Deliverable 3.1: Report on methods to assess ecosystem services

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In QueSSA, the following ecosystem service provision in relation to semi-natural habitats were assessed:

 

• Natural predation of pests

• Pollination

• Landscape aesthetic

• Soil fertility and organic matter

• Erosion

• Disservices

 

Assessments were performed following a standardised design in each case study consisting of 18 focal crop fields bordered by semi-natural habitats (SNH) divided equally into three categories (six fields of each): woody SNH, herbaceous SNH or another crop field as control. Fields were selected along a gradient of SNH proportion measured in a landscape sector of 1km radius around each field. Vegetation traits were recorded in the adjacent SNH to the crop field as well as the main management practices applied in the field by interviewing the farmer. Habitats and fields in the landscape sector around the focal field were recorded by ground mapping. Generic and simple methods were developed and tested among case studies regardless of the farming systems and the crop under investigation in order to generate general information.

 

For the predation of pests, sentinel-preys were exposed in fields (standard fishing baits – Calliphora larvae, Ephestia moth eggs, aphids, plasticine preys, weed seeds, etc). Initial testing was conducted to determine the most efficient sentinel-prey techniques that showed sufficient variation in response as well as the most practical for further assessments. Sentinel-preys kept for assessment of general predation overall were the Calliphora larvae exposed on the ground, Ephestia eggs exposed on the ground and on the plants, Chenopodium album and Poa trivialis seeds exposed on the ground. In each case study, the predation rate of crop-specific pests was estimated by using either sentinels of the particular pest or by measuring predation directly with predator-exclusion methods. Natural enemies were recorded by using pitfalls for ground dwelling predators, and with pan and sticky traps for flying ones. Camera recording was used to identify predators acting on sentinel-preys.

 

Pollination delivery was assessed by:

 

1. Comparing bagged and hand-pollinated plants with an open pollination treatment to determine the level of insect pollination

2. Assessing the potential for yield gain under optimal pollination (supplementing the pollen deposition on stigmas by hand) compared to the actual level of pollination, and analysing the potential pollination deficiency on yield

3. Identifying the flower visitors and measuring the rate of visits

4. Recording the pollen deposition on flowers by single pollinators using several techniques, e.g. by providing non-pollinated flowers (“mobile bouquet”) to pollinators in the field. The insect pollination efficiency on yield was estimated by measuring the fruit and the seed set as well as seed weight and oil content (oilseed rape).

 

Other ecosystem services in QuESSA included landscape aesthetic (8 case studies), soil erosion (1 case study), soil fertility (4 case studies), organic matter storage (2 case studies), and biodiversity conservation. In addition, the impact of semi-natural habitats on so-called disservices was recorded, namely weed invasion (3 case studies) and bird damage (1 case study). Regarding the landscape aesthetic, photographs were taken of element combinations of woody SNH or grassy SNH, or another crop field as control as for pollination and predation assessment. Pictures were taken at three or four different vegetation stages during the season. Soil erosion by water was quantified by using astroturf mats having grass-like features installed on upslope and downslope sides of elements of the four SNH classes, and inside the crop fields with and without green manure crop. Soil fertility was assessed by taking soil samples from focal fields and from woody linear and herbaceous linear SNH. Soil organic carbon content was measured with dry combustion method with a carbon/nitrogen analyser. Decomposition rate was also measured by burying tea bags. Organic matter storage was calculated using loss on ignition from soil samples collected in the SNH classes and crop fields. While recording the vegetation, the predators and the pollinators to characterise SNH, a large part of biodiversity was simultaneously assessed (vegetation, pan, sticky and pitfall traps). All collected organisms put together provide the basis for a biodiversity conservation value of the SNH.

 

As disservices, weed populations and bird damage were recorded. Weed composition was determined by scoring density and percentage cover of the species in sunflower fields in Italy and Hungary. Bird damages were estimated by quantitative observation of damages on fruits at harvest in pear orchards in the Netherlands, and by interviewing farmers.

 

2013, the first project year was used to test some of the methods. Complete assessments were then carried out in 2014 and 2015.