Today watch for Week 12 Review Assessment ties up loose ends from carbon cycle (if any) and will delve into the biosphere

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1 Monday, November 27, 2017 Today watch for Week 12 Review Assessment ties up loose ends from carbon cycle (if any) and will delve into the biosphere Homework 5 due Wednesday, December 6 on carbon footprint (not too difficult, but will involve some browsing on the web and use of calculators ) Grade summary so far 3 exams (50%), 4 homeworks (13%), Assessments (about 6%), clickers (a few percent). Add points from recitations to get a sense of where you stand and decide how you want to handle Exam 4.

2 Lecture 1 - Loose ends re: life on Earth (I will probably do this as a summary of key points - history of atmosphere, oxygen rise, and ozone, followed by biodiversity and threats due to climate change). Lecture 2 - Paleoclimate - ice ages (primary focus on 2.5 million years and shorter, with references to snowball earth), Milankovic orbital drivers of recent changes in NH ice sheets (i.e., 700,000 years) Lecture 3 - Feedbacks that may contribute to the dominant 100,000 year cycle and implications for modern global warming Lectures Societal implications, economics, policies, adaptation, mitigation, IPCC projections, etc.

3 Chapter 9 Characteristics of Life (p ) Structure of the biosphere (p ) Species interactions (p ), Disturbance and Succession (p 185) Biodiversity (p )

4 Chapter 9 Disturbance and Succession (p ) Biodiversity over time (Figure 13-3, but from another source) Ecotones (p 183) Chapter 11 Oxygen, ozone, and life (p , p 214, p 217, p 222) A brief timeline for earth s atmospheric composition

5 Why did I pick the photo on the first slide? What is the photo on the previous slide? I don t know the exact species of tree, but it was on the island of Oahu during one of my field trips for Semester at Sea. I was telling students about how life optimizes the consumption of energy life forms that are more efficient will outcompete other forms. And when given time, those species will win the day and procreate, taking over a particular niche. Over time, this means that life, taken as a whole, follows a path of highest efficiency and least pollution. But that doesn t mean that every species in a particular ecosystem wins, and some will become extinct when it is outcompeted by another species. This photo shows how a single tree is spreading out its leaves and branches to fill nearly every gap in the canopy, literally taking up the maximum amount of sunlight it can. Anything trying to complete must do the same, or find a way to kill the tree to get it out of the path of the sun.

6 Objectives for this short section of the class Chapter 9 basic aspects of life on Earth and important ecological principles Chapter 11 The role of the biosphere in shaping the composition of the atmosphere. Overarching Question - How does life affect Earth s climate? Or is life just something that exists in the space created by climate, exploiting the available resources and, otherwise, reacting to changes driven by other factors? Of course we know the answer with humans we can shape the climate and well as being affected by it. But the same is true to life as a whole ecosystems shape the very climate around them.

7 Chapter 9 Biota:Ecosystems Chapter 11 Life s impact on the atmosphere We already know that climate is important for creating habitats that are conducive for life. But what about life? Can it also affect climate in a way that, in turn, is beneficial for life? The simple answer is Yes we will see later that feedbacks in the Earth system involving life have played important roles in modulating climate helping to keep interglacial periods warm and contributing to positive feedbacks that result in rapid cycling between ice ages and interglacials

8 Characteristics of life that allow it to interact with the other Earth systems and help create a habitable planet How is the biosphere structured? How is energy transferred within the biosphere? What is an ecosystem? What is biodiversity and how is it measured?

9 Some important characteristics of life It spreads exponentially, It needs energy the food chain starts with either photosynthesis (sunlight) or chemosynthesis (ocean thermal vents) It pollutes the physical environment It is versatile e.g. evolution/natural selection

10 Pollution Energy Flow in an Ecosystem

11 Food chain Energy flows from trophic level to trophic level trophic - of or involving the feeding habits or food relationship of different organisms in a food chain.

12 The biosphere contributes to important climate feebacks Example of feedback between the biosphere and the cryosphere (or hydrosphere) and climate Figure 9-2

13 Note that life, because it involves more complex changes that can be affected by behavior and adaptation, can lead to very complex feedback loops, and it is often tricky to figure out whether they are strictly positive or strictly negative. Figure 9-2

14 Other examples Particle (aerosol) production from dimethyl sulfide (DMS) (the stuff that makes a beach smell like a beach) Reduction of erosion by plants Even plate tectonics!!!

15 Categorizing life Life can be categorized taxonomically (e.g. by species, genera, families, etc.), it can also be categorized on the basis of ways in which organisms obtain and metabolize energy Autotrophs primary producers that take CO 2 and water and make hydrocarbons, either using the sun or sulfur. Key they convert inorganic carbon to organic carbon. Organic carbon is a way to store this solar or chemical energy for later conversion at a time that it is needed ( metabolized ) Heterotrophs controlled burning of the energy stored in organic molecules produced by the autotrophs. Requires an oxidant (O 2, nitrate, sulfate, iron, manganese oxides)

16 Which term below characterizes the largest group or set (i.e., all the others fall within it)? (a) population (b) species (c) biosphere (d) ecosystem (e) community

17 Which term below characterizes the largest group or set (i.e., all the others fall within it)? (a) population (b) species (c) biosphere (d) ecosystem (e) community

18 Biosphere Hierarchy Ecosystem Subset of the global biosphere (e.g. forest and all plants, animals, fungi, microbes and their interactions) Community two or more groups of interacting species. May include any combination of animals, plants, fungi, and microbes. regions with characteristic plant community is called a biome e.g. desert, tropical rainforest, Population all the members of a given species Species one specific kind of plant, animal, fungus, or microbe

19 Question when did we talk about biomes? Answer Chapter 4, when we were relating how life has adapted to a particular set of climate variables biome a major biotic community characterized by the dominant forms of plant life and the prevailing climate

20 Tundra Deciduous Forest Savanna Taiga Chaparral Rainforest Grasslands Desert Alpine Desertscrub

21 Geographical vs. Functional A is a major geographical area of ecologically similar communities of plants, animals, and soil organisms, often referred to as ecosystems. (a) biome (b) ecosystem (c) community (d) family

22 A is a natural unit consisting of all plants, animals and micro-organisms in an area functioning together with all the non-living physical factors of the environment. (a) biome (b) ecosystem (c) community (d) family Geographical vs. Functional

23 Ecosystems and biomes are often confused a biome represents a region Tropical rainforest Savannah Mountains Temperate forest Biosphere represents the sum of all life on the planet

24 What is a Biome? ( A biome is a large geographical area of distinctive plant and animal groups, which are adapted to that particular environment. The climate and geography of a region determines what type of biome can exist in that region. Major biomes include deserts, forests, grasslands, tundra, and several types of aquatic environments. Each biome consists of many ecosystems whose communities have adapted to the small differences in climate and the environment inside the biome. All living things are closely related to their environment. Any change in one part of an environment, like an increase or decrease of a species of animal or plant, causes a ripple effect of change in through other parts of the environment. The earth includes a huge variety of living things, from complex plants and animals to very simple, one-celled organisms. But large or small, simple or complex, no organism lives alone. Each depends in some way on other living and nonliving things in its surroundings.

25 An ecosystem represents a functional relationship between all the living parts of the system species, communities, populations fern frog bacterium Ecosystem communities

26 fern frog bacterium Ecosystem communities

27 fern frog bacterium Ecosystem communities

28 Ecosystems exist on a variety of scales. An example of a small scale ecosystem (micro) is a pond. A medium scale ecosystem (meso) could be a forest. The tropical rainforest is an example of a very large ecosystem (biome).

29 Ecosystem 1 Ecosystem 2 ecotone the transition between two ecosystems

30 ECOTONE Figure 9-3

31 ECOTONE Increased diversity Figure 9-3

32 Figure 9-4 unique habitat?

33 Diversity The term biological diversity was coined by Thomas Lovejoy in 1980, while the word biodiversity itself was coined by the entomologist E. O. Wilson in 1986, in a report for the first American Forum on biological diversity organized by the National Research Council (NRC) Rainforests are the most biodiverse ecosystems on Earth

34 No single objective measure of biodiversity is possible, only measures relating to particular purposes or applications. For practical conservationists, this measure should quantify a value that is at the same time broadly shared among locally affected people. For others, a broader and economically more defensible definition is that measures should allow the ensuring of continued possibilities for both adaptation and future use by people, assuring environmental sustainability. As a consequence, biologists argued that this measure is likely to be associated with the variety of genes. Since it cannot always be said which genes are more likely to prove beneficial, the best choice for conservation is to assure the persistence of as many genes as possible. For ecologists, this approach is sometimes considered inadequate and too restricted.

35 Biological diversity has no single standard definition. One definition holds that biological diversity is a measure of the relative diversity among organisms present in different ecosystems. Diversity in this definition includes diversity within species and among species, and comparative diversity among ecosystems. Another definition, simpler and clearer, but more challenging, is the totality of genes, species, and ecosystems of a region. An advantage of this definition is that it seems to describe most instances of its use, and one possibly unified view of the traditional three levels at which biodiversity has been identified: Genetic diversity - diversity of genes within a species. There is a genetic variability among the populations and the individuals of the same species Species diversity - diversity among species Ecosystem diversity - diversity at a higher level of organization, the ecosystem (richness in the different processes to which the genes ultimately contribute)

36 There are three common metrics used to measure species-level biodiversity. Species Richness (subjective) Simpson Index (takes into account the number of species present, as well as the abundance of each species) Shannon-Wiener Index (takes into account the number of species and the evenness of the species. The index is increased either by having additional unique species, or by having a greater species evenness)

37 Estimates of the present global macroscopic species diversity vary from 2 million to 100 million species, with a best estimate of somewhere near 10 million.

38 Next time we will look at how life has affected the atmosphere.

39 Chapter 11 Effect of Life on the Atmosphere: The Rise of Oxygen and Ozone Key Questions How did early forms of life on earth affect atmospheric composition? When did oxygen become more abundant? When did the ozone layer form and how did it affect life on earth? How much has atmospheric oxygen changed over the past 540 million years? What determines the abundance of atmospheric oxygen today?

40 Why Is Ozone Essential for Life on Earth? Absorption of DNA-Damaging UV radiation!

41 A time line for Earth s Atmospheric Composition 4.5 bya (educated guess) No free O 2 (would have reacted with hydrogen to form water and also with rocks) Probably lots of N 2 and H 2 O from early bombardment period CO 2 from outgassing (e.g., volcanoes), but not well understood at this point CH 4 would be oxidized by oxygen in rocks and water to form CO 2 Lots of ultraviolet light hitting Earth due to lack of a oxygen or ozone shield 3.5 bya (from stromatolites) photosynthetic methanogenic bacteria likely first appeared, but in an atmosphere with H 2 O vapor and CO 2, the most likely product of this early photosynthesis was CH 4 via the reaction CO H 2 CH H 2 O

42 ~ 2.7 bya cyanobacteria (blue green algae) CO 2 + H 2 O CH 2 O + O 2 Evidence fossils and banded-iron formations (most of which formed 1.9 bya) ~2.3 bya O 2 begins to rise in the atmosphere Where the early oxygen went is still a mystery, but likely into rocks (forming the banded iron) or it reacted with reduced compounds coming out of rocks (volcanoes). ~1.9 bya enough ozone (O 3 ) was produced by O 2 to absorb UV light O 2 was probably about 1-15% of the present-day value of 20% of the atmosphere 560 mya multicellular organisms appear in the fossil record

43 Banded Iron Formations (sedimentary appearing 3.7 billion years ago, and lasting and 570 million years ago)

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45 The buildup of O 2 had consequences the sun was dimmer back then, and the greenhouse effect was even more important. Extra oxygen in the atmosphere resulted in loss of CH 4, a greenhouse gas that is 20 times more potent than CO 2 - ICE AGES!