North American Agroforestry. Группа авторов

Appendix 3‐1

       Comparative 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 Скачать книгу В начало < 45 46 47 48 49 50 51 52 53 54 > В конец