Ecology of the Central Andes final exam

What are several adaptation mechanisms of plants in coastal dry forests?

1) Dropping leaves during the dry season

2) Green bark (Ceiba) which is photosynthetic through the dry season when the tree lacks leaves

3) Storing water in cortical cells of the trunk (Ceiba)

• can give trunk a swollen appearance

4) Nitrogen fixation in the roots: improves the condition where the plant lives

What are the two different syndromes with respect to photosynthetic activity in woody stems?

1. Presence of stomata in the epidermis of the stem

2. Chlorophyllous cells in the bark cortex refix a portion of the CO2 respired

How do El Niño events effect coastal dry forests and what does this indicate about the adaptions of this ecosystem?

Most tree growth is concentrated in years with unusually high precipitation, coincident with El Niño events

• Physiology that can tolerate several years of sub-optimate growth conditions

During El Niño precipitation events: increased growth of all species

In some cases major El Niño events can result in forest recolonization in arid areas of the Sechura desert.

Thus, in N. Perú, ENSO fundamentally shapes these unique and highly endemic ecosystems

Are coastal dry forest species generally adapted to fire?

No, the lack of adaptations to fire indicates that this has not been an evolutionary force in this biome

What can coastal dry forests tell us about past climatic events?

El Niño events cause increased growth rates and therefore affect tree rings formed in these years. Thus, analysis of tree rings can indicate when these events occurred

What are some of the ecosystem services of tropical dry forests?

• High amounts of carbon sequestration - might help to mitigate climate change

• Provision of resources:

  • Food

  • Fibers (from ceiba)

What are some of the major threats to tropical dry forests?

• Selective extraction of forest species for firewood, coal, and manufacturing crates

• Illegal capture of parrot/parrakeet species for pet market, hunting of some animals for consumption

• Grazing, agriculture and urban expansion

What is an East-Andean mountain cloud forest?

Evergreen mountain forest in tropical areas, where local conditions cause cloud and mist to be frequently in contact with the forest vegetation

What are the most important characteristics of an East-Andean mountain cloud forest?

• Enhanced net precipitation through direct canopy interception of cloud water and low water use

• In comparison with lower latitude tropical moist forest:

  • reduced tree stature

  • high stem density

  • tree characteristics: gnarled trunks/branches, dense compact crowns, small/thick/hard leaves

  • high proportion of biomass as epiphytes (air plants)

  • highly organic soils

  • high endemism

What is an epiphyte? Why are they common in cloud forests?

Also called air plants, grows upon another plant or object merely for physical support—not parasitic

Cloud forests:

• access to sunlight by growing near the crowns in dense shaded forests

• Access to nutrients available leaf and other organic debris that collects high in the tree canopy

• Access to moisture in fog

Where are East-Andean cloud forests found and why?

Eastern slope of the Andes between 500 and 4000m asl

• westbound winds from the Atlantic region hit the Andes and are forced to rise

• Water in moist rising air masses condenses creating a shroud of mist and fog

What characterizes the biodiversity of the East-Andean cloud forests?

• Extremely high biodiversity

• High endemism

• Remoteness/difficult access used to protect them from human encroachment

What is the limiting factor for vegetation growth in East-Andean cloud forests and why?

N-limitation because there are slower decomposition and mineralization rates due to lower temperatures

What characterizes net primary productivity (NPP) in East-Andean cloud forest?

• total NPP declines with elevation

• Factors controlling NPP: temperature limitation of mineralization in non-saturated soils, and inhibition of mineralization caused by water-saturation in the cloud forest zone (satured soils)

  • reduces the mineralization rate of organic matter and thus the availability of nutrients such as nitrogen, but it also increases the content of soil carbon

What is soil carbon? Why is it important?

Carbon that is fixed by plants and transferred to the soil via dead plant matter

Improves the physical properties of soil: major factor in its overall health

• increases the water-holding capacity

• contributes to the structural stability

• soil organic matter (carbon is a major part) holds a great proportion of nutrients—prevents nutrient leaching and buffers soil from changes in pH

largest terrestrial reservoir of organic carbon

• high in regions with slow carbon mineralization

What does the color of soil tell us?

Darker color —> more organic matter than light color

What are the major threats to East-Andean cloud forests?

• Erosion: steep slopes and fragile soils

• Sensitive to climate change: trees are migrating upwards, but the treeline is in many cases not moving upwards

• Agriculture, deforestation

• dams, roadbuilding

• oil mining

What is a tree line?

Tree line = edge of the habitat at which trees are capable of growing. found at high elevations/high latitudes

• beyond this line trees cannot tolerate the environmental conditions (usually cold temperatures, extreme snowpack, or associated lack of available moisture)

How is the tree line in East-Andean cloud forests changing with climate change?

Inability of tropical cloud forest species to invade grasslands above the treeline with climate change → not changing

• Many cloud forest species at low/middle elevations have already begun responding to increases in temps by shifting their distributions upslope

• But none of the sites from the Andes reported an upslope movement of the treeline

• Additional factors besides temperature affect treelines

  • Microclimate: harsher conditions such as more frequent/severe frosts

  • location of cloud immersion zone

  • exposure to solar radiation

  • reduced dispersal and survival of tree seeds outside of the forest

  • human activities (grazing)

Why are Amazon peatlands important?

Tropical peatlands are among the most carbon-dense ecosystems

What are coastal wetlands, and why are they important? What feeds them?

Mangroves, marshes, or lakes

Water sources: groundwater, some connected to rivers, seawater

• With fog oasis, form part of a biological corridor along the Peruvian desert coast

• Fauna in wetlands: wide distribution in other countries but restricted in Peru

• Resting, feeding, breeding sites

• Shoreline stabilization

• Protection against sea-level rise

• Sediment and nutrient retention

• Flood attentuation

• Provision of habitats and shelters for residents and migratory species

• Carbon sequestration

• water source

• fodder for livestock, medicinal, and edible plants

• recreation, tourism, education

What are the major threats to coastal wetlands?

• Overexploitation of groundwater

• Most are located near human settlements and are influenced by anthropogenic activities

  • Pollution (eutrophication)

  • agriculture

  • urbanization

  • illegal water abstraction

What are andean wetlands? What feeds them?

Lakes, marshes, and peat bogs

Main water source = precipitation, rivers or groundwater

Naturally open peatlands

What is the importance of Andean wetlands?

• essential role in the dynamics of highland catchment areas

• Habitat to endemic species

• stop over for migratory birds

• shelter and reproduction site for some threatened animals

What is peat?

Accumulation of partially decayed vegetation

• Histosol = soils that contain mostly peat

• peat forms in wetland conditions, when organic matter is inhibited from decaying fully by acidic and anaerobic conditions

• Organic matter accumulates over 1000s of years → records of past vegetation and climates

What characterizes the climate of the Andean highlands?

Very complex and fragile ecosystem

• extreme temp fluctuations

• little rainfall (central/southern part)

• sharp seasonal changes

• soil with low natural fertility

• low oxygen pressure

How does biodiversity change with altitude in the Andes?

• Different types of vegetation correspond to gradients in altitude

• In general: diversity decreases with altitude and endemism increases

What is phytoremediation?

Using plants to treat heavy metals, organic pollutants and radionuclides like uranium from soil

• Antibiotics remediation has been demonstrated

What types of plants characterize Andean highlands and why?

Low growth, cushion plants

• less exposure to wind, stays below snow

What are some adaptation mechanisms to high altitude in plants?

storage of nutrients, moisture and energy

• stems or rhizomes which extend deep beneath the soil’s surface and allow food storage in order to begin immediate growth in the spring

• Waxy substance on their leaves that seals moisture in, because the thin mountain soil cannot retain moisture

• Being evergreen: no requirement for energy and nutrients to develop new leaves during the short growing season

• Increase the ability of the plant surface to reflect sunlight (white waxy substance or white hairs)

What are some animal adaption mechanisms to high altitude?

• hibernation to save energy and avoid harsh winter conditions

• Reducing activity levels such as by having a generalized diet not requiring traveling long distances for food

• physical adaptations to navigate the rocky, steep terrain (like hooves)

• Thick coats of fur to protect from the cold

• Larger hearts/lungs (yaks in himalayas)

• Increased oxygen-affinity of the haemoglobin and faster transport of oxygen

How have Andean peoples adapted to high altitude? How does this differ from other communities that live at high altitudes?

• Andean people: breathe at a normal rate, but have the ability to deliver oxygen throughout their bodies more effectively than people at sea level

• Tibetan people: increase oxygen intake by taking more breaths per minute than people who live at sea level. Also show expanded blood vessels, allowing them to deliver oxygen throughout their bodies - offset low oxygen content in their blood with increased blood flow

What are the major threats to central andean ecosystems?

• Agriculture

• Deforestation

• Mining

What is the difference between a landrace and a cultivar?

• Landrace: local variety of a species that has developed through natural selection in a specific environment, typically adapted to local conditions and cultural practices over generations. Generally aligned with traditional agricultural practices and not deliberately bred

• Cultivar: a plant variety that has been selectively bred for specific charcteriistics, such as yield, disease resistance, or aesthetic appeal. Tend to focus on commercial production.

What characterizes agricultural activity on the peruvian coast?

• recent emergence of highly productive commercial agriculture oriented mainly around the production of high value export crops

• large contribution to the agricultural GDP

• potatoes, maize…

What are some possible solutions to water scarcity at the coast?

• store water in reservoirs

  • risks: earthquakes, contamination, droughts (volume)

• recycling

• water transfer from other reservoirs

• desalination of seawater

• groundwater

  • risk: saltwater intrusion, cost

• Amunas

What characterizes the agriculture of the andean highlands?

• Generally low yields

• Dominated by small-scale, subsistence-oriented mixed farming systems in which production of stapes (potatoes, wheat, quinoa) is combined with livestock keeping

• Growing importance of livestock keeping

What are some types of prehistoric agricultural techniques to deal with water scarcity at the coast?

• sunken field agriculture

• Aqueducts of Nazca

What are some reasons why Peru is considered particularly vulnerable to climate change?

• low-lying coastal area

• arid and semi-arid lands

• areas liable to flood/drought/desertification

• fragile mountain ecosystems

• disaster-prone areas

• areas with high urban atmospheric pollution

• economies highly dependent on income generated from the production and use of fossil fuels

What explains water scarcity in Peru?

Peru holds one of the major availability of renewable freshwater in Latin America

• the problem is how it is distributed

• very little water available at the coast - most of the population located there

What is Equilibrium Line Altitude (ELA)? Why is it important

ELA refers to the altitude at which the mass balance of a glacier is zero, so the input is equal to the abstraction.

• As climate change causes higher temperatures, ELAs are getting higher, meaning that glaciers are receding

What is a Representative Control Pathway?

Representative control pathways are models for how the climate will change depending on different emission scenarios

What is Peak Water?

As glaciers melt with climate change, peak water is the point at which there is the maximum runoff of meltwater. This represents a tipping point after which the runoff will decline as the glacier disappears.

What are Glacier Lake Outburst Floods (GLOFS)? Why are they important?

Outburst flood caused by increased melting of glaciers due to climate change. These floods can have catastrophic impacts on surrounding communities, including mortality and destruction, as well as on nearby ecosystems.