Ecosystem and Biodiversity Lecture Notes
Core Concepts of Biodiversity and Species
Biodiversity is defined as the number and variety of organisms found within a specific region or across the entirety of Earth. It encompasses all forms of life and the complex interactions between them. Within this framework, a species is defined as a group of organisms that share similar physical and genetic traits and possess the biological capability to produce fertile offspring.
Biodiversity is categorized into different levels of variety. Genetic diversity refers to the variety of genes or inheritable traits present within a single population. Examples of these inheritable traits include eye color, hair texture, skin color, and height. Species diversity accounts for both the total number of different species in an ecological community and the quantity of individuals representing each of those species. Ecosystem diversity represents the variety of different ecosystems present within the biosphere.
Methods for Measuring Biodiversity
Scientists utilize several distinct methods to measure and monitor the biodiversity of different environments, depending on the types of organisms being studied and the nature of the habitat. Canopy fogging is a technique used specifically with insects. This method involves spraying a lethal insecticide into the tree canopy and subsequently collecting the dead insects as they fall, using a large sheet or a collecting tunnel.
Transect sampling is a method characterized by counting plants or animals along a straight line to study how nature changes from one point to another. While this method is described as quick, it is noted as not being very accurate. It can be performed on land or in water. Quadrant sampling is a similar technique but is considered more accurate than transect sampling. It involves counting the wildlife found inside a square frame to estimate the total populations of an area. Like transect sampling, quadrant sampling is applicable to both land and water environments.
Mist netting is a technique used to safely capture small, flying animals, such as birds or bats. It employs nearly invisible, fine mesh nets and can be used in both terrestrial and aquatic settings. For larger animals that travel in herds, aerial photos are utilized. This involves taking pictures of the landscape from the sky to map large habitats and count wildlife populations from above, covering both land and water. General surveys are another method, usually conducted on foot or by boat. Surveys are best used for birds and involve counting and mapping the wildlife found within a specific area.
Mathematical Assessment of Biodiversity
The Biodiversity Index is a mathematical tool used to quantify the variety of life in a specific area. The formula for calculating this index is as follows:
The resulting biodiversity index value ranges from to . The closer the index value is to , the lower the biodiversity of that area. Conversely, the closer the index value is to , the higher the biodiversity of the area.
Ecosystem Dynamics and Environmental Zones
Ecosystems strive for a state of dynamic equilibrium, which refers to a stable ecosystem that may still experience specific changes or disturbances. If a disturbance occurs, natural processes will eventually bring the ecosystem back into a state of balance. Resilience is the specific ability of an ecosystem to maintain this dynamic equilibrium even when faced with significant outside disturbances.
On a larger scale, a biome is a geographical area on Earth that contains ecosystems with similar biotic and abiotic features. Within marine and coastal environments, the intertidal zone is defined as the specific area of the ocean shore located between the lowest and highest tide marks.
Ecosystem Services
Ecosystem services describe the various benefits that organisms, including humans, experience from a healthy, functioning ecosystem. These services are categorized into four main types: provisioning, regulating, cultural, and supporting services.
Provisioning services are the direct products provided by the ecosystem, such as food, medicine, natural resources, and water. Regulating services are the benefits received through the natural regulation of ecosystem processes. These include pollution control, water purification, protection from natural disasters, erosion control, and climate regulation. Cultural services represent the non-material benefits that people obtain through their experiences and interactions with the ecosystem. Supporting services are the underlying processes that allow the other services to function.
Threats to Biodiversity and the Environment
Biodiversity faces several significant threats that can destabilize ecosystems. Invasive species are organisms introduced into an ecosystem, either by accident or on purpose, that spread on their own and outcompete native species for resources. Pollution is the contamination of the environment with any substances that are harmful to life. Habitat destruction occurs when an ecosystem is altered in such a way that it can no longer support the organisms that naturally live there.
Overexploitation is the overuse of animal and plant species by humans, which can lead to population collapses. Additionally, climate change refers to the long-term changes in global climate patterns over time. A major component of this is global warming, which is characterized by the rising temperatures of both land and sea surfaces.