Natural Capital, Biodiversity, and Ecosystem Services Study Notes

Natural Capital and Biodiversity

Natural resources are defined as materials from Earth that can be used for economic gain. Examples of natural resources include water, minerals, lumber, fertile soil, coal, oil, and natural gas. These resources can be classified into two categories:

Renewable resources - resources that can be replenished naturally over time, such as solar energy and timber.
Non-renewable resources - resources that have a finite supply, such as fossil fuels and minerals.

Ecosystem Services

Ecosystem services are the benefits that humans derive from ecosystems. They are categorized into several types:

Provisioning services - These services provide goods that people can use directly. Examples include lumber, water, food crops, medicinal plants, and minerals such as gold and oil.
Regulating services - These services consist of cycles and systems that regulate environmental conditions, such as flood control from wetlands, biogeochemical cycles, and photosynthesis.
Cultural services - These services provide recreational and aesthetic value to humans, including national parks, city parks, and natural areas that inspire art or contribute to spiritual enrichment.
Supporting services - These are ecosystem processes that would be very expensive for humans to replicate, such as pollination, water purification, and decomposition.

Biodiversity

Biodiversity refers to the variety of living organisms in a given ecosystem and encompasses genetic, species, and habitat diversity. It is crucial as it confers numerous benefits to humans:

Stability of ecosystems - Biodiversity-rich ecosystems are less susceptible to disturbances like food web collapses or species extinctions, leading to a more resilient environment.
Potential for medical cures - A significant portion of pharmaceuticals, estimated at 70%, is derived from natural sources. For instance, Taxol, a cancer drug, is extracted from the Pacific yew tree, and horseshoe crabs are harvested for their blood that helps in clotting.
Economic advantages - Genetic diversity, species diversity, habitat diversity, and ecosystem diversity all contribute to economic stability and resilience.

Measuring Biodiversity

Species Diversity

Species diversity is quantified by two main components:

Species richness - The total number of different species present in a community.
Species evenness - The comparative number of individuals of each species present in a community.

Example of Species Diversity in Forest Communities

Consider two forest communities:

Community 1 has 16 trees with total species richness of 4. The evenness is calculated as follows:
- % Species A: 4/16 = 25%
- % Species B: 4/16 = 25%
- % Species C: 4/16 = 25%
- % Species D: 4/16 = 25%
Community 2 also contains 16 trees with the same species richness of 4, but different evenness:
- % Species A: 1/16 = 6.25%
- % Species B: 11/16 = 68.75%
- % Species C: 4/16 = 12.5%
- % Species D: 2/16 = 12.5%

Community 1 demonstrates greater species evenness, indicating a higher species diversity compared to Community 2, despite both having the same richness.

Simpson's Diversity Index

Simpson's Diversity Index (D) is a formula that incorporates both species richness and evenness to assess biodiversity in a community. The formula is structured as follows:
D = 1 - \frac{\sum n(n-1)}{N(N-1)}
Where:

$n$ = total number of organisms of a particular species.
$N$ = total number of organisms of all species in the community.
$\sum$ = denotes summation.

Calculating Simpson's Diversity Index for Communities

Community 1 calculation:
- For each species:
  - Species A: $4(4-1)$ = 12
  - Species B: $4(4-1)$ = 12
  - Species C: $4(4-1)$ = 12
  - Species D: $4(4-1)$ = 12
- Thus, $\sum n(n-1) = 12 + 12 + 12 + 12 = 48$
- N(N-1) = 16(16-1) = 240
- $D = 1 - \frac{48}{240} = 1 - 0.2 = 0.8$
Community 2 calculation:
- For each species:
  - Species A: $1(1-1)$ = 0
  - Species B: $11(11-1)$ = 110
  - Species C: $2(2-1)$ = 2
  - Species D: $2(2-1)$ = 2
- Thus, $\sum n(n-1) = 0 + 110 + 2 + 2 = 114$
- N(N-1) = 16(16-1) = 240
- $D = 1 - \frac{114}{240} = 1 - 0.475 = 0.525$

From the calculations, Community 1 has a higher diversity index value (D = 0.8) compared to Community 2's D value of 0.525. This reinforces that Community 1, while having the same species richness, has greater biodiversity due to its higher species evenness.

Simpson's Diversity Index Lab Example

In a study of a stream ecosystem in Sweden conducted in 1992 and 2001, researchers noted the counts for various species along with their respective calculations of Simpson’s Diversity Index.

Species Data from 1992 and 2001:

Species Name	1992 Count (n)	n(n-1)	2001 Count (n)	n(n-1)
Mayfly	8	56	16	240
Dragonfly	5	20	0	0
Caddis fly	4	12	0	0
Stonefly	4	12	0	0
Pond skater	3	6	13	136

Totals:

1992: Total N = 42, $\sum n(n-1) = 140$
2001: Total N = 57, $\sum n(n-1) = 558$

Using these totals, the D values can be calculated:

For 1992:
D = 1 - \frac{140}{1722} = 0.918
For 2001:
D = 1 - \frac{558}{3192} = 0.825

In conclusion, analysis of the data shows a decline in biodiversity, supporting the claim that the factory built nearby emitted pollutants leading to diminished species diversity in the stream ecosystem.

Ecological Succession

Definition of Ecological Succession

Ecological succession is defined as the predictable replacement of one group of species by another over time. It can be categorized as:

Primary succession - This type occurs in lifeless areas where soil has not yet formed, such as on bare rock after a volcanic eruption. Pioneer species, like lichens and mosses, initiate this process by helping to create soil.
Secondary succession - This occurs in areas where soil exists but has been disturbed, such as after a forest fire. In this case, recovery tends to be faster because the soil is already present.

Climax Community

A climax community represents the final stages of ecological succession where ecosystems are fully established, exhibiting stable species composition.

Types of Disruptions

Disruptions in ecosystems can be classified as:

Natural disruptions - Including floods, fires, and volcanic eruptions.
Anthropogenic (human-caused) disruptions - Such as deforestation and pollution.
Periodic disruptions - Occurring naturally and regularly, like seasonal fluctuations.
Episodic disruptions - Events that happen irregularly, such as random storms or wildfires.
Random disruptions - Unexpected events, such as volcanic eruptions.

Theory of Island Biogeography

The Theory of Island Biogeography asserts that species richness on an island is determined primarily by two factors:

Immigration rate - The rate at which new species arrive from the mainland.
Extinction rate - The rate at which species become extinct locally on the island.

These rates are influenced by the island's distance from the mainland, with closer islands exhibiting higher species diversity due to better immigration rates. Additionally, the size of the island plays a role, as larger islands can support more resources and have lower extinction rates.

Threats to Biodiversity - HIPPCO

HIPPCO outlines the biggest threats to biodiversity:

Habitat Fragmentation/Loss - Including urbanization and deforestation.
Invasive Species - Non-native species that outweigh the impact native species have.
Population Growth - Human population expansion that strains natural resources.
Pollution - Contaminants that degrade health and biodiversity.
Climate Change - Altering ecosystems unpredictably.
Overexploitation - Harvesting species faster than they can replenish.

Definition of Habitat and Niche

Habitat refers to where an organism lives, encompassing the food, shelter, and mating opportunities it finds.
Niche refers to the role that an organism plays in its community, including how it interacts with the environment and other species.

Conservation Efforts

Global measures such as CITES aim to protect endangered species from overexploitation, ensuring trade does not threaten survival for species at risk.