Value of Biodiversity Flashcards
what is biodiversity?
“The variability among living organisms from all sources… including diversity within species, between species, and of ecosystems” – CBD, 1992
what are the three components of biodiversity?
- Elements (e.g. species, genes, ecosystems)
- Relative abundance of those elements
- Differences among them (e.g. functional, phylogenetic)
what are the three types of diversity and the differences?
- Species Diversity
- Species richness = number of species
- Evenness = relative abundance
Most common metric due to its practicality and existing data - Functional Diversity
- Based on ecological roles or traits (e.g. feeding methods)
- Often aligns with phylogenetic groups - Phylogenetic Diversity
- Reflects evolutionary relationships among species
what has been the main cause in major fluctuations of species richness over geologic time?
- Periods of growth punctuated by mass extinctions
→ Six major events: e.g., End-Permian, End-Cretaceous
what are the current global trends in species richness?
- Extinction rates now 100–1000× higher than the fossil baseline
(WWF, 2022) - -69% average species population decline since 1970
o Freshwater species: worst hit (–83%)
o Global patterns vary, but declines occur across all continents
(WWF Living Planet Report)
what are the UK trends in species richness
- Species extinction & colonisation are roughly balanced since 1900
(Gurney, 2015) - 1.7% of UK species are new colonists; flying species more likely to arrive
what does the Stat of Nature report (2023) say for UK biodiversity changes?
- 19% decline in abundance (753 species since 1970)
- 27% increased, 38% declined
direct drivers of biodiversity loss (WWF, 2022)
o Land/sea use change
o Overexploitation
o Pollution
o Invasive species
o Climate change (increasingly important)
Already caused 1.2°C global warming
1.5°C → 70–90% coral loss; 2°C → >99%
what is the ecosystem impact of biodiversity loss?
Loss of connectivity disrupts gene flow, migration, reproduction
→ Leads to ecological dysfunction → Undermines resilience & services (pollination, water flow, etc.)
What did Franco et al. (2009) find with reserve design as a conservation strategy
Goal: Identify high-priority conservation areas across Britain
Method: Used ZONATION algorithm to analyse species distribution/connectivity
Findings: Conservation based on one taxonomic group (e.g. birds) doesn’t protect others (e.g. butterflies)
* Narrow-range species are better biodiversity surrogates
* Multi-taxa approach = better conservation outcomes
- a connectivity-based reserve design is crucial
what do ecosystems provide?
o Climate regulation
o Water purification
o Pollination
o Carbon storage: Forests absorb ~7.6 Gt CO₂/year (18% of human emissions)
what are some examples of connectivity conservation?
o Maintains species movement and ecological function
o Tools: corridors, linkage zones, wildlife crossings
o Evidence supports that connected habitats preserve biodiversity more effectively
(WWF, 2022)
what are the intrinsic values of biodiversity?
- Non-utilitarian perspective: Organisms have value simply because they exist—independent of human use.
- Ethical stance of biocentrism: Nature has moral rights and interests (e.g., growth, reproduction).
what did Silvertown (2015) warn?
commodifying nature can oversimplify its value and may not result in better conservation outcomes.
Placing a cash value on nature may reduce its perceived importance and make it vulnerable to exploitation
Instrumental Value of Biodiversity
- Anthropocentric view: Nature is valuable because it provides goods and services essential to human well-being.
- Goods: Food, fibre, fuel, biochemicals
- Services: Pollination, climate regulation, water purification
- Cultural value: Recreation, aesthetics, identity, spirituality
what are the 4 main categories of Ecosystem Services defined by the Millennium Ecosystem Assessment.
- Provisioning
* Tangible products: food, water, timber, medicines - Regulating
* Climate regulation, pest & disease control, flood mitigation, pollination - Cultural
* Recreational, spiritual, educational, aesthetic, heritage-based value - Supporting
* Underlying processes: soil formation, nutrient cycling, primary production
what is biodiversity’s role in ecosystem function?
Functional Complementarity
* Different species perform different ecosystem roles → more functions maintained
* Diversity helps cover a wider range of ecosystem needs
Selection Effect
* Higher chance of including a high-functioning “super species” in a diverse system
what is the example of pollination as an ecosystem service?
Californian Watermelons
* ~1000 pollen grains needed per fruit.
* Wild pollinators in species-rich habitats (near wild areas) are more effective.
Pollination service rapidly declines as bee species richness drops.
what is the example of carbon stage as an ecosystem service?
European Grasslands
* Plant communities with reduced diversity store less carbon.
* Impacts carbon sequestration, a key function for climate regulation
what is the example of pest control as an ecosystem service
Agroecosystems
Thies & Tscharntke (1999):
* Complex landscapes (with uncultivated patches) support more natural enemies of pests.
* Parasitoid populations thrive in older, larger non-crop areas → reduced crop damage.
* Threshold effect: <20% non-crop area = dramatic drop in pest control efficiency
what is ecosystem multifunctionality? where is relevant?
the more species = the more functions sustained at once.
o For multiple functions, a larger number of complementary species is required.
o At larger spatial/temporal scales, more species are essential to maintain ecosystem performance.
what does ecosystem stability depend on?
- Perturbation
- Resistance
- Resilience
how does biodiversity affect resistance and resilience?
Biodiversity provides stability through resistance, but not necessarily faster recovery.
what are the grassland experiments by Isabell et al. (2015) demonstrating this.
46 grassland experiments
* Resistance: High-diversity plots had smaller drops in productivity during droughts/floods (16–32 spp. = ~25% loss; 1–2 spp. = ~50% loss).
* Resilience: Ecosystems tended to recover regardless of biodiversity, but high diversity buffered initial impact better.
