The Influence of Landscape Position on Temporal Variability in Four North American Ecosystems

Kratz, Timothy K.; Benson, Barbara J.; Blood, Elizabeth R.; Cunningham, Gary L.; Dahlgren, Randy A.

doi:10.1086/285222

Cited by 49 publications

(31 citation statements)

References 22 publications

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“…Further, recognising lakes as integral components of a region, lake ecologists have begun to implement a basic tenet of landscape ecology, namely that the spatial position of an ecosystem within a landscape influences the properties of that very system. In doing so, Kratz and colleagues (Kratz et al, 1991(Kratz et al, , 1997Webster et al, 1996;Soranno et al, 1999;Magnuson and Kratz, 2000;Riera et al, 2000) developed the concept of lake landscape position. One of the metrics used so far to define a lake's position in a landscape is lake chain number (LCN), which measures lake landscape position with respect to lakes connected along a linear chain through primarily surface-flow systems (Soranno et al, 1999).…”

Section: Introductionmentioning

confidence: 99%

Freshwater bacterioplankton richness in oligotrophic lakes depends on nutrient availability rather than on species–area relationships

et al. 2011

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A central goal in ecology is to grasp the mechanisms that underlie and maintain biodiversity and patterns in its spatial distribution can provide clues about those mechanisms. Here, we investigated what might determine the bacterioplankton richness (BR) in lakes by means of 454 pyrosequencing of the 16S rRNA gene. We further provide a BR estimate based upon a sampling depth and accuracy, which, to our knowledge, are unsurpassed for freshwater bacterioplankton communities. Our examination of 22 669 sequences per lake showed that freshwater BR in fourteen nutrient-poor lakes was positively influenced by nutrient availability. Our study is, thus, consistent with the finding that the supply of available nutrients is a major driver of species richness; a pattern that may well be universally valid to the world of both micro-and macro-organisms. We, furthermore, observed that BR increased with elevated landscape position, most likely as a consequence of differences in nutrient availability. Finally, BR decreased with increasing lake and catchment area that is negative species-area relationships (SARs) were recorded; a finding that re-opens the debate about whether positive SARs can indeed be found in the microbial world and whether positive SARs can in fact be pronounced as one of the few 'laws' in ecology.

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Section: Introductionmentioning

confidence: 99%

Freshwater bacterioplankton richness in oligotrophic lakes depends on nutrient availability rather than on species–area relationships

et al. 2011

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“…For the four systems, vegetation structure and species composition varied with elevation due to corresponding variations in geomorphic processes. For most terrestrial systems, landscape positions are defined as geo-referenced points with little or no change in physical features over time (Kratz et al 1991). For example, an alpine meadow may show no change in slope, aspect, elevation or other landscape features over decades, centuries and perhaps millennia, but importance of environmental drivers may change slowly as climate patterns shift through time.…”

Section: Introductionmentioning

confidence: 99%

Landscape position and habitat polygons in a dynamic coastal environment

et al. 2011

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Abstract. In contrast to stable inland systems, coastal landscape positions are dynamic, changing as shorelines migrate and storms alter topography. We define landscape position by distance to ocean shoreline and elevation above sea level, two metrics that integrate a suite of environmental and biotic factors. As shoreline and elevation change, suitability of a geo-referenced position for a given plant species may also change. The objectives of our study were to use two methods for measuring landscape position (GPS and hyperspectral/light detection and ranging or LIDAR) to develop habitat polygons, compare habitat polygons for five species representing several adaptive strategies, and illustrate change in landscape position due to migrating shoreline for a Virginia, USA barrier island. Habitat polygons for each species were distinct, represented several growth forms or functional groups, and were indicative of tolerances to biotic and abiotic stresses. The habitat polygon for Cakile edentula (annual forb) was relatively small, indicating narrow habitat requirements for the strand environment. Cirsium horridulum (biennial forb), with succulent shoots and roots, occurred on dunes where water is most limiting. For the dunebuilding grass, Ammophila breviligulata, as distance from shoreline increased, minimum elevation also increased. Two woody species occurred across the entire island; however, Morella cerifera (N-fixing shrub), was limited to mesic swales whereas Juniperus virginiana (evergreen tree), with the largest habitat polygon, occurred on both dunes and swales. For a geo-referenced point on the north end of Hog Island, distance to shoreline increased from the shoreline to 1100 m inland over 139 years. In contrast, the geo-referenced point on the eroding portion of the island decreased from 1700 m to 120 m from the ocean shoreline over the same time period. Where sea level rise and storms are expected to alter shorelines and island topography, generation of habitat polygons from hyperspectral and LIDAR imagery provide rapid assessment of potential effects on species distribution patterns at local and regional scales. Habitat polygons have broad applicability beyond coastal systems and may contribute to a rapid assessment or identification of vulnerability for species as climate patterns shift through time.

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“…As a result, limnologists have increasingly considered lakes to be dynamic ecological units connected and organized across the landscape, rather than spatially independent entities Kratz et al, 1991;Webster et al, 2000). Because lake behaviour is a product of both extrinsic forces and intrinsic processes, determining the relative importance of these drivers is fundamental to the understanding of the dynamics and function of a lake (Stoddard et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

“…In general, physical variables such as the water surface temperature are strongly coherent over large distances among different lakes (Livingstone and Dokulil, 2001). Water chemistry has also been shown to be temporally coherent for a myriad of variables (Folster et al, 2005), although to a lesser extent than the physical properties because dissolved ions and substances are also greatly affected by lake size, morphometry and landscape position (Kratz et al, 1991). Biological variables, on the other hand, are less coherent than most physical variables and chemical compounds Takahashi et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Temporal coherence among tropical coastal lagoons: a search for patterns and mechanisms

et al. 2010

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Temporal coherence (i.e., the degree of synchronicity of a given variable among ecological units within a predefined space) has been shown for several limnological features among temperate lakes, allowing predictions about the structure and function of ecosystems. However, there is little evidence of temporal coherence among tropical aquatic systems, where the climatic variability among seasons is less pronounced. Here, we used data from long-term monitoring of physical, chemical and biological variables to test the degree of temporal coherence among 18 tropical coastal lagoons. The water temperature and chlorophyll-a concentration had the highest and lowest temporal coherence among the lagoons, respectively, whereas the salinity and water colour had intermediate temporal coherence. The regional climactic factors were the main factors responsible for the coherence patterns in the water temperature and water colour, whereas the landscape position and morphometric characteristics explained much of the variation of the salinity and water colour among the lagoons. These results indicate that both local (lagoon morphometry) and regional (precipitation, air temperature) factors regulate the physical and chemical conditions of coastal lagoons by adjusting the terrestrial and marine subsidies at a landscape-scale. On the other hand, the chlorophyll-a concentration appears to be primarily regulated by specific local conditions resulting in a weak temporal coherence among the ecosystems. We concluded that temporal coherence in tropical ecosystems is possible, at least for some environmental features, and should be evaluated for other tropical ecosystems. Our results also reinforce that aquatic ecosystems should be studied more broadly to accomplish a full understanding of their structure and function.Keywords: synchrony, temporal coherence, local factors, regional factors, shallow lakes, coastal lagoons. Coerência temporal entre lagoas costeiras tropicais: uma busca por padrões e mecanismos ResumoA coerência temporal (i.e., o nível de sincronismo de uma dada variável ecológica entre unidades ecológicas) tem sido demonstrada para uma vasta gama de variáveis limnológicas em lagos de clima temperado, permitindo que predições sobre a estrutura e o funcionamento destes ecossistemas sejam realizadas. Entretanto, há pouca evidência da coerência temporal de variáveis limnológicas entre ecossistemas aquáticos tropicais, onde a variação climática é menos pronunciada entre as estações do ano. Neste estudo, utilizamos dados de longa duração do monitoramento de variáveis físicas, químicas e biológicas para testar a ocorrência de coerência temporal entre 18 lagoas costeiras tropicais. A temperatura da água e a concentração de clorofila-a apresentaram, respectivamente, a maior e a menor coerência temporal entre as lagoas, enquanto que a salinidade e a coloração da água apresentaram padrões intermediários. Fatores climáticos regionais foram os principais fatores responsáveis pelos padrões de coerência da temperatura e coloração d...

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The Influence of Landscape Position on Temporal Variability in Four North American Ecosystems

Cited by 49 publications

References 22 publications

Freshwater bacterioplankton richness in oligotrophic lakes depends on nutrient availability rather than on species–area relationships

Freshwater bacterioplankton richness in oligotrophic lakes depends on nutrient availability rather than on species–area relationships

Landscape position and habitat polygons in a dynamic coastal environment

Temporal coherence among tropical coastal lagoons: a search for patterns and mechanisms

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