At Home in Nature

  (Agate, Colorado)
TwoInTents Blog
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Are tree leaves nutritious for animals?

We are currently testing the nutrient levels in the blood of our animals as we feed them tree leaves, and while tree leaves may seem unusual, they are common foods for animals in most other places.  The TDN, RFV, and mineral content varies considerably from forage to forage, even two different fields of grass will be significantly different in most respects depending on species of grass, or variety of alfalfa.  The FAO and many foresters agree, trees are no different.  However, studies (FAO: 4.1 The Nutritive Value of Tree Legumes, Dr.B.W. Norton indicate that there is little difference between tree leaves and most standard hays.
Many people supplement based on a belief of what they are feeding their animals.  Often, they are wrong in their assumptions, and attempts to perfectly balance diet are futile unless you are working with laboratory formulated feeds, such as those which are manufactured by Purina and other vendors.
Leaves are excellent food for not only ruminants (it is the food of choice throughout most of the world, though in the Americas, we are just discovering this), but also animals with simpler stomachs.  Even people eat quantities of tree leaves without harm.  Some tree leaves are poisonous in small quantities, others are poisonous in large quantities; others are wholesome and healthsome in even minute quantities.  Many trees have medicinal properties. 
The answer for those who supplement to overcome deficiencies in diet when using conventional grass and alfalfa feeds is the same for those who supplement to overcome deficiencies in tree leaf diets: hedge on the side of too much rather than too little.  Few nutrients cause disease when overfed in moderate amounts.  In Colorado, selenium deficiency is common because the soil is so poor in selenium. Most leaves have about 10% crude protein, with about 60% digestibility, and while oaks may have up to 15% mean taninnic acid equivalent, most trees typically have much less than half that and 15% is not bad, if the oaks are diluted with other feed ("Nutritive Value of Tree Leaves in the Kansas Flint Hills," JR Forwood and CE Owensby: Journal of Range Management 38(1), January 1985).  I, myself, enjoy the linden leaves best.  They make an excellent salad. 

Debris essential to reforestation

Drs. Tomasz Zielonka and Mats Nildasson (Ecological Bulletins, 2001. 49:159-163) of the Institute of Botany in the Polish Academy of Sciences and the Southern Sweedish Forest Research Center of the Swedish University of Agricultural Sciences remark how important it is for dead wood to be present in a healthy forest. However, when reforesting, it is necessary and beneficial to introduce your own deadwood. In establishing the windbreaks you read about in today’s Herald, remember that the deadwood, as it decomposes, improves the soil and, in the time that the lowest levels of the windbreak decompose, the tree roots will be seeking the vital organic material there. A thick layer of mulch near the trees will not go amiss, either. Deadwood, according to the Doctors, significantly assists the establishment of new trees and the regeneration of forests.

We investigated regeneration patterns and dead wood dynamics in high altitude natural Norway spruce Picea abies forest in the Tatra Mountains, Polish Western Carpathians, and used dendrochronological cross-dating to asses the age of fallen logs. We compared the exact time since tree death with physical features reflected in a 5-degree classification of the decomposition stage. In more decayed logs where wood samples were impossible to cross-date we used the maximum age of saplings growing on logs as an indicator of minimum log age. The total volume of dead wood on the forest floor was ca 60 m³ / ha. Dead wood covered ca 5% of the forest floor. The log ages were for class A (least decayed) -- up to 4 yr, for class B: 8-44 yr and for class C: 44-115 yr. The minimum age of the most decayed classes D and E was estimated to 50 and 60 yr, respectively. One year-old seedlings were present on logs of all decay stages except on fresh windbreaks and windthrows of class A. The highest number of seedlings was found on logs in decay classes C and D which indicates that the middle stage of decomposed wood is the best substrate for germination. The successful cross-dating of over one hundred years old spruce logs is an evidence that some portion of fallen logs may escape fast deterioration even in species normally regarded as not resistant to decay.

Tree planting tips

Any time the ground is not frozen is a good time to plant trees.  Provide extra water in the wintertime, and extra mulch, though.  As always, mulch at the bottom of the hole, in the middle (half way up) and again on top of the surface.  Then cover the top mulch with a layer of soil.  Mulches include old leaves, hay, straw, rocks about the size of your fist, and in some places seashells or other soil modifiers.  Old leaves are best!


A handful or five of ashes in the bottom of the hole dresses the bottom mulch.  A dressing of stale urine (aged more than 6 months until it ferments and becomes less acidic) or composted manures is a helpful treat to the middle mulch layer, but make sure it is well aged or you'll burn the plant.  But dressings are not necessary.


Trees require tillage like any other crop, and should be planted in east/west rows in Colorado to shade the hot summer sun and break the cold north wind. 


Planting dates aside, it is never too early to dig the tree hole: dig it now, fill it with leaves or straw and let it compost for a little while.  It'll ripen just in time for the trees!  Then stir it by pulling it out to plant the tree and backfill with a little bit of ashes or your favorite dressings.  You may like the smell of lilacs, but you'll be more excited about the fungi, viruses, retroviruses and bacterias you'll smell this winter, I promise!

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