Pinus greggii var. australis Donahue, Jeffrey K. & Lopez A.,R.
Endemic to east-central Mexico where this species is severely fragmented due to deforestation, fire, grazing and agricultural activities
Endemic to east-central Mexico in the States of: San Louis Pitosi, Veracruz, Queretaro, Hidalgo and Puebla. The extent of occurrence is calculated as being 6,980km² based on the mapped distribution of herbarium collections while the area of occupancy is estimated to be 153km².
Subpopulations of this southern variety are reported to be larger on average than those of the northern variety (var. greggii). Genetic analysis suggests there is often little exchange between these subpopulations.
Habitat and Ecology
This variety is generally growing on acid soils. It is a relatively rare pine that always grows sporadically among other species of pine, or in mixed pine-oak woodland. The serotinous cones indicate adaptation to fire, but no studies on how this affects seed dispersal and germination have been undertaken (or published).
Although locally exploited with other pines, this variety is not specifically in demand as a timber tree in Mexico. However, in many areas it has been severely depleted by general logging and overexploitation of forests.
The subpopulations of this variety are often some distance apart and surrounded by agricultural land. The area of occupancy is less than 500km², there are five to six locations and the subpopulations are severely fragmented due to fires, overexploitation and deforestation associated with conversion of forest for agriculture and ranching. Grazing may have a significant effect on regeneration because areas that are not grazed showed regeneration as opposed to those where grazing was evident. On this basis, P. greggii var. australis meets the criteria for Endangered.
The range of this variety, based on herbarium collections data, is inside the threshold for VU (EOO = 6,980km²). The AOO is less than 250km², well inside the threshold for EN. Fires and changes in land use especially conversion to agriculture is widespread in the region and almost certainly affects both EOO and AOO of this taxon. The subpopulations of this variety are often some distance apart and surrounded by agricultural land. Grazing may have a significant effect on regeneration, because areas that are not grazed showed regeneration as opposed to those where grazing was evident.
Some locations are within protected areas such as the Sierra Gorda, Los Marmoles and Cuenca Hidrografica del Rio Necaxa Reserves.