Site index confusion

[jeffreythree]

Is using the site index good for choosing which trees to manage for?  Learning as I go since I am to small and have no pines for the state to help me.  For example, one of my soils(Nahatche) has a site index of 92 for water and willow oak which I assumed was pretty good, but what about other trees they may not have listed like the hickory, ash, and elm I have growing there too?  The strange thing is even with a site index in the 90's this soil says to manage for cottonwood in the NRCS soil survey.  Also, when is a site index to low to bother with?  I have another area(Woodtell) I would like to add some conifers for some diversity, but the site index is 70 for shortleaf and 80 for loblloly, but the NRCS says this soil usually has oaks of various types growing on it.  Thanks for any help.

[ID4ster]

Site indexes are species specific so a site index of 92 for water and willow oaks won't necessarily translate to a good or poor site index for pine or other hardwoods. While the soil plays a major part in the productivity of a site other factors such as aspect, topography climate and local weather patterns will also determine what trees will grow and how well those trees will grow on a particular site. Talk with your local extension, NRCS or state forester and have them do a walk through with you on your property. They'll be able to point out what species are doing well there and what species should or should not be grown on the site. As for site indexes that are too low, you really have to have a harsh site or poor aspect before you get to a point that it is not worth growing timber (assuming that you have a large enough parcel). Make sure that you compare site indexes of equal bases (i.e. 50 yr to 50 yr and 100 yr to 100 yr) so that your comparisons match up and look at the total board foot figures, that are in the specific soils sections, for the rotation to help determine how productive a site is. 

[Clark]

My experience with soil survey maps and site index is that the soil map will miss lots of data.  While soil is usually the biggest determinant of site index and it also strongly influences which species grow best there, soil surveys are not put together with only trees in mind.  All that to say that your soil survey is probably in the right ballpark for site index but there's a decent chance that it doesn't give you the best recommendations for your site.

Invite a forester for a walk through your woods and then start asking the tough questions!  Based on species composition, ground cover and soil data most foresters should be able to tell you what the best species to plant are. 

Kudos to you for checking out what soils support your land, most people never even bother.

Clark

[jeffreythree]

The state forester is one of the problems, no support on that end a few months back.  I may just have to get a consulting forester out to answer my questions since it is my money paying for their time, but the return may not justify the expense.  The property is my own personal experiment: personally milling any thinnnings, cleanings, or culls for my woodcrafts; trying to make my big trees bigger because I am have 6 species(nutmeg hickory, post oak, cedar elm, slippery elm, honey locust, and ERC) close to state champ big tree size; increasing diversity of species which is where the site map to determine what to plant next comes in; and making it all where my disabled wife can enjoy it too.

[Ron Scott]

Ditto, to the above comments. You are on the right track by making use of and interpreting the soil survey for your property. It's good information to use in meeting the management objectives for the property.

Also, check the water table depths for your specific soils to help in determining desired species for vegetative diversity.

[WDH]

Also check out what is growing well on similar sites in your general area.  Nature generally knows best.  Copying what nature does on her own is not a bad strategy.

[jeffreythree]

Also, check the water table depths for your specific soils to help in determining desired species for vegetative diversity.

I have an area of mature willow and post oak that died near our pond.  The soil has an 18" saturation depth and I think the pond raised the water table and killed them.  Will willow  oak, which is regenerating, handle the high water table if grown in it from the beginning?  I already planted 1\2 acre with baldcypress closest to the pond this past january.

[WDH]

Willow oak does well on bottomland soils (at least here in the South), so it should be OK near the pond.  There is a lot of willow oak on the wet low flats in Texas.

[woodtroll]

willow oak is a wet oak, the post oak is a dry oak. But post oak will grow in wet areas that have shallow soil to a hard pan, and that dry out. Cherry bark red oak may be a good candidate, it grows in wet and develops a tree with less branch stobs, it self prunes, like willow oak or pin oak.