3.4. Feasibility studies on the use of biomass by-products

The prescribed wetland vegetation mowing activities require that cut reed/wetland vegetation is also removed from the wetland, though the ability to remove a certain amount of biomass also depends on the potential use of this biomass. Under the LIFE15 NAT/GR/000936 – Prespa Waterbirds project, three alternatives for the use of extracted biomass were examined, as a means to promote its utilisation amongst stakeholders and authorities. More specifically, three feasibility studies were carried out for the use of reed biomass as heating material, as fodder and as soil conditioner.

The potential use of reed biomass extracted from the wetland is defined by four main factors: (a) the quality of the extracted reed vegetation; (b) the quantity that is extracted annually; (c) the financial sustainability of its use; and (d) the potential for synergies between various stakeholders.

The quality characteristics of the extracted vegetation depend mostly on the time it is cut, but also, secondarily, on the long-term management of wetland vegetation within a site. Summer cutting of reed reduces its competitive ability, allows a more diverse mix of vegetation and may ultimately eliminate it; at the same time, when reed vegetation is cut in summer it remains green and it retains higher quality characteristics (e.g. nutrient, protein levels, etc.). Reed cut in summer can be used as fodder or as soil conditioner for nutrient-poor agricultural soils, while repetitive cutting over the long-term tends to lead to the replacement of reed by other herbaceous species, possibly more valuable as fodder. Winter cutting of reed, on the other hand, tends to maintain its dominance, as nutrients are concentrated in the root system, allowing the proliferation of the plant in spring. However, the effects of cutting in winter also depend on the water level regime, as complete flooding of the culms (i.e., cut stems) may result in the rhizomes being deprived of oxygen, preventing subsequent re-growth. Dry reed cut in the winter period exhibits lower moisture content and lower content of ash and other inorganic compounds, making it more useful for use as a heating material, while dry reed is often used in traditional activities, such as thatching or as an insulation material. 

The quantity of reed extracted through cutting or mowing is also unpredictable to an extent, and depends on annual management targets and management implementation, as well as the ability to extract cut biomass from the wetland. Reed cut in the littoral zone, during specific periods and under a favourable water level regime (i.e. at a relatively low water level in summer-autumn) can be extracted with the use of baling equipment, but vegetation cut in waterlogged (but not flooded) soil by amphibious cutters in winter cannot be extracted as easily. Notably, in Lesser Prespa Lake extracted biomass originates from the littoral zone and the amount collected also depends on the degree of co-operation with interested stakeholders.

The sustainability of reed extraction is also related to the chosen use of the material; for example, interested stakeholders (e.g., stockbreeders looking to acquire fodder) will contribute to wetland management in order to increase yields, leading to the implementation of appropriate management in a larger area of the designated wetland sites. Lastly, the identification of potential uses for extracted biomass can bring about synergies between various stakeholders in wetland management, increase the socio-economic benefit and, through a communal management scheme, increase the positive outcomes of wetland management, as long as conservation objectives (and not yield) drive implementation.

Within the LIFE Prespa Waterbirds project, efforts were dedicated to identifying the potential uses of reed biomass early on, and several alternatives were investigated, taking into account the unpredictability of the quantities to be extracted annually.  In this respect, two studies were dedicated to the use of reed biomass as heating material, in combination with other available biomass within the Prespa National Park (e.g., imported reed stalks, and plant material left over from bean cultivation): (a) a feasibility study on heat production for municipal buildings; and (b) a study on the identification of technologies and processes for using reed as a heating material. In parallel, in co-operation with farmers the reed material was tested as a soil conditioner in bean cultivation. Lastly, as there was increased interest in the use of reed and wetland vegetation material from the area’s stockbreeders, the LIFE Prespa Waterbirds project also investigated the quality characteristics of the material extracted in different time periods, both summer and autumn.

The feasibility studies and the results of the investigations on reed use are listed below. Although most of the studies are in Greek, English summaries are provided in the links.

Feasibility study for alternative uses of reed biomass | LIFE Prespa Waterbirds (in Greek with English summary)

Assessment of quality characteristics of biomass extracted from wetland management for use as fodder 

Assessment of the use of extracted biomass as soil conditioner in bean cultivations