Landscape Ecology and Nature Conservation

Comprehensive vocabulary flashcards covering population ecology, community dynamics, island biogeography, biomes, conservation biology, megafaunal defaunation, dryland seed-based restoration, landscape connectivity, and positive ecological feedbacks.

Population

Group of individuals of the same species occupying a particular

space at the same time, which can interbreed

C3 vs C4 Plants

• C3 plants (trees, shrubs, herbs, temperate grasses) use a C3 photosynthetic pathway that produces a 3-carbon sugar as the first product

• C4 plants (tropical grasses, a few herbs) use a C4 photosynthetic pathway that produces a 4-carbon sugar as the first product

• C4 plants are more CO2 efficient, and therefore more water-use efficient as well - they can open their stomata shorter, so less water escapes

  • C4 plants perform better in hot and dry areas or at relatively low levels of CO2

  • C3 plants perform relatively better under high CO2

Phosphorus cycle

• Geologically determined

• P is released by the weathering of rocks

• Importance of the whale pump for re-distribution of P

• P cycling rates through the global environment is now 3x greater than before the industrial and agricultural revolutions

• Due to P fertilizer, P compounds as cleaning agents and increased flows of P-containing dust through the atmosphere due to desertification and land-use change

• This acceleration of the P cycle causes eutrophication (=nutrient loading) in freshwater lakes

Nitrogen cycle

• Determined by microbial processes

• N2 is main component of the atmosphere

• Bacteria and rhizobium symbionts of plants can fix molecular N2, converting it into ammonium (NH 4+): N fixation

Pros of Urban Ecology

Eases pressures on the environment

Cons of Urban Ecology

• Cities replace agriculture and natural ecosystems

• Sites of concentrated air and water pollution

• Made possible by intensification of agriculture

Why study urban ecology?

1. Ecological novelty: novel ecosystems with new assemblages of species

2. Extent of impacts: urban regions can have an impact at the local, regional, or even global scales

3. Global laboratories: environmental conditions are relatively constant for urban areas all over the world

4. Future growth: studying urban ecosystems helps our ability to change future development to be more nature inclusive

5. Resource abundance: high resource abundance in urban areas gives rise to high abundance of a specific community of (mostly generalist) species

Pathways in which megafauna shape ecosystems

• Foraging

• Dispersing seeds, pathogens, etc.

• Physical impacts (Elephants pushing over trees)

• (Re)distribution of nutrients through animal waste

Earth-system level consequences of megafauna restoration:

• Effects on the climate system

• Effects on biogeochemistry

• Ecological anachronisms and biodiversity

• Effects on emerging infectious disease spread

Critiques on protected area narratives

• Species declines are also in protected areas → How effective are protected areas in conserving biodiversity?

• No guarantees that the right areas will be set aside to effectively conserve biodiversity

• Dominant narratives exclude humans and promotes the separation between humans and nature

• Form of green colonialism or green grabbing. Lack of consideration of indigenous titles and rights

IPBES

The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services

Objective: strengthen the science-policy interface for the conservation and sustainable use of biodiversity, long-term human well-being and sustainable development.

Which factors influence extinction proneness?

• Small geographical range

  • Endemic species: restricted to a small area/islands

• Mobility

  • Low dispersal ability

  • Flightless birds/slow moving

• Specialisation of habitat or diet (niche breadth)

  • e.g. species can only feed on one plant/group of plants

  • Cascade effect

• Life-history traits

  • Low reproductive rate (K-species)

• Body size

  • Larger animals are more prone to extinction than smaller ones

  • Need larger habitats - naturally rarer than small species, loss of habitat, food/prey has higher impact

  • Threat to humans/trophies

• Persecution by humans

  • Food, feathers, medicine, pets, fur/skin, conflicts

Populations are characterized by:

Density: number of individuals per unit area

Age structure: distribution of individuals over age classes

Birth rate: number of new individuals per unit time

Death rate: number of individuals dying per unit time

Population Growth

Expressed as r (per capita rate of increase per unit time)

r depends on the age distribution, survivorship and fecundity per age class

If unchecked by limiting resources, population growth would be exponential

Carrying Capacity ($K$)

The maximum population size of a given species that a particular habitat can sustain indefinitely over time without degrading the habitat.

Intraspecific Competition

Competition between individuals of the same species for limited resources as population density approaches carrying capacity ($K$), which can be indirect (exploitative competition, where organisms only interact through resource depletion) or direct (interference/contest competition, where individuals actively contest resources).

$r$-Strategist (species)

species whose populations spend most of their life history in the rapid growth phase, producing many small offspring with short lifespans and no parental care

k - Strategist (species)

species which spend most of their life history near carrying capacity ($K$), producing few offspring with long lifespans, parental care, and a primary focus on survival.

Communities

An assemblage or association of populations of two or more species occupying the same geographical area in a particular time

Interspecific Competition

Competition between species

Ecological Niche

The role a species plays in its ecosystem and the way tolerances and requirements interact to define the conditions and resources needed by an individual or species.

Fundamental niche

The niche potentially occupied by a species

Realized niche

The niche actually occupied by a species

Competitive Exclusion Principle (Gause’s Principle)

The ecological ecological rule stating that complete competitors cannot coexist; two species competing for the exact same limiting resources can only stably coexist if niche differentiation occurs.

Species Richness

The total count of distinct species present in a defined geographic area at a specific point in time, without accounting for relative abundances.

Species Evenness

A community metric describing the equitable distribution of individual abundances across different species, where higher equality in abundances corresponds to higher evenness.

Shannon-Wiener Diversity Index ($H'$)

A diversity metric calculated as $H' = -\sum_{i=1}^{s} P_i \ln(P_i)$ (where $P_i = \frac{N_i}{N_{\text{tot}}}$), which increases with higher species richness and greater species evenness.

Hill Numbers (Effective Number of Species)

A unified mathematical framework of diversity indices that weights species by abundance:

$q=0$ weights all species equally (species richness)

$q=1$ uses the exponential of the Shannon index (common species)

$q=2$ uses the inverse Simpson index (dominant species)

$\alpha$- Diversity

Diversity at a local scale (within a community), highest when there are many species within each community

$\beta$-Diversity

Differences in diversity among communities within a region, high when different communities in a region differ in the species they contain.

$\gamma$-Diversity

Diversity at the whole regional scale (collections of communities), highest when both individual communities are diverse and the communities in a region differ.

Species-area relationship

Strong positive relationship between species richness and size of an area. Forms linear line using a log-log scale. Can also be used to determine minimal plot size to accurately describe a community.

Theory of Island Biogeography

The number of species on an island is determined by a balance between immigration and extinction. The balance is dynamic, with species continually going extinct and being replaced through immigration by the same or different species. Immigration and extinction rates may vary with island size and isolation.

Predictions of Theory of Island Biogeography

• Number of species on an island eventually constant over time (S*)

• Determined by equilibrium between number of extinctions and

immigrations

• Large islands have more species than small islands

• The number of species declines with the distance to the mainland (isolation)

Ecological Succession

The gradual change in species composition of a given area. New environmental conditions allow one group of species in a community to replace other groups until climax state is reached.

Primary succession

The gradual establishment of biotic communities in lifeless areas where there is no soil or sediment

Secondary succession

Series of communities develop in places containing soil or sediment. The sequence of recovery of a community.

Alexander von Humboldt

One of the key founders of current-day ecology. During his travels around the world he recognized consistent vegetation patterns, linking it to climate as central driver, and concluding that forests are the logical climatic climax

Ecological succession in grasslands

From annual, biennial & short-lived perennial forbs and grasses to long-lived perennial forbs, grasses, and underground trees

"Ecosystems Uncertain"

Robert H. Whittaker's (1975) term for intermediate climate envelopes where climate and soils alone do not determine vegetation structure, leading to alternative stable states (such as closed forests or open grassy biomes) mediated by fire and herbivory.

What is classified as degraded land?

Partly properly degraded lands due to deforestation, overgrazing, and soil erosion. Large parts of the savannah, grasslands and shrublands biomes.

Old-Growth Grasslands

Ancient, highly diverse, non-forest ecosystems maintained across millennia by fire and large mammalian herbivory ($C_3$ grasslands developing $20-30\,\text{Ma}$ and $C_4$ grasslands developing $3-8\,\text{Ma}$) that store carbon predominantly underground in root systems and soil organic matter.

Ecoregion

Large unit of land or water containing a geographically distinct assemblage of species, natural communities, and environmental conditions.

Mosaic

Pattern of patches, corridors and matrix

Matrix

The background ecosystem or land-use type in a mosaic

Patch

A relatively homogenous area that differs from its surroundings

Larger patches often have more species because:

• Less disturbed

• More variety in vegetation

• Fewer extinctions

• More immigrations

Types of edge effects

Abiotic (altered microclimate): Temperature, Light, Humidity, Wind

Biotic: Nest predation, Breeding success, Weed invasion, Parasitism.

Central drivers of biodiversity loss

Landscape change and habitat fragmentation, which is potentially re-enforced by increased edge effects. For many species (but not all) this also causes habitat loss. Another key aspect of landscape change is the loss of connectivity and landscape heterogeneity.

Landscape Connectivity (Human)

The degree to which the landscape facilitates or impedes movement among resource patches. Considers the amount and configuration of native vegetation, comprised of corridors, stepping stones and a matrix.

Habitat connectivity (single-species)

Species specific connectivity, for many native species it increases with landscape connectivity.

Ecological connectivity (ecosystem)

The connectedness of ecological processes. For many processes, it increases with landscape connectivity.

Corridors

Can either connect patches and allow movement or dissect patches (e.g. powerlines) and create barriers

Stepping Stones

Series of small, non-connected patches that are used to find shelter, food, or rest. May provide most corridor functions.

Metrics to measure landscape connectivity

• Buffer-based measures (% native vegetation within 1km radius)

• Nearest-neighbor-based measures (distance to nearest patch larger than 10 ha)

• Measures based on requirements of particular species (Cost-distance measures)

Critical species interactions

The dispersal and movement routes of highly interactive species (e.g. pollinators, large carnivores) are part of ecological connectivity

Disturbance at local and regional scales

Both natural and anthropogenic disturbance (e.g. fire, grazing, land clearing) can disrupt or maintain ecological connectivity

Long distance biological movement

Large-scale migration (seasonal or resource-driven) of animals can be part of ecological connectivity

Hydroecological processes

Relates to the role of vegetation in regulating hydrological flows, such as water infiltration, subsurface water flows, and run-off; the spatial continuity of these processes is part of ecological connectivity

Coastal zone flux

Natural flows in the coastal zone (e.g. migrating shorebirds, freshwater ecosystems) can be disrupted by human activities, representing a loss of ecological connectivity

Global Climate Change

Species may need to shift their ranges to adapt to climate change; such range shifts are part of ecological connectivity

Spatially-dependent evolutionary processes

Long-term ecological connectivity is needed to maintain the evolutionary potential of biodiversity

Spatial Heterogeneity (3 types)

The uneven, non-random distribution of objects:

• Structural: Complexity or variability in space of a system property, either horizontally (e.g. land cover) or vertical (e.g. uneven vegetation distribution above ground)

• Functional: Complexity or variability of a system property that affects ecological processes

• Temporal: Variation for a single point in time

Characteristics of island communities

• Low species richness

• Disharmonic biota

• High endemicity

• Few interactions

Characteristics of island species

• Demographic release

• Ecological release

• Flightlessness

• Dwarfism

• Gigantism

• Secondary woodiness

• Loss of defenses

• Tameness

• Slow reproduction

• Loss of dispersal ability

Vicariance Model of Island Biogeography

• Earth is dynamic

• Evolutionary/Geological timescales

• Phylogenies of organisms reflect geological history of fragmentation

• Emphasis on phylogenetic diversification (not on extinction and migration)

• Little attention to ecological processes

Equilibrium model of Island Biogeography

• Species distributions are dynamic

• Ecological timescales

• Communities on islands are loose assemblages (not co-evolved)

• Emphasis on extinction and migration (not on speciation)

• Little attention to evolutionary processes

Key assumptions of the equilibrium model of IBT

• Area influences extinction

• Isolation influences immigration

• Turnover:

  • Species composition is constantly changing

• Dynamic equilibrium:

  • Species richness is relatively constant

Species-Isolation relationship

• Isolated islands support fewer species than islands that are located nearer to continents

• The decline of species richness is often a negative exponential or sigmoidal function of isolation

• Using transformations, this relationship can be linearized to allow statistical analysis and comparisons among studies

Critique on EMIB 1

• Isolation is not purely a function of distance

• Area is not necessarily reflective of carrying capacity

• Immigration may be affected by area → target effect

• Extinction may be affected by isolation → rescue effect

• Anomaly of species richness on small islands (independent of area) → small island effect

• Disturbances may prevent equilibrium

• Interspecific differences and interactions among species

• Importance of speciation

Immigration and colonization in terms of isolation

• Immigration decreases with isolation; function of the distance from the mainland (source of potentially colonizing species)

• Successful immigration (colonization) decreases with species richness

  • Limited pool of species to colonize an area

  • As S increases, fewer new species to immigrate

  • Increased competition (i.e. fewer available niches)

Types of dispersal:

• Active dispersal (sea gulls, bats)

• Passive dispersal (floating terrestrial organisms, rafting on wood, animals, human debris

• Non-standard dispersal (oysters on a buoy)

When does extinction risk increase?

• With decreasing island area (proxy for resources & lower habitat heterogeneity)

  • Smaller islands have higher extinction rates (fewer individuals within a species → more vulnerable to extinction)

• Extinction risk increases with increased species richness

  • Fixed area has finite resources

  • As S increases, so does competition (intra & inter)

Causes of extinction

HIPPO

• Habitat destruction

• Interactions/invasive species

• Pollution

• Population (and consumption)

• Overharvesting

New models for diversity on islands:

• Area and isolation change over time

• Setting a baseline:

  • Island biodiversity patterns

  • Island geographical dynamics

• General Dynamic Model

• Glacial Sensitive Model

Types of interspecific interactions:

• Neutral (0/0)

Inhibition

• Amensalism (0/-) e.g. Bison rolling in grass

• Predation (+/-)

• Herbivory (+/-)

• Competition (-/-)

• Antagonism/parasitism (+/-)

Facilitation

• Commensalism (0/+)

• Mutualism (+/+)

  • Three stage mutualism

Reforestation vs. Afforestation

Reforestation is the establishment of trees on historically forested lands that were previously cleared, whereas afforestation is the planting of trees or commercial plantations onto historically open, non-forest ecosystems such as natural grasslands and savannas.

Conservation Biology (Soulé’s Definition)

A crisis-driven, mission-oriented, interdisciplinary discipline formalized in 1985, grounded in normative postulates including that biological diversity is good, ecological complexity is good, evolution is good, and biotic diversity possesses intrinsic value.

Ecosystem Services

The conditions and processes through which natural ecosystems and their constituent species sustain and fulfill human life (Daily, 1997), categorized by the Millennium Ecosystem Assessment (2005) into provisioning, regulating, supporting, and cultural services.

Nature’s Contributions to People (NCP)

The IPBES framework for describing all contributions—both positive and negative—of living nature to people's quality of life, emphasizing indigenous and local knowledge, the central role of culture, and plural valuation.

Relational Values

Values that reflect the meaningful relationships, cultural attachments, responsibilities, and bonds of care between humans and nature, distinct from both intrinsic and instrumental values.

IUCN Red List Categories

A standardized categorization system of global extinction risk maintained by the Species Survival Commission (SSC), comprising Extinct (EX), Extinct in the Wild (EW), Critically Endangered (CR), Endangered (EN), Vulnerable (VU), Near Threatened (NT), Least Concern (LC), Data Deficient (DD), and Not Evaluated (NE).

Functional Extinction

The reduction of a species' population to such low numbers that it ceases to play its functional ecological role or support significant ecological processes within its ecosystem, occurring before numeric extinction.

30 by 30 Initiative

Target 3 of the Kunming-Montreal Global Biodiversity Framework (COP 15, 2022) aiming to effectively conserve and equitably manage at least $30\%$ of Earth's terrestrial, inland water, coastal, and marine areas by the year 2030.

Equilibrium Model of Island Biogeography

A model formulated by Robert MacArthur and Edward O. Wilson (1963, 1967) proposing that island species richness reaches a dynamic equilibrium ($S^*$) balance between immigration (which decreases with isolation from the mainland) and extinction (which decreases with island area).

Species-Area Power Law

The mathematical relationship $S = c A^z$ (or $\log(S) = \log(c) + z \log(A)$) describing how species richness ($S$) scales with area ($A$), where $z$ typically ranges from $0.15$ to $0.39$, generally yielding a rule of thumb where a tenfold increase in area doubles species richness.

Target Effect and Rescue Effect

Two modifications to MacArthur-Wilson theory: the ___ effect states that larger islands have higher immigration rates because they are easier for dispersers to intercept; the ___ effect states that less isolated islands experience lower extinction rates due to ongoing demographic replenishment from the mainland.

Small Island Effect

The ecological anomaly where species richness on very small islands varies independently of island area, driven instead by environmental stochasticity, disturbance, or habitat absence.

Tens Rule

A rule of thumb in invasion biology stating that roughly $10\%$ of introduced alien species establish self-sustaining naturalized populations, and roughly $10\%$ of those established species become invasive pests.

Defaunation

The progressive loss, extirpation, or extinction of animal populations, specifically large-bodied mammalian megafauna, from ecosystems due to anthropogenic causes.

Passive Rewilding

The spontaneous recolonization, expansion, and recovery of wild species, carnivores, and ecological processes resulting from land abandonment, reduced hunting pressure, and protective policies without active animal translocations.

Peak Agricultural Land

The global milestone reached around the year 2000 where total land area dedicated to agriculture (croplands plus livestock pasture) plateaued and began to decline globally, primarily driven by reductions in pastureland.

Great Whale Nutrient Pump

The vertical and horizontal biological transport mechanism whereby whales feed on deep-sea nutrients and release faeces in surface waters, fertilizing phytoplankton and driving planetary biogeochemical cycling and atmospheric carbon capture.

Ecological Anachronism

Plant traits (such as large, tough-coated fruits like the avocado) that evolved to facilitate seed dispersal by mutualist partner megafauna that have since gone extinct (Janzen and Martin, 1982).

Main pathways of zoonotic transmission

• Vectors (ticks)

• Direct contact with animals (food)

• Proximity to animals and/or animal waste

Cross-Species Herd Immunity

The disease-dilution mechanism in diverse, intact megafaunal assemblages where high pathogen sharing among diverse non-competent hosts lowers host-specificity and pathogen virulence, reducing zoonotic transmission spillover to humans.

Aridity Index ($AI$)

The ratio of mean annual precipitation ($\text{MAP}$) to mean annual potential evapotranspiration ($\text{PET}$), used to define drylands ($AI < 0.65$), which are subdivided into hyper-arid ($AI < 0.05$), arid ($0.05 < AI < 0.20$), semi-arid ($0.20 < AI < 0.50$), and dry subhumid ($0.50 < AI < 0.65$).

Grassland Degradation (Socio-Ecological Definition)

A condition assessed from a socio-ecological perspective where the aggregate supply of multiple ecosystem services provided by a grassland fails to satisfy the demands of local stakeholders (e.g., pastoralists, ranchers, conservationists).

Cenchrus ciliaris (Buffel Grass)

A perennial, highly drought-tolerant African rangeland bunchgrass possessing deep fibrous roots ($> 2\,\text{m}$) and allelopathic properties, which serves as valuable forage in native ranges but acts as a destructive invasive pyrophyte altering fire regimes when introduced in Australia and the Americas.

Seed Enhancement Technologies

Post-harvest seed treatments, such as deterrent coatings (e.g., chili pepper, pine oil, anthraquinone) or biological priming, applied to protect sown seeds from rodent and bird predation, break dormancy, and improve field emergence.