20250602-004: Ashe Juniper's role in central Texas ecosystem — original pdf

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Role of Ashe Juniper in Central Texas Ecosystems Lisa O’Donnell Senior Environmental Scientist Ashe Juniper (“cedar”) is both a pioneer… …and an old growth species Ashe Juniper Helps to Build Nutrient-Rich Soils That Are High In Organic Carbon ) % ( I N O B R A C C N A G R O L I O S 16.00 14.00 12.00 10.00 8.00 6.00 4.00 2.00 0.00 Open Young Junipers Old Junipers Juniper-Oak Canopies Keep Temperatures Cooler and More Stable During Summer Droughts Summer Soil Temperatures No Vegetation Forest Canopy 120⁰ F 86 ⁰ F air temperature = 104 ⁰ F 5 Roots are also important! • Help infiltrate water into the ground • Promote carbon sequestration and storage in soil Ashe juniper and shin oak roots (and Dr. Brian Pickles) Cotterell Cave Bray (1904) believed the forests of the Edwards Plateau were critical to protecting water supplies downstream and advocated for their protection: • Forests build soil • Forests protect soil from erosion, keep it cool and moist • Forest soils act as a sponge and promote recharge He concluded: “For all these reasons, forests tend to conserve the water supply and to maintain full springs and an even flow of streams.” Ashe juniper supports a diversity of rare and endemic plants Texas Amorpha Cedar Sage Texas Madrone Twistleaf Yucca Buckley’s Tridens © Chuck Sexton Canyon Mock-Orange Heller’s Marbleseed Shade During Summer Drought is Critical to Oak Seedling Survival l t o P / s g n i l d e e S e v L i f o # August: Under Canopy August: No Shade Texas Red Oak Seedlings (planted as acorns in fall 2017) caged, 60% shade caged, no shade uncaged, no shade 35 30 25 20 15 10 5 0 -5 Both living and dead trees (“nurse trees”) can promote the growth of other plants Texas red oak sapling growing under living tree Carolina buckthorn sapling growing under dead tree Juniper also provides essential habitat for a variety of wildlife Robin Golden-cheeked Warbler Cedar Waxwing Juniper Hairstreak 11 Endangered and rare species that depend on or occur in juniper-oak ecosystems © John Ingram © John Ingram Contribution of “cedar” to economic growth and development “With the exception of cedar, the hill timber finds a market chiefly as fuel, of which enormous quantities are consumed….Cedar likewise is extensively consumed as fuel and in charcoal burning; but its great value lies in its yield of railway ties, poles, posts, sills, and innumerable other articles which utilize its great durability.” –W. Bray, 1904 Historical photo of Ashe juniper-oak forest, described as having “almost impenetrable growth of cedar and mixed timber” and a “deep layer of rich soil.” -- William Bray 1904 The writer knows of no region in which any species of cedar is so uniformly abundant and dominant as is the mountain cedar in the limestone country of Texas… [Mountain cedar] is the most valuable tree of the semiarid hill country of Texas.” –W. Bray, 1904 15 • A sanctuary for endangered/rare species and unique community of plants and animals • Land managed to protect habitat Questions? Lisa O’Donnell Senior Environmental Scientist Lisa.odonnell@austintexas.gov Join us to hike or volunteer! 17