- by A Sunjian and Li H.
|Sunjian A and Li H. (2005) Did the Texas Bonanza Era in 1876-1930 facilite the spread of Atta texana into Louisiana?. Notes from Underground 11 (1)|
(revision date: Jan 27, 2006)
The thesis of this article is that extensive deforestation of the old-growth Pineywoods by the logging industry in East Texas from 1876-1930 facilitated the rapid spread of Atta texana in force from Texas to Western Louisiana during that time period.
A quick look at the current distribution of A. texana shows that this species occupies most of Eastern and Central Texas, as well as a large swath of Western and Central Louisiana (see figure). This may not have been the case in the early 1900s, when Wheeler noted:
"I have found no indications of its occurrence outside a rather restricted area in Texas. This area appears to have its center at Austin and to comprise the territory for some hundreds of miles north and south in a narrow belt......I have never seen it in the dry western portions of the state nor have I heard of its occurrence in the more humid eastern counties, in Louisiana or the other Gulf States." (Wheeler 1907).
Furthermore, in the original descripion of Atta texana made in 1860, Buckley asserted that the ant was "scattered through western and central Texas." (Buckley 1860).
However, by the mid-1930s, the Southern Forest Experiment Station, US Forest service, began control work against A. texana, after recognizing its presence and pest status on young pines in reforested areas in the Kisatchie National Forest of Louisiana (Smith 1963).
The boundary of East Texas and Lousiana is guarded by the Texas Pineywoods, which consisted in the early 1800s of a vast forest of old-growth pines and hardwoods broken only by meandering rivers. Individual trees often grew to 30 m heights, with diameters of nearly 2 m.
The destruction of these old growth forests within a 50 year period from 1876-1930 was due to a confluence of factors. The first factor was the coming of the logging industry into Texas, after ravaging other parts of the new nation. The second factor was the construction of railroads all over East Texas, which was financed by the liberal policies of the state at this time right afer the civil war. Without the railroads and trains, extensive logging would not have been possible due to the tedious and time-consuming process of getting cut timber to the mills. Finally, the invention of the band saw enabled safer and more efficient milling operations (TBH 2004).
During the 50-year "bonanza" period, lumbermen logged about 7 million hectares of pine timber and left behind a devastated land with most of the virgin pine harvested. Under the New Deal program of President Roosevelt, the federal government purchased much of the cut-over land and started reforestation efforts, including the creation of monoculture pine plantations in East Texas (Ellis et al 2004).
Various studies have shown that many leafcutter ant species tend to do much better in secondary growth forests and man-simplified habitats (Jaffe and Vilela, 1989; Fowler et al 1986; Sunjian and Li 2005). In this light, the vast and dark old-growth forests that straddled the border of East Texas and Louisiana must have posed a barrier to the strong easterly expansion of A. texana. The removal of these virgin forests during the next 50 years, and its replacement with secondary forests and monoculture plantations may have facilitated the spread of A. texana eastwards into the Parishes of Louisiana.
Such drastic expansions by leafcutter species due to the activities of man are not unknown. Atta capiguara, Atta cephalotes and Atta sexdens have all been known to spread rapidly into new territory in Brazil in historical times when conditions became favorable (Weber 1972), while Weber (1969) examined the quickly-changing distribution of Atta colombica and Atta sexdens in Panama.
Thanks to Dr. John Moser and Dr. Jerry Howard for discussions and comments on the subject, and Dr. Don Grosman for distribution map info.
Buckley, SB (1860) The cutting ant of Texas. Proceedings of the Academy of Natural Sciences. of Philadelphia 12: 233-236.
Ellis LT, Pohl JW, and R Tyler (2004). The Handbook of Texas Online. http://www.tsha.utexas.edu/handbook/
Fowler GH, V Pereira-da-Silva V, Forti LC, and NB Saes (1986b) Population dynamics of leaf-cutting ants. A brief review. In: Fire Ants and Leaf Cutting Ants: Biology and Management (eds Lofgren CS, Vander Meer RK), pp. 123–145. Westview Press, Boulder
Jaffe K and E Vilela (1989) On nest densities of the leaf-cutting ant Atta cephalotes in tropical primary forest. Biotropica 21(3): 234-236
Sunjian A and Li H. (2005) Atta mexicana in the resort community of Nuevo Vallarta, Mexico. Notes from Underground 11(1)
Smith MR (1963). Notes on the leaf-cutting ants, Atta spp, of the United States and Mexico. Proc Ent Soc Wash 65(4): 299-302
Texas Beyond History (2004) Aldridge Sawmill History. http://www.texasbeyondhistory.net/
Weber, N. A. 1969. Ecological relations of three Atta species in Panama. Ecology 50: 141-147
Weber NA (1972) Gardening Ants: The Attines. Mem Am Phil Soc 92:1-146
Wheeler WM (1907). The fungues growing ants of North America. Bull Amer Mus Nat Hist 23:669-807