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Stewards of an Endangered, Prehistoric Tree

Torreya taxifolia Safeguarding Project

It is our responsibility to the land and our ecosystem to do everything we possibly can to help endangered plants and animals find a safe haven here at the Reserve.  One project we have been working on since April of 2018 is safeguarding Torreya taxifolia seedlings.  Working with the Atlanta Botanical Garden, we signed a Memorandum of Understanding (MOU) memorializing our commitment to protect this endangered species to the best of our ability. In 2018 we set up five 3’x3’ square raised beds and filled them with different substrates.  The boxes have a mesh bottom to prevent burrowing animals digging from underneath and a high arching fence to deter squirrels from eating the seeds before they germinated.

Torreya taxifolia was one of the first species to be federally listed as an endangered plant in 1984, in large part due to fungal and needle blights and logging.  This tree has been around for 160 million years!  It is estimated that there are about 500-600 trees left in the wild – only 0.3% of their original population – making them one of the rarest conifers in the world. Scale and root rot are other factors in their decline.  Planting seeds we acquired from Atlanta Botanical Garden in various substrates allowed us to determine how these soils affect the growth of the tree.  Although the common name for this species is Florida nutmeg or stinking cedar, North Carolina has claim to the largest living T. taxifolia at 45 ft tall and 35” wide.  All five of the trial bed substrates contain pine bark fines, sand, and lime.  The first trial bed had aged pine bark fines as the variable while the next two beds have fresh pine bark fines as the variable.

DieHard was added as the variable in the third raised bed. DieHard contains mycorrhizal fungi, bacteria, humic acid, sea kelp, vitamins and amino acids, all things that are important to a plant’s growth and development.  The mycorrhizal fungi rely on the plants to sustain their existence, so when the seedling is stressed, the mycorrhizal fungi kick into action, supplying nutrients to the seedling.

The last box has Biochar as the amendment. Biochar is found all over the world and occurs naturally from vegetation fires.  When biochar is added to the soil it acts as a moderator of soil acidity, helps with water retention, increases soil microbes and sequesters carbon in the soil.  There is research suggesting that the reduction in natural forest fires could be a reason why fungal pathogens are going unchecked and attacking T. taxifolia.  Thankfully, there are organizations such as The Nature Conservancy that offer fire management courses that talk about the beneficial effects of controlled burns. Biochar can be made at home too (think about a metal firepit at a campsite).  That solid ring around the pit excludes oxygen while the high temperature of the fire heats the wood.  If you put a fire out with water before the wood turns to ash, you have made biochar!

This year we measured the Torreya taxifolia seedlings in all the raised beds and found that the plot with the biochar is the tallest, averaging 7”, with one reaching a full 12”!  In second place is the plot with the well-aged pine bark fines at 6.8”.  Third is the plot with fresh pine bark fines at 6.5”.  Fourth place goes to the plot with the DieHard at 6.2”. Lastly, the second plot with fresh pine bark fines only germinated eight out of 100 seedlings with an average height of 5”.  These results do support the effects of biochar on Florida nutmeg seedlings (see Tables below).  The germination rate of biochar plot also performed best by far, with 80 out of 100 seedlings sprouting. Interestingly, between 2019 and 2020, five extra seedlings per plot germinated – we’ll take it!

Plot Height Average 2019 Height Average 2020
A (Biochar) 5” 7”
B (Aged pine fines) 4” 6.8”
C (Fresh pine fines) 4.5” 6.5”
D (DieHardÔ) 3.3” 6.2”
E (Fresh pine fines) 2.7” 5”

 

Plot Germination Rate 2019 Germination Rate 2020
A (Biochar) 75/100 80/100
B (Aged pine fines) 50/100 49/100
C (Fresh pine fines) 64/100 70/100
D (DieHard) 55/100 64/100
E (Fresh pine fines) 3/100 8/100

We plan to pot up all seedlings in April while they are still dormant and send our results to the Atlanta Botanical Garden.  Increasing the population of this endangered species by 271 new trees is important and allows us to continue our mission of research to help sustain biodiversity.