Establishing Plots to Monitor Growth and Treatment Response Some do’s and don’ts A discussion

The question: Someone in the organization has proposed to install a bunch of 1/10 acre plots across their ownership. They are planning to have ½ controls and ½ treated (not necessarily the same stand). The objective of the study is to determine if the treatment is effective.

A resource on establishing and maintaining permanent plots: Curtis, R.O Procedures for establishing and maintaining permanent plots for silvicultural and yield research. General Technical Report PNW-155. USDA Forest Service, Pacific Northwest Research Station, Portland, OR. 56p.

Considerations Sampling Design Plots Measurements Miscellaneous

Sample Design Location of Plots (sampling/inference) –CFI Design –Strata/stands of interests e.g. young stands likely to be managed eco-physiographic regions

Sample Design Location of Plots (sampling/inference) –Strata/stands of interests –Demonstration plots and observational studies (no inference)

Sample Design Location of Plots (sampling/inference) –Strata/stands of interests –Demonstration plots and observational studies (no inference) –Randomize!! Choose from a list of candidate stands Do the stands exist Avoid bias

Sample Design Location of Plots (sampling/inference) –Strata/stands of interests –Demonstration plots and observational studies (no inference) –Randomize!! Replication/Blocking –How important is within stand variability –LOGS vs. SMC

Sample Design Location of Plots (sampling/inference) –Strata/stands of interests –Demonstration plots and observational studies (no inference) –Randomize!! Replication/Blocking True replication (row plots)

Plots Plot Size -- Bigger Please –Bigger plots cost more –Smaller plots are more variable (more difficult to detect differences)

Plots Plot Size -- Bigger Please –Bigger plots cost more –Smaller plots are more variable (more difficult to detect differences) –Think about the end of the experiment Numbers of trees (within plot variability) Expansion Factor (trees per acre – plot size) How long do you want to carry it? –Regeneration to harvest (nesting?) –LOGS

Plots Plot Size -- Bigger Please Nested plots

Plots Plot Size -- Bigger Please Nested plots Fixed vs. Variable Plots –Fixed simpler –Variable more like inventories

Plots Plot Size -- Bigger Please Nested plots Fixed vs. Variable Plots Edge effect and buffers

Plots Plot Size -- Bigger Please Nested plots Fixed vs. Variable Plots Edge effect and buffers Control vs Treatment –Should be paired (within stand) –Carefully (same species composition, diameter distribution, etc.)

Plots Plot Size -- Bigger Please Nested plots Fixed vs. Variable Plots Edge effect and buffers Control vs Treatment Tree plots (trials)

Measurements Are you collecting the data the model needs (adequately)? –Tree heights –Crown Ratio –Small trees often omitted (ingrowth) –Site index (difficult in young ages and small plots) –Age ???

Miscellaneous Documentation and data management – the value of these plots will most likely be in the future (by someone else) Protect the plots (investment) –Signs –GIS ??