Climate Change and Agricultural Development Adapt

Authors: Mikołaj Piniewski Ignacy Kardel Marek Giełczewski Paweł Marcinkowski Tomasz Okruszko

Publish Date: 2013/10/24

Volume: 43, Issue: 5, Pages: 644-660

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Abstract

Currently there is a major concern about the future of nutrient loads discharged into the Baltic Sea from Polish rivers because they are main contributors to its eutrophication To date no watershedscale studies have properly addressed this issue This paper fills this gap by using a scenariomodeling framework applied in the Reda watershed a small 482 km2 agricultural coastal area in northern Poland We used the SWAT model to quantify the effects of future climate land cover and management changes under multiple scenarios up to the 2050s The combined effect of climate and land use change on NNO3 and PPO4 loads is an increase by 20–60 and 24–31  respectively depending on the intensity of future agricultural usage Using a scenario that assumes a major shift toward a more intensive agriculture following the Danish model would bring significantly higher crop yields but cause a great deterioration of water quality Using vegetative cover in winter and spring VC would be a very efficient way to reduce future PPO4 loads so that they are lower than levels observed at present However even the best combination of measures VC buffer zones reduced fertilization and constructed wetlands would not help to remediate heavily increased NNO3 loads due to climate change and agricultural intensificationAquatic eutrophication caused by excessive loads of biogenic substances transported by rivers to sea waters is now the primary environmental issue related to the Baltic Sea a problem that intensified during the 20th century due to rapid economic development in the region Glasby and Szefer 1998 The increasing scale of eutrophication forced members of society policymakers and researchers to adopt elaborate mechanisms to reduce pollution sources in the Baltic Sea Basin BSB and thus prevent further deterioration of sea water quality Among the proposed measures the most significant one is the Baltic Sea Action Plan BSAP HELCOM 2007 which combats eutrophication by reducing biogenic substances in rivers discharging into the sea As one of the BSAP signatories Poland is obliged to implement a policy that will stimulate activities that will achieve the objectives of this plan An additional stimulus for implementing measures aimed at reducing nutrient loads in Polish watersheds was the country’s acceptance as a member of the EU in 2004 and the related transposition of regulations resulting from the Water Framework Directive 2000 and the Nitrates Directive 1991 both aimed at achieving the good ecological status of all bodies of waterThe proposed measures seem to be effective as a reduction of the total nitrogen TN and phosphorous TP loads reaching the Baltic Sea has been observed at different scales the entire basin HELCOM 2011 and the Vistula and Odra basins Kowalkowski et al 2012 In Poland the reduction is predominantly related to a radical modernization of wastewater treatment plants that took place over the past two decades while Poland’s share of the generated load remains the largest among all the Baltic countries when expressed in percentages Kowalkowski et al 2012 TN and TP loads to the Baltic Sea originate mainly from agricultural diffuse sources HELCOM 2011 hence European leaders have shifted their focus to agriculture with a number of research programs executed recently eg Baltic Deal Baltic Compass Baltic Manure BERAS Implementation etc in order to achieve environmental targets However questions remain concerning the estimation of potential loads related to different alternatives for Polish agricultural development The future trends related to driving forces such as climate land use demography global food market demand competitiveness of Polish farmers in the EU market and the nonagricultural sector’s demand for land are far from being properly understood and quantified One of the methods that can be employed to move forward in bringing together and quantifying these trends is multidimensional scenario development using current stateoftheart approaches recently set by the SCENES project Kämäri et al 2011 Quantification of the potential range of future nutrient loads generated from rural areas as well as the assessment of the efficiency of measures that could be applied in agriculture to combat eutrophication in the forthcoming decades can be done using a combination of scenario studies with mathematical models that are capable of evaluating the effect of changing climate population land use and other important drivers on the state of the environment This is also a topic about which science could provide needed insight during the policymaking processThe Reda watershed A its location in the Baltic region B and its land cover map C Key to land use classes URMD—urban residential medium density URLD—urban residential low density FRSE—forests WATR—water FALL—fallow land GO2–GO9 arable land on soils of different quality UZ2–UZ3—grassland on soils of different qualityThe River Reda is situated in northern Poland close to Tricity Gdańsk Gdynia and Sopot the largest urban zone on the Polish seaside Fig 1 Its drainage area is equal to 482 km2 which makes it the largest subwatershed of the Puck Bay watershed The Puck Lagoon is a very shallow coastal water body which is particularly sensitive to eutrophication due to its limited water exchange with the outer part of the Puck Bay Krzymin´ski and Kamin´ska 2005 It belongs to the marine area of the Nadmorski Landscape Park a designated HELCOM Baltic Sea Protected AreaAverage 1991–2010 daily minimum and maximum temperatures at the nearby IMGW station in Gdynia are −15 and 29°C for January and 154 and 215°C for July while the annual mean basinaveraged precipitation is 793 mm The watershed is characterized by a hilly landscape particularly in its southern part that belongs to the Kashubian Lakeland where the maximum elevation reaches 234 masl and sandy soils dominate the landscape In the northern part the RedaŁeba ice marginal valley is filled with peat deposits that stretch from west to east Agricultural land occupying 512  of the watershed area is the predominant land cover class while forests are the secondlargest class occupying 416  The proximity of a large metropolitan area is reflected in the share of urban mainly low density residential land which yields 66 Most of the farms in studied area are rather small in size only 28  of farms are larger than 10 ha which is still much higher than the average 15  in Poland GUS 2011 Mean farm size in Poland is several times smaller than in western European countries in the same climatic zone Germany Denmark and the Netherlands Banski 2010 Crops cultivated on arable land include the dominant spring cereals on better quality soils in the northwestern part of the basin and extensive farming of winter cereals and potatoes on poor quality soils in the southern part of the basin The majority of grasslands are cultivated as permanent meadows and pastures The share of commercial crop production in global agricultural production is estimated to be only 30  while the remaining crop production is used mainly for a farm’s livestock feeding Mean livestock density was estimated at 056 LSU ha−1 with a dominance of pigs which is well below 15 LSU ha−1 the maximum allowed livestock density considered to be not harmful to the environment in the Polish best practices codex

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