FES 240 1.1 Forest Ecosystem Services - GENERAL NOTES (knowt)

Definition of a Forest

• Area-based criterion

  • Typically >0.5 hectare (ha) in size.

• Vegetation dominance

  • Must have >10\% tree-canopy cover.

  • Includes trees, shrubs, vines, and other woody plants.

• Ecosystem perspective

  • Forest is not just trees; it also comprises:

  • All other living organisms (microbes, plants, animals).

  • Physical environment: soils, rocks, landforms.

  • Hydrologic components: surface water, groundwater, precipitation inputs.

• Plurality of definitions

  • >250 separate definitions exist worldwide, each reflecting differing cultural, economic, and ecological emphases.

  • Implication: management and policy debates often hinge on which definition is adopted.

Global Forest Distribution & Tree Cover

• Present-day forest cover ≈ 25 % of Earth’s land surface.

• Historical estimates suggest ≈50 % forest cover prior to large-scale human conversion.

• Tree-cover gradient (DeFries et al., 2000; WRI):

  • <10\%, 10!\text{–}25\% , 25!\text{–}40\%, 40!\text{–}55\% , 55!\text{–}70\%, >70\%.

  • Displayed on Interrupted Goode’s Homolosine projection to reduce high-latitude distortion.

• Climatic control on forest types

  • Tropical, temperate, boreal, montane, mangrove, etc., each adapted to specific temperature-precipitation regimes.

Ecosystem Services Provided by Forests

1. Carbon Storage & Climate Regulation

• Global carbon pool in forests (biomass + deadwood + litter + soil) ≈ 1.5 × atmospheric carbon.

  • Expressed: C{\text{forest}} \approx 1.5\,C{\text{atm}}.

• Services

  • Long-term sequestration moderates atmospheric \text{CO}_2 concentrations.

  • Forest canopies alter albedo and latent heat flux, influencing regional temperature.

  • Enhanced evapotranspiration ⇒ higher local and regional precipitation.

• Dynamic processes covered in course

  • Carbon inputs: photosynthesis, net primary production (NPP).

  • Storage pools: living biomass, coarse woody debris, soil organic carbon.

  • Loss pathways: respiration, decomposition, disturbance (fire, harvest).

2. Biodiversity & Wildlife Habitat

• U.S. forest-dependent taxa (Iverson 2002):

  • 865 native woody plant spp.

  • 419 mammals; 281 reptiles; 240 amphibians.

  • 800 freshwater species.

  • Forest lands host ≈90 % of U.S. bird, freshwater, and amphibian spp.; ≈80 % of mammal & reptile spp.

• Tropics as biodiversity hotspots

  • Tropical forests harbor ≈50 % of global species richness on ~7 % of land area.

• Habitat functions

  • Structural complexity (canopy strata, snags, coarse woody debris) → niche diversity.

  • Connectivity corridors for migration & gene flow.

3. Water Regulation & Supply

• Interception: tree crowns capture rainfall, reducing erosive kinetic energy.

• Infiltration & filtration: litter layer and porous soils enhance percolation, remove sediments & pollutants.

• Base-flow maintenance: deep roots sustain streamflow during dry periods.

• Outcome: high-quality, stable water resources for human consumption, agriculture, and aquatic ecosystems.

4. Provisioning Services – Wood & Fiber

• Products: lumber, engineered wood, pulp and paper, bioenergy feedstocks.

• Economic relevance: supports global forest-product trade and rural livelihoods.

• Sustainability considerations: rotation length, reduced-impact logging, certification (FSC, PEFC).

5. Non-Timber Forest Products (NTFPs)

• Edibles: mushrooms (e.g., Pleurotus spp.), berries (e.g., mountain huckleberry), nuts.

• Medicinals: bark, leaves, roots used in traditional & modern pharmacology.

• Floral greens, mosses, lichens for horticulture & craft.

• Socio-economic note: critical seasonal income for many forest-adjacent communities.

6. Recreation, Aesthetic & Spiritual Values

• Activities: hiking, camping, hunting, fishing, wildlife watching.

• Scenic beauty: redwood groves, waterfalls, fall foliage.

• Cultural & spiritual sites: sacred groves (e.g., Ambohimanga in Madagascar), Christmas-tree traditions, contemplative landscapes.

• Psychological benefits: stress reduction, inspiration, sense of place.

Influence on Regional Weather Patterns

• Temperature moderation

  • Dense canopies in lower latitudes often yield cooler understory microclimates.

  • Boreal forests may increase regional temperature by lowering albedo (dark surfaces absorb solar radiation).

• Precipitation enhancement

  • Evapotranspiration contributes water vapor → cloud formation → increased rainfall.

  • Feedback loops can sustain moist forest biomes (e.g., Amazon Basin).

Integrative Perspective & Ethical Implications

• Forests act as life-support systems

  • Stabilizing climate, conserving biodiversity, protecting water, providing resources.

• Ethical stewardship questions

  • Intergenerational equity: maintaining forest functions for future generations.

  • Rights of indigenous peoples & local communities.

  • Balancing extractive use with ecosystem integrity (sustainable forest management).

• Policy intersections

  • REDD+ (Reducing Emissions from Deforestation and Degradation) for climate mitigation.

  • Biodiversity conventions, water-quality regulations, recreation access planning.

Key Numerical & Statistical References

• 0.5\,\text{ha} threshold for forest definition (course standard).

• >10\% canopy cover for “dominated by trees.”

• Present vs. historical forest cover: 25\% vs. 50\% of land area.

• Carbon pool differential: C{\text{forest}} = 1.5\,C{\text{atm}} (≈50 % more).

• U.S. species counts (plants 865; mammals 419; reptiles 281; amphibians 240; freshwater spp. 800).

• Biodiversity reliance: forests harbor 90\% of U.S. bird/freshwater/amphibian spp.

Real-World Examples & Visual References (from slides)

• Amazon River basin: illustrative of vast tropical forest-water interactions.

• Redwood National Park (USA): iconic recreational & aesthetic value.

• Wapta Falls (Canada), Big South Fork National Park (USA): scenic forested watersheds.

• Cordwood & bale imagery: demonstration of timber & biomass products.

• Huckleberries, oyster mushrooms: NTFP diversity.

Course Trajectory & Foundational Linkages

• Builds on ecological principles (energy flow, nutrient cycling).

• Will delve into:

  • Forest biogeochemistry (carbon & nutrient fluxes).

  • Disturbance ecology (fire, pests, land-use change).

  • Silviculture & management strategies for sustaining ecosystem services.

• Understanding forest ecosystem services provides context for subsequent modules in forest biology, conservation, and resource policy.