Chapter 23 Summary

Conservation Biology Key Concepts

CONCEPT 23.1: Conservation biology is an integrative discipline applying ecological principles to protect biodiversity.
CONCEPT 23.2: Global biodiversity is declining.
CONCEPT 23.3: Primary threats to diversity include habitat loss, invasive species, overexploitation, pollution, disease, and climate change.
CONCEPT 23.4: Conservation biologists manage declining populations using various tools at multiple scales.
CONCEPT 23.5: Prioritizing species helps maximize biodiversity protection with limited resources.

Can Birds and Bombs Coexist? A Case Study of the Red-Cockaded Woodpecker and Fort Bragg

Bombing on Fort Bragg military base in North Carolina Sandhills has inadvertently protected longleaf pine savanna, aiding the endangered red-cockaded woodpecker.

The Red-Cockaded Woodpecker ( Picoides borealis )

Once abundant in pine savannas of the United States.
Severely reduced in numbers due to habitat loss.
Military training exercises at Fort Bragg have involved destructive activities such as off-road vehicles, earth-moving equipment, and explosives, which have degraded the ecosystem.

Longleaf Pine Savanna

Depends on fire for its persistence; fires from explosions benefit the ecosystem.
Designation of large forest blocks for military use prevents conversion to farmland, forest plantations, and residential areas.
Only about 3% of the original 35 million hectares (>134,000 square miles) of longleaf pine savanna remains.
- Decline caused by human population growth, clearing land for plantations (e.g., loblolly pine), and fire suppression.
The decline of the longleaf pine savanna ecosystem has led to substantial declines in associated plant, insect, and vertebrate species.

Decline of the Longleaf Pine Savanna Community (Figure 23.2)

Longleaf pine (Pinus palustris) savanna consists of open forest with a grass understory.
Estimates of Hectares Covered:
- 1500: Large area (Estimate from graph needed)
- 1935: Reduced area (Estimate from graph needed)
- 2004: Very small area (Estimate from graph needed), with no change to the present.
The annual loss of longleaf pine savanna was greater from 1500 to 1935, compared to 1935 to 2004.

Red-Cockaded Woodpecker (Picoides borealis)

Small insectivorous bird requiring large tracts of open pine savanna.
Population Decline:
- Historical: 1.3 million breeding pairs (clusters).
- Current: Approximately 7,500 clusters.
Requires mature, living pine trees (especially longleaf pine) for nesting cavities, unlike other woodpeckers that nest in dead snags.
Periodic fires historically maintained longleaf pine savanna.
Without fires, succession occurs with an understory of young oaks and hardwoods, causing red-cockaded woodpeckers to abandon nesting cavities due to decreased food.
Woodpeckers used to move to recently burned areas, but declining mature longleaf pines limit available habitats.
Loss of habitat has made the woodpecker vulnerable to problems associated with small, isolated populations (Concept 11.3).
Evidence of genetic inbreeding among the birds.
In 1989, Hurricane Hugo killed 70% of one population.

Species Decline and Conservation

The red-cockaded woodpecker's recent history mirrors that of thousands of other imperiled species facing population declines due to habitat loss.
Species requiring specific degraded habitats experience population reductions, potentially leading to extinction.
Questions to consider:
- What can be done to protect species like the red-cockaded woodpecker?
- Do we have a responsibility to protect existing biodiversity and restore lost biodiversity?
- How can we best allocate limited resources for effective conservation efforts?

Introduction to Biodiversity Loss

Over the last few centuries, human population growth and resource use have caused habitat loss and changes, precipitating an increase in species extinctions and loss of diversity.
The 2019 analysis of the Red List of Threatened Species (IUCN) lists 27,159 species as threatened with extinction (approximately 1% of all described species worldwide).
The percentage of threatened species is an underestimate due to:
- Only 5% of described species have been evaluated
- Many species have yet to be taxonomically described.
Ecologists play a crucial role in measuring species losses and their causes, working within diverse teams to slow species and habitat decline.

Table 23.1: Global Summary of Documented Imperiled Species (2019)

Vertebrates:
- Mammals: 6,495 described species, 5,850 evaluated, 1,244 threatened (25% estimated threatened).
- Birds: 11,147 described and evaluated, 1,486 threatened (14% estimated threatened).
- Reptiles: 10,793 described, 7,829 evaluated, 1,409 threatened (insufficient data for percentage).
- Amphibians: 8,104 described, 6,794 evaluated, 2,200 threatened (41% estimated threatened).
- Fishes: 35,315 described, 19,199 evaluated, 2,674 threatened (insufficient data for percentage).
Invertebrates:
- Insects: 1,053,578 described, 8,696 evaluated, 1,647 threatened (insufficient data for percentage).
- Molluscs: 87,975 described, 8,749 evaluated, 2,250 threatened (insufficient data for percentage).
- Crustaceans: 80,604 described, 3,181 evaluated, 733 threatened (insufficient data for percentage).
- Corals: 2,175 described, 864 evaluated, 237 threatened (insufficient data for percentage).
- Arachnids: 110,615 described, 344 evaluated, 197 threatened (insufficient data for percentage).
Plants:
- Mosses: 21,925 described, 281 evaluated, 164 threatened (insufficient data for percentage).
- Ferns and allies: 11,800 described, 641 evaluated, 261 threatened (insufficient data for percentage).
- Gymnosperms: 1,113 described, 1,014 evaluated, 402 threatened (40% estimated threatened).
- Flowering plants: 369,000 described, 36,623 evaluated, 14,938 threatened (insufficient data for percentage).
  Note: An asterisk () indicates insufficient coverage for accurate estimation of the percentage of threatened species.*

Conservation Biology as an Integrative Discipline

CONCEPT 23.1: Conservation biology is an integrative discipline applying the principles of ecology to the protection of biodiversity.
The preservation of longleaf pine savanna and legal protection, coupled with extraordinary human effort, has led to the stabilization and slow recovery of red-cockaded woodpeckers.
This recovery requires expertise from biological disciplines (population biology, genetics, pathology) and contributions from disciplines outside biology (law, economics, political science, communications, and sociology).
A successful management approach requires data collection and analysis, creativity, and the ability to work with various stakeholders.
Conservation biology: The scientific study of the amount of biodiversity (including genetic diversity, species richness, and landscape diversity), how human activities are impacting it, and how best to maintain it and prevent its loss.
Biodiversity includes genetic diversity within a species, the diversity of species, and the diversity of communities across landscapes (see Figure 16.7).
Conservation biology applies ecological principles and tools to halt or reverse biodiversity declines.

Why is Preserving Biodiversity Important?

Protecting biodiversity is vital for practical and moral reasons.
Humans rely on nature's diversity for food, fuel, fiber, medicines, building materials, spices, and decorative items.
Natural communities provide valuable ecosystem services, such as water purification, soil generation and maintenance, crop pollination, climate regulation, and flood control.
Emotional and spiritual health relies on nature’s beauty and complexity.
Ethical considerations include the inherent value of biodiversity, religious or spiritual beliefs about stewardship, and the view that other species have a right to exist.

The Rise of Conservation Biology

Conservation biology arose in response to global biodiversity losses.
Scientists have long recognized the impact of human activity on the abundance and distribution of organisms.
Alfred Russel Wallace foresaw the current biodiversity crisis in 1869, warning that humanity risked obscuring the record of past evolution through extinctions.
In the United States, public outcry arose over the decline of bison, the extinction of the passenger pigeon, and the use of bird feathers in fashion.

The Passenger Pigeon (Ectopistes migratorius) (Figure 23.3)

Once one of the most abundant birds in North America, hunted extensively in the nineteenth century.
The last passenger pigeon died in the Cincinnati Zoo in 1914.
The ecological effects of its extinction on the eastern deciduous forest are presumed to be considerable.

Conservation Efforts and Organizations

Before 1945, the Ecological Society of America advocated for national parks and better management.
In 1948, the society separated science from advocacy, leading to the formation of the Ecologists’ Union.
In 1950, the Ecologists’ Union became The Nature Conservancy, integrating science with advocacy and conservation work.
Conservation biology emerged as a scientific discipline in the early 1980s, applying knowledge to the preservation of species and ecosystems.
The Society for Conservation Biology, founded in 1985, arose in response to the biodiversity crisis.
Professional journals and academic programs dedicated to conservation biology demonstrate the growing acceptance and need for this discipline.

Conservation Biology as a Value-Based Discipline

Science aims for objectivity in data collection and interpretation.
However, science is not free of human values and takes place within a larger social context.
Conservation biologists acknowledge the implicit and explicit values in their work.
The discipline is “mission-driven” and “crisis-oriented,” revealing the values behind the science.

The Role of Ecologists

Ecologists understand the biological consequences of changes taking place on the planet.
Tropical biologist Dan Janzen emphasized the need for biologists to invest care, energy, effort, strategy, tactics, time, and cash to conserve the tropics.
Motivation does not detract from the objectivity of scientific studies.
Conserving biodiversity requires sound and credible analyses, weighing trade-offs between conservation and resource extraction.
Analyses are subjected to rigorous scientific review by other scientists.

Biodiversity Declines Globally

CONCEPT 23.2: Biodiversity is declining globally.
The Anthropocene: The term