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Appendix 3‐1
ОглавлениеComparative characteristics of a native tallgrass prairie, a conventional corn–soybean farm, and an oak–hickory forest.
| Characteristic | Native tallgrass prairie | Conventional farm | Oak–hickory forest |
|---|---|---|---|
| Physiography | central lowlands of level to undulating terrain | central lowlands of level to undulating terrain | central lowlands and Ozark Plateaus |
| Climate | eastern Kansas | east‐central Nebraska | north‐central Missouri |
| Mean annual temperature,°C | 12.8 | 10.0 | 12.2 |
| Mean January temperature,°C | −2.3 | −6.2 | −2.5 |
| Mean July temperature,°C | 26.7 | 25.0 | 25.5 |
| Avg. frost‐free period, d | 190 | 167 | 194 |
| Mean annual precipitation, mm | 800 | 695 | 1015 |
| Quarterly precipitation, % of annual(Jan.–Mar./Apr.–June/July–Sept./Oct.–Dec.) | 12/38/32/18 | 12/40/33/15 | 18/32/27/23 |
| Annual precipitation variability, yr(1961–1990) | |||
| <75% of avg. | 4 | 5 | 3 |
| >125% of avg. | 4 | 7 | 2 |
| Hydrology | |||
| Actual evapotranspiration, mm | 760 | 649 | 747 |
| Potential evapotranspiration, mm | 780 | 704 | 842 |
| Percolation and runoff, mm | 40 | 46 | 268 |
| Soil | |||
| Predominant soil order | Mollisol | Mollisol | Alfisol |
| Suborder | Udoll | Ustoll | Udalf |
| Total SOM, g m−2 (0–100 cm) | 31,600 | 19,640 | 7,027–13,403 |
| Soil N (0–100 cm) | |||
| Inorganic N, g N m−2 | 4.5 | 4.6–11.0 | 3.2–6.1 |
| Organic N, g N m−2 | 1,550–1,580 | 982 | 410–782 |
| Community composition & structure | |||
| Physiognomy | grasses dominant with a 0.5–3.3‐m closed canopy | maize or soybean monocultures with uniform closed canopies (2.5–3 m maize; 0.7–1 m soybean) | broadleaf deciduous forest in which 50% or more of the trees are oak or hickory with a 5.5–8.3‐m (avg. 6.3) |
| Dominant floristic type | perennial grasses | annual grass (maize) or annual broadleaf (soybean) | perennial broadleaf trees |
| Species richness (250 ha) | 200–300 vascular plant species | dominance by two crop species | ~94 vascular plant species |
| Species evenness | >50 % of aboveground biomass in 3–4 species | >90 % of aboveground biomass in 2 species | >90% of aboveground biomass in 3–4 species |
| Avg. annual max. aboveground biomass (includes litter), g m−2 | 650–1,075 | 870 (live only) | 10,934 |
| Avg. annual max. belowground biomass, g m−2 | 1,869–1,985 | 160 | 2,592 |
| Belowground OM (includes living and SOM), % of total OM | >98 | 96 | 47–59 |
| Leaf area index, m2 m−2 | 4 | 4–4.5 | 2.5–4.5 |
| Root depth distribution | 90% of root biomass in top 50 cm | >90% of root biomass in top 75 cm | >50% in upper 30 cm |
| Energy flow | |||
| Solar radiation, growing‐season PAR, kJ m−2 | 2227 × 103 | 1772 × 103 | 2017 × 103 |
| Non‐solar energy inputs, MJ ha−1 (Mcal acre−1) | 0 | 17.3 × 103 (1670) | 0 |
| Annual aboveground NPP, g m−2 | 300–700 | 983 | 597.6 |
| Annual belowground NPP, g m−2 | 500–1200 | 177 | 950 |
| Proportion of total NPP as seed or grain, % | 6 | 45 | 2 |
| Energy capture efficiency (%) | 0.72‐1.09 | 0.74 | 1.08 |
| Water use efficiency | 1.8–2.18 | 1.87 | 2.07 |
| Partitioning of aboveground NPP, % | |||
| Herbivores | 13–45 | 5 | <0.2 |
| Detritivores | 55–87 | 50 | 99 |
| Exported from the system | 0 | 45 | 0 |
| Nutrient cycling | |||
| Avg. annual N inputs, g N m−2 | 1.0 | 8.2 | 2 |
| Avg. annual N losses, g N m−2 | 0.26–0.6 | 2.2 | 2 |
| Avg. annual N export in harvested crop, g N m−2 | 0 | 10.9 | 0 |
| Belowground N, % of total | >98 | >98 | 92 |
| Soil erosion, kg ha−1 yr−1 | minimal | 11,200 | minimal |
| Changes in soil SOM pool | stable | loss of ≥ 30% in first 30 yr of cultivation | stable |
Note. SOM, soil organic matter; OM, organic matter; PAR, photosynthetically active radiation; NPP, net primary productivity.
