ENVIR ST 260 1st Edition Lecture 18Outline of Last Lecture I. Ideas from Last LectureII. Questions of Monetary Value in Forest EcosystemsIII. Conservation and Restoration ChallengesOutline of Current Lecture I. Forests and Climate ChangeII. Desertsa. Factors that Form Desertsb. Plant and Animal AdaptationsCurrent LectureForests and Climate Change Things we need to consider Increased CO2 could lead to increased tree growth rates (where there’s enough rain) On a global scale, there could be increased growth rates, but you still need enough water. Water is the limiting factor Range Shifts – species may migrate north or to higher altitudes If you have forest species that live in one region, a lot of them will migrate further north as climate changes. With altitude you get changes in precipitation and temperature. It’s similar to moving north in latitude as elevation More extreme…- More extreme events; a slight shift in temperature combined with these extremes might be the thing people need to be concerned about.  Droughts Flooding Precipitation To accommodate shift in latitude or altitude…These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Wildlife corridors would be very import to allow this shift on the landscape. Wildlife corridors aregreen spaces that connect one protected area to another; they allow for movement between thetwo  This idea seems plausible, but it doesn’t work quite as well for plants. They move very slowly andit takes a long time to get from point A to point B. In addition to setting up green pathways with animals in mind, there are suggestions to plant the species from one place in another more northern place. Deserts Factors that Form Deserts What is a desert? Areas where evaporation exceeds rainfall- This is the biggest thing. There can be cold and hot deserts, but all that matters is that evaporation exceeds rainfall. Clicker: What do you think is the most important factor in the formation of deserts? Topography Wind currents Ocean temperatures Latitude Soil Nutrients- Answers were all over the place. Depending upon sources that you look at, people will argue about what the most important factor is.- Topography is a good answer. Wind currents are also a big contributing factor. With soil nutrients, it’s a bit tricky, because yes they’re low in nutrients, but it’s not that being nutrient poor causes a desert to occur, but the factors that cause deserts to occur lead to low nutrients.  Latitude Where deserts occur on global scale- You don’t really have deserts along the equator, but they come a lot closer to 30 degree latitude. For the most part, they’re fairly concentrated along these lines. Why we see deserts in these latitudes- There are air currents around the world. In some regions, high pressure dominates and others low pressure dominates. You end up with places without much wind and it shifts fronts and moisture systems away from this region. That’s where latitude is a contributing factor Topography Big mountain ranges can affect the formation of deserts. As fronts move across mountain ranges, it forces the moisture out of the clouds so you get a lot of rain and snow on one side.However, by the time the air masses drop to the downward side, there isn’t a lot of moisturein the air. Now you have less precipitation than evaporation. Plant and Animal Adaptations (Focus on Southwester US Hot Deserts) Factors Species Need to Adapt To  Limited rainfall Extreme temperatures  High solar radiation Plants Adaptations (Sonoran Desert) Roots- Big Cacti: They send out shallow, fibrous roots just under the surface so that when it does rain they can take the water from the soil and put it right up into the stem. - Trees: They send down long tap roots in the hopes of hitting the water table. A lot of times you’ll find them by streams that form when it does rain or natural sinks for water where the water table may be higher.  Small leaves- They have little, tiny leaflets. They don’t need big leaves because they already have a lot of sun. Small leaves are effective for absorbing solar energy, and they minimize the area for water loss. Water Storage- Pleats in Cacti: They expand and contract to store water - Aloe plant has a similar system where the leaves can swell and store water. - This system of water storage is fairly common in desert ecosystems world wide Photosynthesis- Typically, plants photosynthesize in full sun during the day, during which they transfer gases through pores on the leaves. - Desert plants essentially store the energy they pick up from the sun during the day and keep the pores closed during the day so they don’t lose water through them when givingout gas. Then, when it gets later and temperatures drop, they can photosynthesis at night. By shifting the timing of when plants are photosynthesizing, they’re losing less water.  Pointy- Cacti have spines. It’s meant to keep things from eating them. They’re really slow growing plants; it takes them hundreds of years to reach big sizes. By adapting spines, things are less likely to eat them. - Desert leaves often build up a waxy exterior, so they’re less palatable to insects and animals that might be trying to eat them.  Seeds- A lot of desert plants are good at creating seed banks in the top layer of the soil. The seeds will remain dormant until they’re trigged to start growing by rain. This is good because if they sprout immediately, without rain, it’ll be too hot or dry and they’d fail - The success rate is still fairly low because very few seeds will end up in the right place to be able to maintain a full size. If they’re in the shadow of tree, they’ll do better than if they’re out in the open. - Lots of animals eat these seeds. - If you have this huge deposit of seeds in the soil, plants are hedging their bets to have a few that don’t get eaten and land in the right spot with a little bit of shade and take advantage of where there is a bit of moisture. Thinking about adaptations: Desert ecosystems are less likely to have problems with invasive plant species: True or False Half and half.- Why people thought True: Potential that you have an invasive that’s adapted is less likely- Why people thought False: Humans may move