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Similarly in his studies of the Casuarinaceae Johnson notes previously undescribed 
ecological differences at the generic level. His new genus AUocasimrim, is 'usually on 
soils markedly deficient in nutrients' (Johnson 1982), whereas Casiiarim, at least in 
Australia, occurs on the more fertile soils (LASJ pers. comm.). 
Implications for biodiversity conservation 
Plant systematics is a key component in the identification and conservation of 
biodiversity. Recognition of taxa and the variation within taxa is necessary if adequate 
conservation of biodiversity is to be achieved. Systematic work such as that of Johnson 
provides assessments of the extent of variation within and between populations — 
how revisions of certain groups have been made affects the way plant communities 
have been described and species conserved. 
For example, the number of eucalypt species recognised has increased from about 450 
in 1971 to 800-900 in 1995, as a result of the work of Johnson and others in the 1980s 
and 90s. The increasing number of species has been partly due to the discovery of 
many previously unknown species in remote areas as well as in some frequented 
places [despite a 1971 prediction by Pryor & Johnson that 'It is likely that relatively 
few taxa still await discovery as a result of exploration in relatively little-known areas']. 
The increased number has also been due to an increasing focus on previously 
described species. Johnson's eucalypt research includes extensive reassessment of 
formerly accepted species and their subdivision into new taxa (mostly species). He 
has always been interested in the importance of recognising areas of variation and 
potential genetic diversity within taxa, often leading to the recognition of many 
species within former large groups. He regards ecological aspects, including habitat, 
soil type, nutrient levels, drainage, geographical distribution etc as important 
contributory data in determining the distinctiveness of taxa. By considering aspects 
such as geographic isolation and local habitat, Johnson highlights the variation within 
previously broadly-defined species and separates them into separate species. Species 
recognised by Johnson include the mallee ashes. Eucalyptus dendromorpha, E. rupicola 
(Johnson & Blaxell 1972) and E. laophylla (Hill & Johnson 1991); Eucalyptus dorrigoensis, 
previously a subspecies of Eucalyptus bentliamii, Angophora crassifolia, previously a 
subspecies of A. bakeri, and Angophora euryphylla, a subspecies of A. costata (Johnson 
& Hill 1990). Formal systematic recognition of variation makes its overall conservation 
achievable, as conservation strategies to protect each species (the most frequently 
used unit of biodiversity) can then be established. Of the 70 taxa of Eucalyptus and 
Angophora on the national Rare or Threatened Australian Plants list (ROTAP) 41 
have Johnson as author or coauthor. 
L.A.S. Johnson has always been prepared to argue for the protection of occurrences 
of localised rare species. He encouraged the author to recommend the protection of 
Eucalyptus benlhavtii at Bents Basin (subsequently Bents Basin State Recreation Area), 
for example, and personally took up the case for a small area of Allocasuarina diminuta 
at Kingsford. He has also been a strong advocate for recognising the importance of 
conserving examples over the whole of species' distributional range including 
geographical extremes. 
Plants in their landscape 
Perhaps L.A.S. Johnson s most perceptive ecological insights are in his work on the 
sclerophyllous flora, doubtless influenced by Noel Beadle's work (for example Beadle 
1954). Because Johnson's ecological contributions have been included as often-incidental 
