Interactions and Linkages among Ecosystems during Landscape Evolution

Vegetation succession in deglaciated landscapes: implications for sediment and landscape stability

“…The dominance of unconsolidated sediments at this time have a high bulk density (Figure 7), associated with a high degree of compaction and decreased water infiltration, resulting in increased rates of erosion, as previously illustrated by Crocker and Major (1955). These soils are subject to physical and chemical weathering, leading to the leaching of organic matter and nutrients (Luizao et al, 2004;Milner et al, 2007) and low Crocker and Major, 1955) as plant colonisation helped to stabilise the sediment structure.…”

“…During this process, pioneer plant species colonise and stabilise land surfaces, and a succession of communities undergo a pattern of colonisation and extinction controlled by both biotic and abiotic factors over time (Matthews, 1992). During succession plant communities undergo a gradual increase in structural complexity, biomass, species diversity and ecosystem interaction (Odum, 1969;Matthews, 1992;Milner et al, 2007) over a time period similar to that of paraglacial adjustment. Sediment availability and soil characteristics evolve as terrestrial succession progresses, changing from soils with a characteristically high sediment availability and simple structure to a complex soil structure with lower sediment availability, stabilised by vegetation growth at later successional stages.…”

“…Rapid surface sediment reworking and stabilisation were also found to occur within decades of deglaciation following the Little Ice Age maximum as a result of upslope processes (Matthews, 1992;Orwin and Smart, 2004;Moreau et al, 2008), and vegetative colonisation (Moreau et al, 2008;Eichel et al, 2013). As succession progresses, and species composition and the structural complexity of terrestrial plant communities begin to change, sediment mobilisation declines as tensile strength and sediment binding by roots and organic matter (OM) begin to increase (Crocker and Major, 1955;Milner et al, 2007), resulting in increased infiltration and interception of rainfall.…”

“…The repeat survey capabilities of the Landsat satellites were highlighted as being particularly useful to study vegetation change, as landscape dynamics and physical processes which occur over relatively short (<10 2 years) timescales are deemed too difficult to measure directly (Reinhardt et al, 2010). These timescales are also of particular importance in the study of the interactions of biological and physical processes with one another over the long term (Rull, 2012) as physical-biological feedbacks and interactions often require significant time to develop before influencing their surroundings (Reiners et al, 1971;Milner et al, 2007). Given the opportunities for the space-for-time substitution available at GBNP, combined with the existence of repeat aerial Landsat satellite images in this area over a 22 year period and an extensive body of literature available regarding processes of vegetation succession, soil development and changes in sediment yield over time within GBNP, we aim to determine the rate and processes of vegetation-landscape interactions which influence sediment availability, and by proxy, paraglacial adjustment on glacier forelands over the 250 year time period since the Neoglacial maxima.…”

Disconnect of microbial structure and function: enzyme activities and bacterial communities in nascent stream corridors

“…As a result, effects of community change on ecosystem functions can be easily masked. However, this masking effect could be alleviated by taking advantage of the physically and biologically simple structure of nascent ecosystems formed by volcanism (Vitousek, 2004), glacier retreat (Milner et al, 2007;Brankatschk et al, 2011) or humans (Gerwin et al, 2009;Gerull et al, 2011), where species numbers are reduced but artifacts caused by greatly simplified laboratory systems are avoided.…”