Human Impacts on Ecosystems

Introduction

Imagine a forest where resource extraction and ecosystem integrity coexist harmoniously. This scenario exemplifies the dual advantages—ecological and economic—of sustainable management strategies: approaches that equitably balance resource utilisation and ecosystem preservation. These strategies are essential in maintaining biodiversity while addressing human resource requirements.

What is an Ecosystem?

• Ecosystem: A community comprised of interacting organisms and their physical surroundings, such as forests or marine environments.

Ecosystems are vital for sustaining the earth's biodiversity, which includes genetic, species, and ecosystem diversity. They deliver crucial ecological services such as pollination, climate regulation, flood control, and carbon storage.

Components of Ecosystems

• Producers: Transform solar energy into accessible energy for other organisms. Example: Photosynthesis in green plants.
• Consumers: Encompass Herbivores, Carnivores, and Omnivores, who have a significant role in energy transfer within the ecosystem.
• Decomposers: Decompose dead material, recycling nutrients back into the environment. Examples: Fungi and bacteria breaking down organic matter.
• Abiotic Elements: Non-living components that impact the ecosystem, such as sunlight, water, temperature, and soil.

Natural Balance Pre-Human Intervention

• Equilibrium: Inherent natural balance sustained through dynamics like predator-prey relationships and symbiosis.
• Resilience: The capacity of ecosystems to recover naturally from changes, like forest regrowth following minor disturbances.

Introduction to Human-Induced Selection Pressures

• Selection Pressures: Environmental factors that influence an organism's ability to survive and reproduce. Human activities accelerate species extinction rates beyond historical norms.

Case Studies of Human Impacts

• Dodo and Passenger Pigeon: Extinction caused by hunting, habitat destruction, and introduced species, leading to ecosystem destabilisation and reduced biodiversity.

Genetic Bottlenecks and Other Human-Caused Pressures

• Genetic Bottlenecks: Low genetic diversity affecting adaptability and heightening extinction risk.
• Habitat Destruction: Activities like deforestation and urbanisation.
• Pollution Impact: Detriments to ecosystem health.

Invasive Species and Predation Pressure

• Cane Toad Example: Invasive species such as cane toads in Australia disrupt native ecosystems, posing threats to indigenous species.

Introduction to Predictive Models

Predictive models are tools used to anticipate changes in ecosystems, crucial for mitigating biodiversity losses stemming from climate change and human actions.

Types of Predictive Models

• Climate Models: Forecast climate impacts, crucial for anticipating changes influencing species migration and survival.

• Population Viability Analysis (PVA): Evaluates extinction risks and guides conservation strategies.

• Species Distribution Models (SDM): Predict habitat modifications due to environmental changes.

Tools and Technologies

• Software:
  • R and Python facilitate model development and analysis.
  • Leverage simulations and statistical methods to enhance understanding and data representation.

Key Concepts and Definitions

• Climate Change: Long-term shifts in Earth's climate patterns, primarily due to rising atmospheric CO$_2$ levels.
• Rate of Climate Change: The velocity of changes in climate variables, affecting ecosystem adaptability.

Impacts on Ecosystems and Species

• Coral Reefs: Experience bleaching due to elevated temperatures.
• Species Shifts: Numerous species relocate to cope with changing conditions, forming new ecosystems with novel interactions.

Key Strategies for Future Management

Sustainable Practices

• Conservation Biology: Promotes ecosystem health, exemplified by wolf reintroduction in Yellowstone.
• Restoration Ecology: Initiatives like coral reef restoration and wetland recovery restore biodiversity.

Legal Frameworks and Policies

• Emphasise the implementation and enforcement of conservation laws and environmental protection legislation.

Legal Framework	Function
Conservation Acts	Safeguard habitats and species
Marine Reserves	Preserve biodiversity

Community Role in Management

• Public Engagement: Integral in promoting sustainable practices and conservation efforts.
• Involvement in Education: Projects in areas like Costa Rica enhance local biodiversity through community education.

Conclusion and Future Considerations

Planning and Challenges

• The integration of technology and interdisciplinary collaboration strengthens resilience and adaptive management.
• Addressing economic pressures and data deficiencies through international cooperation and public engagement is crucial.

This document outlines critical concepts and strategies for understanding future ecosystem management and human impacts. By comprehending these dynamics, we can actively advocate for sustainable and harmonious ecosystems.

Worked Example: Calculating the Impact of Habitat Loss

Consider a forest ecosystem that has lost 30% of its area due to human development. If the original forest contained 500 species, and we use the species-area relationship formula $S = cA^z$ (where S is number of species, A is area, and c and z are constants with z typically around 0.25):

Original situation: $S_1 = cA_1^{0.25} = 500$ New situation: $S_2 = cA_2^{0.25} = c(0.7A_1)^{0.25}$

To find the number of species after habitat loss: $S_2 = 500 \times (0.7)^{0.25} = 500 \times 0.92 = 460$ species

Therefore, the 30% habitat loss results in approximately 40 species being lost from the ecosystem.

Practice Question

1. Explain how climate change might affect species distribution in mountain ecosystems, and suggest one management strategy to mitigate negative impacts.

Solution: Climate change causes warming temperatures, forcing mountain species to move upward to maintain their preferred temperature ranges. This "escalator to extinction" effect can lead to population isolation and eventual extinction when species reach the summit with nowhere else to go. A suitable management strategy would be to establish protected corridors connecting mountain ranges to allow species migration, or to create assisted migration programs for the most vulnerable species to suitable habitats in other regions.