WHAT WE'RE DOING
Teaching landowners and the general public that pioneer thickets of mountain cedars are part of the solution to regenerating degraded Texas karst country. Older tree mountain cedars growing with other trees inside of woodlands and forests, on the other hand, help to maintain health karst function and groundwaters.
Teaching landowners and the general public that pioneer thickets of mountain cedars are part of the solution to regenerating degraded Texas karst country. Older tree mountain cedars growing with other trees inside of woodlands and forests, on the other hand, help to maintain health karst function and groundwaters.
MOUNTAIN CEDAR BASICS
There are two primary types of mountain cedar cover: old-growth forest and pioneer thickets. Historically, pioneer thickets were uncommon. Now they are ubiquitous because of the harm we caused to Texas karst country.
Old-growth mountain cedar forests never consist of 100 percent mountain cedars. However, mountain cedars are the dominant tree, often growing alongside various native oaks and other trees. These forests help MAINTAIN karst country health and spring flows. Forests and woodlands such as these covered more than 50 percent of the eastern Edwards Plateau historically, and much of the karst to the north up to the Red River. They grew inside canyons and covered hillsides.
Pioneer thickets spread across degraded karst country. We began causing this degradation starting in the late 1800s by clearcutting, overburning, and overgrazing. The degradation continued throughout the mid-1900s and involved chaining and herbicides.
We have viewed mountain cedars as something to fight and have used strategies that are more akin to tactical warfare. This needs to stop because not only have these strategies caused more harm than good, they were carried out without the knowledge we now have: where mountain cedars and other woody plants spread, they improve infiltration and karst porosity. The more porous karst is, the more groundwater it can hold.
With this new information in hand, we need more creative strategies that work with or mimic the work being done by mountain cedars. By doing this, we can finally realize long-term solutions that sustain spring flows through droughts, increase land productivity, biodiversity, and profits, decrease downslope flooding, and help reduce wildfire risk.
PIONEER CEDAR THICKETS SHOW US WHAT NEEDS TO BE DONE
 credit: Elizabeth McGreevy
SLOW THE RAIN
Texas karst country is prone to gully-washing rains. Slowing down overland water flows reduces erosive velocities and allows more water to soak into the soil to help hydrate vegetation to reduce fire risk, replenish groundwaters, and reduce downslope flooding. |
 credit: Elizabeth McGreevy
COVER THE GROUND
Dense vegetation cover protects and adds organic matter to shallow karst country soil. Sparse vegetation cover exposes soil to erosion and degradation. If you can see bare caliche between plants, it's not covered enough. Get the ground covered or keep it covered. |
 credit: Elizabeth McGreevy
REVIVE THE SOIL
Slower overland water flows and covered ground will support the revival of soil biology. Healthy Texas karst country soil can be identified by its darker color and ability to hold a loose ball when squeezed. |
LIMESTONE JUNIPERS OF TEXAS |
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Mountain cedars are native junipers with a preference for limestone karst country. They are most abundant on the eastern Edwards Plateau and on karst country north to the Red River. They are less common on the semi-arid western Edwards Plateau:
Ashe juniper (Juniperus ashei) is the most commonly mentioned. It grows as a bushy shrub and is most often seen colonizing degraded rangelands. †Adams Juniper (Juniperus ovata) is a more ancestral juniper species that would have been more widely dispersed during the last ice age (10K+ years ago). Current populations exist in western New Braunfels (several are growing in Mission Hill Park) and western Comal County. There is also a population near Big Bend National Park. Ashe-Adams Juniper is a hybrid of Ashe Juniper and Adams Juniper. Ashe Junipers do not hydridize with any other juniper species, Field observations reveal that Adams junipers and the hybrids tend to grow as trees inside established woodlands and forests of the Eastern Edwards Plateau and karst country regions northward. Two other junipers grow on limestone karst country, but neither has a preference for limestone: Eastern Red Cedar (Juniperus virginiana) that grows from the central region of Texas to the Atlantic Ocean, can occasionally be found growing on limestone karst country. Redberry Juniper (Juniperus pinchotti) is found mostly on the western Edwards Plateau and grows as a shrub. Although common on karst country, it is just as common on non-karst country. † Adams Juniper is named after the recent Dr. Robert Adams of Baylor University who identified this separate species. |
Young Ashe-Adams hybrid growing in a bottomland forest in northern Hays County.
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