Papers by Marcel Rejmanek
Biodiversity and Conservation, 1999
In this paper we examine whether the occurrence of cheetahs (Acinonyx jubatus) in Uganda can be p... more In this paper we examine whether the occurrence of cheetahs (Acinonyx jubatus) in Uganda can be predicted from habitat characteristics extracted from a vegetation map. We first established the status of the cheetah in Uganda through field-interviews that Gros conducted in 1990. Cheetahs occurred almost exclusively in the Karamoja region where we estimated 53-310 individuals. Based on 216 sightings, the average number of adults in all-adults sightings was 1.65 + SD 0.95 and the average number of cubs in family groups 2.5 + SD 1.65. Compared to Graham and Parker's 1965 East African survey, average adult group size was slightly smaller in 1990 and large family groups were rarer. Comparison with Gros' 1990 survey showed considerably lower cub-to-adult ratio and percent of observations with cubs in Uganda than in Kenya. A Geographic Information System (GIS) analysis of vegetation structure in areas where cheetahs were observed and in those where none were reported suggested that cheetahs might favor habitats with 25-50% woody cover and grasses of medium height (50-100 cm). A discriminant analysis correctly classified 72.1% of 'used' habitats and 70.4% of 'no-report' habitats. A logistic regression analysis improved the correct allocation of 'used' habitats by 2.2%. Either the discriminant function or the logistic regression, which require only four easily obtainable vegetation characteristics, may help to pinpoint suitable cheetah habitats for conservation purposes. Our approach could be adapted for analyzing habitat suitability for other species of carnivores.
It has been suggested that alien species with close indigenous relatives in the introduced range ... more It has been suggested that alien species with close indigenous relatives in the introduced range may have reduced chances of successful establishment and invasion (Darwin's naturalization hypothesis). Studies trying to test this have in fact been addressing four different hypotheses, and the same data can support some while rejecting others. In this paper, we argue that the phylogenetic pattern will change depending on the spatial and phylogenetic scales considered. Expectations and observations from invasion biology and the study of natural communities are that at the spatial scale relevant to competitive interactions, closely related species will be spatially separated, whereas at the regional scale, species in the same genera or families will tend to co-occur more often than by chance. We also argue that patterns in the relatedness of indigenous and naturalized plants are dependent on the continental/ island setting, spatial occupancy levels, and on the group of organisms under scrutiny. Understanding how these factors create a phylogenetic pattern in invasions will help us predict which groups are more likely to invade where, and should contribute to general ecological theory.
Toward a causal explanation of plant invasiveness: Seedling growth and life-history strategies of 29 pine (Pinus) species
The American Naturalist, Apr 1, 2002
We studied 29 pine (Pinus) species to test the hypothesis that invasive species in disturbed habi... more We studied 29 pine (Pinus) species to test the hypothesis that invasive species in disturbed habitats have distinct attributes. Seedling relative growth rate (RGR) and measures of invasiveness were positively associated across species as well as within phylogenetically independent contrasts. High RGR, small seed masses, and short generation times characterize pine species that are successful invaders in disturbed habitats. Discriminant analysis and logistic regression revealed that RGR was the most significant factor among these life-history traits separating invasive and noninvasive species. We also explored the causes of differences in RGR among invasive and noninvasive species. While net assimilation rate, leaf mass ratio, and specific leaf area (SLA) were all found to be contributing positively to RGR, SLA was found to be the main component responsible for differences in RGR between invasive and noninvasive pines. We investigated differences in SLA further by studying leaf anatomy, leaf density, and leaf thickness. We also evaluated relative leaf production rate as an important aspect of SLA. We proposed a hypothetical causal network of all relevant variables.
On the terminology used in plant invasion studies
... term 'invasive' as describing an alien which has become successful ... more ... term 'invasive' as describing an alien which has become successful in the area into which it was introduced (some definitions mention as an important feature that the species is creatingseIf-regenerating populations ... Macdonald, IAW, Loope LL, Usher, MB and Hamann, 0 . 1989 ...
Convergence or divergence : what should we expect from vegetation succession?
Oikos, Nov 1, 1991
Page 1. FORUM FORUM FORUM FORUM is intended for new ideas or new ways of interpreting existing in... more Page 1. FORUM FORUM FORUM FORUM is intended for new ideas or new ways of interpreting existing information. It provides a chance for suggesting hypotheses and for challenging current thinking on ecological issues. ...
Spatial arrangement, density, and competition between barnyardgrass and tomato: II. Barnyardgrass growth and seed production
Weed Sci, 2001
ABSTRACT
Taiwania, 2004
This study was conducted in years 2000 to 2003 to compile a comprehensive list of naturalized spe... more This study was conducted in years 2000 to 2003 to compile a comprehensive list of naturalized species with background information, including origins, life forms, habits, usages, year of the first collection, and status. Major herbaria (TAI, HAST, TAIF, and NCKU) were visited to examine specimen records. Relevant publications and reliable websites and many other resources were also examined extensively for background information. Total 341 species in 222 genera and 60 families were documented as naturalized in Taiwan, representing 7.9% of the local flora. Besides, 25 species were considered as possibly naturalized due to insufficient evidences. A large portion (90.6%) of species reported here, were reported as "weeds" in other countries. Almost a half of the naturalized species (48.3%) were introduced from Americas.
When is eradication of exotic pest plants a realistic goal
... Keywords Costs of eradication; early detection; eradication effort; exotic pests; initial inf... more ... Keywords Costs of eradication; early detection; eradication effort; exotic pests; initial infestation; invasive plants; noxious ... But when is complete eradication a realistic goal ... marianum on Santa Barbara Is-land and Osteospermum frutkosum on Santa Cruz Island, California (Junak ...
Biotic Interactions in the Tropics: Their Role in the Maintenance of Species Diversity D. Burslem, M. Pinard, S. Hartley . 2005. Biotic Interactions in the Tropics: Their Role in the Maintenance of Species Diversity. Cambridge University Press. xv +. 564 16 × 23 cm, paperback, US$85.00. ISBN: 0-5...
Ecoscience, 2007
Naturalized Fabaceae (Leguminosae) species in Taiwan: the first approximation
Botanical Bulletin of Academia Sinica, 2003
What helps Opuntia stricta invade Kruger National Park, South Africa: Baboons or elephants?
Http Dx Doi Org 10 1658 1402 200110 265 Whosik 2 0 Co 2, 2007
Biological Invasions, Jul 11, 2010
Biological invasions affect virtually all ecosystems on earth, but the degree to which different ... more Biological invasions affect virtually all ecosystems on earth, but the degree to which different regions and biomes are invaded, and the quality of information from different regions, varies greatly. A large body of literature exists on the invasion of savannas in the Neotropics and northern Australia where invasive plants, especially African grasses, have had major impacts. Less has been published on plant invasions in African savannas, except for those in South Africa. Negative impacts due to plant invasions in African savannas appear to be less severe than in other regions at present. As savannas cover about 60% of the continent, with tens of millions of people relying on the services they provide, it is timely to assess the current status of invasions as a threat to these ecosystems. We reviewed the literature, contrasting the African situation with that of Neotropical and Australian savannas. A number of drivers and explanatory factors of plant invasions in savannas have been described, mostly from the Neotropics and Australia. These include herbivore presence, residence time, intentional introductions for pasture improvements, fire regimes, the physiology of the introduced species, and anthropogenic disturbance. After comparing these drivers across the three regions, we suggest that the lower extent of alien plant invasions in African savannas is largely attributable to: (1) significantly lower rates of intentional plant introductions and widespread plantings (until recently); (2) the role of large mammalian herbivores in these ecosystems; (3) historical and biogeographical issues relating to the regions of origin of introduced species; and (4) the adaptation of African systems to fire. We discuss how changing conditions in the three regions are likely to affect plant invasions in the future.
Folia Geobotanica et Phytotaxonomica, 1982
MISRA et MxS~A (1981) have concluded, on the basis of an analysis of a grassland community~ that ... more MISRA et MxS~A (1981) have concluded, on the basis of an analysis of a grassland community~ that there is significant negative correlation between species diversity and dominance indices. It is shown that this result is an unfortunate misunderstanding because negative correlation i s an inevitable consequence of indices definitions. Some other shortcomings concerning diversity, stability and species-abundance distributions, contained in the paper, are pointed out.
Disentangling vegetation diversity from climate-energy and habitat heterogeneity for explaining animal geographic patterns
Ecology and evolution, Jan 9, 2016
Broad-scale animal diversity patterns have been traditionally explained by hypotheses focused on ... more Broad-scale animal diversity patterns have been traditionally explained by hypotheses focused on climate-energy and habitat heterogeneity, without considering the direct influence of vegetation structure and composition. However, integrating these factors when considering plant-animal correlates still poses a major challenge because plant communities are controlled by abiotic factors that may, at the same time, influence animal distributions. By testing whether the number and variation of plant community types in Europe explain country-level diversity in six animal groups, we propose a conceptual framework in which vegetation diversity represents a bridge between abiotic factors and animal diversity. We show that vegetation diversity explains variation in animal richness not accounted for by altitudinal range or potential evapotranspiration, being the best predictor for butterflies, beetles, and amphibians. Moreover, the dissimilarity of plant community types explains the highest pr...
d 15 N as an indicator of N 2 -fixation by cyanobacterial mats in tropical marshes
Biogeochemistry, 2004
Canoco 4.5 and Some Comparisons with Pcord and Syn-Tax
Bulletin of the Ecological Society of America, 2003
... CANOCO 4.5 AND SOME COMPARISONS WITH PC-ORD AND SYN-TAX Software for Canonical Commu-nity Ord... more ... CANOCO 4.5 AND SOME COMPARISONS WITH PC-ORD AND SYN-TAX Software for Canonical Commu-nity Ordination (version 4.5). ... 1) The most widespread program package in the United States is prob-ably PC-ORD (McCune and Mefford 1999). ...
A growing number of studies seeking generalizations about the impact of plant invasions compare h... more A growing number of studies seeking generalizations about the impact of plant invasions compare heavily invaded sites to uninvaded sites. But does this approach warrant any generalizations? Using two large datasets from forests, grasslands and desert ecosystems across the conterminous United States, we show that (i) a continuum of invasion impacts exists in many biomes and (ii) many possible species-area relationships may emerge reflecting a wide range of patterns of co-occurrence of native and alien plant species. Our results contradict a smaller recent study by Powell et al. 2013 (Science 339, 316-318. (doi:10.1126/science.1226817)), who compared heavily invaded and uninvaded sites in three biomes and concluded that plant communities invaded by non-native plant species generally have lower local richness (intercepts of log species richness-log area regression lines) but steeper species accumulation with increasing area (slopes of the regression lines) than do uninvaded communities. We conclude that the impacts of plant invasions on plant species richness are not universal.
Journal of Biogeography, Oct 31, 2003
Aim The flora of northern Mesoamerica conventionally has been thought to be derived from taxa tha... more Aim The flora of northern Mesoamerica conventionally has been thought to be derived from taxa that emigrated from South America, but this view has recently been challenged as too simple. The dominance of limestone substrata in much of northern Mesoamerica, and its rarity in the rest of the continental Neotropics, may be one cause of the complexity of northern Mesoamerican floristics. Furthermore, northern Mesoamerica experiences longer and more intense seasonal drought than the rest of the continental Neotropics. As edaphic drought is accentuated with elevation on limestone soils, it may be expected that different topographic features have different phytogeographical affinities for seasonally drought-prone areas of the Neotropics. The objective of this study was to test for effects of different topographic positions on the composition, phytogeography and diversity of tree species in a limestone area of Belize.
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Papers by Marcel Rejmanek