Exotic Brome-Grasses in Arid and Semiarid Ecosystems of the Western US

236

Table 8.2

(continued)

Mojave (

n = 172)

Colorado Plateau (

n = 195)

Great Basin (

n = 30)

Chihuahuan (

n = 14)

Minimum

Maximum

Minimum

Maximum

Minimum

Maximum

Minimum

Maximum

Zn

0.12

0.81

0.06

3.5

0.4

8.2

0.02

1.6

K

/Mg be

0.64

6.2

0.13

4.6

0.46

4.3

0.04

5.2

P/ANP

<1

166

<1

391

<1

528

<1

1.5

Perennial plant % cover

0

57

0

80

12

80

14

50

Annual plant % cover

0

48

0

50

0

75

0

0

Subscripts indicate the extracting agent. Phosphorus (P

) and K (K be

) were extracted with NaHCO be

, and exchangeable cations (Na 3

, Ca ex

, K ex

, and Mg ex

) were ex

extracted with NH

C 4

H 2

O 3

buffered to pH 8.5 to match the soils. Micronutrients (Cu 2

, Fe ex

, Zn ex

, and Mn ex

) were extracted with diethylenetriaminepentaacetic ex

acid (DTPA). P/ANP is the ratio of P

to the acid-neutralizing capacity of the soil (ANP). Concentrations of elements are expressed as mg element/kg dry soil. be

Subscripts av = available; ex = exchangeable; be = bicarbonate extractable. Total N was measured using the Kjeldahl method

J. Belnap et al.