ESRM 410 Forest Soils and Site Productivity

2013

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

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.

DF - DF

DF - RA

RA - DF

RA - RA

• 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

So, the these groups will respond to the above questions with the following comparisons:(many other comparisons can be made but just concentrate on answering the questions related to these forest plots)

Group 1 will compare = RA-RA vs. DF-RA Group 2 will compare = RA-DF vs. DF-DF

Figure 1. Layout of study.