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Agroforestry: a trend in global land useInternational Symposium on Agroecology for Sustainable Agriculture and Food Systems
Kunming, Yunnan, China, 29th - 31st August, 2016
Jianchu Xu PhD Principal Scientist, World Agroforestry Center
Distinguished Professor, Institute of Animal Science, Chinese Academy of Agricultural SciencesDistinguished Professor, Kunming Institute of Botany, Chinese Academy of Sciences
What landscape do we want?
Tree cover loss globally: 42-51%, 2.4-3.4 billion haTree cover loss in China: 59-67%, 0.19-0.27 billion ha
Ahrends, Xu et al. 2016 (unpublished)
How much tree cover has been lost in human history?
Significantly increasing tree cover on agricultural land
http://www.nature.com/articles/srep29987
The contribution of agroforestry to global and national carbon budgets
http://www.nature.com/articles/srep29987
Change in Amount of AgriculturalArea with Tree Cover
From 2000-2002 to 2008-2010
• Globally, proportion of land under at least 10% tree cover increased from 40% to 43%
• The amount of land with at least 10% tree cover increased in almost all regions
• South America showed the largest increase
• Only decrease was in North and Central Asia
• South Asia increased from 21% to 28%, East Asia from 43% to 48%
• In Central America, agricultural land with at least 10% tree cover increased to 96%
Change in Population of Agricultural Area with Tree Cover
From 2000-2002 to 2008-2010
• The share of the global population living in agricultural areas with at least 10% tree cover increased from 41% to 46%: more than 90 million more people
• In almost all regions, the population living in areas with at least 10% tree cover increased
• South Asia showed the largest increase: 44 million more people; increased to 34% of all persons in ag area
• The only region which showed a decrease was North and Central Asia
• In Central America, the population living on agri. land with at least 10% tree cover increased to 95%
Average Tree Cover by Population Density
2000-2002 & 2008-2010
• Central America has the overall highest ratio of tree cover vs pop. density, which increased during the period 2008-2010
• South Asia and Sub-Sahara Africa have high levels of tree cover at low pop. densities, but low levels of tree cover at higher pop. densities, lower than the global average
• South America and SE Asia both show increased levels of tree cover at higher pop. densities
The area of planted trees across China has exceeded 46 million hectares, ranking it first in the world
Forest Land: Average Tree Cover in 2000 was 35%; by 2010, this had increased by 3.3% to 38%Agricultural Land: Average Tree Cover in 2000 was 12%; by 2010, this had increased by 2% to 14%
Significant opportunities for up-scaling of agroforestryAlthough China increased tree cover overall, including on agricultural land, more than 30%
of all agricultural land was found to have lost tree cover
SylvopastureRiparian buffer
Alley cropping
Windbreaks
Mixed planting
Trees as hotspots for biodiversity and ecosystem services
More people, more trees and more productivity:Almost all production land equivalency ratios in agroforestry are greater than 1
Graves et al. (2007b)
Mead & Willeay (19080)
Nodules
Roots
During the N-fixation process, C acts as both an energy source and a substrate for amino acid production, incorporating the fixed N into an organic form
N-fixation draws CO2 below ground, acting as a C sink
CO2Pump model
Mortimer, Hyde, Xu Jianchu, Biology Letter (under review)
Tree as carbon pump
Trees in Nutrition Cycle
Mortimer et al. 2015 Applied Soil Ecology 96:25-32
The honey bee genus—nine Apis species in the world, of which six species are present in China
Trees in land sharing and land sparing landscape management
Teichroew J., Xu J, et al. 2016. Biological Conservation http://dx.doi.org/10.1016/j.biocon.2016.05.023
