TheImprovement ofTropical and Subtropical Rangelands

0R1TER1A 'OR PLANT SICLEOTION 195
meet common toxic elements in soils are sodium, boron, and various
chloride or sulfite and copper salts. The presence of toxicity
calls for the use of specialized tolerant species, and often has important
implications with regard to how the land and vegetation are
utilized. Salt-tolerant species may be further differentiated as xerohalophytes,
mesohalophytes, hygrohalophytes, and tropohalophytes
(plants adapted to dry, mesic, wet, and alternately wet and dry soil
conditions, respectively).
Revegetation projects are often concerned with the reclamation
of soils that have been drastically disturbed or are inherently poor
in their ability to support a vegetative cover. These soils call for
specialized plant species adapted to particular habitats and able
to grow well under various climatic conditions. Examples of these
special areas, and the genera adapted to them are presented below:
Sand dunes:
CtUligonum, HtUoz,lon, Acacia, Phyllodineae, Hedy.arum, Caragana,
TamaN, Et.calypt.., Celina, Celluarina, Panicum,
Pennildum
Badlands (shales and marls eroded in gullies):
Pinu., CupreN", Ailanthu., Opuntia, Fe.tuca, Agf'opyron,
Hedy.arum, Atriplez
Shallow soils:
Pinu., Eucalypt.., Opuntic, Pro.opU, Agropyron, Oryzopm,
Medicago, Bromu.
Flooded/waterlogged soils:
TClZodium, Pinu., StUiz, Popul.., Saccharum, Arundo, Phragmite.
Mine waste:
Eucalypt.., TamaN, Atriplez, Maireana, Elym.., Agropyron
Saline/alkaline soils:
Atriplez, Maireana, Tamariz, Lagunaria, Phoenu, ElaeagnUl,
Spor0601.., Puccinellia, Spartina, Dilticl&lil.
ADAPTATION TO PHYSIOGRAPHY, GEOMORPHOLOGY,
TOPOGRAPHY, SLOPE, AND ASPECT
Physiographic characteristics ofa site may playa very important
role in positively or negatively modifying regional climatic data in
terms of energy flow, temperature, evaporation, rainfall, and soilwater
budget (throup runoff/infiltration and erosion/eedimentation,