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Summary

New Environment Class 06

## BRIEF OVERVIEW OF PREVIOUS CLASS (5:21 PM)

- Faculty revised **aquatic ecosystems** and **wetlands**.
- General discussion on how to approach prelims from now-onwards.

## WETLAND (5:25 PM)

- ***Difference between Lakes and Wetlands:***
- |  |  |  |
  | --- | --- | --- |
  | **Characteristic** | **Lake** | **Wetland (Shallow Lake)** |
  | **Origin** | Largest due to tectonic forces i.e. geomorphic | Mostly fluvial and residual lakes |
  | **Water** | Permanent | Permanent to Temporary |
  | **Water level changes** | Relatively small | Relatively large |
  | **Vertical mixing** | Thermally regulated | Wind regulated |
  | **Thermal Stratification** | Yes | No |
  | **Dominant** | Phytoplankton | Macrophytes |
  | **Food chain** | Grazing Pathway | Detritus Pathway |
  | **Productivity** | Low | High |
  | **Trophic status** | Oligotrophic | Mostly eutrophic |
  | **Flood control** | Less significant | Significant |
  | **Waste treatment** | No | Yes |
- **Significance:**
- Wetlands are called **kidneys** of the Environment as it helps in filtering sediments and pollutant and purify the water.
- It helps in **nutrient recycling** as it helps in the conversion of waste and organic biomass through the food chain.
- It helps in **groundwater recharge** as it slows down the water percolates into the lower layer.
- They provide **drinking water** and **food** to people as well as cattle for grazing.
- It provides **habitat** and supports a large diversity of life.
- It helps in **disaster control** such as controlling floods as well as droughts.
- It helps in controlling **soil erosion.**
- It helps in **climate mitigation** as it helps in ***maintaining ecological balance*** and ***keeping the environment coo***l.
- Cultural and Eco-tourism
- **Issues:**
- Wetlands in urban areas are e**ncroached** and **converted** due to rapid **urbanisation. For example-** Banglore, Chennai, Mumbai and Hyderabad **etc**
- Increased **water pollution** fue to excessive release of sewage and industrial waste or agriculture.
- Excessive fertiliser usage in urban areas causes **eutrophication** and **algal blooms.**
- Deforestation
- Overgrazing
- Land degradation
- Over-fishing
- The release of methane from wetlands and paddy fields contributes to global warming. **For example: Balandur lake** catches fire due to the release of methane.
- Usage of antibiotics in aquaculture
- **Note:** we will study separately all the acts and rules related to wetlands.

## BIODIVERSITY (6:19 PM)

- As per the **United Nations Earth Summit, Biodiversity** is defined as the ***variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems***.
- **Types of biodiversity:**
- ![biodoiversity-types](https://i.ibb.co/GxRGVTN/biodoiversity-types.png)
- **Genetic diversity:** It is the number of genetic diversity in the genetic make-up of a species and naturally occurring genetic differences among individuals of the same species. The higher genetic diversity enables a species to survive hard conditions.
- **Species diversity:** It is the number of species found in an ecosystem. **For example**- a rainforest ecosystem has higher species diversity than a coniferous ecosystem
- **Ecosystem diversity:** It is the variation in ecosystems within a larger geographical area or habitat. For example- different types of ecosystems are found in equatorial rainforests.
- **Species diversity:**
- *It considers two main factors while measuring diversity:*
- 1. **Richness:** It is a number of different species present in an ecosystem.
- 2. **Evenness:** It is the number of individuals per species and their relative abundance.
- ***Species Richness***
- ![speciesdiversity](https://i.ibb.co/m0zQ7Bj/speciesdiversity.png)
- ***It can be divided into three types i.e. alpha, beta and gamma diversity.***
- i. **Alpha (α) diversity** refers to diversity within a particular area, community or ecosystem and is measured by counting the number of taxa(usually species) within the ecosystem.
- ii. **Beta (β) diversity** is species diversity in the ecosystem; this involves comparing the number of taxa that are unique to each of the ecosystems.
- iii. **Gamma (γ) diversity** is a measurement of overall diversity for different ecosystems within a region.
- Biodiversity in an ecosystem brings **stability**.
- A stable system does not show too much variation in productivity.
- It shows resistance or resilience to occasional disturbances
- The India State of the Forest report by the Forest Survey of India featured the **Shannon-Wiener Index**, providing data on species diversity and abundance in regions.

## ENDEMISM (7:37 PM)

- It is an ecological state of species being unique to a defined geographic location.
- ***Importance of endemism in ecosystems:***
- It is an **indicator** of the **richness** of biodiversity.
- It acts as an **indicator species** of ecosystems.
- It contributes to the **stability** and resilience of ecosystems.
- Protecting these species helps in **preserving their unique diversity** and **niche**.
- It also helps in **understanding** the **unique adaptation** and **evolution process**.
- **Note**:
- ***The species can classified into native and alien species.***
- **Native Species**: These are species that naturally occur and have evolved in a specific region without human intervention
- It can be further classified into endemic and non-endemic.
- **Endemic:** Species that are native and unique to a specific geographical area or region.
- **Non-Endemic:** Native species that exist in a particular region but are not exclusive to that region and might be found elsewhere within their native range.
- **Alien/Invasive Species**: These species are introduced to a region by human activities, intentionally or unintentionally
- These can be further classified into invasive and non-invasive.
- **Invasive:** Species introduced to a region where they are not native and cause harm to the environment, economy, or human health.
- **Non-Invasive:** Species introduced to a region but do not cause significant harm to the environment or other species in that area.

## DISTRIBUTION OF BIODIVERSITY (7:44 PM)

- **Biogeographic realm:**
- It is any of the large special regions of the earth's land surface with ecosystems sharing similar biological evolutionary history and distributional patterns of terrestrial organisms.
- There are 8 terrestrial biogeographic realms which share similar processes and major vegetation types.
- ![realm](https://i.ibb.co/gz6fpmm/realm.png)
- The ***Paleartic realm (Himalayas) and Indo-Malaya realm (rest of India).***
- **Megadiverse countries:**
- It is a group of countries which account for at least 70% of the planet, terrestrial biological diversity within 10% of Earth's surface.
- There are 17 such countries.
- ![megadiverse](https://i.ibb.co/YBYGS02/megadiverse.png)
- **Conditions:**
- 1. It must have ***at least 5000 endemic plants***.
- 2. ***Marine ecosystem within its borders***.

## The Topic for the next class: Biodiversity (Continuation)