Desertification

DesertificationRachel Vincent, Adam Ali, Yuna FarahEcosystems EcologySpring 2014

What IS Desertificatio

n? “Conversion of productive, arable

areas to non-productive”

Change in…Soil Properties

VegetationClimate

Results in… Loss of ecosystem

services food security, carbon

sequestration, supply of forage, fibers &

wood, maintenance of biodiversity

Stress in human societies

What’s the Nature of Desertification?

Occurs mainly in arid, semi-arid and sub-humid areas Drylands are very vulnerable to changes A form of land degradation

Reduction of biological or economic productivity of dry lands Consequences = loss of soil fertility Degrades dry but productive land so that it can no longer

sustain life Affects large dryland areas 1/3 of world population

resides in drylands If disturbances (climatic change or human causes) are

severe enough, land productivity might not reversible

Causes of Desertification

Human Causes Contribute the most Overgrazing Over-cultivation Tillage Irrigation

Inefficient irrigation Over-irrigation

Deforestation Population

Growth & migration

Climatic Causes Aridification fertile

regions becoming increasingly dry

Precipitation limited rainfall Water scarcity

Increases in drought Anthropogenic increase

in greenhouse gases Affect precipitation

pattern

Why is this important to

people?Increase of bare

soilGeneral decrease in ecosystem services &

productivityShifts in types of

vegetation

What are the Causes of

Desertification?

Poor land management

Anthropogenic forces

migration & conflicts

Climate change

Desertification has resulted in…

Agricultural declines Famines Loss of income

US loses $42 billion yearly

Reduction in resilience Due to climactic

variability

How does this problem alter the flow of energy, water, and nutrients throughout the

system? Less vegetation > more erosion/ dust emissions

High levels of dust in the atmosphere can lead to cooling

Dust emissions reduce precipitation and impede plant growth

Less vegetation > less evapotranspiration > less precipitation recycling

Less vegetation > less transpiration from plants, same amount of evaporation (unproductive) and can lead to salt accumulation

How does this problem alter the flow of energy, water, and

nutrients throughout the system? Increased run-off and evaporation > less water for

infiltration and transpiration Loss of vegetation > change in atmospheric CO2

Increased albedo from vegetation loss Surface temperature increase from decrease soil

moisture High temp/low precipitation leads to low soil organic

matter Soil degradation > infertile soil

How to Address and Remediate

Desertification

IdentificationMitigationControlReversal

Identification Biophysical

Land cover changeBiodiversitySoil fertility Economic

Market efficiencyDecreasing crop yields

SocialIncreasing migration from

rural to urban areasDeclining health

PoliticalDeclining state power

Immigration-related issues

Mitigation

“The success of biophysical remediation and mitigation measures depends on the the existence of favorable societal conditions…Local and ‘stakeholder involvement’ appear to be crucial” COLLECTIVE ACTION!

Control Importance of identification and

monitoring Soil, wind, water

erosion control Ex: mulching crop

residues, create vegetation shelterbelts controls wind erosion

Manage grazing and livestock mobility

maintains biodiversity

ReversalIMPOSSIBLE TO REVERSE BUT…

Improve agriculture & promote sustainability of resources Soil erosion control Salinity remediation

Manage grazing/livestock Biodiversity among crops

Improve & introduce better manmade systems/management

References Bakr, Noura, David C. Weindorf, Mohamen H. Bahnassy, Mohamend M, El-Badawi.

“Multi-temporal assessment of land sensitivity to desertification in a fragile agro-ecosystem: Environmental indicators.” Ecological Indicators 15 (2012): 271-280. Print Verón, S.R., J.M. Paruelo, M. Oesterheld. “Assessing desertification.” Journal of Arid Environments 66 (2006): 752-763. Print.

D’Odorico, Paolo, Abinash Bhattachan, Kyle F. Davis, Sujith Ravi, and Christiane W. Runyan. "Global Desertification: Drivers and Feedbacks." Advances in Water Resources 51 (2013): 326-44. Print.

Jiang, Zhongcheng, Yanqing Lian, and Xiaoqun Qin. "Rocky Desertification in Southwest China: Impacts, Causes, and Restoration." Earth-Science Reviews 132 (2014): 1-12. Print.

King, Caroline, and David S.g. Thomas. "Monitoring Environmental Change and Degradation in the Irrigated Oases of the Northern Sahara." Journal of Arid Environments 103 (2014): 36-45. Print.

Sivakumar, M.V.K. “Interactions between climate and desertification.” Agricultural and Forest Meterology 142 (2007): 143-155. Print

Zhao, Ha-Lin, Jin Li, Ren-Tao Liu, Rui-Lian Zhou, Hao Qu, and Cheng-Chen Pan. "Effects of Desertification on Temporal and Spatial Distribution of Soil Macro-arthropods in Horqin Sandy Grassland, Inner Mongolia." Geoderma 223-225 (2014): 62-67. Print.