sures. Quaking aspens, which also need a 

 lot of water, can also be found in these lo- 

 cations. 



Douglas firs germinate poorly in the 

 lava because of the heated surface of the 

 rock. Botanist Alton Lindsay has found 

 that during the summer, the surface tem- 

 perature of the lava rises as high as 129° F. 

 According to Lindsay, the roots of Dou- 

 glas firs get under the surface crust of the 

 lava and grow along small tunnels that are 

 warm and moist, but contain no soil. As 

 the roots get older, they may break through 

 the thin lava crust and be partly exposed. 

 The growth of many of these trees is 

 stunted by lack of nutrients and water, and 

 they are often bent eastward in response to 

 the strong prevaihng winds. Lindsay, who 

 has studied the vegetation patterns on El 

 Malpais for years, found one mature, 

 cone-bearing Douglas fir that was only 

 sixteen inches high. 



At about 7,000 feet and below, Douglas 

 firs drop out and the plant community is 

 dominated by ponderosa pines, with a va- 

 riety of shrubs, wildflowers, and grasses 

 often creating an understory. Ponderosa 

 pines have thicker needles than the Dou- 

 glas firs, and their roots penetrate more 

 deeply, keeping them well supplied with 



Paxton Cone 



For visitor information write: 

 Forest Supervisor 

 Cibola National Forest 

 2113 0sunaRoadNE 

 Albuquerque, New Mexico 87113 

 (505) 761-4650 



water. And because their very large seeds 

 produce sturdy seedlings that send out 

 roots promptly and deeply, they can ger- 

 minate in spite of the hot lava surface. 



The Douglas fir zone and the ponderosa 

 pine zone extend to lower altitudes in El 

 Malpais than in nearby areas free of lava. 

 As a possible explanation for this, Lindsay 

 suggests that the dark lava becomes hotter 

 than nonlava rock, stimulating an upward 

 convection of heated air that causes an 

 extra measure of rain to fall on the lava. 

 Rainwater accumulates in the fractured 

 lava long enough for plants growing there 

 to replenish their supply. 



Here and there in El Malpais are sink- 

 holes in which water accumulates, drain- 

 ing down from the Zuni Mountains or 

 emerging from natural springs. These 

 oases are home to duckweeds, sago pond- 



.4 dead juniper stands among the living 

 on a lichen-covered lava flow. 



George H. H. Huey 



weed, and watercress, surrounded by a 

 border of cattails, soft-stem and three- 

 square bulrush, reed grass, and swamp 

 milkweed. But at the lowest altitudes, be- 

 tween 6,200 and 7,000 feet, water is usu- 

 ally scarce. Plants that can make it here in- 

 clude pirions, one-seeded juniper, banana 

 yucca, and cactuses. Broad-leaved shrubs, 

 such as Apache plume, skunkbush sumac, 

 New Mexico privet, and a couple of gnarly 

 oaks, grow in lava-free zones or where 

 shallow soil has slowly built up in lava fis- 

 sures. The broad-leaved plants often have 

 some mechanisms to prevent desiccation, 

 such as leaves that are extremely smaU, 

 succulent, or covered with hairs. 



In many places, the aa supports only 

 gray, yellow, or orange lichens, which ce- 

 ment themselves to the black, craggy sur- 

 face of the lava. Requiring few nutrients 

 for their minimal growth and effectively 

 conserving the moisture in their tissues, 

 the hchens may remain glued to the lava 

 for hundreds of years. Lava does not cover 

 all of the the Malpais area, however. Is- 

 lands of deeper soil with richer vegetation, 

 called kipukas, dot the landscape. Today's 

 kipukas probably resemble the region as it 

 was prior to volcanic activity. 



Robert H. Mohlenbrock, professor emeri- 

 tus of plant biology at Southern Illinois 

 University, Carbondale, explores the bio- 

 logical and geological highlights of the 

 156 U.S. national forests. 



100 Miles 



3 



Grants 



MEXICO 



Joe LeMonnier 



24 Natural History 1/94 



