ICAR AICE-JRF/SRF Agroforestry & Trees on Farms for Sustainability: practice questions

1 · Classification of agroforestry systems · medium

Nair's classification groups agroforestry systems on four bases. They are:

1. Climatic, edaphic, biotic, physiographic and historical factors
2. Annual, biennial, perennial and permanent
3. Structural, functional, socio-economic and ecological
4. Public, private, communal and open access

2 · Tree-crop interactions: competition and facilitation · easy

In the interaction equation I = F - C used for agroforestry, C stands for:

1. Carbon stored in tree biomass each year
2. Competition for light, water and nutrients
3. Crop yield in the sole-crop control plot
4. Cost of establishing the tree component

3 · Tree-crop interactions: competition and facilitation · hard

In a tree-crop system the crop yields 70% of the sole crop and the trees 60% of a sole plantation. The land equivalent ratio is:

1. 0.65
2. 0.42
3. 1.3
4. 1.0

4 · Shelterbelts, windbreaks and boundary plantations · hard

Africa's Great Green Wall initiative has increasingly emphasised:

1. A continuous belt of planted exotic trees across Africa
2. Mosaics of land use and farmer-managed regeneration
3. Removal of all trees from Sahelian farms
4. Irrigated plantations of a single species

5 · Agroforestry for soil fertility and erosion control · easy

The actinorhizal tree Casuarina fixes nitrogen in symbiosis with:

1. Rhizobium
2. Azotobacter
3. Frankia
4. Anabaena

6 · Agroforestry for soil fertility and erosion control · medium

Trees on farms can improve soil phosphorus and potassium supply mainly by:

1. Fixing phosphorus and potassium directly from the air
2. Creating new phosphorus in their roots
3. Recycling nutrients from deep layers in litter
4. Converting nitrogen into potassium

7 · Agroforestry for soil fertility and erosion control · hard

Research in eastern Zambia found maize after Sesbania improved fallows compared with continuous unfertilised maize gave:

1. Lower yields, due to nitrogen loss from the fallow
2. Identical yields, as fallows add no nitrogen
3. Higher yields, but below fully fertilised maize
4. Yields higher than any fertiliser treatment

8 · Carbon storage in agroforestry · easy

The IPCC default carbon fraction of dry woody biomass is:

1. 0.047
2. 4.7
3. 0.85
4. 0.47

9 · Carbon storage in agroforestry · easy

To convert a mass of carbon to carbon dioxide, multiply by:

1. 12/44
2. 32/12
3. 44/12
4. 16/12

10 · Carbon storage in agroforestry · hard

Carbon sequestration in an agroforestry system is described as time-limited because:

1. Stocks level off as trees mature or are harvested
2. Trees stop photosynthesis entirely after their first year
3. Soil carbon always falls steadily under any tree cover
4. Carbon in wood converts to methane within a decade