Undergrowth

About: Undergrowth is a research topic. Over the lifetime, 795 publications have been published within this topic receiving 11911 citations. The topic is also known as: understorey & underbrush.

An Ecologic Study of Epiphytic Bryophytes and Lichens on Pseudotsuga menziesii on the Olympic Peninsula, Washington. I. A Description of the Vegetation

Abstract: Six epiphytic vegetational unions occur on northeast and southwest exposures of Pseudotsuga menziesii in mature forests of the Olympic Peninsula, Washington. The Hypnum circinale-Dicranum fuscescens-Scapania bolanderi Union and the Hypnum circinale-Dicranum fuscescens-Lepraria membranacea Union both occur in very mesic habitats. The Hypnum circinale-Lepraria mem- branacea Union and the Hypnum circinale-Lepraria membranacea-Sphaerophorus globosus Union occur in habitats of intermediate moisture. The lichen-dominated unions of Platismatia glauca-Parmeliopsis hyperopta-Lepraria membranacea and Alectoria sarmentosa-Parmeliopsis hyperopta-Ochrolechia tartarea-Myco- blastus sanguinarius both occur in relatively xeric habitats. The relationships between epiphytic vegetation and surrounding vascular vegetation are general; bryophyte-dominated unions occur in mesic habitats where the undergrowth is characteristic of the Polystichum munitum Union,

Occurrence of species-rich crab fauna in a human-impacted mangrove forest questions the application of community analysis as an environmental assessment tool

Abstract: Diversity and composition of the intertidal brachyuran crab community in the Segara Anakan Lagoon (SAL), Java, Indonesia, during the dry season of 2005 and the rainy season of 2006, shows that crab community composition and structure alone appeared to be poor indicators for the state of a forest in terms of tree diversity and wood-cutting intensity. The lagoon is surrounded by the largest mangrove stand in Java and is under constant anthropogenic pressure, mainly due to logging, land conversion for agriculture, overfishing and industrial pollution. This study aims to determine the crab community composition at different sites of the lagoon in relation to vegetation composition and sediment parameters. In addition it investigates if mangrove crabs can be used as bioindicators to describe the environmental state of mangrove forests (tree diversity, degree of logging). It was assumed to find a low crab diversity and species richness and a strong dominance of a single species at highly disturbed forest sites compared to moderately disturbed sites. A stratified, hierarchical design was used to sample the crab fauna at 13 stations distributed over the entire lagoon. Additionally, abiotic parameters and vegetation composition were recorded. In total 6463 crabs were caught belonging to 49 species, 5 superfamilies and 10 families, with Ocypodidae and Sesarmidae being the families of most note. Mean density of adult crabs was 27.7 individuals*m −2 and mean biomass was 12.8 g wet mass*m −2 or 1.3 g ash free dry mass*m −2 . Density and biomass varied strongly within and between stations but they where within the range reported for other mangrove forests of the Indo-West-Pacific. Species composition was significantly different between stations. The distribution of facultatively leaf-feeding grapsid crabs was related to vegetation parameters (tree, seedling and undergrowth density), but the occurrence of single crab and tree species was not correlated. The distribution of ocypodid crabs, feeding on detritus and microphytobenthos, correlated with sediment characteristics like median grain size and organic content. The crab community was strongly dominated by one species at six stations, however, this was not correlated to the degree of logging. Leaf-feeding crab and mangrove tree diversity was correlated at areas of one hectare (stations), but not at a lower spatial scale (areas of 100 m 2 , “zone”). Species richness of leaf-feeding crabs was not linked to forest diversity. Hence a functional relation between leaf-feeding crab and tree species diversity could not be proven.

Day-night changes in the leaf water relations of epiphytic bromeliads in the rain forests of Trinidad.

Abstract: A study was made of the bulk-leaf water relations of selected species of epiphytic bromeliads growing in their natural habitat in Trinidad (West Indies). Field measurements were made during the rainy season at three forest sites centred on the wetter part of the island. The epiphytic bromeliads were sampled in situ using modified rock-climbing techniques at 4- to 6-h intervals during complete day-nigh cycles. Eleven species were studied that differed in their photosynthetic pathways and habitat preferences. The C3 species among the epiphytic bromeliads characteristically showed maximum values of xylem tension (measured with the pressure chamber) during the day, whereas the species with crassulacean acid metabolism (CAM) attained maximum values towards the end of the night. In addition, the CAM species showed large nocturnal increases in leaf-cell-sap osmotic pressure and titratable acidity. These nocturnal increases showed mean values of 0.601 MPa and 289 mol H+ m-3, respectively, for four species sampled at an exposed forest clearing (250 m), where CAM species were well represented. At the other two sites, a lowland forest (60 m) and a ridge forest (740 m), CAM bromeliads were found in the forest canopy, but in the lowest strata all the bromeliads were C3 species. This species distribution was associated with a marked vertical stratification of microlimate, the forest canopy being characterized by much bigger day-night changes in temperature and water-vapour-pressure deficit than the undergrowth. The C3-CAM intermediateGuzmania monostachia var.monostachia showed significant nocturnal acidification in the forest clearing but not in the understory of the lowland forest. Taken as a whole, the C3 and CAM bromeliads were very similar in the range of values observed for xylem tension and osmotic pressure, as well as in aspects of their leaf anatomy. However, epidermal trichomes covered a large percentage of the leaf surface area in xeromorphic species (e.g.Tillandsia utriculata), whereas they were poorly developed in shade-tolerant species (e.g.G. lingulata var.lingulata). The absolute values of sylem tension and osmotic pressure were low for all species. Mean minimum xylem tension during the day-night cycles was in the range of 0.18–0.23 MPa and mean maximum in the range 0.41–0.53 MPa; during periods of rain, xylem tension reached a mean minimum of 0.12 MPa. Mean minimum osmotic pressure was in the range 0.449–0.523 MPa. Such between-site and between-species differences as were observed in the water relations of the bromeliads could be related to the microclimatic conditions prevailing in the various epiphytic habitats.

Activity and habitat use of lesser mouse-deer (tragulus javanicus)

Abstract: Activities and habitat use of lesser mouse-deer (Tragulus javanicus), a common but poorly studied ruminant native to lowland tropical forests of Southeast Asia, were investigated by full-day radiotracking and direct visual observations in the Kabili-Sepilok Forest Reserve, Sabah, Borneo. The mouse-deer was thought to be nocturnal, but diurnal distance moved per hour and behaviors observed directly in wild mouse-deer indicated that they were mainly active during the day and rested at night. Active individuals foraging or moving from shelter to shelter were mainly observed during the day, and inactive individuals resting on open forest floor were mainly observed during the night. Captive mouse-deer observed in a farm enclosure (1.5 ha in size) also showed activities similar to those observed in the forest. Radiotracking for 24 h revealed that mouse-deer significantly preferred crown-gap areas with dense undergrowth of creeping bamboo (Dinochloa) during the day but that they tended to move to the higher and drier ridge areas at night. These results indicated that mouse-deer used crown-gap areas as foraging sites and ridge areas as resting sites. Our results strongly suggest that mouse-deer use food resources in gap areas in tropical forests. Key words: activity, Borneo, gap, habitat use, home range, mouse-deer, Tragulidae, Tragulus javanicus, tropical forest

Soil nematodes in five spruce forests of the Beskydy mountains, Czech Republic

Abstract: Sununary Soil nematode communities were studied in five 5 to 138 year-old spruce forests in the Beskydy Mountains, Northern Moravia, Czech Republic. A total of 92 species was found in ail stands studied. Nematode abundance ranged from 272.9 to 6238.9 x 103 ind·m-z (mean value 1409.6 x 103 ind·m-Z), biomass varied from 33.6 mg·m-z to 1.197 mg·m-z (mean value 337.2 mg·m-Z). Myco-phyrophagous nematodes of the order Tylenchida had the grearest abundance but individual genera differed in their preference for the spruce forests studied. The abundance of bacreriophagous nematodes was similar in alllocalities. The composition of nematode communities was influenced by the age of spruce trees, herbaceous undergrowth and altitude.