How sustainable are sustainability standards? Impact of farm sustainability certifications on farmers' performance and environmental outcomes
by Bruno Paz
Date of Examination:2025-05-27
Date of issue:2025-07-30
Advisor:Prof. Dr. Meike Wollni
Referee:Dr. Bernhard Dalheimer
Referee:Dr. Goedele Van den Broeck
Persistent Address:
http://dx.doi.org/10.53846/goediss-11396
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Abstract
English
Voluntary Sustainability Standards (VSS) have emerged as a promising market-based response to global sustainability challenges within agricultural supply chains. By offering certifications for compliance with sustainability criteria, VSS aim to incentivize more responsible agricultural practices, especially in tropical commodity sectors such as coffee. Although the uptake of certification has grown substantially, particularly in the coffee sector, the effectiveness of these standards in delivering both economic and ecological benefits remains contested. Empirical evidence shows mixed outcomes, with some studies reporting modest gains for farmers or improvements in sustainable practices, and others finding little or no impact, especially beyond the farm level or across both economic and environmental dimensions. Moreover, research has disproportionately focused on third-party certifications, leaving in-house standards largely understudied. This dissertation addresses these gaps by exploring whether VSS can simultaneously support farmer livelihoods and promote ecological sustainability, contributing to a better understanding of their role in shaping more equitable and resilient food systems. The first essay of this dissertation examines the effect of Voluntary Sustainability Standards (VSS) on agricultural productivity and forest conservation among Rwandese coffee farmers. It relies on a stratified random sample of certified and non-certified farmers collected between November 2022 and January 2023 in Western and Southern provinces. While VSS aim to promote sustainability by establishing guidelines for improved agricultural practices and environmental protection, their effectiveness in enhancing coffee production while specifically mitigating forest degradation remains unclear. This essay first estimates the effect of certifications on productivity growth, considering its two main sources: technical efficiency and technical change. Additionally, it assesses whether VSS protect vegetation health and density at the landscape level, providing empirical evidence on broader environmental effects beyond individual farms. Finally, it explores the underlying pathways through which certification influences conservation outcomes, distinguishing between productivity-driven land-sparing effects and regulatory mechanisms enforced by sustainability standards. This essay contributes to the broader debate on how market-based sustainability initiatives impact smallholder agricultural systems, highlighting opportunities to reconcile certification programs’ economic and environmental effects. The second essay of this dissertation examines the economic and ecological effects of Voluntary Sustainability Standards (VSS), focusing on in-house certifications (e.g., Starbucks C.A.F.E. Practices) and third-party certifications (e.g., Rainforest Alliance, Fairtrade). It relies on a stratified random sample of certified and non-certified farmers surveyed between November 2022 and January 2023 in Western and Southern provinces and a subsample of farmers for ecological data collection. While VSS have been widely adopted as a sustainability tool in global agri-food supply chains, most research has focused on third-party certifications, leaving the impact of company-led (in-house) certifications largely unexplored. This essay addresses this gap by analyzing how in-house and third-party certifications affect the coffee plot’s economic performance (gross revenue, net revenue, costs, yield) and ecological outcomes (vegetation structure and animal diversity). It also examines whether different VSS schemes help balance economic and environmental trade-offs. This essay contributes to debates on corporate responsibility in sustainable supply chains and informs policies on aligning certification programs with rural development and conservation efforts. The third and final essay of this dissertation examines the relationship between VSS and farm household resilience among coffee farmers in Rwanda. It moves beyond traditional outcome indicators to assess whether VSS can help farmers sustain consistently high levels of economic, dietary, and environmental outcomes in the face of shocks. It relies on two rounds of a stratified random sample of certified and non-certified farmers collected between November 2022 and January 2023 and November 2023 and January 2024 in Western and Southern Province. While VSS aim to promote sustainability in agricultural supply chains, their effectiveness in long-term outcomes, such as preventing farmers from falling into poverty, poor diet quality, and environmental degradation following short-term disruptions, remains unclear. This study addresses this gap by analyzing whether VSS contribute to economic, dietary, and environmental resilience, offering insights into the discussion on the effectiveness of VSS as a rural development instrument and resilience-enhancing mechanism in smallholder farming systems.
Keywords: Voluntary sustainability standards; Coffee production; Rwanda; Economic and ecological outcomes
