Distribution of Cryptostigmata and Mesostigmata (Acari) within the litter and soil layers of two subtropical forests

Differences in the litter and soil of northern temperate and tropical and subtropical forest soil and soil faunas are noted. Analyses of the distribution and abundance of Cryptostigmata and Mesostigmata mites in the litter and soil of two Australian subtropical forests are presented. The faunal associations in the litter and soil of these forests are different. It is suggested that the litter and soil habitats of subtropical and tropical forests should be regarded as separate but connected habitats in relation to their fauna. This contrasts with the assumption, for temperate forests, that litter and soil communities are portions of a single system.     

The identification of coca (Erythroxylutn species): 1860–1910

The taxonomic history of plants known under the name 'coca' is complex. During the period 1860–1910, botanists, horticulturalists and pharmacists became increasingly interested in the varieties of coca then known in cultivation. A debate over the correct identity of the cultivated cocas ensued which continues today. During the latter part of the 19th century and early part of the 20th century, several new taxa were described from cultivation which significantly -complicated the taxonomy. Notable contributors were D. Morris in Kew, W. Burck in Bogor, H. H. Rusby in New York and O. E. Schulz in Berlin. In order to evaluate the complex interaction among these workers, it is necessary to examine the problem chronologically. Two cultivated species of commercial coca are now recognized: Erythroxylutn coca Lam. and Erythroxylutn nooogranatense (Morris) Hieron., each of which has one distinct variety in cultivation: E. coca var. ipadu Plowman and E. novogranatense var. truxillense (Rusby) Plowman, respectively.     

The Effect of Light and Temperature on Competition between Atrazine Susceptible and ResistantBrassica rapa

Biotypes ofBrassica rapasusceptible (S) and resistant (R) toatrazine were grown in competitive replacement series in allpossible combinations of two light levels and three temperatureregimes in controlled growth cabinets. Photosystem II functionwas investigated in all conditions by fluorescence-inductiontechniques. There were no significant differences in the dryweight of the two biotypes when grown in pure stands. In purestands both biotypes produced more biomass under the high lightlevel. Under high light both biotypes yielded more biomass athigh temperature; in low light they did so at medium temperature.Under high light conditions at high and medium temperaturesthe susceptible biotype had a greater photon yield and relativecompetitive ability than the resistant due to the greater vulnerabilityof triazine-resistant biotypes to photoinhibition. However,surprisingly, the resistant biotype was the better competitor,and had a higher photon yield, in the high light/low temperatureregime. In low light no photoinhibition was expected and indeedthere were no significant differences in any fluorescence parametersbetween the resistant and susceptible biotypes. Nevertheless,there were differences in the whole plant performance; the susceptiblebiotype was a better competitor at low and medium temperatures,but the resistant biotype was better at high temperature. Relativelysmall variations in both light and temperature, well withinthe range encountered during British summer time, can have largeeffects on the relative competitiveness of triazine R and Sbiotypes in this species with implications for the spread ofresistance genes through semi-natural communities. In lightof predicted climate changes, interactions between climate andresistance should be studied across a wider range of herbicidetypes and weed species.Copyright 1997 Annals of Botany Company Brassica rapa; chlorophyll fluorescence; competition; light; navew; temperature; triazine resistance     

Cocaine and Cinnamoylcocaine Content of Erythroxylum Species

The dried leaves of 31 species and two varieties of the genusErythroxylum were quantitatively analysed for cocaine and bothcis- and trans-cinnamoylocaine, using a stable-isotope dilutionmethod and gas chromatography-mass spectrometry selected-ionmonitoring. Both cocaine and cinnamoylcocaine were detectedin all four varieties of cultivated coca (E. coca var. coca,E. coca var. ipadu, E. novogranatense var. novogranatense andE. novogranatense var.truxillense). Cinnamoylcocaines (cis andtrans) were found in much higher concentrations in both varietiesof E. novogranatense than in either variety of E. coca. Amazoniancoca (E. coca var. ipadu) contained consistently lower cocainelevels than the montane variety (E. coca var. coca). Twenty-ninewild species of Erythroxylum, selected to represent morphological,ecological and taxonomic diversity, were analysed for the samealkaloids; cocaine was detected in 13 neotropical species, representingfive sections of the genus. No cocaine was detected in the OldWorld species. Two wild species from Venezuela, E. recurrensand E. steyermarkii, contained cocaine levels comparable tothose found in the commercially cultivated species. Erythroxylaceae, Erythroxylum, coca, cocaine, cinnamoylcocaine, alkaloids, chemotaxonomy     

Litter and soil fauna of two Australian subtropical forests

The abundances of litter and soil fauna and some related environmental measures are given for two Australian subtropical forests, a notophyll vine forest (or rainforest) and a wet sclerophyll forest. Animals were more abundant in the wet sclerophyll forest; peak abundances were recorded in summer in both forests. Mites and Collembola accounted for 79% of the rainforest fauna and for 85% of the wet sclerophyll forest fauna. Most mites in the wet sclerophyll forest were Crypto stigmata (68%); in the rainforest both Cryptostigmata and Mesostigmata were well represented (84%). Patterns of aggregations of individuals within major faunal groups differed for the two forests. Correlations are made between the numbers of individuals of Collembola, of mites and of each order of mite and the environmental measures. Significant correlations emerged for some environmental measures in some seasons. Results are compared with those of other studies and it is concluded that poor or no humus development restricts the numbers of individuals living on tropical or subtropical forest floors. Speculations are presented to account for the difference between the faunas in the two Australian subtropical forests.