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Don’t hate invasives, they all have a place (if they keep to it)
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Fire (continued) Chicago Wilderness –Passing the Drip torch In healthy woods and savannas, representatives of every age— seedlings, saplings, teenagers, and adults http://www.chicagowildernessmag.org/issues/spring2007/editorsessay.html one community of “pioneer plants” prepares the way the growth of the next generation of oaks as “recruitment”
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Healthy burns in the arboretum Burns over large areas Rotation of a 4-year burn schedule Adjacent to areas not burned in the last 2 years Seasonal rotation of burns
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The dry Plains were provided the perfect conditions for fires to start. The long hot summers left the Prairie Grass and the homesteaders’ crops bone dry. Accidental fires started by a spark or a bit of broken glass lying on the ground and reflecting the sun were a disaster for the homesteaders. Unless the fire could be stopped quickly by beating, it soon spread. Without any water to put out the fire, the homesteaders were forced to hide in their sod houses until their crops were destroyed and the fire died.
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Canopy fire Hot (300-400 F) Widespread mortality Strongly linked to fire weather Potentially large spatial scale Dominant vegetation removed Yellowstone National Park, 1988
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Surface fires Grasses regenerate because growth tissues are underground Seedlings and saplings killed; adult trees spared Lower temperature than canopy fires Tallgrass prairie, Kansas
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http://climate.konza.ksu.edu/ Tall and short grass prairie
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Disturbance agents: fire and drought, and historical grazing from bison. 5-10 yr return intervals for tall grass prairie Fires removes litter (or duff) and woody shrubs Perennial grasses have greater seed production and germination rates following fire Trees found on the eastern sides of rivers because of prevailing westerly winds. Mowing is not a good replacement for fires, as it does not remove the litter. Grazing by domestic cattle is not a good replacement as it exerts a selective pressure on only a few species. Burning is required for the restoration and maintenance of prairie reserves Is fire carbon Negative?
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Other physical effects of fire Creates environmental heterogeneity Promotes species coexistence, particularly between early and late successional species
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Cerro Grande fire in New Mexico, 2000 –Controlled burn escapes and destroys homes in Los Alamos Biscuit fire in southern Oregon, 2002 –Lightning-ignited fire burns uncontrollably over wide area and burns national forests and homes in local communities Esperanza fire in southern California, 2006 –Arsonist starts fire at suburban-wildland interface in southern California
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1990’s-2006: increased pressure to suppress fire and thin forests in response to uncontrollable natural wildfires, escape of controlled burns, and a growing population at the suburban-wildland interface. The recent Healthy Forests Restoration Act advocates salvage logging after fires to pre-emptively thin them In-class short readings 2-4
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Secrets of the Soil Chapter 4 Justin Borevitz
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Fungal, bacterial, insect, nematodes Water Bear, Spring Tails Nitrogen Fixing Allelopathy Soil Microbe diversity
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A multi-disciplinary approach to research in soil related ecosystem services Ecosystem functions Soil processes Ecosystem services for human welfare Soil Organisms Soil Biodiversity soil biology - microbiology Soil ecology Soil science Environmental economics Resource economics Sociology Political sciences Let me start with a challenge to soil science to embrace other disciplines and together come with workable solution to improve the livelihoods of rural populations. The discussion now-a-days is all about the sustainable use of our natural resources, with increasing emphasis on the biological and genetic resources (in other words – soil science has long neglected the biological component of the soils and this is surfacing maybe as the most important subject and resource available to us. With the advent of biotechnology the future is in the use of our biological and genetic resources) Concern about the increasing loss of biodiversity (or loss of species) have raised the question about the effect on the ecosystem functioning and therefore also the question of what loss of soil biodiversity means for the functioning of the soil as being maybe one of the most important (and often overlooked) component of terrestrial ecosystems. The graph shown at the same time gives an idea of the complexity of the projects as well as the subject we are dealing with in this context. Attention should be focussed on the linkages or boundary objects. We make a distinction between the soil organisms that constitutes the soil biodiversity, the ecosystem processes in which often many different soil organisms are involved, the ecosystem services that then result from interplay of different processes in the soil. Let me briefly address these three different components separately and highlight the challenges before going into perspectives for management of BGBD for improved ecosystem services. http://www.fao.org/ag/AGL/agll/soilbiod/default.stm
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KEY FUNCTIONAL GROUPS OF SOIL BIOTA Pests and Diseases e.g. fungi, invertebrates Decomposers e.g. cellulose degraders Micro-symbionts mycorrhizal Fungi N-fixing Bacteria C&N transformers e.g.methanogens & nitrifiers Microregulators Nematodes Macrofauna (Ecosystem Engineers) –Earthworms –Termites Maize Legume Source Swift (2002)
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What do fungi “eat?” Decomposers break down complex molecules into sugars or consume sugars found in environment Symbiotic fungi receive their energy (carbohydrates) directly from a plant or algal partner Examples: mycorrhizal fungi (live on plant roots) lichens (contain algae) Briana Timmerman timmerman@biol.sc.edu
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What else do fungi “eat?” Predatory fungi, catch and digest other organisms (like nematodes) But still absorptive nutrition! Just have to catch it first… Briana Timmerman timmerman@biol.sc.edu
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Lichens Briana Timmerman timmerman@biol.sc.edu
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Mycorrhiza symbosis A mycorrhiza (Greek for fungus roots) is the result of a mutualistic association between a fungus and a plant. This mutualism takes place at the root level, where individual hyphae extending from the mycelium of a fungus colonize the roots of a host plant, either intracellularly or extracellularlymutualistic mutualismhyphaemyceliumfungus rootsplant
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Transport P, K from great distances Extend the root system Trade Minerals for sugars.. 95% of all plant families are predominantly mycorrhizal An ericoid mycorrhizal fungus isolated from Woollsia pungens [2].[2] Midgley, DJ, Chambers, SM & Cairney, JWG. 2002.. Australian Journal of Botany 50, 559-565
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Mycorrhizae “myco” = fungus and “rhiza” = root Symbiotic association between plant roots and fungi Several different types of association (defined by structure of fungus:plant interface) Briana Timmerman timmerman@biol.sc.edu
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Fungi can access more of the soil because 1.Hyphae are smaller than plant roots Hyphae are 1/500th the diameter of a plant root hair Root Hair hyphae Briana Timmerman timmerman@biol.sc.edu
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and fungi expand the surface area available for nutrient uptake Briana Timmerman timmerman@biol.sc.edu
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These connections can form forest-wide networks! If mycorrhizae can move significant amounts of carbon (sugar) between different plant species, this could reduce competition and contribute to the stability and diversity of ecosystems. Briana Timmerman timmerman@biol.sc.edu
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Biological Nitrogen Fixation (BNF) Plant receives ‘reduced’ nitrogen Bacteria receives energy and other nutrients Nitrogen fixation is the process by which atmospheric nitrogen gas is converted into ammonia. The ammonia is subsequently available for many important biological molecules such as amino acids, proteins, vitamins, and nucleic acids. The reaction can be presented as follows: N 2 + 16 ATP + 8e - + 8H + -> 2NH 3 + 16 ADP + 16 P i + H 2 Root nodules
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Biological Nitrogen Fixation (BNF) Infection, nodule development, and fixation occurs when: Proper match occurs (strain specific) Surface chemistry conditions are met (Ca ++, NO 3 - levels) Bacteroid is formed capable of fixing N 2 Synthesize nitrogenase Jointly with plant synthesize leghemoglobin N 2 is reduced to NH 3 NH 3 is attached to glutamate Amino acid is made or transported as glutamine or ureide
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allelopathy denotes the production of specific biomolecules by one plant that can harm, or give benefit to, another plant. However, it is most commonly used in the former sense - an interaction in which one plant causes suffering to another plant Competition or toxicity Direct or through microrhyzhoa
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Some plants that use allelopathy are black walnut trees, sunflowers, wormwoods, sagebrushes, trees of heaven Pine trees, Eucalyptus
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In 1 teaspoon of agricultural soil there are… Bacteria 100 million to 1 billion Fungi 6-9 ft fungal strands put end to end Protozoa Several thousand flagellates & amoeba One to several hundred ciliates Nematodes 10 to 20 bacterial feeders and a few fungal feeders ArthropodsUp to 100 Earthworms5 or more Mary Barbercheck Dept. of Entomology Penn State University
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Soil Health Indicator
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Some Factors Affected by Tillage Soil Moisture Soil Temperature Range of Temperature and Moisture Fluctuations Surface Residue Soil Fauna Abundance and Diversity Plant Diversity Favors Bacteria > Fungi
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(After Moldenke, 2002) Tilled Bacterial-based No Till Fungal-based Densities are much lower than in unmanaged systems, regardless of level and types of inputs Favors bacteria over fungi Soil arthropods tend to consume fungi Soil Health Indicator
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Effects of Cover Crop Rye Management in Reduced Tillage Corn Clark et al. 1993. J. Entomol. Sci. 28: 404-416 a a ab b a a b a b b
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Systems Experiment 1999-2002 Microarthropods Cumulative Average Barbercheck, unpubl.
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