Vegetation

Straightforward mapping of detailed heathland habitat patches and their quality using remote sensing is hampered by (1) the intrinsic property of a high heterogeneity in habitat species composition (i.e. high intra-variability), and (2) the occurrence of the same species in multiple habitat types (i.e. low inter-variability). Mapping accuracy of detailed habitat objects can however be improved by using an advanced approach that specifically takes into account and exploits these inherent patch characteristics. To demonstrate the idea, we developed and applied a multi-step mapping framework on a protected semi-natural heathland area in the north of Belgium. The method consecutively consists of (1) a 4-level hierarchical land cover classification of hyperspectral airborne AHS image data, and (2) a kernel-based structural re-classification algorithm in combination with habitat patch object composition definitions. Detailed land cover composition data were collected in 1325 field plots. ...

Despite the importance of litter on forest floor albedo and brightness, previous studies have not documented forest floor albedo or litter cover in any detail. Our objective was to describe the seasonal influence of litter on spectral albedos and nadir reflectances of a forest snowpack in a mixed-hardwood stand in the Sleepers River Research Watershed (SRRW) in Danville, Vermont (37°39′ N, 119°2′ W). Experimental measurements in a nearby open area at the Snow Research Station of the SRRW nearly duplicated the spectral trend observed in the forest. Spectral albedo and nadir reflectance measurements in the visible and near infrared (350–2500 nm) transitioned from a gently curved shape through the visible range (for finer-grained, lightly littered snow) to one having a peak in the red/near-infrared (near 760 nm) as the snowmelt season progressed (for coarser-grained, more heavily littered snow). The snowpack became optically thin as surface litter reached high percentages. A point-in-time digital photographic survey of the late-lying snowpacks of three forest stands and the open showed that median litter cover percentages in the coniferous, deciduous, mixed-forest, and an open area were 17·5, 6·1, 1·2, and 0·04 respectively. A Kruskal–Wallis ANOVA on ranks and pairwise comparisons using Dunn's test indicated that the litter covers of the three forest stands were significantly different with >95% confidence. The snowpack was relatively shallow (<1 m), as is typical for this area of Vermont. From a remote-sensing standpoint, and since shallow snow and increased grain size also lower the visible albedo, we can expect that snowpack litter will cause decreased albedo earlier in the snowmelt season, at deeper snow depths, and will tend to shift the maximum albedo peak to the red/NIR range as the melt season progresses. Published in 2001 by John Wiley & Sons, Ltd.

PL: Wieloletnia presja antropogeniczna wywarła głębokie zmiany w krajobrazie doliny Kłodnicy w Gliwicach. W artykule przedstawiono różne warianty rewitalizacji doliny rzeki Kłodnicy, możliwe do realizacji w ramach funduszy unijnych, krajowych, partnerstwa publiczno-prywatnego i budżetu obywatelskiego. Zdecydowana większość mieszkańców (81%) źle ocenia stan badanego odcinka doliny, wskazując na potrzebę jej rewitalizacji (76%). Zaproponowane w pracy rozwiązania, zgodne z koncepcją zielonej architektury, pozwoliłyby na odtworzenie potencjału ekohydrologicznego doliny Kłodnicy i stworzenie przyjaznej dla mieszkańców przestrzeni publicznej. Przywrócenie właściwego stanu ekosystemów rzeki umożliwiłoby uzyskanie wielu usług ekosystemowych (poprawa bezpieczeństwa powodziowego, poprawa warunków aerosanitarnych, estetyzacja krajobrazu), podnoszących jakość i standard życia mieszkańców. Przewidziane w projekcie obiekty i infrastruktura stanowiłyby interesującą ofertę spędzania czasu wolnego oraz służyłyby podniesieniu świadomości ekologicznej mieszkańców. EN: Long-term anthropopressure caused negative changes in the landscape of the Kłodnica valley in Gliwice. The article presents various variants of revitalization of the Kłodnica valley. They are possible to realize within European funds, national funds, public-private partnership and the civil budget. Most inhabitants (81%) poorly assessed the state of the studied section of the Kłodnica valley. The inhabitants pointed also at the need to the revitalization of the valley (76%). Solutions proposed in the article, according to green architecture concept, would allow the reconstruction of the ecohydrological potential of the Kłodnica valley and creating friendly public space. The restoration of the proper state of river ecosystems would allow many valuable ecosystem services (improving flood safety, micro-climate regulation, aesthetization of landscape), which increases the standard and quality of life of inhabitants. Objects and infrastructure proposed in the project would be an interesting offer for spending leisure time and would increase the ecological awareness of inhabitants.

Field observations were carried out to determine the influence of a park on the urban summer climate in the nearby areas. The possibilities of reduction in air conditioning energy were investigated. Air temperature, relative humidity and other meteorological factors were measured at many locations inside a park and in the surrounding areas in the Tama New Town, a city in the west of the Tokyo Metropolitan Area, Japan. The observations indicated that vegetation could significantly alter the climate in the town. At noon, the highest temperature of the ground surface of the grass field in the park was 40.3 °C, which was 19 °C lower than that of the asphalt surface or 15 °C lower than that of the concrete surface in the parking or commercial areas. At the same time, air temperature measured at 1.2 m above the ground at the grass field inside the park was more than 2 °C lower than that measured at the same height in the surrounding commercial and parking areas. Soon after sunset, the temperature of the ground surface at the grass field in the park became lower than that of the air, and the park became a cool island whereas paved asphalt or concrete surfaces in the town remained hotter than the overlying air even late at night. With a size of about 0.6 km2, at noon, the park can reduce by up to 1.5 °C the air temperature in a busy commercial area 1 km downwind. This can lead to a significant decrease of in air conditioning energy in the commercial area.

Abstract. Links between plant traits and the environment, i.e. sets of plant attributes consistently associated with certain environmental conditions, are the consequence of the filtering effect of climatic, disturbance and biotic conditions. These filters determine which components of a species pool are assembled into local communities. We aimed at testing for consistent association between plant traits and climatic conditions along a steep regional gradient, divided into 13 climatically homogeneous sectors, in central-western Argentina. We analyzed 19 vegetative and regeneration traits of the 100 most abundant species along the gradient. For each trait, we tested for homogeneity of frequencies of different categories between sectors and the regional species pool, using the χ2 statistic. We rejected H0 in 71% of the pair-wise comparisons, which strongly suggests a ‘filtering effect’ of climatic factors on key plant functions. Vegetative traits were filtered more often than regeneration traits. Specific leaf area, life span, ramification, canopy height, leaf weight ratio, carbon investment into support tissue and pollination mode were the traits showing differences in the largest number of pair-wise comparisons.This is probably the first attempt to detect, on a quantitative, statistically conservative basis, consistent linkages between climatic factors and numerous plant traits, over a broad spectrum of environmental conditions and plant growth forms. We discuss the advantages and limitations of this approach in predicting vegetation structure and functioning under present environmental conditions, and those expected for the next century as a consequence of global change.

We aimed to assess the impacts of recreational trampling on rare species, plant communities and landscape structure in the Iroise Biosphere Reserve (western France). Focusing on coastal grasslands, we first identified indicators discriminating human-induced short grasslands (i.e. maintained short by intensive trampling) from natural short grasslands (i.e. maintained by environmental constraints): the presence of lichens and succulent or woody species, which are known to be highly sensitive to trampling, as well as a shallow soil were good indicators of natural short grasslands. Recreational activities affected the majority of plots containing rare species, but one third of rare species (according to their habitat preference) appeared currently not threatened by recreational activities. The other rare species were found in grasslands with low trampling intensity and were not found in grasslands with greater trampling intensity. One lichen species (Teloshistes flavicans) was not affec...

Wildland fuelbeds are exceptionally complex, consisting of diverse particles of many sizes, types and shapes with abundances and properties that are highly variable in time and space. This complexity makes it difficult to accurately describe, classify, sample and map fuels for wildland fire research and management. As a result, many fire behaviour and effects software prediction systems use a generalised description of fuels to simplify data collection and entry into various computer programs. There are several major fuel description systems currently used in the United States, Canada and Australia, and this is a source of confusion for many in fire management. This paper (1) summarises the challenges of describing fuels, (2) contrasts approaches (association, classification and abstraction) for developing fuel description systems and (3) discusses possible future directions in wildland fuel description and science to transition to a universal fuel description system. Most discussio...

In this study, we compared the soil seed bank and current vegetation under coniferous plantations and adjacent native deciduous forests. The objective was to assess how much of the initial plant diversity is retained in such plantations, and the potential to restore this initial plant community from seed bank in case of reversion to broadleave stands. Four stands growing side by side and with different dominant species were selected at two locations (site of Haye: Quercus petraea, Pseudotsuga menziesii, Pinus sylvestris and Picea abies; site of La Petite-Pierre: Quercus petraea, Fagus sylvatica, Pinus sylvestris and Picea abies). In each stand, ground vegetation was surveyed and soil seed bank was sampled. Composition of ground flora and seed bank of stands were quite different: only 11 to 30 % of the species were in both the ground flora and the seed bank. Composition of the seed bank was mainly influenced by site location and sylvicultural practices such as the type of afforestation or the tree cover. Species richness of seed banks and vegetation were higher in the site of Haye than in the site of La Petite-Pierre. Seedling density strongly decreased with stand age. Whereas between 65 and 86 % of species found in the ground vegetation of native deciduous stand were also present in the understory or the seed bank of mature coniferous stands, this was only about 50 % in young coniferous stands. Species of deciduous stands which were absent from coniferous stands were typical of old forests. In contrast, species mainly found in the coniferous stands were often ruderal. In the studied areas, it would be possible to restore up to 86 % of the native deciduous forest vegetation, but some plant species typical of ancient forests may have disappeared during the coniferous stage.

1 The species composition of fragmented semi-natural grasslands may change over time due to stochastic local extinction and colonization events, successional change and/or as a response to changing management or abiotic conditions. The resistance of vegetation to change may be mediated through the effects of topography (slope and aspect) on soils and microclimate.2 To assess long-term vegetation change in British chalk grasslands, 92 plots first surveyed by F. H. Perring in 1952–53, and distributed across four climatic regions, were re-surveyed during 2001–03. Changes in vegetation since the original survey were assessed by comparing local colonization and extinction rates at the plot scale, and changes in species frequency at the subplot scale. Vegetation change was quantified using indirect ordination (Detrended Correspondence Analysis; DCA) and Ellenberg indicator values.3 Across all four regions, there was a significant decrease in species number and a marked decline in stress-tolerant species typical of species-rich calcareous grasslands, both in terms of decreased plot occupancy and decreased frequency within occupied plots. More competitive species typical of mesotrophic grasslands had colonized plots they had not previously occupied, but had not increased significantly in frequency within occupied plots.4 A significant increase in Ellenberg fertility values, which was highly correlated with the first DCA axis, was found across all regions. The magnitude of change of fertility and moisture values was found to decrease with angle of slope and with a topographic solar radiation index derived from slope and aspect.5 The observed shift from calcareous grassland towards more mesotrophic grassland communities is consistent with the predicted effects of both habitat fragmentation and nutrient enrichment. It is hypothesized that chalk grassland swards on steeply sloping ground are more resistant to invasion by competitive grass species than those on flatter sites due to phosphorus limitation in shallow minerogenic rendzina soils, and that those with a southerly aspect are more resistant due to increased magnitude and frequency of drought events. The species composition of fragmented semi-natural grasslands may change over time due to stochastic local extinction and colonization events, successional change and/or as a response to changing management or abiotic conditions. The resistance of vegetation to change may be mediated through the effects of topography (slope and aspect) on soils and microclimate. To assess long-term vegetation change in British chalk grasslands, 92 plots first surveyed by F. H. Perring in 1952–53, and distributed across four climatic regions, were re-surveyed during 2001–03. Changes in vegetation since the original survey were assessed by comparing local colonization and extinction rates at the plot scale, and changes in species frequency at the subplot scale. Vegetation change was quantified using indirect ordination (Detrended Correspondence Analysis; DCA) and Ellenberg indicator values. Across all four regions, there was a significant decrease in species number and a marked decline in stress-tolerant species typical of species-rich calcareous grasslands, both in terms of decreased plot occupancy and decreased frequency within occupied plots. More competitive species typical of mesotrophic grasslands had colonized plots they had not previously occupied, but had not increased significantly in frequency within occupied plots. A significant increase in Ellenberg fertility values, which was highly correlated with the first DCA axis, was found across all regions. The magnitude of change of fertility and moisture values was found to decrease with angle of slope and with a topographic solar radiation index derived from slope and aspect. The observed shift from calcareous grassland towards more mesotrophic grassland communities is consistent with the predicted effects of both habitat fragmentation and nutrient enrichment. It is hypothesized that chalk grassland swards on steeply sloping ground are more resistant to invasion by competitive grass species than those on flatter sites due to phosphorus limitation in shallow minerogenic rendzina soils, and that those with a southerly aspect are more resistant due to increased magnitude and frequency of drought events.

Refúgios úmidos, matas serranas, brejos interioranos, serras úmidas, são alguns dos sinônimos utilizados para designar as formações vegetacionais conhecidas como brejos de altitude. Estes constituem encraves de vegetação úmida no semiárido nordestino. O objetivo deste trabalho foi investigar, por meio do georreferenciamento, tratamento de dados vetoriais e visitas a campo, a ocorrência de brejos de altitude em Alagoas, visando acrescentar informações acerca deste tipo de ambiente e levantar questionamentos sobre a influência antrópica a que estão sujeitos. Brejos de altitude em território alagoano são representados sob a forma de pequenos fragmentos, muitas vezes inseridos no perímetro urbano das cidades onde estão situados. Localizados, predominantemente, ao norte do estado, onde recebem influência, em sua altitude média, do Planalto da Borborema, resultante da sua divisa com Pernambuco. A deterioração destes ambientes é notada, relacionando-se intimamente com atividades de subsistência da população, como a extração de madeira e a criação de animais.