Mountain Norway spruce forests under climate change (BIOFORMA)

Mountain Norway spruce-dominated forests (MSF) have been recognised as highly sensitive to the changing environmental conditions caused by climate change. However, in the alpine biogeographic region across Europe, these forest ecosystems are of great ecological, economic, and cultural importance. It is therefore crucial to understand future development trajectories of these forests in order to maintain their functionality and resilience. 

Our main objectives in this project, are 

1. to evaluate the consequences of different forest management scenarios in the context of climate change for biodiversity and ecosystem functions of spruce-dominated mountain forests and
2. to provide recommendations to stakeholders for adaptive management options in these sensitive forest ecosystems. 

To achieve our goals, we will conduct a detailed assessment of forest structures in 500 plots of 100 forest stands, covering the broad spectrum of structural diversity in MSF and reflecting the outcome of the different forest management systems traditionally applied in Switzerland, Croatia, Bulgaria and Romania: from no management to small-scale irregular shelterwood to clearcut harvesting. We then assess the biodiversity of key functional groups of organisms in these plots, covering a wide range of taxonomic groups including soil microorganisms, vascular plants and mosses, fungi, insects, and birds, and link this to forest structural properties. Using forest growth models, we will assess development trajectories of MSF under different forest management and climate scenarios and identify best practices to maintain the biodiversity and ecosystem functions for more resilient future forests. In addition, we will use remote sensing data to upscale biodiversity values to the landscape level. Ultimately, the results of this project will inform stakeholders and practice on how to adapt future management of MSF across the alpine biogeographic region of Europe, taking into account potential trade-offs between wood production and structural and biotic diversity. Moreover, the project will promote knowledge transfer and capacity building in the participating countries.

BIOFORMA has two main objectives:

1. to evaluate the consequences of different forest management scenarios in the context of climate change for biodiversity and ecosystem functions of spruce-dominated mountain forests,
2. to provide recommendations to stakeholders for adaptive management options in these sensitive forest ecosystems.

To assess and predict biodiversity in MSF and inform future management practices, we'll employ a multifaceted methodology elaborated in four working Packages (WP 1 to 4; Fig. 1).

WP1: Data acquisition and Linking stand structure to biodiversity (lead by WSL Switzerland) 

WP1 will generate the data basis for the other work packages. In each CSA, representative MSF will be selected based on similar site conditions but differing in structure and management/disturbance history. Fieldwork will include measuring stand structural parameters and assessing biodiversity. A comprehensive assessment of biodiversity will be carried out across a wide range of taxonomic groups, including soil microorganisms, vascular plants and mosses, fungi, insects, and birds. This will be directly linked to the structural properties of the forest. 

WP2:  Forest Development Trajectories (lead by University of Zagreb, Croatia)

We will use forest growth models to simulate the development of MSF under various forest management and climate scenarios. This allows us to predict how different practices will affect biodiversity and ecosystem functions. To scale these findings to a landscape level, we'll leverage remote sensing data from multiple sources. By doing so, we aim to identify best practices for creating more resilient future forests.

WP3: Synthesis of current and future links between forest structure, use, and biodiversity (lead by IBER-BAS Bulgaria)

WP3 will integrate the data from the other WPs to asses how various types of forest management affect biodiversity across spatial (stand to landscape) and temporal (present to the next 100 years) scales. It will focus on identifying trade-offs and synergies between the social aspects of production forestry and ecological values, using relevant indicator species at different spatial scales.

WP4: Capacity building and Knowledge Transfer (lead by INCDS „Marin Drăcea”, Romania)

WP4 aims to build capacity across participating countries and promote project outcomes in forest education, practice, and policy. It will strengthen international cooperation, identify practical needs by interaction with different stakeholders and report on adaptive forest management measures for MSF that support biodiversity. Scientific outputs (e.g., ISI papers, conferences), workshops and meetings with the representative stakeholders and social media will be used for broad dissemination.

The project is centered on four Case Study Areas (CSAs), which were strategically chosen to represent a broad geographical and ecological range. These sites span from the marginal, spruce-dominated forests of southeastern Europe, specifically Croatia and Bulgaria, to the core distribution areas of Norway spruce in the Carpathians (Romania) and the Alps (Switzerland).

The CSA Bulgaria is located in the Bulgaria ’s Rhodopes Mountains, one of the country’s most forested regions (>80% forest cover). Forests support both the local economy and social well-being through timber production, tourism, and non-timber products. At 1200–1500 m elevation, forests are mixed (fir, pine, spruce), while higher elevations (1600–2100 m) are spruce-dominated. Most forests are privately owned and managed under traditional shelterwood systems. The selected for the present project area is located in the Western Rhodopes and is part of the Natura 2000 network, reflecting its ecological value. 

The CSA Croatia is located in the Northern Velebit massif of the Dinaric Alps, a key representative area of this Mediterranean mountain range. The site features ecologically marginal spruce populations surviving in sinkholes and valleys, shaped by steep altitudinal and climatic gradients (900–2500 mm/year precipitation). These relict spruce stands, situated in the southernmost edge of the species’ European range, have declined significantly in recent decades due to droughts, insect outbreaks, and beech expansion driven by climate warming. The area contains a mosaic of forest types, from unmanaged near-primary stands to historically and currently managed ones, offering a unique research gradient. This diversity of forest structures and conditions makes CSA Croatia ideal for studying forest dynamics under changing environmental pressures.

The CSA Romania is located in the southern Eastern Carpathians near Brașov, focusing on Postăvaru and Ciucaș Mountains, which host around 300 ha of virgin spruce forests. Forests in the area are dominated by pure spruce stand at higher elevations, transitioning to mixed stands with silver fir and European beech at mid and lower mountain elevations. The area features diverse mountain spruce dominated forests, ranging from unmanaged to various managed stands, serving protective or production purpose, and under mixed ownership. The CSA provides an opportunity to assess links between forest biodiversity and structure across different management histories and stand structures.

The CSA Switzerland is located in the Prealps (canton of St. Gallen), where forests are dominated by Norway spruce, the most important conifer for both timber production and protective functions. Most forests in this region are managed for timber, while protective forests account for 60–65% of the total area. The majority of stands are uniform and single-layered, reflecting large-scale reforestation following the extensive deforestation of the 19th century. The windstorm Vivian (February 1990) strongly affected forests in the Prealps, resulting in forest areas with today’s young, structurally diverse stands. Climate change is bringing warmer temperatures, increasing the risk of disturbances such as windthrow, drought, fire, and bark beetle outbreaks. In response, forest managers are exploring adaptive strategies to enhance forest resilience.

The wide geographical and ecological range of the project's case study areas (CSAs) reflects the variability of spruce-dominated forests in Europe and their vulnerability to projected climate change. These regions differ significantly in management history—from large-scale shelterwood systems in Bulgaria and clearcutting in Romania, to small-scale tree- or group selection cuttings in Croatia and Switzerland. Additionally, unmanaged over 50 years forests will serve as references for understanding forest dynamics driven by natural disturbances. This variation allows the project to assess how past management influences the structural and functional adaptability of Norway spruce forests and to identify optimal strategies for future adaptive management. 

Ultimately, the project's findings will be synthesized to provide recommendations for stakeholders and practitioners on how to adapt MSF management across the European alpine biogeographic region. Our focus will be on navigating the trade-offs between wood production and biodiversity.