Seed collection, storage, and planting:
Collect samples of fresh seeds, usually in the late summer or early fall, from large and robust native trees growing in natural areas without benefit of supplemental irrigation to increase the likelihood of preserving genetic traits of many individual trees which have survived repeated cycles of drought. Trees growing before the drought of record in the 1950s are the minimum age for seeds to be pedigreed in the project, although most are considerably older. Alternative sources are seeds from extensive wild groves likely to have increased vigor from genetic diversity, Champion Trees, historic trees, and trees which are threatened due to limited distribution such as the oak wilt resistant Lacy Oak (Quercus glaucoides,) the heat and drought adapted local maple tree (Acer grandidentatum,) famous from Lost Maples State Park, and Bastrop State Park’s equally well-known Lost Pines island forest (Pinus taeda) the isolated and most western natural grove of the great loblolly pine forests of southeastern United States. If conditions are right, consider even the beautiful Madrone (Arbutus xalapensis.) For greatest success when first starting, use native acorns, pecans, and walnuts. Red oak and live oak species can be grown for tree adoption, but due their susceptibility to oak wilt, avoid planting them at the tree research site. Bur Oak (Q. macrocarpa) is a favorite with children and adults alike due to the large size of the acorn it produces.
Be sure to record the location of the parent tree and the date of the seed collection. Over the next few months, the date will become important in the plant life cycle on which this activity is based. By recording the location of the parent tree, preferably with latitude and longitude coordinates using a GPS receiver, students can access the pedigree of the trees they are planting for future studies, and even return to the site of the parent tree for seeds produced the next year, or additional documentation.
Acorns, pecans, and walnuts dry and lose the ability to germinate if they are not processed in a timely fashion. After collection, store them in baggies with a wet paper towel to provide some moisture. Place the seeds in the refrigerator, not the freezer. Within the next week or so, remove the acorn cap or husk from the pecan and walnut seeds. Use gloves, especially with walnuts, to avoid staining fingers and nails. Next do the float test. Place seeds in a container of water large enough to determine if seeds will sink or float. Those that float will not sprout and can be used as gifts or for demonstration purposes with students.
Place the wet seeds back into the baggies with a wet paper towel and return to the refrigerator. This is a simplified cold stratification technique and the dates should be recorded, preferably written directly on the bag of seeds. Seeds are adapted to remain dormant until conditions are favorable for germination, usually in the following spring. Cold, wet, and dark conditions inside the baggie in the refrigerator closely simulate winter conditions and more reliably trigger the germination which is an adaptation for young plants to break dormancy during the milder weather of spring. Keep pecans and acorns in the cold for at least 6 weeks, but the walnuts will need 3 full months cold stratification. Keeping them in the cold and dark for a longer time is acceptable although germination rates may start to decline. After the winter solstice, when students return after the break, and after the suggested times mentioned above, remove the baggie from the refrigerator and allow it to remain at room temperature. Seeds can be planted at this time, although by spring break many can already be seen to be sprouting in the baggie. This is the same time of year the squirrels are eating their caches of nuts which they also stored.
In the intervening weeks and months, collect and store several gallons of fallen leaves. Wait until conditions are dry so the leaves do not mold in storage. These leaves will become a critical component during the later planting phase. When stored dry, they emit the wonderful aroma of autumn. If they smell moldy, spread them on a tarp in the sunshine to dry before storing for later use. Most trees drop their leaves in the fall, but live oaks provide another opportunity to collect leaves that fall in the early spring.
Start collecting soda bottles in advance. For inexpensive pots with a recycling theme, use soda bottles (2 or 3 liter, clear or green is okay.) The first soda bottle planting is a learning activity for students and will take most of the class period; however a second or even third planting may be possible if the materials have been collected in advance. The additional trees will be useful when provided as a free tree adoption to participants of various garden and planting events. To make the soda bottle pot, cut the top off of one soda bottle and the bottom off of another soda bottle. Start the cut with a knife or box cutter since student scissors can’t make the initial penetration into the bottle. Place the soda bottle with the bottom removed, upside down into the bottle with the top removed. By removing the tapered portion at the top of one bottle, and the curved portion at the bottom of the other, the bottles should stack stably and provide easy access to the inside for planting. Clothes pins can be used to clip several of these bottle columns together making them less likely to tip over. The bottle scraps make great soil scoops or funnels and should be properly recycled after use.
Planting will be messy inside of a classroom so plan accordingly, however it is a great time to schedule an observation by your administrator. A handful or two of leaves should be placed into the inverted soda bottle (the one with the bottom removed.) This prevents the soil added next, from falling through the neck of the inverted bottle. Next fill the upside down bottle about half full of soil, on top of the initial handful of leaves. Use just about any type of soil, although a blend of garden soil from a landscape or nursery is preferable. This portion of the model represents several hundred years of forest floor soil formation as fallen leaves decompose into rich forest loam.
Next students model the seasonal cycle in nature representing the events from this year. Students drop seeds on top of the soil in the bottle. It is not important to place seeds up or down since they are modeling the drop of the seeds from the parent tree. Be careful not to break off any roots that might have sprouted while the seeds waited in the baggie. Roots and shoots are gravity sensitive and will orient themselves to grow the correct direction (gravitropism or geotropism) in their new conditions. To improve the chances of a tree in every bottle, consider planting about 3 seeds in each bottle. Recreate falling leaves and their break down into soil this past season by gently placing over the seeds another scoop of soil, followed by small handful of leaves on the very top.
The last handful of leaves on top helps reduce erosion in the bottle just as in a forest. Model a spring rain by pouring about one or two cups of water over the top, enough to allow the water to percolate down through the soil and drain into the lower bottle which had the top removed. It is a good idea to pour the water which drained through, back over the bottle several times to make sure the soil is fully moistened. Add more water to keep this water reservoir at a depth of about one inch. The water will eventually be reached by the roots of the tree seedling which will start to show leaves over the next few weeks. Because the lower bottle is closed from evaporation by the upper bottle, the system provides readily available moisture for the plant until transplanted in the soil of the tree’s permanent location by students. The long taproot which many trees grow may coil into the water in the lower bottle. At the time of planting, this taproot may be pruned to the length of the neck of the bottle where it emerged to reach for the moisture in the lower bottle. Studies show this technique, called root pruning, produces bushy root growth and enhances survival of the young tree. It also makes the eventual planting much easier for young tree planters since the hole will only need to match the depth of the soil in the inverted soda bottle.
Place the soda bottle forest somewhere outside, and consider using close pins to clip the tops of the bottles to their neighbors to increase the stability of the bottles and keeps them from blowing over during the next few weeks. Occasionally pour the contents of the lower bottle back over the upper bottle, and add more water if needed to keep the water level about an inch deep in the lower bottle. A determined squirrel is a formidable opponent and they are very attracted to the seeds in the bottles at this stage of the project. Consider placing chicken wire over the tops of the bottles and remember the squirrels will eventually become allies by helping disperse seeds when the trees mature.
When the young tree is transplanted from the bottle back into nature, make sure it is planted at the same depth as in the bottle so that the surrounding soil surface matches the soil surface the tree grew in inside the soda bottle. If planted with the bottle’s root ball too high the tree will dry out, and if planted so that it is down in depression, it can become too wet during rainy weather. If planting in a natural area during a school event, record the location carefully because a small native tree seedling in a natural area quickly blends into the surroundings. Without deer or rabbit predation, and without supplemental water, a survival rate of 50% is considered successful. Consider planting multiple trees in a grid pattern at intervals of 10 to 20 feet. Such an array is typical for tree research and helpful for tracking tree growth and survival. To reduce wildlife predation of the young trees, consider the use of the inexpensive transplant tube used in the forest industry. It looks like a cylinder of plastic netting and is held by a bamboo stake but is made of corn starch and will break down into powder after a few years.
Plan the layers of the project in advance since many portions of the activity are built on the annual cycle of the seasons meaning a serious omission could set the project back an entire year. During the planning stage is the best time to determine what to do with the trees which will eventually be produced. Many trees can be given away as tree adoptions for participants during events such as garden weed pulling in the spring or mulching in the winter, and certainly during planting day. In south central Texas, our planting day is scheduled between Halloween and Veterans Day following the age old tradition of planting trees in honor of a family member or perhaps a member of the community who defended our rights. Those who plant a tree during the activity are allowed to adopt and take home an additional tree.
Contact the native plant organizations in your area to find how to get permission to plant on public lands if planting in a park or natural area. Planting native trees of good genetic stock by children as during an environmental education activity who will continue monitoring the results for several years, it is likely permission will be given to plant. Partnerships formed in advance form allies of the project and show due respect for those who work to maintain public land and restore disturbed habitat. They will know the best place to plant what will eventually become a grove of native trees available to the community.