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Microhabitat Types (microhabitat + type)
Selected AbstractsCorticolous arthropods under climatic fluctuations: compensation is more important than migrationECOGRAPHY, Issue 1 2005Andreas Prinzing Animals can cope with fluctuating climates by physiological tolerance, tracking of climatic fluctuations (migration) and compensatory redistribution among (micro)habitats (compensation). Compensation is less demanding and thus more important than migration at large geographic scales. It is not clear however which strategy is more important at the small scale of a microhabitat landscape. I investigated how six arthropod species (Collembola, Oribatei, Psocoptera, Isopoda) respond to microclimatic fluctuations at the surface of exposed tree trunks. Across a nine-month period I characterized the microclimatic zonation of 299 trunks, and focally sampled the arthropods from different microhabitat types (different cryptogam species and bark crevices) within different microclimatic zones. I found that compensatory microhabitat-use was a general phenomenon. The distribution of all species across microhabitats was influenced significantly by ambient microclimate. Also, the arthropods' microhabitat use changed throughout their ontogeny, and microhabitats were used even if they were rare. Most interestingly, the arthropods responded to microclimatic fluctuations primarily by redistribution among microhabitats and less by fluctuations of overall abundances across all microhabitats. Hence compensation was more important than migration. The animals moved for centimeters to decimeters rather than for decimeters to meters; they perceived and utilized their environment primarily at the finest, but also most complex scale. This has implications for the resilience of arthropod populations, their interactions with cryptogams and the turnover of species between macrohabitats. [source] Spatial scale and the diversity of macroinvertebrates in a Neotropical catchmentFRESHWATER BIOLOGY, Issue 2 2010RAPHAEL LIGEIRO Summary 1.,Lotic ecosystems can be studied on several spatial scales, and usually show high heterogeneity at all of them in terms of biological and environmental characteristics. Understanding and predicting the taxonomic composition of biological communities is challenging and compounded by the problem of scale. Additive diversity partitioning is a tool that can show the diversity that occurs at different scales. 2.,We evaluated the spatial distribution of benthic macroinvertebrates in a tropical headwater catchment (S.E. Brazil) during the dry season and compared alpha and beta diversities at the scales of stream segments, reaches, riffles and microhabitats (substratum types: gravels, stones and leaf litter). We used family richness as our estimate of diversity. Sampling was hierarchical, and included three stream segments, two stream reaches per segment, three riffles per reach, three microhabitats per riffle and three Surber sample units per microhabitat. 3.,Classification analysis of the 53 families found revealed groups formed in terms of stream segment and microhabitat, but not in terms of stream reaches and riffles. Separate partition analyses for each microhabitat showed that litter supported lower alpha diversity (28%) than did stones (36%) or gravel (42%). In all cases, alpha diversity at the microhabitat scale was lower than expected under a null model that assumed no aggregation of the fauna. 4.,Beta diversity among patches of the microhabitats in riffles depended on substratum type. It was lower than expected in litter, similar in stone and higher in gravel. Beta diversities among riffles and among reaches were as expected under the null model. On the other hand, beta diversity observed was higher than expected at the scale of stream segments for all microhabitat types. 5., We conclude that efficient diversity inventories should concentrate sampling in different microhabitats and stream sites. In the present study, sampling restricted to stream segments and substratum types (i.e. excluding riffles and stream reaches) would produce around 75% of all observed families using 17% of the sampling effort employed. This finding indicates that intensive sampling (many riffles and reaches) in few stream segments does not result in efficient assessment of diversity in a region. [source] Patterns of invasion within a grassland communityJOURNAL OF ECOLOGY, Issue 5 2002A. Kolb Summary 1Relatively few studies have looked for patterns of invasion by non-native species within communities. We tested the hypotheses that: (i) some types of microhabitats within a community are more invasible than others; (ii) microhabitat types that differ in invasion also differ in resource availability; and (iii) invasibility is mediated by effects of these resources on competition between native and non-native species. 2To test the first two hypotheses, we measured plant cover and soils in a coastal grassland in northern California. Consistent with these hypotheses, cover of non-native plants was consistently high where nitrogen-fixing shrubs had recently grown, in the bottoms and sides of gullies and on deep soils, and these microhabitats tended to have relatively high nitrogen or water availability. 3Cover and number of native species tended to be lower where cover of non-native species was higher, indicating that non-native species as a group negatively affected native species. However, the number of non-native species also tended to be lower where the total cover of non-natives was higher. This suggests that a few non-native species excluded natives and other non-natives alike. 4To test the third hypothesis, we grew a common non-native, the annual grass Lolium multiflorum, and a common native, the perennial grass Hordeum brachyantherum, at different levels of water and nitrogen. The relative competitive ability of the native was higher at lower nitrogen availability but not at lower water availability. When 10-week-old native plants were grown with non-native seedlings and nitrogen was relatively low, the native out-competed the non-native. However, the non-native out-competed the native at all resource levels when species were both grown as seedlings. Competition between native and non-native grasses in this system may thus help prevent invasion by non-natives in microhabitats where nitrogen availability is low, but invasion may be relatively irreversible. [source] Succession and Micro-elevation Effects on Seedling Establishment of Calophyllum brasiliense Camb. (Clusiaceae) in an Amazonian River Meander Forest1BIOTROPICA, Issue 4 2003Rachel T. King ABSTRACT I investigated the effects of successional stage and micro-elevation on seedling establishment of Calophyllum brasiliense (Clusiaceae), a common canopy tree of seasonally flooded lowland forest along the Manú River meander zone in southeastern Peru. To compare seedling establishment between microhabitat types, I planted C. brasiliense seeds in a fully crossed experimental design of three successional stages (early, mid, and mature) and two micro-elevations (levees and backwaters). Seedling establishment success in this study was affected by both successional stage and micro-elevation, but micro-elevation was most important in mid-successional habitats. In general, seedlings in early succession experienced better conditions than in mature forest; light levels were higher, herbivory lower, and seedling growth higher. In mid-successional forest, micro-elevation determined habitat quality; backwaters had higher light levels, lower herbivory, and higher seedling growth and survival than levees. Mid-successional backwaters were similar in quality to early successional forest for seedling establishment, while levees in that same successional stage were the poorest microhabitats for establishment. Although mid-successional backwaters are similar to early succession for seedling establishment, in the long run, seedlings that establish in mid-succession have a lower chance of reaching reproductive size before their habitat ages to mature forest than members of their cohort that established in early succession. I hypothesize that successful recruitment for C. brasiliense in the Manú River meander system requires dispersal to early successional habitat. RESUMEN Yo investingé el efecto de microhábitats del sistema serpentine ribereño, los cuales se diferencian en estado sucesional y en microelevación, en el establecimiento de plántulas de Calophyllum brasiliense (Clusiaceae), un árbol común en bosques estacionalmente inundados alrededor de los meandros del Río Manú en Perú. Para comparar establecimiento de plántulas entre los microhábitats, sembré semillas de C. brasiliense en seis condiciones de microhábitat, combinando los efectos de tres estados sucesionales (bosque temprano, mediano, y maduro) y dos microelevaciones (lomos y depresiones). El establecimiento de plántulas en este estudio fue afectado por estado sucesional y por microelevación, pero microelevación fue más importante en sucesión mediana. En general, plántulas en sucesión temprana tenían mejores condiciones que plántulas de bosque maduro; niveles de luz más altos, menor herbivoría, y una mayor tasa de crecimiento. En sucesión mediana, microelevacion determinó calidad de hábitat; depresiones presentaron más luz, menos herbivoria, y mayor crecimiento y sobreviviencia de plántulas que los lomos. Depresiones en sucesión mediano fueran similares en calidad a sucesión temprano en cuanto al establecimiento de plántulas, mientras que lomos en este mismo estado sucesional fueron los peores microhábitats para establecimiento. A largo plazo, las plántulas establecidas en sucesión mediano tienen menos probabilidad de alcanzar el tamaño reproductive (antes de que el hábitat llega a ser bosque maduro) que las plántulas de la misma edad, establecidas en sucesión temprana. El reclutamiento efectivo de C. brasiliense en el sistema serpentino del Río Manú probablemente requiere la dispersión al hábitat de sucesión temprana. 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