Timing Our Management Practices
The timing of land management practices such as planting, harvesting, and/or burning have historically been determined by seasonal changes and moon phases. While these occasionally predictable events still influence the timing of our management practices on the Browning Ranch, our objective to maintain a functioning Texas Hill Country ecosystem requires us to take into consideration several other micro-events that occur within the seasons. Incorporating the timing of these natural events into the work calendar creates a management plan that identifies when field activities might interfere or assist with critical ecosystem processes. As the climate evolves, it is likely that central Texas will continue its drying trend and rainfall will become less and less predictable. Poorly timed land management practices can therefore have significant negative consequences. This will require us, as land managers, to adapt quickly to the current weather conditions while incorporating long range climate predictions into our planning process. The following discussion will highlight some of the natural events that influence the timing of management activities on the Browning Ranch.
One of the primary tasks on the Browning Ranch over the past twelve years has been the mechanical removal of high-density Ashe juniper located in former grasslands in an attempt to strengthen the grass community. This process requires intensive field work with engine-driven equipment that directly affects the plants and wildlife in the work area. Because of its impact on the ecology, the timing of juniper control projects on the Browning Ranch recognizes two important micro-events: the breeding season for wildlife and plants and the beginning of fungal-mat growth on the oak trees.
Many of the wildlife species in central Texas that utilize the ground for nesting purposes are camouflaged by design and seldom does an equipment operator see the critter before they are already too close, if not too late. Most of the newborn wildlife species in central Texas are programmed to stay put during their first few moments of life - sometimes days. This creates the clear risk of damage to wildlife nesting sites by equipment operation that can be avoided altogether by not operating equipment in the field during the nesting season. White-tailed deer, Rio Grande turkey, and Bobwhite quail are three of our target management species which are all ground nesters. Any activity of ours that disturbs them while on the nest is obviously not good. Therefore, most of our equipment operation on the Browning Ranch is confined to July through February.
The second reason why we avoid heavy equipment operation in the spring is to prevent the spread of Oak Wilt - a primary pathogen fungal disease that resides in the tree’s vascular (water-pump) region. A common vector for the spread of oak wilt is the sap beetle that is attracted to the tree by the sweet aroma of the fungal mat. The fungus naturally wants to bust through the bark so that its smell can enter the air to attract more beetles. Operating heavy equipment under oak trees to control Ashe juniper will inevitably cause minor damage to the oak tree, increasing the chances that additional amounts of fungal odor will enter the air. This minor damage becomes major if it occurs when the fungal mats and the beetle are most active, which is commonly spring and fall. A saying we use on the ranch is ‘when you are uncomfortable, then the beetle is uncomfortable”, and therefore it is a good time to remove juniper underneath oak trees. As a result, the coldest days in the winter and the hottest days in the summer are the only days we do any heavy equipment work around the oak trees.
The leaf blades of last year's Lindheimer's muhly grass are often too rough for livestock and wildlife to eat. They prefer instead the fresh tender growth from the muhly after an early spring prescribed burn.
The most common times to apply fire to the range are at the beginning of a growing season. Historically, the climate of central Texas has provided two growing seasons that typically begin in mid-to-late February and mid-to-late September. The purpose for the timing of burning is twofold in that the range manager desires to remove last year’s biomass to assist new growth and to time this biomass removal activity when seasonal change naturally spurs new growth so as to prevent a prolonged state of bare ground. With an evolving climate, the rains that sustain these growing seasons are no longer predictable. As a result, we must incorporate long range weather forecasts into our decisions of when to burn or not. As faulty as these reports can be at times, we still take them into consideration as we try to make an informed decision. For example, on a five year plan I created in 2007, I had identified 2009 as the year to burn one of our old agricultural fields. As the date approached, there were already reports surfacing of a La Nina pattern in the Pacific that often pushes rain away from Texas. Fortunately, we canceled the burn and this field was not bare ground during the drought of 2010-11. The winds associated with that drought would have likely blown away significant amounts of topsoil, taking centuries to replace. Since the El Nino / La Nina oscillation patterns have such significant influences on rainfall in central Texas, we attempt to time our prescribed burning efforts to their cycles. For example, the strongest El Nino pattern on record is currently developing in the Pacific which could bring substantial rainfall to central Texas, and therefore we are preparing areas now for both brush pile burning and prescribed range burning.
This image shows sea surface temperature departure from normal. Notice the deep red colors up against the coast of Central and South America. This El Nino pattern will hopefully bring rain to central Texas. From the NOAA Climate Prediction Center.
While it might seem that the Texas summer is the most likely time for wildfires, it is actually the winter time that is considered our main wildfire season. In the winter, the dry continental air masses that push down from the north lower humidity levels. Whereas in the summer, moist tropical air predictably pushes up from the gulf, increasing humidity levels. With this in mind, we time our wildfire mitigation activities to conclude by the first major freeze event. These measures include prescribed mowing around structures and along fence-lines, distributing fire-suppression water into storage tanks throughout the ranch, maintaining clearance on all roadways for emergency services vehicles, and priming of our in-house fire suppression equipment. In previous journal entries, I have discussed our rainwater collection for fire suppression project, and in preparation for the fire season, we host an orientation meeting for all emergency services personnel at the barn to discuss its operation. We are fortunate that none of these timing decisions or activities directed towards fire suppression preparation have been tested. With such a quickly evolving climate, it is doubtful that claim will last long.
For those woody species that require chemicals to control, the ideal time for treatment is when the plant is actively photosynthesizing and devoting energy to new growth. Due to the intense summers in central Texas, most woody plants temporarily lower their activity levels starting around July 15th. While chemical application after this date can be successful, it is usually an inefficient use of time and chemical when compared to how effective the applications can be when the plant is more active. Our target species for chemical control are Catclaw mimosa, Mesquite, Poverty willow, Prickly-pear, and Texas persimmon. We are not attempting to eradicate any of these species since they all provide benefits to the ecosystem. Instead, we want to limit their growth in certain areas like meadows and open fields while promoting their growth in woodland areas such as oak mottes and canyons. We have found the most effective method for chemical application to be the ‘cut-stump’ method. This process begins with mechanically cutting the plant a foot or so off the ground, which is followed by a few drops of chemical on the fresh cuts. By directly injecting the chemical in this manner, we are not hindered by windy days or light rain showers, and use a fraction of the chemical than we would if we foliar-sprayed the leaves on the whole plant. While I have an applicator’s license, I do not use restricted chemicals. I encourage all land managers to take the course for an applicator’s license to learn how to safely handle chemicals, and use this knowledge in their application of non-restricted chemicals that are equally as effective if applied properly.
A few years back, we created a calendar matrix that compared our typical field activities to natural events as a guide for our timing decisions. Our work items ranged from facilities maintenance to prescribed burning, while the natural events ranged from wildlife nesting seasons to individual plant growth cycles. It is not perfect, but it does help us to remain proactive. It has been especially beneficial during new employee orientations and planning activities. Any landowner or manager can easily create an individual work calendar using Excel or a similar spreadsheet program.
My time on the Browning Ranch has taught me that ‘when’ you act is just as important as ‘how’ you act. Knowing when to get out of nature’s way is equally important for the agricultural producer as it is the wildlife manager, and there are several other examples not mentioned above. Hopefully this discussion has been a reminder that there is an annual rhythm to the land that managers should consider when scheduling. As always, we appreciate your comments on these discussions, which can be made to clbrowningranchATgmail.com.
Posted Summer 2014 | Permalink | Land management practices; climate change; work scheduling