Arizona-Nevada Academy of Science Biotic Communities in the Sub-Mogollon Region of the Inland Southwest Author(s): Charles H. Lowe Jr. Source: Journal of the Arizona Academy of Science, Vol. 2, No. 1 (Aug., 1961), pp. 40-49 Published by: Arizona-Nevada Academy of Science Stable URL: http://www.jstor.org/stable/40025670 Accessed: 21/05/2010 20:41 Your use of the JSTOR archive indicates your acceptance of JSTOR's Terms and Conditions of Use, available at http://www.jstor.org/page/info/about/policies/terms.jsp. JSTOR's Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Please contact the publisher regarding any further use of this work. Publisher contact information may be obtained at http://www.jstor.org/action/showPublisher?publisherCode=anas. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Arizona-Nevada Academy of Science is collaborating with JSTOR to digitize, preserve and extend access to Journal of the Arizona Academy of Science. http://www.jstor.org BIOTIC COMMUNITIES IN THE SUB-MOGOLLON REGION OF THE INLAND SOUTHWEST Charles H. Lowe, Jr.* The University of Arizona The Sub-Mogollonregion is a highly varied land- Table 1. Five World Ecologic Formation-types in North scape that is common to those fractions of Arizona, America, Their Ecologic (Biotic) Formations in New and Sonorawhich lie essen- the Inland Southwest, and the Major Association- Mexico, Chihuahua, types (= Vegetation Types) that Comprise Them. tially between the ColoradoPlateau to the north and the SierraMadre to the south (Fig. 1). The natural- Desert Formation-type ist is immediately struck by the wide expanses of 1. Northern Desert Scrub Formation1 lowland habitats (deserts and grasslands) which Sagebrush associations the or Saltbush associations separate highly disjunctive upland highland Blackbrush associations areas (woodlands and forests). An unusuallyfertile 2. Southern Desert Scrub Formation2 laboratoryis presented here for the study of evolu- Creosotebush associations tionary rates in diverse forms of animals and plants Saltbush associations in the biotic communities isolated in the Tarbush associations recently Sandpaperbush associations disjunctiveranges. Joshuatree associations The Basin and Range Province is an ecological Paloverde associations and evolutionaryprize. On the other hand, the evolu- Mesquite associations tionary prize is not yet won in the present almost Grassland Formation-type3 total absence here of a recent paleoclimaticpicture 3. Desert Grassland Formation such as could be based on either plant megafossils Desert Grassland associations or microfossils In to 4. Plains Grassland Formation (e.g., leaves) (pollen). regard Shortgrass Plains associations this, Dr. Martin has joined the symposiumto discuss 5. Mountain Grassland Formation paleoecologicalaspects of southwesternbiogeograph- Mountain Grassland associations ical problems. Woodland Formation-type3 BIOTIC COMMUNITIES.-The biotic commun- 6. Chaparral Formation4 ities of the Sub-Mogollonregion are listed in Table Chaparral associations 1. The northerndesert scrubformation of the Inland 7. Evergreen Woodland Formation Oak Woodland associations Southwest is the only formation listed in the table Encinal associations5 that is not representedin the Sub-Mogollon region. Pine-oak Woodland associations0 The classificationof these plant-animalcommunities Pinyon-juniper Woodland associations is a classificationof the for 8. Riparian Woodland Formation representedvegetation, woodland associations7 the mappablereality of the biotic communityis only Riparian the mappablereality of its vegetation. Forest Formation-type What is 9. Coniferous Forest Formation actually classified in Table 1? Does a Pine Forest associations8 biotic communityreally exist? In this symposiumon Fir Forest associations9 bioecology, we are already pledged by at least our Spruce-fir Forest Associations10 title to the existence of biocommunities,i.e. recog- Aspen associes11 nizable and predictableplant-animal associations and Tundra Formation-type formationsof various orders of magnitude.There is, 10. Alpine Tundra Formation12 in fact, a large body of convincing evidence in both Alpine Tundra associations the New and Old World literaturein supportof this ecologic principle (see Allee, et al., 1949; Dice, 1952; 'Great Basin Desert (Shreve, 1942). Dansereau,1957). 2Mojave, Sonoran, and Chihuahuan Deserts (Shreve, 1942). The general vertical relationships of the several "Savannas" (whether or not to be recognized as forma- formations in western North from lower tions) are, in this region, grassland-woodland and grass- America, land-desert and the desert to elevations,are clear. One of the formations ecotones, grassland (part). higher 4Petran or Interior Chaparral (riparianwoodland), however, differs from the oth- (auct.). "Shreve (1915); see text. ers in that it occurs throughoutall of the rest with Mexican Pine-Oak Woodland (auct.); see text. '"Developmental associes" (allogenic), with stability as per- * Paper presented in a symposium on "Bioecology of the manent as the drainage characteristics; see text. Arid and Semiarid Lands of the Southwest," arranged by sMontane Forest (auct.). Linton Gardner J. and Charles H. Lowe, Jr. of the Com- 9Montane Forest (auct.), Abies and/or Pseudotsuga. mittee on Arid Zone Research of the Southwestern and Forest Rocky Mountain Division of the American Association For 10Subalpine (auct.). The Advancement of Science, held at New Mexico High- ^Developmental (autogenic). lands University, Las Vegas, New Mexico, April 29, 1958. Petran or Rocky Mountain Alpine Tundra (auct.). 40 August 1961 LOWE- BIOTICCOMMUNITIES 4l the exception of alpine tundra. The riparian wood- floodplains and which is further characterizedby land associationsof the Southwest are, in general, different species and/or life-forms than that of the relativelylitle known to most ecologists. The follow- immediately surrounding non-riparian climax. The ing is a brief discussionof distributionaland floristic southwestern riparian woodland formation is char- aspectsof this formation. acterizedby a complex of trees, and their plant and A riparian associationof any kind, is one which animal associates, restricted to the major drainage- occurs in or adjacent to drainagewaysand/or their ways that transgressthe landscapeof desert upward through forest. It is incorrect to regard this biotic Table 2. The Ecologic Formations Comprising Merriam's formation as merelya temporaryunstable, serai com- (1899) Life-zones in the Inland Southwest. See It is an with an Table 1 for formationsand formation- munity. evolutionaryentity enduring types. stabilityequivalent to that of the landscapedrainage- which form its habitat. Moreover, it Life-zones Formations ways physical Ecologic is, as are all ecologic formationsand their subidivions, to Lower Sonoran NorthernDesert Scrub locally subject and often dissolved by the vicissi- SouthernDesert Scrub tudes of human occupation. ( + disjunctDesert Grassland In the Sonoranand ChihuahuanDeserts in South- relicts)1 ern southern New Mexico and RiparianWoodland Arizona, adjacent Mexico, riparian woodland reaches its greatest ex- Upper Sonoran Desert Grassland2 pression of size and complexity in the immediate Plains Grassland proximity of permanentand semi-permanentstreams Chaparral at the lower elevations of conifer-clad mountains. EvergreenWoodland In the centerof the the RiparianWoodland Sub-Mogollonregion, riparian "big-five"are cottonwood (Populus fremonti), wil- Transition ConiferousForest ( = Ponderosa low (Salix bonplandiana and others), sycamore Pine Forest) {Platanus wrighti), ash (Fraxinus velutina and MountainGrassland and walnut Often three RiparianWoodland others), (fuglans major). or four of these species may occur together, and, Canadian v ConiferousForest (= Fir Forest) occasionally,all five. All of them are large, winter j MountainGrassland deciduous broadleaf trees of different genera and f RiparianWoodland families than the of the > Boreal species immediatelybordering non-riparian climax desert, etc., communities (see Fig. 2). This broadleaf associationforms the con- Hudsonian ConiferousForest (= Spruce-Fir spicuous and dominant plant component of a biotic Forest) community which includes characteristicspecies of MountainGrassland and terrestrial animals; for RiparianWoodland aquatic, semi-aquatic, example, the Summertanager (Piranga rubra), Bul- Arctic-Alpine Alpine Tundra lock oriole (Icterus galbula), Yellow warbler (Den- droica petechia), Black-neckedgarter snake (Tham- nophis cyrtopsis), Leopard frog (Rana pipiens), Canyon tree-frog (Hyla arenicolor), Longfin dace Table 3. Examples of Small Isolated Populationsof Trees (Agosia crysogaster), other vertebrate species, and Restrictedto Sheltered Slopes Near Summits of a number of invertebrates. Rangesin the Basin and Range Province,listed in large order of decreasing maximum range elevation