Lecture 4: Threats to Biodiversity PDF

Lecture 4 Threats to Biodiversity  Learning Objectives Explain what are the main threats to biodiversity in a concise and informative manner - List the main causes of habitat loss and where it is more extensive Discuss the -...

Lecture 4 Threats to Biodiversity  Learning Objectives Explain what are the main threats to biodiversity in a concise and informative manner - List the main causes of habitat loss and where it is more extensive Discuss the - impact of habitat fragmentation on biodiversity Discuss the threats of exotic species on endemic biodiversity r Explain the problem of>-overhunting and environmental degradation and what can humans do to minimize their effects Present an overview of how- the effects of combined threats exaggerates the problems facing Nature and biodiversity - - Use the study case data and results effectively to build a case for an environmental problem facing the local community  Always go to the INTRODUCTION of any section and LISTEN TO THE eminent E.O. WILSON introducing the subject! Look at the deforestation map carefully Notice that tropical areas, which harbor > 50% of species, are severely affected Same can be said for Mediterranean region, which is next to tropics in terms of biodiversity Notice the GREEN areas where there is actually GAIN in biodiversity!! Go to compare maps and compare this map to biomes map of all regions! Read the Overview, explorations (your SECOND HW2!!), and thought question. Click on the link to Global Pattern of Deforestation Read the OVERVIEW…VERY IMPORTANT! Click on the “borders on/off” just to check it out! ☺ Now, go to the link to the Interactive Model: Deforestation Rates” Very IMPORTANT!! Learn the information it delivers! Compare how many years it would take to half forests in Brazil to those of Indonesia and Philippines…OUTRAGEOUS!  > - paierit and Measuring Deforestation Q wetland los, Look at figure on the bottom left: IMPORTANT! Look at figure on right Satallite Measuring deforestation rate are problematic manganore > - Done differently by different people and countries > - coral leafs Need to compare current forests to historical forests areas Done through remote sensing (satellite photos) and/or ground mapping Remote sensing is problematic: clouds, can’t distinguish forest from a tree plantation, etc. Ground mapping is laborious if not impossible Another problem is getting historical maps! Ecologists have to reconstruct from climate and soil data and “imagine” how this forest of land used to be!! Big problem! Add to that the problem that some countries give “fake” data for certain interests!! One more problem☺: definitions of what is a forest, woodland, open- or closed-forest, etc. is a problem and makes comparisons not easy! Read CAREFULLY the example of Myers and FAO: EXCELLENT! Conclusion!? Read last paragraph. - 2 data Sets history 2 > - contemp - Settite - -gaumut - lack of consistency of definitions - moist tropical Myers > - forests ↳ comme of preception Forest Loss in the USA Look at the animation and compare forest loss across years ands & d Mangrove Loss in fleir vor v Go to link and learn about mangroves: IMPORTANT! What are mangroves, their distribution, importance in terms of - biodiversity and other services, and summary of threats facing them Also, it is a good time to learn about tropical rainforests Go to tropical rainforest link: IMPORTANT! What are tropical rainforests, their distribution, importance in terms of biodiversity and other services, and summary of threats facing them - Mangrove forests are lost at an alarming rate; 1% in SE Asia Mangroves are under multiple threats, which exaggerates the - problem - Population growth → go to that link! Notice where population density GROWTH is highest: ASIA & AFRICA!! - Follow ALL links in this map and go to explorations (HW3!) Let’s do the thought question together!! murgebe in Posts ↳ enviromet > - coastline ↳ Thearts : coastal darofsprent - stringes % > - 1 O.k., back to Mangrove Loss - So overpopulation is causing threats to mangroves People cut wood to grow rice, use in fire, salt condensation, etc. Shrimp aquaculture is best in mangroves, and high demands for shrimps in the rich countries, make local people use the mangroves areas more, which results in more pollution and destruction of the mangrove forests This can be avoided by a sustainable and wise practice of aquaculture for shrimp and rice agriculture, the main polluting farming practices Read the example of mangrove forests destruction in Thailand Government argues that rice fields, roads, etc. are the cause of mangrove destruction Studies show that it is the shrimp farms Notice, however, no matter what the reason is, the government acknowledges that mangroves are being destroyed and doing nothing about it! If you forgot to look at the figures, DO IT NOW AND READ THE LEGENDS!! Coral Reef Loss Go to the link and read about coral reefs: IMPORTANT! The “tropical rainforests of the sea”!! Seriously; read all this carefully. It is important What is a coral reef, importance, time to form a reef, threats, phylum!, etc. Do you know what corals are and how they get nourishment!? Go to link! Problems Overpopulation in corals areas (warm and beautiful beaches!) Natural disturbances: Hurricanes, storms, etc. Coral bleaching (what is that? → hot temperatures Natural disturbances are infrequent and their damage is minimal Human caused disturbance: 70% will disappear in 40 yr!! Overfishing is the most threatening problem. Why? Dynamite and cyanide!! What are they used for here!? Coastal development and tourism, ship traffic, etc. Dredging is BAD! Agricultural and industrial poisoning and pollution Sewage! → choking of corals. How it does that? Continue…Coral Reef Loss Problems Population outbreaks of sea stars (natural predators of corals) Read what it did to the Australian Great Barrier Reef!! Oil spells, collecting corals for souvenirs, etc. Coral bleaching due to anthropogenic global warming The interaction of several threats (human influence, diseases, hurricanes), when combined, exaggerates the threats to coral reefs! Did you forget looking at the photos again!!? Do it NOW! See how beautiful coral beaches are No wonder why people like going there! Prairie Loss in North America Once covered 20% of the USA Consists of several types of tall, short and mixed temperate grasslands; go to the link Main loss in tall grass; > 95% Accompanied by almost extinction of the bison! See Figure at bottom right…IMPORTANT! Causes of loss Agricultural transformation V Grain farming; most of world’s wheat comes from there! - Facilitated by warm, moist summers, and fertile soils - Deep plowing changes soil fertility ~ Abandoned fields do not revert to prairie! Many exotic species dominate ~ ~ Short and mixed grass lands are less fertile so used for cattle grazing; use of exotic grasses since cattle do not eat natural grass like bison Cattle herds movement unlike that of bison: detrimental to grasslands → grazed grasslands do not resemble original prairie ~ Causes…continued Changing Patterns Prairie ecosystem further damaged by disruption of disturbance regimes and elimination of large mammals Fires, keeping trees from colonizing the prairies and changing to forests ~ and keeping natural diversity, has been eliminated Altered the structure and composition of prairie communities V Few large herbivores and predators remain; key species have ~ been lost Makes it hard to restore prairies!! Urbanization Prairie region, although lightly populated compared to other regions, has& grown substantially Urbanization further threatens any habitat since it reduces the natural areas The prairies are the most endangered ecosystem in N.A. Wetland Destruction Agriculture and development threaten freshwater sources > 50% wetlands are severely degraded; some areas even more GO TO LINK on wetland destruction in the US Wetlands decreased from 11% within the US to 5% !! Most common cause is agricultural practices Look at the map of the wetland loss in the US California, a dry state, retains 9% of the original wetlands; lost 91% Alaska lost less than 1% only! Look at the two figures included to learn examples of wetlands Causes of wetlands loss Agriculture - Learn the different types of wetlands and go to HW5!! Accounts for > 80% of loss in the US and world No attention to valuable wetlands services People care about immediate returns v See the link for quick review…IMPORTANT ~ Pollution Wetlands are usually drainage areas for water~ Sewage, agricultural chemicals (pesticides, nutrients, etc.), etc. collect there - Wetlands can not purify all that unnatural influx Changes to wetland landscape Humans altered most wetlands for their use ~ ---- Dams, channels, levees, roads, etc. Although human reasons are o.k. to humans ()power generations, - flood control, municipal water use, waste disposal etc.), they - result in LOSS of wetlands! - Extraction -- Many wetlands are mined for extraction of peat (what is that?), coal, nutrients, etc. Extraction of oil and ground water also destroy wetlands: they sink and disappear! Loss due to Natural processes Drought, hurricanes, sea-level rise, eutrophication(?**), succession (?), etc. can cause wetlands to shrink or disappear Although can occur naturally, anthropogenic causes (climate change click!) can lead to loss indirectly LINK-Succession!  eutrophication excessive richness of nutrients in a lake or other body of water, frequently due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen. What can be done to minimize loss of wetlands? Read the Ramsar Convention THOROUGHLY! The “Convention on Wetlands of International Importance Especially as Waterfowl Habitats” Adopted in Ramsar, Iran in 1971 Drainage of wetlands is done in many developing nations to combat Malaria Many nations use wetlands for agriculture and aquaculture Destruction of wetlands would require more destruction of wetlands to bring back the services of the original wetlands!!! Read last paragraph on this!