FOR 2060 1nd Edition Lecture 10 Outline of Last Lecture I. Nitrogen CycleA. AmmoniumB. Nitrification C. Denitrification II. NutrientsIII. LoggingOutline of Current Lecture IV. Assart Effect V. Role of Pioneer Species VI. Temperate vs Tropical ForestsA. Slash Burning Current LectureIV. Assart Effect The Assart effect is when accelerated nutrient mineralization following a disturbance creates a pulse of available nutrients. In clear-cutting, you are left with increased litter, no trees taking thenutrients out of the soil, more sunlight making it warmer, and a lot of decomposition. Some of the nutrients that are released will stay in the soil and some may leach and run off. The high nutrients are only temporary! V. The Role of Pioneer Species Pioneer species colonize sites following clear-cutting and disturbances. They have small seeds, grow fast, and do well in open sunlight. They have evolved to capitalize on the assart effect. Then soil nutrient levels rapidly decline, sometimes below the pre-disturbance levels, and the pioneer species no longer have any advantages over other species. They help to maintain minerals on the site. Then they decompose and give way to other species. VI. Temperate vs Tropical ForestsTropical forests may experience a more rapid decline in soil fertility following harvesting than temperate forests. Residence times in tropical forests are very low so the Assart effect is quick. Sometimes it is so quick that pioneer species are unable to come in. The resources are lost so 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.quickly that tropical forest forestry techniques are unsustainable. With slash burning most of the soil surface becomes ash. This leads to a large loss of nutrients because nitrogen volatilizes. Immediately after burning there is an increase in nutrient availability; however, this also leads toan increase in potential for leaching