise and familiarity with the organisms in question
  • Beginners may find it difficult to use the key without assistance from an expert

6. Limited to physical characteristics

• • Dichotomous keys are limited to the physical characteristics of organisms and may not take into account other important factors, such as behaviour or habitat, which can be important in identifying certain species