Causes and consequences of large-scale windthrow on the development of fir-beech forests in the Dinaric mountains

We investigated several aspects of windthrow that are relevant to our understanding and management of forest ecosystems. As an example, we used an extreme event in December 2017, when the strongest storm in recent history occurred in the Slovenian Dinaric High Karst. We examined influential factors such as soil properties, wind speed, precipitation and ecological consequences for the affected forests. Soil properties were measured around standing and fallen silver fir trees at all three research sites. Tree species composition in the regeneration was observed on plots with chemical and acoustic ungulate deterrents and on control plots without deterrents. Economic estimates of yield loss due to damage were calculated at the national level. A model of the potential threat from windthrow was also developed based on data collected from windthrow events and meteorological data over the past 20 years. Our results indicate that soil depth and mineral fraction depth were similar at sites with and without damaged trees and were not the determining factors for tree toppling. Plots with acoustic deterrents showed the most effective regeneration development, the least decline in silver fir and the greatest increase in noble hardwood seedlings, while plots with chemical deterrents showed the least browsing damage. The estimated economic loss of €16.1 million is 6.6% less than the harvest under normal conditions. The economic loss was relatively low due to the nature of the storm, with the predominant type of damage being uprooted trees with no damaged trunks. The windthrow hazard model revealed that a large number of consecutive events with strong winds in each section weakened the stand, which was subsequently knocked down during the next extreme wind and rainfall event

Risks, benefits, and management of non-native tree species in the Alpine region : online survey results

Prispevek predstavlja mnenja in poznavanje tujerodnih drevesnih vrst (TDV) deležnikov, ki pri svojem delu prihajajo v stik s TDV v gozdnih, urbanih in periurbanih območjih v Sloveniji. Mnenja smo pridobili s spletno anketo v letu 2020, ki je bila v okviru projekta ALPTREES del raziskave v vsaki od petih partnerskih držav (Slovenija, Avstrija, Nemčija, Italija in Francija) alpskega prostora. Analizirali smo odgovore slovenskih deležnikov in tako pridobili informacije o poznavanju, dojemanju in odnosu deležnikov do TDV. S spletnim anketiranjem smo dobili odgovore na vprašanja 120 posameznikov. Z analizo odgovorov smo ugotovili, da večina anketirancev prepoznava TDV in invazivne tujerodne drevesne vrste (ITDV) v Sloveniji. Na splošno anketiranci menijo, da TDV prinašajo tveganje v alpski prostor. Anketiranci so kot najbolj razširjene TDV ocenili robinijo (Robinia pseudoacacia), veliki pajesen (Ailanthus altissima), pavlovnijo (Paulownia tomentosa), navadno ameriško duglazijo (Pseudotsuga menziesii), rdeči hrast (Quercus rubra) in zeleni bor (Pinus strobus). Med najbolj invazivne TDV uvrščajo robinijo, veliki pajesen, pavlovnijo, octovec (Rhus typhina) in ameriški javor oz. negundovec (Acer negundo). Slaba polovica anketirancev je izrazila srednje veliko zaskrbljenost glede vpliva ITDV, kar četrtina vprašanih pa je zaradi TDV zelo zaskrbljena.The article presents the opinions and knowledge about non-native tree species (NNT) of the stakeholders who get in contact with NNT at their work in the forest, urban, and peri-urban areas in Slovenia. We obtained the opinions through an online survey in 2020it took place in the framework of the ALPTREES project and was a part of the research in each of the five partner countries (Slovenia, Austria, Germany, Italy, and France) in the alpine space. We analyzed Slovenian stakeholders responses to obtain information on the stakeholders’ knowledge, understanding, and approach to NNT. Through an online survey, we obtained responses from 120 individuals. Analyzing the answers, we found that the majority of the respondents recognize NNT and invasive non-native tree species (INNT) in Slovenia. Generally, the respondents believe NNT bring risk into the alpine space. The respondents considered black locust (Robinia pseudoacacia), tree of heaven (Ailanthus altissima), princess tree (Paulownia tomentosa), Douglas fir (Pseudotsuga menziesii), northern red oak (Quercus rubra), and eastern white pine (Pinus strobus) to be the most widespread species. They place black locust, tree of heaven, princess tree, staghorn sumac (Rhus typhina), and boxelder (Acer negundo) among the most invasive ones. Just under half of the respondents expressed moderate concern about the impact of INNT, a quarter of the respondents was very concerned about NNT

Transnational strategy on the sustainable management and responsible use of non-native trees in the Alpine Space

Non-native tree species – defined as those species intentionally or unintentionally introduced by humans – have long been a part of the Alpine Space, providing numerous benefits, but also posing a potential threat to native biodiversity and related ecosystem services. Compared to the urban space where non-native trees comprise most tree species, the number of non-native trees in forests and plantations is relatively low. To evaluate potential risks and benefits of non-native trees in the Alpine Space, a transnational strategy for the responsible use and management of non-native trees is needed. The goals of the strategy are to tailor management practices for a sustainable and responsible use or admixture of non-native trees, to reduce the risks connected with the invasive potential of some non-native tree species, to help forests and urban areas to adapt to climate change, and to improve coordination and cooperation regarding best practices between different regions of the Alpine Space. A proposal was developed in a four-step process including expert-based assessment, stakeholder mapping, an extensive data review, and a public consultation. For implementing the strategy fully, strong collaboration among diverse stakeholders is anticipated and robust governance and an adequate long-term and fair funding scheme is needed

Conservation status assessment of habitat type 91E0* Alluvial forests with Alnus glutinosa and Fraxinus excelsior on Natura 2000 site Ličenca pri Poljčanah

Stanje ohranjenosti sestojev habitatnega tipa 91E0* Obrečna vrbovja, jelševja in jesenovja (Alno-Padion, Alnion incanae, Salicion albae) je v Sloveniji precej zaskrbljujoče. V Sloveniji je bilo njegovo stanje ocenjeno kot slabo, trend pa negativen, kar pomeni dodatno možnost poslabšanja. Omenjeni gozdni habitatni tip sodi med prioritetne ali prednostne habitatne tipe, za katere je predvidena posebna skrb Evropske skupnosti. Zaradi njegove majhnosti in fragmentiranosti je pogosto spregledan in tudi neustrezno obravnavan. Z namenom, da bi izboljšali njegovo prepoznavnost in spoznali njegove značilnosti na terenu, smo mu v okviru LIFE integriranega projekta za okrepljeno upravljanje Nature 2000 v Sloveniji namenili posebno pozornost. V raziskavi smo z uporabo metode terenskega kartiranja podrobneje proučili stanje sestojev habitatnega tipa 91E0* v območju Natura 2000 Ličenca pri Poljčanah. Na tak način smo ugotovili, kakšna je površina sestojev tega habitatnega tipa in jo primerjali z obstoječimi conami habitatnega tipa 91E0*. Ugotavljali smo pojavljanje ključnih drevesnih vrst oz. drevesno sestavo sestojev, njihovo pomlajevanje ter vrste pritiskov in groženj za habitatni tip 91E0* na tem območju. Izmed različnih znanih podtipov habitatnega tipa 91E0* smo na tem območju našli predvsem podtip nižinsko črnojelševje, pa tudi fragmente podtipa vrbovja s topolom. Ponekod so se tudi v gozdu pojavljali manjši sestoji vrb in ozkolistnega jesena. Ugotovili smo, da površine sestojev habitatnega tipa 91E0* na območju Natura 2000 Ličenca pri Poljčanah dejansko zavzemajo le približno četrtino površine obstoječih con habitatnega tipa. Analiza drevesne sestave sestojev je pokazala predvsem vraščanje smreke v sestojih črnojelševja, le-ta naravno ni prisotna v tem habitatnem tipu. Ugotovili smo, da je na proučevanem območju pomlajevanje črne jelše zelo okrnjeno. Na slabšanje stanja sestojev črnojelševja še dodatno vplivajo različni pritiski in grožnje, kot so bližina kmetijskih površin, odpadki, fragmentacija sestojev črnojelševja, širjenje invazivnih tujerodnih rastlin, vodne regulacije, bližina prometnic, izsuševanje rastišč idr. Stanje ohranjenosti sestojev tega habitatnega tipa je bilo posledično v večini primerov ocenjeno kot neugodno do slabo. Z namenom, da bi se stanje obrečnih gozdov na območju Ličence pri Poljčanah izboljšalo, smo v prispevku predlagali nekaj konkretnih ohranitvenih ukrepovThe conservation status of the habitat type 91E0* Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno- -Padion, Alnion incanae, Salicion albae) is rather alarming in Slovenia. In Slovenia, its status has been assessed as bad and the trend as negative which implies an additional possibility of deterioration. The above-mentioned forest habitat is the priority or preferential habitat type for which a special EU care is foreseen. Due to its small size and fragmentation, it is often overlooked and inappropriately treated. In order to improve its recognizability and get to know its characteristics in the field, we gave it a special attention in the framework of the LIFE Integrated Project for Enhanced Management of Natura 2000 in Slovenia. In our research, we studied the status of the habitat type 91E0* in Natura 2000 area Ličenca pri Poljčanah in detail by using the field mapping method. In this manner, we determined the area of stands of this habitat type and compared it with the existing habitat type 91E0* zones. We were detecting the occurrence of key tree species or, respectively, tree composition of stands, their regeneration and kinds of pressures and threats for the 91E0* habitat type in this area. Among the various known sub-types of the habitat type 91E0*, we found primarily the black alder (Alnus glutinosa) forest subtype, but also fragments of the subtype with willows and poplar. In some places, smaller stands of willows (Salix spp.) and narrow-leafed ash (Fraxinus angustifolia) were also found in the forest. We discovered that the habitat type 91E0* area in the Natura 2000 Ličenca pri Poljčanah actually occupies only around a fourth of the existing habitat type zones area. The analysis of the tree composition showed mainly the ingrowth of spruce in the black alder forests, which is not naturally present in this habitat type. We discovered that the regeneration of the black alder is very reduced in the studied area. The decline of the black alder stands is additionally influenced by diverse pressures and threats, e. g. the vicinity of the agricultural lands, waste, fragmentation of black alder stands, spreading of the non-native invasive plants, water regulations, vicinity of the traffic roads, sites drainage, etc. Consequently, the conservation status of the stands of this habitat type has been in most cases evaluated as unfavorable to bad. In order to improve the status of the riparian forests in the Ličenca pri Poljčanah area we also presented suggestions for concrete conservation measures