Uses of Ecosystem Modeling for Range Management


Table 1. Typical values of response times and sizes for selected entities of a plant ecosystem. A leaf cell is the basic unit of plant leaf structure and function. Chlorophyll represents a principal class of pigments responsible for light absorption in photosynthesis. A photon is a basic unit of light energy. SOM refers to soil organic matter.

 

Entity

Description

Response time

Size or density of entity

chlorophyll

absorbing a photon*

0.1 second

1.4ยด10-7 in. (length)

leaf cell

volume change*

34 seconds

0.002 in. (diameter)

tomato stem

change in water potential*

66 seconds

0.008 in. (cross-section)

stoma opening

responsiveness

minutes

0.0008 in. (length)

soil soluble C

C = carbon**

 days

4.5 lb/acre

soil soluble N

N = nitrogen**

days

6.3 lb/acre

C in met. litter

met. = metabolizable**

weeks

18 lb/acre

leaf

longevity

weeks-months

0.01 in. (thickness)

C in cel. litter

cel. = cellulose**

months

900 lb/acre

root

longevity**

months-years

-

C in lig. litter

lig. = lignin**

years

1,300 lb/acre

C in uSOM

uSOM = unprotected SOM**

years

3,600 lb/acre

C in pSOM

pSOM = protected SOM**

20 years

36,000 lb/acre

C in sSOM

sSOM = stabilized SOM**

250 years

54,000 lb/acre


* Source Nobel (1999). **Source Thornley (1998), 3 ft soil depth assumed.


Table of contents

  
NDSU Central Grasslands Research Extension Center
Home | Livestock Research | Economics Research | Range Research | 2001 Annual Report