Inspiration from nature

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Riparian ecosystems are found at the interfaces between terrestrial and aquatic zones and can range from a few metres to over 100 metres (Gregory et al., 1991). They consist of vegetated areas that are very distinct from surrounding upland areas, due to the soil moisture. Riparian zones contain a large variety of habitats as a result of natural disturbances, such as periodic flooding and blowdown of shallow-rooted trees; they therefore offer high biodiversity. The highly dynamic system causes several stages -in age and form- of vegetation (Ward et al., 1998).

Riparian biomes have several ecosystem services: they protect habitat and aquatic species; they provide shade and keep the water cool, as well as stabilise the banks, via trees along the streams; they provide habitat, structure and organic matter in the water through the falling of leaf litter and branches (Bilby and Likens, 1980). Furthermore they regulate water flow and reduce peak flows, allowing for the water to infiltrate and the sediments to deposit. The soil filters pollutants by fixing them onto soil particles, and the vegetation prevents excessive nutrient run-off by absorbing and allocating them into the plant biomass. The occurrence of different plant species provides diverse root structures and depths; this variability results in the exploitation of different soil layers, which contributes to an efficient nutrient uptake (Barley, 1970). Riparian ecosystems are thus original living filters.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Riparian zones are efficient in recycling nutrients and preventing nutrient runoff. Nature also offers systems that can facilitate the selective re-capturing of nutrient. An example on organism level is a plant’s root that selectively absorbs nutrients from the soil and later moves these nutrients upwards to the leaf area. The majority of the nutrients moves from the soil to the root surface through the mass flow process, triggered by leaf transpiration (Barber et al., 1963). The transpiration stream causes the movement of the water towards the root surface, drifting the nutrients close to the root area. Consequently, the selective uptake of nutrients is based on the presence of proteins in the plant membranes. Those proteins recognize and actively transport each particular nutrient into the cell, against the concentration gradient, which costs energy (Anon, 2015; Swamy, 1998). Despite the high efficiency of the root system in the absorption of all the essential elements for plant growth, the nutrients have to be available. The role of microorganisms is extremely important as they facilitate nutrient cycling in the soil, contributing to plant diversity and productivity of terrestrial ecosystems (van der Heijden et al., 2008). So, soil fauna and microbes positively influence plant productivity through mineralisation of organic matter (Bradford et al., 2002).

 

Another inspiring example for the selectivity of nutrient uptake on organ level can be found in vertebrate’s bodies; more specifically in the nephron, which is the functional unit of the kidney. The nephron operates by selectively filtering and reabsorbing important molecules in the organism (Pocock et al., 2013). The basic mechanisms present within the nephron are the facultative and obligatory osmosis (modifying the concentration of the medium); passive diffusion of ions such as K+ and Ca2+ through electrochemical gradients; active transport of Na+ and of big molecules like glucose; passive and facilitated diffusion of urea; and endocytosis of small proteins (Pocock et al., 2013).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This project has a double approach: an arrangement of riparian vegetation is proposed in order to better enclose the agricultural fields and limit surface runoff. Furthermore, a filtration and reabsorption system based on the roots and kidney functioning is designed to further improve the recapturing of nutrients from the leached water. As a result the nutrient cycling becomes more efficient and the nutrient input can be reduced.