contemp issues in env science final

What is a hot spot?

"A biodiversity hotspot is a biogeographic region that is both a significant reservoir of biodiversity and is threatened with destruction" areas featuring exceptional concentrations of highly vulnerable species and often experiencing exceptional loss of habitat. To qualify: must have 1,500 plants as endemics (irreplaceable) and <30% of its original vegetation (threatened) endemics: species that are only found in that location & are irreplaceable. has to have lost at least 70% of its original habitat (the region is threatened) currently 35 hotspots covering slightly more than 2% of the earth's land area.

Soil loss versus soil formation calculation

(Pounds of soil lost per year) / (acres) = How long it would take to lose an inch It takes 500 years to gain an inch of soil Ex. 28 years to lose an inch of soil 500/28 = 17.857 Soil is being depleted 18 times faster than it is being built up.

Water use data -broadly, how much do we use?

* 150 gallons of water per day used by Americans Freshwater Use: 87%; Saline Use: 13% 70% surface water used

Soil Formation Process

Additions - organic matter is added as organic matter falls to the top layer (leaf litter, death). Precipitation with dissolved ions and suspended particulates (O + A Horizon) Removal of material - uptake from plants removes ions and erosion removes ions, particulates, and organic matter (O + A Horizon) Leaching also causes loss of ions from profile. Translocation - ions, humus, compounds and clays get moved down the profile from O and A through E into B. Ions move up the soil profile through capillary action. Transformation - Leaf litter and other organic matter is transformed by soil macro and micro invertebrates into humus. Minerals are transformed via chemical weathering (carbonation, oxidation).

Water Compartments/Where Our Water is Stored

All Water: Oceans/saline lakes 98% Fresh water 2% Fresh Water: Ice and snow 87% Liquid water 13% Liquid Water: Ground water 95% Soil moisture 2% Lakes streams rivers 3%

What is a biological corridor and what do they do?

An area of habitat connecting wildlife populations separated by human activities or structures (such as roads, development, or logging). This allows an exchange of individuals between populations, which may help prevent the negative effects of inbreeding and reduced genetic diversity (via genetic drift) that often occur within isolated populations. narrow passes through which species can move from reserve to reserve without crossing a human dominated landscape Biological corridors account for island isolation Not always dedicated structures Plant communities: Monarch Butterflies & Milkweed Marine Protected Areas Culverts, ditches, drainage pipes

Global Warming

An average increase in the temperature of the atmosphere near the Earth's surface and in the troposphere, which can contribute to changes in global climate patterns. In common usage, global warming refers to the warming that can occur as a result of increased emissions of greenhouse gases from human activities or an anthropogenic acceleration of the greenhouse effect.t

Why is biodiversity important? That is, why should we bother saving wildlife and nature?

Biodiversity boosts ecosystem productivity where each species, no matter how small, all have an important role to play. For example, A larger number of plant species means a greater variety of crops. Greater species diversity ensures natural sustainability for all life forms. -our survival depends on it; species depend on one another to keep species in check and support them -economic and environmental benefits of biodiversity estimates at $319 billion a year -ecosystem with high diversity is healthier -provides medicines, food, and energy by maintaining ecosystem functions Aesthetic-unique Pragmatic- medicines Ecotourism Helps an ecosystem recover from disasters Increases sustainability for all organisms in the ecosystem Help prevent extinction A loss of biodiversity can have negative effects of a community

The Carbon Cycle natural versus human-made contributions

Carbon is the building block of life on Earth. Most of our carbon - about 65,500 billion metric tons - is stored in rocks with the rest stored in the ocean, atmosphere, soil, plants, and fossil fuels. Carbon flows between each of these so-called "reservoirs" in an exchange called the carbon cycle, which has both slow and fast components. Over millennia, the carbon cycle maintains a balance that prevents all of Earth's carbon from entering the atmosphere (as in this case in Venus) or from being entirely stored entirely in rocks. This balance helps keep Earth's temp relatively stable. Scientists have discovered this works over the timescale of hundreds of thousands of years; we refer to this as the slow carbon cycle. From an enviornmental perspective, we are more concerned with the fast carbon cycle that operates over shorter time periods -tens to hundred of thousands of years. Over these timescales, earth's temp can vary, and in fact, our plant swings between ice ages and warmer interglacial periods. the diagram above is a schematic of the fast carbon cycle and shows the movement of carbon between land, atmosphere, and oceans. blue numbers represent natural fluxes while red are anthropengic contributions in gigatons per year. Note that the ocean absorbs about 2 gigatons of carbon more from the atmosphere than it gives off to the atmosphere. Marine organisms use that extra amount of carbon which is eventually incorporated into deep-sea deposits and sedimens. So the net level of carbon in the ocean remains roughly the same every year. The bottom line is that humans are adding about 11.5 gigatons of carbon into the atmosphere each year mostly due to fossil fuel burning and land use changes such as deforestation. +11.5 a year ; +870g already in the atmosphere

Keeling Curve

Charles Dvid Keeling, a scientist who developed the first instrument capable of measuring CO2 in air samples, started the MLO measurements in 1958. The data show that CO2 levels have been rising steadily throughout the record, a graph that became known as the Keeling Curve. This data is the longest intstrumental record of atmospheric CO2 in the world and is considered an extremely reliable indicator of current trends in CO2 levels. The data show that the atmospheric concentration of carbon dixoide has increased from approx 315 ppm in 1958 to 411 ppm in 2019. Overall, CO2 in the atmosphere has risen by 40% since the industrial revolution.

Rates of Deforestation

Deforestation has been occurring for centuries but recently the rate as increased dramatically because of humans. Research shows 40% of earth's total ice-free surface has been transformed into agricultural land and settlement since 1700. In the early 1980's. the FAO estimated tat about 14 million hectares of tropical forests were being destroyed each year, an area the size of North Carolina. Of this, 21,000 sq. miles (5.4 million hectares) were deforested annually in South America, primarily from the Amazon Basin. 9.7 million hectares in 2005 total tropical forest loss worldwide (2018) 12 million hectares 30 million acres 121,410 km^2

Land Degradation

Deterioration in the quality of land, its topsoil, vegetation, and/or water resources, caused usually by excessive or inappropriate exploitation. Research suggests that one third of the world's arable land has been lost since 1960 due to human activity. Each year, an estimated 10 million hectares of cropland worldwide are abandoned due to lack of productivity caused by soil erosion. Land area the size of China and India combined has been severely degraded in the last 60 years.

The Oxygen Sag

Diagram shows what happens when you introduce sewage or unprededed waste into a river : Oxygen sag downstream of an organic source Biochemical oxygen demand : oxygen demand from microorganisms or bacteria in sewage that will decompose organic waste When you dump sewage, the biochemical oxygen demand goes up a lot and dissolved oxygen goes down Oxygen sag = as you move downstream, oxygen levels decrease 2-3ppm = fish die ; septic or dead zone Water in rivers is naturally cleaned up : the sewage gets consumed and decomposed by the microorganisms and bacteria does not need as much oxygen ; biochemical oxygen demand goes down 5-6ppm of Dissolved Oxygen is healthy for fish * As waste enters the water, it increases the BOD (Biochemical Oxygen Demand) for the fish * As fish consume more waste they consume more dissolved oxygen * Eventually microorganisms clean the water down stream and return it to normal

Why is sediment a pollutant?

Excessive sediment can smother fish eggs Expensive to control Increases the turbidity of the water which has been shown to negatively affect fish Sediment also functions as a storage unit for other pollutants like DDT, fertilizers, etc. A lot of the soil run off takes some sort of harmful chemical into the water with it, compromising water quality.

Herringbone versus clear-cut and the impact of "edge" effects

Herringbone: Taking interwoven areas of forests to prevent large patches of missing forests. (bad because "edge effect") Clear-cut: cut down and remove every tree from an area. (less severe "edge effect") Edge-effect: Changes in population or community structures that occur at the boundary of two or more habitats. Areas with small habitat fragments exhibit especially pronounced edge effects that may extend throughout the range. As the edge effects increase, the boundary habitat allows for greater biodiversity.

What is eutrophication?

In this process, excess nutrients can leach from soil into groundwater and surface waters, leading to excessive growth of aquatic plants called algal blooms. Then, as the algae die off and are decomposed by the bacteria, oxygen in the bottom waters drop to levels that can be deadly for many marine organisms, a condition called hypoxia.

The Situation on the High Plains

In western parts of Texas, Oklahoma, and Kansas, over-pumping of the High Plains aquifer for irrigation and ranching has resulted in water levels declining by more than 100 ft since predevelopment. In some cases, over-pumping far exceeds natural recharge, leading the loss of aquifer as a water source, as in the case with the High Plains aquifer. 60%of the aquifer's groundwater will be used by 2060 ; 30% of all water used to irrigate crops in the U.S. comes from this aquifer.

What are the two most important soil types in the U.S.?

Mollisol Ultisol

The Nitrogen Cycle

Nitrogen is the key nutrient in plant growth. Large quantities of nitrogen, in the form of N2 gas, reside in the atmosphere above the surface of earth However, this form of nitrogen cannot be used by plants. The N2 must first be changed by microorganisms into organic forms then ionic forms. In the first step, N2 gas is taken from the air and changed into forms used by the plants, a process called fixation. This is accomplished by microorganisms either in the soil or in root nodules of plants. The first conversion process is mineralization, where organic nitrogen is changed into the ammonium form (NH4+). Bacteria then convert ammonium first into nitrite (NO2-), which occurs slowly and is highly toxic, and then quickly into nitrate (NO3-) via nitrification. Plants can absorb both NH4+ and NO3-; however, the latter is highly soluble and mobile in soils which means plants can easily get at nitrate nitrogen. Nitrate can also be converted back to gaseous nitrogen (N2) through bacteria in the soil and returned to the atmosphere via denitrification. Anthropogenic additions to the cycle occur via fertilizer which can be applied in a variety of nitrogen-based forms. If nitrogen fertilizer is added as ammonium nitrate (NH4NO3), the nitrate ions are immedietly available for plant use whereas the ammonium ions nitrify to nitrate via nitrification. If nitrogen fertilizer is applied as anhydrous ammonia (NH3), it reacts with water to produce NH4+, which then undergoes nitrification. Nitrogen losses occur primarily through NO3- leaching in percolating water and with eroding soil. Leaching losses are increased when plant growth is not sufficient to absorb the nitrates which often occurs because of over-fertilization of agricultural fields.

How much soil are we losing Pt 2

Normally takes 500 years to build up an inch of topsoil (1/500th inch each year, or 0.002 inches per year) To grow good crops requires approximately 6 inches 3,000 years required to build up a reasonable topsoil•12 T/ha = 0.04 inches (or about 1/25th of an inch) Since 1/500th of an inch is being built up naturally annually, soil is being depleted on the average each year 20 times faster than it is being built up in nature!

Six Soil Horizons and Characteristics of Each

O: Surface Litter - most organically rich horizon, Fallen leaves and partially decomposed organic debris A: Topsoil - agriculturally, the most important soil (where we grow things), Organic matter (humus), living organisms, inorganic materials E: Zone of Leaching- Dissolved or suspended materials move downward B: Subsoil - Accumulation of iron, aluminum, humic compounds, and clay from A and E horizons C: Weathered Parent Material: Partially broken down inorganic minerals R: Bedrock - Impenetrable layer

Point versus Non Point Pollution

Point Pollution : refers to effluent being released from a single outlet, meaning it is generally easier to monitor and control. ex: factories, homes, cars, ect Non Point Pollution: refers to a pollution that cannot be linked directly to one specific source, such as when runoff picks up pollutants from agricultural fields and deposits them into rivers, lakes, coastal waters, or even groundwater. some pollutants make include fertilizers, herbicides, and insecticides from agricultural lands and residential areas; toxic chemicals from urban runoff, sediment from improperly managed construction sites, ect.

Indirect Drivers of Deforestation

Poverty and overpopulation are the most often cited as the underlying causes of tropical deforestation Also, unequal land distribution, unrestrained development and the excessive consumption habits of the rich, corruption, intimidation industrialized countries are directly responsible for forest loss Debt also leads to deforestation Countries sell permits to cut down forests to pay of debt and poor countries are almost always forced to exploit their natural resources to pay of debt government policies encouraging economic development, such as road and railway expansion, have also caused significant, unintentional deforestation. unequal land distribution, western consumption habits, corruption, and profit-driven multinational companies•International debt

Ulitsol Soil

Second most important soil , low-moderately fertile soils highly leached, acidic, must have E horizon, 12.8% in the U.S., well washed out thin light A, E not nearly as fertile as Mollisols

Common characteristics of threatened species

Small (localized) range: Species that are restricted to relatively small geographic area are inherently vulnerable to extinction. Populations on islands are especially vulnerable to extinction. They have incurred the greatest number of extinctions in the past 400 years. Specialized habitat and/or diet : Species that depend on a certain type of habitat or food source and do not adapt well to changes, either natural or human-caused, are more prone to extinction. Low reproductive rates and low natural mortality : Slow-reproducing species that have few young at longer intervals and low natural mortality rates tend to be less resilient to population losses than those species that reproduce at frequent intervals. Slow-moving animals : These species are helpless in the face of hunting and predation by humans and/or introduced predators. Tortoises and sea turtles are killed for trade or by vandals for sport. Large animals are vulnerable to over-hunting, many times killed merely because they make large targets or trophies. Animals of large size also require considerable amounts of habitat are are, therefore, naturally rarer than species with smaller habitat requirements. Perceived Value : Wild animals and plants which have value as food, pets, ceremonial objects, or marketable products to humans are prime candidates for extinction. The once abundant sturgeon of the Caspian Sea, for example, sources of Beluga and other expensive caviar, are now critically endangered as a result of unrestricted fishing and poaching for the luxury gourmet market 1. Small (localized) range 2. Extensive range but significantly modified by humans 3. Island dwellers (limited immigration; isolated evolution free from competitors, predators and diseases and thus fewer defenses when introduced) 4. Low reproductive success 5. Large (easily hunted)

Model predictions and possible outcomes of global warming

Temperature predictions are made with climate models that are mathmatical representations of the interactions among the atmosphere, oceans, land surface, and ice with the sun. These models are far from perfect and naysayers in the climate change debate most frequently use the "uncertainty of tthe model predictions" tp justify their position. to be sure, predicting climate is a very complex task, so models are built to estimate trends rather than events. The models also have to be tested to find out if they work. Models are tested agaisnt the past, agasint what we know happened. Global warming projections using computer models from several climate change research centers showing the wide range of possible outcomes through to 2100. The surface record 1980-2019 are highlighted and used as one projection through to 2100. The large red circle represents the consensus among 6 carbon dioxide scenarios - that is, the most likely global warming outcome.

T Value

The Tolerable Erosion Value, or T-Value, defines an upper or allowable rate of soil loss in a particular region. The T-Value basically depends on the thickness of a soil in a region. Thin soils, where the productive topsoil is less than 10 inches thick, have low T values, about 2-3 tons per hectare per year. Deeper soil, where the topsoil is thicker than 60 inches, can afford to lose more soil and therefore have higher T-values, usually in the range of 11 tons per hectare per year. Any soil loss that exceeds this amount is deemed excessive. In the U.S., our average T-Value is 11.5 to 12 tons per hectare per year.

The latitudinal diversity gradient

The increase in species richness or biodiversity that occurs from the poles to the tropics is one of the most widely recognized patterns in ecology. Put another way, in the present day localities at lower latitudes generally have more species than localities at higher latitudes.(less species the farther you get from the equator.)

Mollisol Soil

The most important agricultural soil in the U.S. Very productive agricultural soils underlying the breadbasket of the United States About 1/4 of our soil Thick dark A over B Rich fertile topsoil

Long-term trends in temperature (broad changes over the last 1,000 and 100 years)

The plant's near surface atmospheric temperature has risen by 1.5 celcius (2.7farhenheit ) over the past 140 years. The last 5 years have been the warmest on record whilst the last 20 warmest years have all come since 1998. In Figure 6.9 (January-December temp anomalies, 1880-2019) the warming actually occurs during 2 periods : 1910-1945 and 1976 to present day. Scientists say the 20th century warming could be due to a combo of factors : GHGs and natural forcings, such as decreased volcanic activity., which allows increased radiation to reach the the ground, as well as greater solar irradiance. Scientists also agree that in the second half of the century, increased concentrations in GHGs, specifically CO2, are largely the cause of this warming. shows earth's atmosphere has warmed over the past century

Possible Outcomes of Global Warming

The possible effects of global warming fall into two categories : the impact on oceans, specifically rising at sea level, and changes in the amount and patterns oor precipitation. These impacts will operate at local, regional, continenal, and global scales. rising sea level (sea level change : +5.8 mm per year) changes in precipitation - if temperatures continue to rise globally, a highly likely scenario, droughts will intensify, with potentially devestatting consquences for agriculture and water supply. Hot temperatures and dry conditions also increase the likliehood of forest fires. finally, climate change is transforming ecosystems. in particular, two important types of ecological impacts of climate change have been observed : shifts in species' ranges (locations in which they can survive and reproduce) and shifts in phenology (timing of biological activities that take place seasonally). As earth warms, many species are shifting their ranges to areas with more tolerable climate conditions. However, some organisms -those who cant move far enough or those whose ranges are shrinking-are being left with no place to go.

The Greenhouse Effect

The warming of the surface and lower atmosphere of a planet (as Earth or Venus) that is caused by conversion of incoming shortwave solar radiation into heat in a process involving selective transmission of short wave solar radiation by the atmosphere, its absorpotion by the planet's surface, and reradiation as infrared which is absorbed and partly reradiated back to the surface by atmospheric gases.

U.S. Water Usage By Category

Thermoelectric power = 42% Irrigation = 37% Public Water Supply = 12% Industrial = 5% Agriculture = 2% Mining =1% Domestic = 1% Livestock < 1% Total : 322 billion gallons per day

Why forests are important and why we consider them "system regulators"?

Tropical rainforests not only act as a habitat but also as system regulators. Rainforests moderate air temps, maintain atmospheric humidity levels through evapotranspirtation, and regulate stream flows by allowing rainfall to enter streams more slowly. The amazon rainforest, which alone comprises 30%of the world's rainforests, plays a critical role as Earth's "lung", absorbing carbon dioxide and generating oxygen. Tropical rainforests also provide us with a wide range of industrial wood products that account for about 25% of a $400 billion global market each year. They are also important sources of new pharmaceuticals. Some 150 million native or indigenous peoples rely soley on the forests for their way of life. The forests provide food and shelter and play a major role in their religious and cultural traditions. Most of the rainforest timber sold on the international market is exported to wealthy countries where it is sold for hundreds of times greater than the price paid to the indegious people whose forests have been plundered.

Observations and Impacts : what do we see that supports the fact that the earth is warming?

Wildfire seasons in the U.S. are getting longer and wildfires are getting larger. Melting ice, sea level change Sea Level Change : 1880 - 2019 +5.8 mm/year ; Rate of sea level change 2015-2019. Average monthly arctic sea ice extent : December 1979-2019. 7.12 million sq. average minimum Arctic sea ice extent, 1979-1983. 4.3 million sq. km. average minimum arctic sea ice extent, 2015-2019.

What is the over-riding principle of the biodiversity hotspot?

a focus on protecting the highest number of species we can, esp the ones that are most threatened by human activity. That also gives us the greatest chance at increasing species richness.

How much soil are we losing

average soil loss on U.S. cropland : an average of 12 tons per hectare in context. In 1982 in the U.S. soil erosion was 3.1 billion tons/ year 1992 it was cut by 1/3 to 2.2 billion tons per year Since that, the average rate has been about 1.7 billion tons per year over the past decade. Aka 12 tons of soil lost each year for every hectare of cropland in the United States. The most recent research on soil erosion confirms we are losing about 6.7 tons/hectare/year just by water erosion, a rate more than 3 times the natural rate on non-agricultural land.

Soil

covers most of the land surface with a fragile, thin, but invaluable layer. Without soil, no plant life could exist. Soil not only serves as the medium for terrestrial plant growth but also functions as a recycling system for nutrients and organic waters as well as habitat for soil organisms. a single gram of productive agricultural soil typically contains several million bacteria and tens of thousands of algae, fungi, and other soil life. The unconsolidated mineral or organic material on the immediate surface of the Earth that serves as a natural medium for the growth of land plants.

Various Functions of Soil

medium for plant growth engineering medium system for water supply and purification habitat for soil organisms recycling system for nutrients and organic wastes

Endangered

numbers so low that extinction imminent

Threatened

population low but extinction less imminent

Direct Drivers (Agents) of Deforestation

the single biggest direct cause of tropical deforestation is conversion to cropland and pasture. this occurs on two scales : large plantation (i.e. commercial) farming and small subsistence farming. These commodities are key agricultural drivers of forest loss : soybeans, beef cattle, and palm oil. also wood products like pulp (to produce paper) and timber (used for construction and furniture) soybeans : concentrated in 3 countries : U.S., Brazil, and Argentina. most of the world's soy is used to feed pigs, chickens, dairy cows, and farmed fish. ab half a million hectares is deforested annually for soy beef cattle : accounts for more than 2/3 of tropical forest loss worldwide, Almost exclusively Columbia, Argentina, Paraguay, and Brazil palm oil: concentrated in Indonesia and Malaysia. used in countless processed foods and personal care products, as well as biofuel and vegetable oil.

A basic understanding of the global diversity map (i.e., what causes high diversity zones across the globe)

the tropics are the world's mega-diverse zones. many areas in the tropics have abundant rainfall and warm temps year-round so that ecosystems are highly productive. the year-round dependability of food, moisture, and warmth supports a great exuberance if life and allows a high degree of specialization in the physical shape and behavior of species. the general decrease in diversity from the tropics towards the poles evident in figure 8.3 is known as the latitudinal diversity gradient (LDG) and is one of the most widely recognized patterns in ecology. Places that have a higher diversity have similar characteristics: moisture, warmth, closeness to the equator. (tropics) warmer areas have higher diversity. diversity decreases as you go further from the equator. The warmer the color the richer the species diversity Tropics are the world's mega diverse zones Abundant rainfall and warm temperatures year round so that ecosystems are highly productive

How is biodiversity impacted by mountains?

there are other zones where plant diversity is highly concentrated, for example mountainous areas such as the Andes in South America, where elevation changes allow for different climate zones and hence greater diversity in habitat. this is known as the elevational diversity gradient (EDG)

Explain why the tropics are so diverse is a little more complex than simply having plenty of sunshine and abundant rainfall?

there is more land area between 0 degrees and 10 degrees north than there is between 50 degrees and 60 degrees north - that is, the earth's circumstance is largest at the equator, which means more space for species to live. the diversity in any region is also due to the result of speciation (new species evolving), extinction (species dying), and species moving in and out.

What do we mean by the term "biodiversity"?

variety of life on earth and the natural distribution and patterns of organisms result of billions of years of evolution, shaped by natural processes and influences of humans

How many species have we identified?

we don't know how many species are on earth ; scientists estimate between 2 and 8 million. 1.7 to 1.9 million named species 70% invertebrates between 3-50 million alive 10-15% live in North America

Aquifer & Its Types

when underground water is held in permeable rock in quantities that make it a significant water store, the formation is said to be an aquifer. They will generally have these characteristics : * a large volume in relation to the amounts of water being removed annually * a moderately high porosity. this means that the pore spaces in the rock are large, such as in sandstone, and large amounts of water can be stored within the pores * a well-conducted network of pores, fractures, and fissures. this is called permeability and speeds up water movement through the geological movement. Aquifers are either ... 1) Confined - water is under pressure between two confining layers of very low permeability, called aquitards 2) Unconfined - one where the water table defines the upper surface of the aquifer.