Plant Ecology Lecture 1 and 2

EXAM 1 - introduction to global change & biomes and plant physiognomy

What four items did David Attenborough listed as four factors that plants need for life? Did he omit any particularly important element? If so, why this omission?

water, nutrients, sunlight, and warmth. he omitted oxygen/air.

How do some arctic plants, like poppies, maximize solar radiation/warmth they receive during the long days of short arctic summers to facilitate fruit maturation?

poppies turn their flowers to track the moving sun to gain maximum light during short summers.

How do some plants extend their growing/flowering seasons in cold alpine environments?

plants grow flowers in fall so they are already developed and blooming as soon as the snow melts.

In what biome would you find cushion plants? How are they adapted to their environment?

alpines. they’re adapted to conserve heat, reduce windchill, and absorb sunlight easily.

How do tall plants like giant lobelias and cabbage groundsels protect themselves against freezing air temperature at night in tropical alpine zones?

giant lobelias have hair on leaves to keep warm and reduce windchill. cabbage groundsels have outer layers that protect inner rosettes from cold.

How does moss handle frost heaving in alpine environments?

moss is unattached from soil so it can be carried up by ice formation instead of being ripped from the ground.

What three adaptations were mentioned for the quiver tree that allow it to live in the hot and dry environment of the Namib Desert? Do they differ from the adaptations of the saguaro cactus to the environment of the Sonoran Desert and if so how?

quiver trees have branches with white power coating to reflect light, leaves with small pores to prevent water loss, and the trunk is smooth and mostly impermeable. The saguaro cactus has flowers at the tops of trunks to maximize rainfall intake and spikes to defend their water storage.

How did the window plant adapt to the scorching sun (and blowing sand) of the desert? Are there any drawbacks of that strategy and if so what are they?

they keep most of the plant and its resources underground with only the tips above ground for sunlight to minimize heat and wind damage. the drawbacks are that wind can cause sand to cover the plant and halt sunlight intake and that this exposes the plant to herbivory by mole rats underground.

How do desert annuals survive dry spells that can often last for many years?

desert annuals produce many desiccation-resistant seeds which are able to withstand years of dry spells and only grow when conditions are favorable.

Why are the dessert blooms so colorful?

the short growing season creates an urgent need for pollination, so flowering plants grow bright flowers to compete for pollinators.

Mt. Roraima is a small sandstone plateau \~9,000 feet high emerging from lowland rainforests on the edge of the tropical eastern Amazonia with 30% of plant species endemic to the mountain. What particularly unique life strategy did some of these species evolve and why?

some plants are carnivorous (eat insects) in order to gain nutrients for growth that are unavailable in the nutrient poor soil of the rainforests.

Contrast the ways by which pitcher plants, sundews, and bladderworts obtain nutrients.

pitcher plants have tubes with downfacing hairs that sucks insects inside and drowns them. sundews have sticky hairs which trap insects then fold over to keep them stuck and crush them. bladderworts use their sensitive hairs that trigger the bladder to open and sweeps bugs in.

What are the positives and negatives that aquatic plants in the Amazon lowlands experience?

aquatic plants must compete for light and adapt to the heavy rainfall which leads to a constantly changing water level. amazon lilies have a large surface area to combat this which also allows pollination by beetles. cypresses use the mud deposition from the changing water level to help secure its roots in the lake floor.

How are mangrove root systems and fruit adapted to the coastal environment?

mangroves have a tangled network of prop roots to help keep them upright despite the changing tides, which have large pores on their arches which allow them to take in oxygen. Their fruit germinates while still on the parent tree which gives them a better chance of establishing themselves on the sea floor.

What are the adaptations that allow kelp to inhabit marine environments?

they grip onto the rocks and have no rigid stem but rather a strong flexible cable-like stem which allows them to flow with the water without getting torn.

What are the greatest threats to biodiversity over the next 80 years? How would you rank them and Why?

1. land use 2. climate change 3. nitrogen deposition 4. biotic exchange 5. atmospheric CO2

What are some of the key trends in global concentrations of CO2? What is the preindustrial level of CO2, and what is the current level?

global concentrations of CO2 have increased especially after industrialization. today’s CO2 levels are 45% higher than preindustrial levels (280 ppm compared to 420 ppm).

What are the key changes to the global nitrogen cycle caused by humans? How do they affect the biosphere and plants specifically?

humans are fixing more nitrogen than is fixed naturally. for the biosphere, this causes eutrophication and increased global warming. for plants, this causes increased biomass, lower species richness, faster decomposition rates, decline in symbiotic nitrogen fixation (including mycorrhizae), and lower tolerance to stress.

What are some of the key linkages between global climate change and changes in two global biogeochemical cycles that we discussed?

carbon dioxide and nitrogen are greenhouse gases so the increasing quantities of both add to global climate change.

What are some of the success stories suggesting that humanity can limit its negative influence on global biogeochemical cycles, atmosphere, and climate?

Clean Water and Clean Air Act both reduced acid rain and subsequently improved tree growth in Eastern US. The Montreal Protocol significantly improved the hole in the

ozone layer by regulating CFCs and HCFCs.

What are some of the land-use changes that threaten biodiversity the most?

increasing agricultural crops, pastures, settlements, or industry

Explain changes across various trophic levels documented in some of the remote tropical rainforests in Puerto Rico.

insect populations are declining which has led to declining populations of animals in higher trophic levels like lizards.

Discuss how can a non-native invasive plant species change human land use, cause economic costs, and affect the natural disturbance regime.

invasive plant species change human land use by encouraging the use of herbicides and pesticides, causing economic cost due to crop damage, and affect the natural disturbance regime by increasing the amount of disturbance of an ecosystem.

Which environmental & socioeconomic indicators discussed in the two Ripple papers suggest improvements over the past four decades and why?

ozone depletors and marine catch were both declining in the 2017 Ripple paper. in the 2019 paper, total fertility rate, ice mass change, and glacier thickness are improving as they’re values are ranked some of the lowest recorded values in the last four decades.

what is the climate and vegetation of the tropical rainforest?

climate: 250cm rainfall annually distributed evenly throughout the year, temperatures are 20 degrees Celsius and above, nutrient poor soils. vegetation: multilayered canopy w sparse ground layer. epiphytes, lianas, broad-leaved evergreen trees.

what is the climate and vegetation of the tropical montane forest?

climate: similar to the tropical rainforest but at a higher elevation. vegetation: many epiphytes b/c plants derive moisture from condensation of clouds.

what is the climate and vegetation of tropical deciduous forests?

climate: rain shadows of mountains, the wet season encourages plant growth. vegetation: drought deciduous trees (lose leaves during dry season)

what is the climate and vegetation of tropical woodlands?

climate: warm with highly season precipitation, frequent fires. vegetation: open canopy, short trees with thick fire-resistant bark

what is the climate and vegetation of thorn forests?

climate: much drier than tropical dry forest, pronounced wet and dry seasons. plants: drought deciduous tree, thorny legume trees, succulents with thorns

what is the climate and vegetation of hot deserts?

climate: less than 25cm precipitation annually, very dry. vegetation: shrubs, succulents, grasses, annual forbs

what is climate and vegetation of temperate rainforests?

climate: cool, abundant precipitation and foggy, long growing season. vegetation: cold deciduous, tallest trees on the planet, high productivity but low biodiversity.

what is the climate and vegetation of temperate deciduous forests?

climate: warm moist summer with cold snowing winters, maritime or continental, precipitation 50-250 cm. vegetation: oak, maple, beech, chestnut, walnut, elm

what is the climate and vegetation of temperate evergreen forests?

climate: pronounced seasons and drier than temperate deciduous forests, low precipitation, soil has poor soil retention, frequent fires for regeneration. vegetation: conifers, sclerophyllous evergreens, fire resistant plants, low productivity and biodiversity

what is the climate and vegetation of temperate shrubland?

climate: cool wet winters and warm to hot dry summers, 40-100cm precipitation concentrated in cool season, foggy, frequent fires. vegetation: sclerophyllous evergreen shrubs, annuals forbs, high endemism

what is the climate and vegetation of temperate grassland?

climate: moderately dry, continental, cold dry winter with warm moist summer, season precipitation leading to drought, frequent fires. vegetation: grasses, no trees due to fires and grazers.

what is the climate and vegetation of temperate woodlands?

climate: transition between forest and grassland. vegetation: short and open vegetation, sclerophylls, conifers, and deciduous broadleaf (pines, junipers, oaks).

what is the climate and vegetation of cold deserts?

climate: freezing temperatures in the winter, very hot in summers, rain shadows in center of continents. vegetation: shrubs, grasses, frost excludes succulents from growing.

what is the climate and vegetation of taiga/boreal forests?

climate: continental with cold long winters, 38-50cm precipitation (low) but humid, disturbances include fire and large insect outbreaks. vegetation: conifers (spruce, fir, larch pine) and deciduous (aspen, birch, alders), young soil and slow decomposition

what is the climate and vegetation of the arctic tundra?

climate: long dark winters, cool short summers, high winds in winter, precipitation is mostly snow, young soils. vegetation: shrubs, grasses, sedges, perennials, mosses, lichens, permafrost limits deep root growth, too cold for trees.

what is the climate and vegetation of alpine grasslands and shrublands?

climate: cold, mountainous, cold air drainage. vegetation: \[shrubland\] heath (low growing shrubs), \[grassland\] sedges, dwarf trees, cushion plants, perennials

what are the greatest threats to each biome?

climate → arctic tundra, alpine, boreal forests

land use → grassland, savanna, Mediterranean, desert, southern hemisphere temperate forest, tropical rainforest

n deposition → northern hemisphere temperate forest