Can current management maintain forest landscape multifunctionality in the Eastern Alps in Austria under climate change?

Abstract

In Central Europe, management of forests for multiple ecosystem services (ES) has a long tradition and is currently drawing much attention due to increasing interest in non-timber services. In face of a changing climate and diverse ES portfolios, a key issue for forest managers is to assess vulnerability of ES provisioning. In a case study catchment of 250 ha in the Eastern Alps, the currently practiced uneven-aged management regime (BAU; business as usual) which is based on irregularly shaped patch cuts along skyline corridors was analysed under historic climate (represented by the period 1961-1990) and five transient climate change scenarios (period 2010-2110) and compared to an unmanaged scenario (NOM). The study addressed (1) the future provisioning of timber, carbon sequestration, protection against gravitational hazards, and nature conservation values under BAU management, (2) the effect of spatial scale (1, 5, 10 ha grain size) in mapping ES indicators and (3) how the spatial scale of ES assessment affects the simultaneous provision of several ES (i.e. multifunctionality). The analysis employed the PICUS forest simulation model in combination with novel landscape assessment tools. In BAU management, timber harvests were smaller than periodic increments. The resulting increase in standing stock benefitted carbon sequestration. In four out of five climate change scenarios, volume increment was increasing. With the exception of the mildest climate change scenario (?2.6°C, no change in precipitation), all other analysed climate change scenarios reduced standing tree volume, carbon pools and number of large old trees, and increased standing deadwood volume due to an intensifying bark beetle disturbance regime. However, increases in deadwood and patchy canopy openings benefitted bird habitat quality. Under historic climate, the NOM regime showed better performance in all non-timber ES. Under climate change conditions, the damages from bark beetle disturbances increased more in NOM compared with BAU. Despite favourable temperature conditions in climate change scenarios, the share of admixed broadleaved species was not increasing in BAU management, mainly due to the heavy browsing pressure by ungulates. In NOM, it even decreased and mean tree age increased. Thus, in the long run NOM may enter a phase of lower resilience compared with BAU. Most ES indicators were fairly insensitive to the spatial scale of indicator mapping. ES indicators that were based on sparse tree and stand attributes such as rare admixed tree species, large snags and live trees achieved better results when mapped at larger scales. The share of landscape area with simultaneous provisioning of ES at reasonable performance levels (i.e. multifunctionality) decreased with increasing number of considered ES, while it increased with increasing spatial scale of the assessment. In the case study, landscape between 53 and 100 % was classified as multifunctional, depending on number and combinations of ES.

Future ecosystem services from European mountain forests under climate change

“…No negative influences of climate change were detected except for one south-exposed RST with a low water holding capacity where a droughtinduced dieback of Norway spruce was simulated under the driest scenarios (CC2 and CC5; Figs S1.2 and S3.1). These outcomes generally agree with other studies reporting that upper montane forest stands in the Eastern Alps would not be significantly affected by climate change unless natural disturbances such as bark beetle infestations or wind-throw are considered (Seidl, Rammer & Lexer 2011;Irauschek, Rammer & Lexer 2015).…”

Capturing ecological processes in dynamic forest models: why there is no silver bullet to cope with complexity

“…Simulating decadal‐ to centennial‐scale forest dynamics is of high interest for manifold purposes, from testing assumptions about fundamental ecological processes (Botkin et al 1972 b , Berzaghi et al 2018) to projecting future stand development, forest composition, and ecosystem service provisioning under scenarios of forest management and/or climate change (Biber et al 2015, Irauschek et al 2015, Shugart et al 2018). Dynamic, process‐based vegetation models (DVMs), particularly dynamic global vegetation models (DGVMs; Foley et al 1996, Friend et al 1997) and forest gap models (FGMs; Botkin et al 1972 a , Bugmann 2001, Shugart et al 2018), are important tools for assessing long‐term forest dynamics because they incorporate the key processes of tree regeneration, growth, and mortality.…”

Trade-offs between ecosystem service provision and the predisposition to disturbances: a NFI-based scenario analysis

“…The rockfall protection index accounts besides stand structural parameters also for rock dimension, initial fall height, forested and un-forested slope length and inclination (Berger and Dorren 2007). While the statistical models have been validated over a wide range of forest and stand structural types, it remains to be tested how they perform with output of forest models as in this and previous studies (Irauschek et al 2017;Mina et al 2017a), where assumptions on rock dimensions, initial falls height and slope length had to be made. The avalanche protection index as used here and in a number of previous studies does not account for canopy gaps even though they are important for avalanche release (Cordonnier et al 2013).…”

“…We used the empirical functions developed for the ROCKFORNET tool (Berger and Dorren 2007, http:// www.ecorisq.org/rockfor-net-en) to estimate protection against rockfall. These functions have recently been used in a number of simulation model applications to estimate protection against rockfall in response to forest management scenarios (Cordonnier et al 2013;Bugmann et al 2017;Irauschek et al 2017;Mina et al 2017a) and have been integrated as a risk management tool in the broadly accepted NaiS recommendations for protection forest management (Dorren et al 2015). They quantify the risk that a rock passes through a stand as a function of number of stems per ha, quadratic mean diameter (QMD) of stems, basal area per ha, the basal area ratio of conifers and broadleaves and slope angle.…”

“…Previous assessments of management effects on ESB provision that were based on forest development models have accounted for disturbances such as windthrow and bark beetles at the level of stands and management units (Temperli et al 2012;Maroschek et al 2014;Thom and Seidl 2016;Cantarello et al 2017;Irauschek et al 2017). However, inventory-based assessments representative for a whole region or country have rarely evaluated forest management scenarios with respect to both ESB provision and disturbance risks (Gutsch et al 2018;Huang et al 2018;Jandl et al 2018).…”