BIOLOGY-LICHENS report in Evolutionary Botany.pptx

report

1. www. liceo .edu.ph LICHENS GLADYS OLIVEROS-REAL, MAED-General Science GenSci 205- Evolutionary Botany

2. www.liceo.edu.ph Learning Objectives To understand the nature and characteristics of lichens as symbiotic organisms. To identify the morphology of lichens and describe the different structural types of lichens. To explore the ecological and environmental significance of lichens, as well as their potential negative impacts.

3. www.liceo.edu.ph Lichens are unique, symbiotic organisms formed by the association of a fungus (mycobiont) and a photosynthetic partner (photobiont), usually a green alga or cyanobacterium. They are found in diverse and often extreme environments and play critical ecological roles, such as bioindicators of air quality and pioneers in soil formation.

4. Origin of Lichens Lichens evolved around 400–600 million years ago as a partnership between a fungus (usually from the Phylum Ascomycota). The fungus (mycobiont) gives the lichen its shape and protects it. The alga or cyanobacterium(photobiont) makes food through photosynthesis (using sunlight, water, and carbon dioxide).They live in all kinds of places—even very harsh ones like rocks, deserts, or frozen areas.

5. This cross-section of a lichen thallus shows its various components. The upper cortex of fungal hyphae provides protection. Photosynthesis occurs in the algal zone. The medulla consists of fungal hyphae. The lower cortex also provides protection. The rhizines anchor the thallus to the substrate. Morphology of Lichens

6. www.liceo.edu.ph Lichens come in various forms, but they are generally categorized into three main structural types: Crustose Lichens- These are flat and crust-like lichens that grow tightly attached to surfaces like rocks, tree bark, or soil. Example: Graphis species. They cannot be easily removed without damaging the surface they grow. on. Three Types of Lichen Structures (Classification Based on Growth Form)

7. www.liceo.edu.ph Foliose Lichens Leafy and flat with distinct upper and lower surfaces. They are loosely attached and can be easily lifted from the substrate. Example: Parmelia species.

8. www.liceo.edu.ph Fruticose Lichens- These have a bushy or shrubby appearance and are often branched. They can hang from trees or grow upright on the ground. Example: Cladonia or Usnea (old man’s beard).

9. www.liceo.edu.ph Environmental Indicators Lichens are highly sensitive to air pollution and are used as bioindicators to assess air quality, especially levels of sulfur dioxide and heavy metals. 2. Soil Formation and Stabilization In barren environments, lichens contribute to the formation of soil by breaking down rocks through physical and chemical processes. They also help prevent soil erosion. Importance of Lichens

10. www.liceo.edu.ph 3. Ecological Roles- Lichens provide food and habitat for various animals, including insects, snails, and reindeer. They also play a role in nutrient cycling in ecosystems. Importance of Lichens

11. www.liceo.edu.ph Damage to Structures and Monuments Lichens growing on buildings, statues, and gravestones can cause surface degradation over time by trapping moisture and secreting acids that break down stone and metal. 2. Interference with Plant Health While generally not parasitic, heavy lichen growth on trees can sometimes block sunlight, trap moisture, and harbor pests, which may stress the host plant. 3. Economic Impact on Forestry In some cases, lichens can interfere with tree growth in commercial forestry operations, particularly when they host disease organisms or affect aesthetics. Negative Effects of Lichens

12. www.liceo.edu.ph Lichens are fascinating and ecologically important organisms that demonstrate the power of symbiosis. While they play vital roles in ecosystems, including pollution monitoring and soil formation, they can also have negative effects on man-made structures and plant health. Understanding their biology and impact can help us manage and appreciate them better in natural and urban environments. Conclusion

13. www.liceo.edu.ph Thank you and have a great day ahead!