ESRM 410 Forest Soils and Site Productivity

2011

Nutrient Limitation‘What if Scenario’

Cedar River Watershed – plots just located upstream of ‘you are here’ pointer

• This slide and some following contain the design, stand characteristics and initial growth results. Please concentrate on explaining factors that might have led to the differential growth of Douglas-fir vs. red alder on each site and also the differential growth of each species on different initial site (i.e. RA-RA vs. DF-RA – Group 1 orally presents Friday and RA-DF vs. DF-DF – Group 2 orally presents Friday).

Figure 1. Layout of study.

Alder replanted with Alder

DF replanted with DF

Alder replanted with DF

DF replanted with Alder

Table 1.

Table 2. Stand C distribution in the 50-yr-old Douglas fir and red alder stands. Tree and understory C concentrations were assumed to be 500 mg C kg-1. Where possible from sampling procedure, variability between plots was assessed and means compared via two-tailed two-sample t-test (Freund, 1988).

Component Douglas fir Red alder ------------------- kg C ha-1 -------------------- Total tree 158000 136000 Aboveground 136000 113000 Leaf 3100 1750

Understory 1550 (500)† * 3000 (1050)*

O horizon 9470 (235)*** 30300 (640)***

Wood 6020 (1130)** 9300 (1250)** Mineral soil 0-15 cm 37700 50200 15-30 cm 21900 32700 30-45 cm 20100 21600

Total soil 79700 105000 Total stand 255000 284000

*,**,*** Significant at the 0.05, 0.01 and 0.001 probability levels, respectively.

† Numbers in parentheses are standard deviations (n=4).

Figure 2. Growth of new plantations.