Last week, we kicked off our Master Woodland Manager training in northwest Oregon. Over the next six months the class will explore many aspects of small woodlands management and the trainees will come away with a better understanding of their own lands as well as a foundation from which to assist others.

We started out with a field tour where we investigated the environmental factors that influence forest growth on a given site. In particular, we wanted to see how variations in climate, topography and soil shape species composition, forest productivity, and management opportunities.

We went to five different sites, at various elevations and topographic positions from the uplands to the Valley floor. Despite the sites all being within a four-mile radius, we saw striking differences in the vegetation. The uppermost site supported a fast-growing stand of Douglas-fir and red alder. Further along, we came upon a rocky, south-facing site dominated by madrone and some not-as-fast-growing Douglas-fir; but this was just a few hundred yards from another site where the madrone were gone. Calculating the site index revealed that the Douglas-fir here were growing faster.

As we traveled down the watershed, the steep slopes along an upland creek supported alder and western redcedar. But on the flats further down the watershed, at our last stop on the Valley floor, the dominant species were Oregon white oak, Oregon ash, and valley ponderosa pine; the Douglas-fir at this last stop looked like they had caught a bad case of the crud.

Prior to the field tour, we spent some time learning how to find information about soils. The Web Soil Survey is a really handy tool for identifying soil types and learning about their properties. Using the Web Soil Survey, we mapped out our field sites and found some possible clues to our site differences. According to our soils map, the madrone were growing on a gravelly Saum soil, whereas the taller firs down the road were on the more productive Jory soil.

soil map

A recently formed gully at the latter site gave us the opportunity to see the soil profile which revealed a deep silty clay loam.

Jory soil profile

Jory phone screenRecently I’ve discovered SoilWeb, which has become one of my favorite natural resources-related mobile apps, available for both the iPhone and Android. Using your phone’s GPS capability, SoilWeb accesses the soil data from the Web Soil Survey for the soil right underneath your feet. That is, assuming A) that you are in a place where you can get a phone signal and B) that the soil maps accurately reflect the soil on your site. As we learned on our field trip, soil types as mapped often contain unmapped pockets of other soils.  The SoilWeb app doesn’t give you everything you can find on Web Soil Survey, but you can quickly ascertain the soil texture as well as the expected depth, drainage, and other important features.

The takeaway from our tour was that what’s growing on your forest can be a clue to your site’s underlying environmental influences, and vice-versa. The growing number of applications such as SoilWeb makes it easier to be a site “sleuth”, finding those clues and piecing together the puzzle.

Amy Grotta

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