Physical Structure Of Vegetation Research Articles

Structural diversity as a reliable and novel predictor for ecosystem productivity

The physical structure of vegetation is thought to be closely related to ecosystem function, but little is known of its pertinence across geographic regions. Here, we used data from over three million trees in continental North America to evaluate structural diversity – the volumetric capacity and physical arrangement of biotic components in ecosystems – as a predictor of productivity. We show that structural diversity is a robust predictor of forest productivity and consistently outperforms the traditional measure – species diversity – across climate conditions in North America. Moreover, structural diversity appears to be a better surrogate of niche occupancy because it captures variation in size that can be used to measure realized niche space. Structural diversity offers an easily measured metric to direct restoration and management decision making to maximize ecosystem productivity and carbon sequestration.

Six years later… New population monitoring data for an endemic and endangered coastal lizard species in Brazil

Habitat degradation is considered a huge threat to biodiversity and could become even worse with climate change. If the current situation of Atlantic Forest is not good, then the Restinga ecosystems are even worse due to the high urbanization rate. Glaucomastix littoralis, a lizard species that is endemic and restricted to Restinga areas of Rio de Janeiro State- Brazil, has become even more threatened in the last 10 years mainly due to degradation of physical vegetation structure, since it is closely related to local vegetation. Fieldwork was carried out in the Restingas of Grussai, Jurubatiba, Marica and Marambaia. We performed two density sampling methods and analyzed the degradation index and loss of substrate in each area aiming to compare and monitor the results over a 13 year sampling period. According to method I, the population density of G.littoralis presented smaller variation between 2013 and 2018, as did the amount of degradation elements, while method II showed an increase in population density. The Jurubatiba Restinga was considered the best area for maintaining this species, while Marambaia is the area where the species are most at risk. The density sampling methods utilized were efficient for understanding the lizards’ responses to small-scale and large-scale degradation items. Monitoring the only four populations of this species and the preservation status of each Restinga where it occurs is essential for tracking the species’ density variations and for preserving it.

Perch selection in Sympetrum species (Odonata: Libellulidae): importance of vegetation structure and composition

1. Perching dragonflies are closely associated with the physical structure of vegetation because adults utilise plants when foraging, thermoregulating, and mate‐seeking. However, little attention has been given to which structural attribute of vegetation is playing a key role within foraging habitat use.2. This study focused on the influence of different features of perches on their selection by adult dragonflies. As a model group, a typical percher behavioural guild of Sympetrum was used and experimental plots with artificial perches and different structural properties were established.3. It was found that adults preferred perch sticks with a wider diameter and larger spacing. It is assumed that these perching sites are advantageous because their base is more stable, they provide the best view for successful foraging, and there is no interference among individuals.4. This study also revealed significant differences between male and female preferences. Females used less structured vegetation formed by thin perches in high densities. It is suggested that female discrimination is influenced by the higher competitiveness of males, which is related to their agonistic behaviour.5. These results suggest that the availability of perches in the foraging habitat might be an essential requirement for adults. However, within the terrestrial surroundings of breeding sites, the structure of vegetation providing conditions for perching may be associated only with certain habitats. In intensive landscapes, physically structured vegetation can be limited or completely absent.

Spatially dependent biotic and abiotic factors drive survivorship and physical structure of green roof vegetation.

Plant survivorship depends on biotic and abiotic factors that vary at local and regional scales. This survivorship, in turn, has cascading effects on community composition and the physical structure of vegetation. Survivorship of native plant species is variable among populations planted in environmentally stressful habitats like urban roofs, but the degree to which factors at different spatial scales affect survivorship in urban systems is not well understood. We evaluated the effects of biotic and abiotic factors on survivorship, composition, and physical structure of two native perennial species assemblages, one characterized by a mixture of C4 grasses and forbs (Hempstead Plains, HP) and one characterized by a mixture of C3 grasses and forbs (Rocky Summit, RS), that were initially sown at equal ratios of growth forms (5:1:4; grass, N-fixing forb and non-N-fixing forb) in replicate 2-m2 plots planted on 10roofs in New York City (New York, USA). Of 24 000 installed plants, 40% survived 23months after planting. Within-roof factors explained 71% of variation in survivorship, with biotic (species identity and assemblage) factors accounting for 54% of the overall variation, and abiotic (growing medium depth and plot location) factors explaining 17% of the variation. Among-roof factors explained 29% of variation in survivorship and increased solar radiation correlated with decreased survivorship. While growing medium properties (pH, nutrients, metals) differed among roofs there was no correlation with survivorship. Percent cover and sward height increased with increasing survivorship. At low survivorship, cover of the HP assemblage was greater compared to the RS assemblage. Sward height of the HP assemblage was about two times greater compared to the RS assemblage. These results highlight the effects of local biotic and regional abiotic drivers on community composition and physical structure of green roof vegetation. As a result, initial green roof plant composition and roof microclimate may have long-term effects on community dynamics, ecosystem function, and urban biodiversity.

Fire Alters Ecosystem Carbon and Nutrients but not Plant Nutrient Stoichiometry

We evaluated the effects of fire on ecosystem biogeochemistry by examining how 56 years of fire manipulations changed carbon and nutrients in soils and plants in an African savanna. Although fire treatment significantly changed carbon and nutrients in the soil, the stoichiometry of individual plants and the community composition of functional groups were remarkably resilient. We also evaluated the relative role of trees vs. grasses in driving changes in the soil pools and discussed possible implications behind shifts in physical vegetation structure for the sensitivity of carbon losses.

Habitat Selection by Swainson's Warblers Breeding in Loblolly Pine Plantations in Southeastern Louisiana

Abstract Although Swainson's warbler (Limnothlypis swainsonii) is typically associated with bottomland hardwood forests, they also breed in even-age pine (Pinus spp.) plantations. We used mist nets and point counts from 1998–2000 to survey intensively managed even-age loblolly pine (P. taeda) plantations of different age classes and management histories to determine breeding status and stand structure preferences of Swainson's warbler in southeastern Louisiana, USA. We detected Swainson's warblers in 23 of 124 sampled loblolly pine stands. We also confirmed breeding in 7–24-year-old pine stands. We found Swainson's warblers in pine stands that had well-developed canopy closure, abundant understory vegetation, and sparse live ground cover. Floristic differences between hardwood and pine breeding habitats demonstrate that Swainson's warblers do not require specific vegetation composition, although they discriminate within habitats based on physical structure of vegetation. Although management of Swainson's ...

The nature and significance of the feedback of changes in terrestrial vegetation on global atmospheric and climatic change

The potential feedback on global atmospheric and climate change of climate-driven changes in terrestrial vegetation is examined by systematically relating the surface exchanges of energy, mass and momentum to two dimensions of vegetation, structure and taxonomy, such that the significance of climate driven changes in these characteristics can be assessed. A detailed quantitative understanding of this feedback is an important prerequisite to realistic and dynamic representations of the Earth's surface within general circulation and biological models (GCMs and GBMs). Without realistic representations of terrestrial vegetation within these models, any forecasts of future climates by these models must be suspect. Several general conclusions are drawn. The first is that the indirect feedbacks, those associated with the clouds and aerosols of the planetary boundary layer, appear to be very powerful but as yet their behaviour and connections with the underlying surface are both poorly understood and captured within GCMs. The physical structure of vegetation, the disposition of biomass in 3-D, is the characteristic that most strongly influences the exchange of momentum (via aerodynamic roughness) and solar radiation (via albedo). Vegetation structure and species composition determine the most important of the mass exchanges, evapotranspiration. Of all of the surface exchanges, the parameterization of evapotranspiration (E τ) and the simulation of the water balance over time is the most critical. Lastly, the problems of scaling and spatial heterogeneity, the sub-grid variability of the modellers, looms as a difficult, but not insoluble, problem. It remains a critical problem however, and the detailed parameterization of the various ‘big leaf’ models stands in absurd contrast to the simplistic generalization of the spatial heterogeneity of terrestrial landscapes. Plant ecologists can contribute to the task of improving the representation of vegetated landscapes within GCMs. There is need to simply and unify the way in which vegetation can be grouped at landscape scales. A classification that is based on function rather than phylogeny is required. The definition of Vegetation Functional Types (VFTs) would expedite research on both the impact of, and feedback on, climate change.