27 research outputs found
Why does fertilization reduce plant species diversity? Testing three competition-based hypotheses
1 Plant species diversity drops when fertilizer is added or productivity increases. To explain this, the total competition hypothesis predicts that competition above ground and below ground both become more important, leading to more competitive exclusion, whereas the light competition hypothesis predicts that a shift from below-ground to above-ground competition has a similar effect. The density hypothesis predicts that more above-ground competition leads to mortality of small individuals of all species, and thus a random loss of species from plots. 2 Fertilizer was added to old field plots to manipulate both below-ground and above-ground resources, while shadecloth was used to manipulate above-ground resources alone in tests of these hypotheses. 3 Fertilizer decreased both ramet density and species diversity, and the effect remained significant when density was added as a covariate. Density effects explained only a small part of the drop in diversity with fertilizer. 4 Shadecloth and fertilizer reduced light by the same amount, but only fertilizer reduced diversity. Light alone did not control diversity, as the light competition hypothesis would have predicted, but the combination of above-ground and below-ground competition caused competitive exclusion, consistent with the total competition hypothesis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75695/1/j.1365-2745.2001.00662.x.pd
Trichoptera (Insecta) in water hyacinth roots: evaluation of the influence of exotic mussel and environmental factors
Size Doesn't Matter: Towards a More Inclusive Philosophy of Biology
notes: As the primary author, OâMalley drafted the paper, and gathered and analysed data (scientific papers and talks). Conceptual analysis was conducted by both authors.publication-status: Publishedtypes: ArticlePhilosophers of biology, along with everyone else, generally perceive life to fall into two broad categories, the microbes and macrobes, and then pay most of their attention to the latter. âMacrobeâ is the word we propose for larger life forms, and we use it as part of an argument for microbial equality. We suggest that taking more notice of microbes â the dominant life form on the planet, both now and throughout evolutionary history â will transform some of the philosophy of biologyâs standard ideas on ontology, evolution, taxonomy and biodiversity. We set out a number of recent developments in microbiology â including biofilm formation, chemotaxis, quorum sensing and gene transfer â that highlight microbial capacities for cooperation and communication and break down conventional thinking that microbes are solely or primarily single-celled organisms. These insights also bring new perspectives to the levels of selection debate, as well as to discussions of the evolution and nature of multicellularity, and to neo-Darwinian understandings of evolutionary mechanisms. We show how these revisions lead to further complications for microbial classification and the philosophies of systematics and biodiversity. Incorporating microbial insights into the philosophy of biology will challenge many of its assumptions, but also give greater scope and depth to its investigations
Environmental variables and Piper assemblage composition: a mesoscale study in the Madeira-Purus interfluve, Central Amazonia
Evenness effects mask richness effects on ecosystem functioning at macroâscales in lakes
Leafâcutting ant abundance and distribution under different agricultural practices in grassland biome
Simple does not mean poor: grasslands and forests harbor similar ant species richness and distinct composition in highlands of southern Brazil
Several studies addressed ant communities in the dense Atlantic Forest that runs along the Brazilian coast.
However, comparatively little is known about the mixed forests and grasslands that occur in the southern range
of the Atlantic Forest domain. In this study we performed the first standardized assessment of ants in the forest-
grassland mosaic found in the highlands of the state of Santa Catarina. We aimed to investigate and compare ant
richness and composition between mixed forests and grasslands in the main mountain range of south Brazil. Ants
were collected in two years with ground pitfalls, tree pitfalls and litter samples. Sixty ant species were recorded,
resulting in 22 new records for âPlanalto Serranoâ region and three for the state of Santa Catarina:
Eurhopalothrix
depressa
,
Pheidole radoszkowskii
and
Wasmannia williamsoni
. There was significant dissimilarity in ant species
composition between grasslands and forests, but no difference in ant species richness, even considering the
higher number of strata in mixed forests. Similar richness and low number of arboreal species suggest that this
ant community is structured similarly to temperate ones. Both habitats presented a large proportion of exclusive
species. The fact that species composition between grassland and forest areas differed, coupled with the similarity
in species richness between habitats and the record of new ant species for the region, calls for strong conservation
efforts in grasslands of southern Brazil, which still are little protected by conservation areas