Which Douglas-Fir (Pseudotsuga menziesii (Mirb.) Franco) Provenances Provide the Best Productivity in the Hilly Area of Croatia?

Background and Purpose: Recently raised questions on adaptability of native tree species to climate changes pointed to Douglas-fir as a species suitable for rapid reforestation and increase of stand resistance. The first results on provenance research need to be confirmed in later stages of stand development, so the paper answers the following two questions: (i) are there differences in growth of 14 Douglas-fir provenances still in the fifth decade of stand development, and (ii) which provenances should be used and which omitted from further use in the hilly area of Croatia? Materials and Methods: Productivity of 14 provenances was evaluated on the basis of height, diameter at breast height and volume in the 46th year after planting. Growth dynamics was also statistically analysed using a repeated measure analysis of variance, for which purpose we partially used published data from the 2010. Results: The analysis excluded Castle Rock and Shady Cove (Oregon) provenances due to their low values of all analysed growth indicators, as well as Castle Rock, Elma and Hvidilde provenances due to their high values. Average values of tree volume ranged from 0.53 m3 (Shady Cove) to 2.05 m3 (Castle Rock), while the tallest trees belonged to Elma provenance (29.6 m). Conclusions: Different growth dynamics of provenances were confirmed for later development stage, so further monitoring is still required. Clear guidelines for the selection of provenances for practical forestry distinguish provenances from lower altitudes of the State of Washington, Denmark and Bulgaria as the most productive. Shady Cove and Salmon Arm provenances are not advised to be used in the future

Expert Supervision and Overview of Production of Forest Planting Material in the Republic of Croatia During 2021

U današnje vrijeme klimatske promjene u vidu elementarnih nepogoda i biotskih ugroza imaju značajan utjecaj na naše šume. Sve češće se provodi umjetna obnova šuma za čiju je uspješnu provedbu neophodan kvalitetan šumski sadni materijal odgovarajuće vrste, provenijencije, starosti, tipa i kvalitete. Kako bi se osigurale navedene značajke ŠRM-a, Hrvatski Šumarski Institut službeno je tijelo koje obavlja poslove sručnog nadzora, odnosno kontrole prozvodnje, stavljanja na tržište i kvalitete šumskog reprodukcijskog materijala na području Republike Hrvatske. U ovom radu prikazat će se postupak obavljanja stručnog nadzora te pregled proizvodnje u 2021. godini. Tijekom provedbe stručnog nadzora 2021. utvrđena je proizvodnja od ukupno 14.603.756 sadnica šumskog sadnog materijala koja uključuje različite vrste šumskog drveća, starosti i načina uzgoja te uključuje listopadne i crnogorične vrste. Hrvatski Šumarski Institut provodi poslove stručnog nadzora 30. godina (1992. – 2022.). Tijekom navedenog perioda broj i površina rasadnika te količina sadnog materijala značajno varira a primjećuje se jasan negativan trend. Analizom proizvodnje vidljivo je da promjene asortimana u rasadnicima ne prate recentno međunardno zakonodavstvo niti znanstvena i stručna kretanja. Ovi problemi se očituju u nedostatku prilagodbe šuma na klimatske promjene i ostale ugroze te nedostatkom prikladnog šumskog sadnog materijala otpornijih vrsta drveća. Uočen je i nedostatak privatnih rasadnika, te nedovoljna količina šumskog sadnog materijala koji ne pokriva potrebe privatnih šumoposjednika niti bioloških revitalizacija. Također neiskorišten je i potencijal izvoza rasadničkog materijala za što se očekuje otvaranje tržišta u bliskoj budućnosti (stvaranje otpornijih sadnica, brendiranje sadnica, razmjena sadnica zbog klimatskih promjena). Nakon provedene analize možemo zaključiti da u Republici Hrvatskoj postoji mogućnost i neiskorišteni potencijal za daljnje proširenje i optimizaciju proizvodnje šumskog sadnog materijala a znanstvena i stručna kretanja ukazuju upravo na sve veću važnost za kvalitetnim i odgovarajućim sadnim materijalom.In recent years, climate change, natural disasters and biotic threats have had a significant impact on our forests, and their intensity is expected to increase in near future. Artificial forest regeneration (indirect conversion) is being carried out more than ever before, and for its successful implementation there is a growing need for quality forest planting material of the appropriate type, provenance and age. In order to achieve the aforementioned features of forest planting material, Croatian Forest Research Institute is the official body that conducts expert supervision of the whole production process. This includes control of the production, placing of material on the market and regulating the quality of planting material in the territory of the Republic of Croatia. This paper will describe the procedure of expert supervision as well as the overview of production in 2021. During the expert supervision in 2021., we recorded a total production of 14,603,756 seedlings of forest planting material, which includes different types of forest trees, age and cultivation methods of broadleaf and conifer tree species. Croatian Forest Research Institute has been conducting expert supervision continuously for 30 years (1992. – 2022.). During that period of time, the number and area of nurseries as well as the amount of forest planting material varies significantly, with a clear negative trend. Analysis of production shows that changes in the assortment in nurseries do not follow recent international legislation or scientific and professional findings. These problems are manifested in the lack of adaptation of forests to climate changes and other threats and the lack of suitable forest reproductive material of more resistant tree species. There is also a lack of private nurseries in Croatia and an insufficient amount of forest seedlings and cuttings that can cover the needs of private forest owners or the needs of biological revitalization. The potential of exporting forest planting material is unused, for which the market is expected to open in the near future (creating more resistant seedlings, branding seedlings, exchanging seedlings due to climate change). After conducting analysis, we can conclude that in the Republic of Croatia there is an opportunity and untapped potential for further expansion and optimization of the production of forest planting material, and scientific and professional trends point to the increasing need for high-quality and appropriate planting material

Issues of Coppice Management in FA Gospić - An Overview of Sceintific and Expert Project Activities

U radu je dat pregled osnovnih znanstveno-stručnih aktivnosti započetih na području Like koje se kontinuirano provode od 2020. godine u okvirima projekta „Problematika gospodarenja panjačama na području Uprave šuma podružnice Gospić“. Cilj istraživanja je utvrđivanje stanja panjača, mogućnosti njihove prirodne obnove (indirektne konverzije), prioriteta za konverziju u visoki uzgojni oblik te mogućnosti unaprjeđenja njihovog gospodarenja i stanja. Problematika gospodarenja panjačama već je samo po sebi složeno pitanje europskog šumarstva, dok ličke panjače karakteriziraju specifične i složene povijesne, gospodarske i društvene okolnosti, prirodna ograničenja, te činjenica da se u geografskom smislu nalaze na području gdje se očekuju izraženije klimatske promjene od ostatka kontinentalnog dijela zemlje. Zbog njihove važnosti i složenosti gospodarenja ovo pitanje možemo svrstati u jedno od najkompleksnijih pitanja gospodarenja šumama u Republici Hrvatskoj. Znanstveno-stručne aktivnosti započete su u okvirima suradnje Hrvatskog šumarskog instituta i „Hrvatskih šuma“ d.o.o. u ožujku 2020. godine. Opći ciljevi projekta su: unaprijediti šumarsku djelatnost, pomoći razvoju ruralnih područja, potpomoći korištenju potpore iz Europskog poljoprivrednog fonda, poboljšati ekonomsku vrijednost i OKFŠ, promicati konkurentnost „Hrvatskih šuma“ d.o.o., povratiti prirodne procese i strukturu u degradirane šume, povećati opću stabilnost, otpornost i plastičnost šumskih ekosustava RH, dugoročno povećati njihovu komercijalnu vrijednost, povećati vezivanje ugljičnog dioksida te pomoći očuvanju njegovih postojećih zaliha. Glavne znanstveno-stručne aktivnosti obuhvaćene projektom uključuju pregled stanja na terenu i dostupnih podataka o panjačama, provođenje ankete na razini šumarija, osnivanje baze podataka, osnivanje komparativnih pokusnih ploha, njihovo trajno obilježavanje, analiza podatka (Stat. soft., deskriptivna statistika, ANOVA s ponovljenim mjerenjem), fitocenološko snimanje, SWAT analizu te ispitivanje mogućnosti upotrebe satelitskih snimaka za prikupljanje podatka koji nisu dostupni klasičnim i skupim metodama. Preliminarni rezultati ukazuju na potrebu definiranja prioritetnih područja u kojima se po novim europskim principima prilagodbe šuma na predstojeće ugroze treba povećati isplativnost gospodarenja, ekonomska i biološka vrijednost, ali i plastičnost i otpornost panjača. Unaprijediti gospodarenje ličkih panjača dugotrajan je proces, ali ovim znanstveno-stručnim aktivnostima poduzima se prvi korak u tome smjeru te daju početne znanstveno-stručne preporuke.Paper provides an overview of the basic scientific and expert activities initiated in the area of Lika, which have been carried out continuously since 2020 within the framework of the project “Issues of coppice management in forest administration Gospić“. The main goal of the research is to determine the state of Lika’s coppices, their ability for natural regeneration (indirect conversion), priority for conversion to high forests and the possibility of improving their management and condition. Coppice management is one of the most complex issues of European forestry and Lika’s coppices are no different in this respect. They are characterized by specific and complex historical, economic and social circumstances, natural limitations and the fact that in the geographical sense, they are located in the area where a high impact of climate change is expected in near future. Scientific – professional activities started in march 2020, as cooperation between the Croatian Forest Research Institute and Croatian Forests Ltd. General goals of the project are: improvement of forestry activities, development of rural areas, support of the use of funds from the European Agricultural Fund, increase of the economic value and ecosystem services, enhancing the competitiveness of Croatian Forest Ltd., restoring natural processes and structure in degraded forests, increase of the general stability, resistance and resilience of forest ecosystems in Craotia and the increase of the commercial value of forests and binding of CO2. Main scientific and professional activities covered by the project include assessment of the situation on the field and available data on coppices, conducting a survey on the forestry office level, establishment of a database, establishment of comparative trial plots, marking of trial plots, data analisys (Stat. Soft., descriptive statistic, ANOVA repeated measurements), phytocoenological recordings, SWOT analysis and the possibility of using satellite images to gather the data that is not available with classic and more expensive methods. Preliminary results indicate that there is a need to identify priority areas in which, according to new European principles of adaptation of forests to upcoming threats, the profitability of management, economic and biological value, but also the resilience and resistance of coppices should be increased. Improvement of management of Lika’s coppices is a long-term process, but these kinds of scientific–professional activities are the first steps in that direction, which will provide initial management recommendations

Production of broadleaves forest planting material in the Republic of Croatia from 2017 to 2021

Analiza kretanja rasadničke proizvodnje šumskog sadnog materijala doprinosi kvalitetnijem planiranju proizvodnog programa kao i radova u uzgajanju šuma. Dostupnost sadnog materijala ključna je za mnoge dionike šumarskog sektora kako u šumarskoj znanosti tako i u šumarskoj praksi. Hrvatski šumarski institut tijekom stručnog nadzora rasadničke proizvodnje, stavljanja na tržište i/ili kakvoće šumskog sadnog materijala sakuplja podatke o kretanju proizvodnje svih rasadnika u Republici Hrvatskoj. To je omogućilo statističku analizu proizvedenog šumskog sadnog materijala prema rasadnicima, vlasništvu i vrstama šumskog drveća u aktualnom petogodišnjem razdoblju. Cjelokupni pregledi i analize rasadničke proizvodnje tek su u manjoj mjeri dostupni posljednja tri desetljeća, a uočava se i nedostatak recentnih znanstvenih publikacija i aktivnije znanstveno-istraživačke djelatnosti. Ciljevi rada su: (I) dati pregled proizvodnje prema vrstama, vlasništvu te rasadniku; (II) utvrditi je li količinom i programom proizvodnja bjelogorice usklađena s rastućim potrebama u šumarskoj praksi i recentnim međunarodnim znanstvenim kretanjima; (III) dati opće preporuke za planiranje proizvodnog programa za bjelogorične vrste u Republici Hrvatskoj. Provedena analiza ukazuje na mali broj vrsta u proizvodnom programu (hrast kitnjak (Quercus petraea (Matt.) Liebl.), hrast lužnjak (Quercus robur L.), obična bukva (Fagus sylvatica L.), poljski jasen (Fraxinus angustifolia Vahl.)), što ukazuje na sve veće oslanjanje prirodne obnove šuma na rasadničku proizvodnju, dok je neznatan udio ostalih vrsta u proizvodnji (manje od 5 %). Udio voćkarica, alohtonih vrsta (pa čak i onih visoko produktivnih i otpornijih prema različitim ugrozama u usporedbi s domaćim vrstama) te pionirskih vrsta koje se koriste za rastuće potrebe biološke sanacije je nizak. Ističe se i važnost kvalitetnog šumskog sjemena kao preduvjeta za uspješnu rasadničku proizvodnju, kao i odabira optimalnih vrsta, provenijencija i karakteristika sadnog materijala. Potrebno je uskladiti proizvodni program s novim izazovima i ugrozama koji stoje pred šumarskim sektorom i šumama u Republici Hrvatskoj. Program treba uskladiti i s međunarodnim, znanstvenim i stručnim kretanjima i politikama Europske Unije, kao i bolje osigurati šumski sadni materijal za druge grane privrede. Karakter suvremenih šumskouzgojnih rješenja mora odražavati brzinu i učinkovitost provođenja zahvata, jer sve učestalije i intenzivnije prirodne nepogode, imaju odlučujući utjecaj na uspjeh sadnje tj. potrebu ponavljanja ovoga skupog i zahtjevnog procesa. Iako su teško predvidive, ugroze su neminovne, pa je pored kvalitetnog proizvodnog programa, kvalitetan, višegodišnji proizvodni plan potrebniji nego ikad. Plan je utoliko kvalitetniji što prepoznaje trenutne i predstojeće obveze i međunarodna kretanja, recentne znanstvene spoznaje, višegodišnje potrebe praktičnog šumarstva i ostalih grana privrede, predviđanja predstojećih ugroza i pomaka areala vrsta te suvremenih rješenja prilagodbe šuma na predstojeće ugroze i izazove.Analysis of nursery production contributes to better planning of production and silvicultural activities. Availability of planting material is crucial for many actors in forestry science and practice. According to Law on forest reproductive material Croatian Forest Research Institute conducts expert supervision and collects data on production programme and process for every nursery in Croatia (Figure 1). This enabled statistical analysis of total amounts of planting material production per nursery, ownership and tree species in recent five-year period. Comprehensive ovierviews and analysis of nursery production are limited for the last three decades, while there is also a lack o recent scientific publications and activities dealing with nursery production issues in Croatia. Aims of this paper are: (1) to give a production overview according to tree species, ownership and nursery, (II) to determine if amount and production programme is harmonised with growing needs of practical forestry and recent international scientific knowledge, (III) to give general guidelines for planning of production programmes for broadleaves in Croatia. Nursery production data used for production analysis is part of electronic database, which was established (based on expert supervision documentation) in period 2009-2011 by Đodan and Perić. Croatian Forests Ltd. are sigle producer of forest planting material in Croatia. Figure 2 gives overview of the size of nurseries in Croatia. Production of broadleaves planting material in respected period drops, while more detailed insight of production per nursery points to Cernik, Limbuš, Oštarije, Zdenački gaj and Višnjevac as the biggest producer in Croatia (Figure 3). Total broadeleaves production in five year period spannes from 12.373.091 pcs. (2021) to 21.654.920 pcs. (2019) (Table 1), with slight drop. Total production of Quercus spp. in respected period amounts to 62.245.950 pcs., while pedunculate and sessile oak participate in total oak production with 98,49% share. Other oaks in production are Quercus pubescens Willd., Quercus cerris L. and Quercus ilex L. In the same period total of 12.574.160 of Narrowed leaved ash was produced, with continuous annual increase. In 2021, due to significant dieback of transplanted ash seedlings (during restoration activities) Croatian Forests Ltd. limit and then stop ash production. Share of European beech varies (from 5,5% in 2018 to 13,8% in 2017) and with its total production of 7.505.337 seedlings takes forth place in braodleaves production. Conducted analysis showed predominance of small nuber of tree species in production (pedunculate oak, sessile oak, common beach and narrow-leaved ash), which points to the conclusion that natural regeneration is strongly dependant on nursery production. Only small share (less than 5 %) of other tree species is represented in production. Share of forest fruits, non native tree species (even highly productive and more resistant then domestic ones), pioneer species (used for growing needs of forest restoration) is relatively low. Importance of quality forest seed as prerequisite of successful nursery production is high, as well as importance of selection of apporpriate provenances and feature of forest planting material. Nursery production programmes need to be harmonised with real needs in practical forestry. Nevertheless, there is even stronger need of setting quality, multi-year nursery production plans, which will include a strong response to forthcoming challenges and threats, reduce risks in practical forestry and take into account international (scientific and expert) efforts, actual EU policies and growing needs of forestry and other sectors

Possibilities of the Application of the Medium-Resolution Landsat 8 and the High-Resolution RapidEye Optical Imagery in Visualization and Detection of Changes in the Forest Cover by Windthrows

U radu su dani prikaz i usporedba satelitskih informacija srednje (Landsat 8, 30 m) i visoke (RapidEye, 5 m) rezolucije radi ispitivanja mogućnosti vizualne i kvantitativne procjene šteta od vjetroizvala na Medvednici, nakon oluje Teodor u studenome 2013. godine, te obnove šumskog pokrova u 2018., odnosno nakon pet godina. Za vizualnu detekciju šteta na čitavom području korišten je 3D prikaz, u 15 m prostornoj rezoluciji, izveden iz RGB kanala vidljivog dijela spektra, izoštren pomoću pankromatskoga kanala. Prostorna razlučivost različitih satelitskih indeksa (NDVI, SAVI, MSAVI, NDMI, NBR, NBR2), kao kvantitativne mjere stanja vegetacijskog pokrova, ispitivana je na temelju snimaka Landsat 8 na čitavom području Medvednice. Od ispitivanih indeksa najbolja razlučivost vegetacijskog pokrova postignuta je na korigiranim SAVI i MSAVI indeksima u odnosu na NDVI, dok su indeksi temeljeni na infracrvenom dijelu spektra (NDMI, NBR, NBR2) pokazali dosta dobru osjetljivost pri detekciji narušenosti šumskog pokrova nakon vjetroizvala. Na ispitivanom dijelu površine s vjetroizvalom, neposredno uz potok Bliznec, utvrđena je znatna komparativna prednost snimaka visoke rezolucije (RapidEye) pri razlučivanju šteta na pokrovu odnosno pri praćenju stanja obnove šumske vegetacije. Na osnovi dobivenih prethodnih rezultata utvrđene su znatne mogućnosti satelitskih snimaka srednje i visoke rezolucije, kako u svrhu detekcije šteta nakon prirodne nepogode, tako i pri praćenju obnove šuma na tim površinama, što će potvrditi daljnji tijek ovog istraživanja.This paper presents a comparison of the satellite information of medium (Landsat 8, 30 m) and high (RapidEye, 5 m) resolutions for the purpose of examining the visual and quantitative estimates of wind damages and the renovation of the forest cover following the Theodor storm in November 2013 in Medvednica mountain, North-western Croatia. 3D visualization of the whole Medvednica area was derived from the Landsat 8 RGB channels of the visible part of the spectrum, pan-sharpened with the panchromatic channel on 15 m spatial resolution for visual forest damages detection. The spatial sensitivity of different satellite indices (NDVI, SAVI, MSAVI, NDMI, NBR, NBR2), based on Landsat 8 imagery, as a quantitative measure of the state of the vegetation cover, was investigated throughout the whole Medvednica area. From the investigated indices, the best detection of the changes in the forest cover was achieved by soil corrected indices such as SAVI and MSAVI in relation to the standard NDVI index. Indices based on the infra-red part of the spectra (NDMI, NBR, NBR2) showed quite good performance in detection of the damages of the forest cover. By the comparative assessment on the chosen pilot area with severe windthrows near Bliznec, a significant advantage of the high-resolution RapidEye imagery in comparison with Landsat 8, was confirmed for the potential purpose of the more precise silvicultural subgroups delineation and monitoring of the success of the restoration of the young forest cover. Based on the obtained results, substantial possibilities of medium and high-resolution satellite imagery have been identified, both for the purpose of damages assessment after natural disasters and for the monitoring of the reforestation on these surfaces, which will be confirmed in the further course of this research

Alohtone vrste s gledišta klimatskih promjena: prilike i mogućnosti u Hrvatskoj

The management of tree species non-native to Republic of Croatia has a certain tradition within Croatian forest management practice; nowadays, their potential should be regarded and re-evaluated in the new frame of climate changes and growing society demands for forest products and services. This paper is a contribution to non-native tree species (NNTS) introduction and use in Croatia, aiming at providing state of the art of NNTS as well as overview of studies and examples of possible management opportunities. Because of the complexity of the matter and growing need to further investigate risks and challenges of NNTS in Croatia, authors have continued their research and will publish the results in a separate paper. Amount of the area occupied by NNTS forest cultures point to the conclusion that the use of these tree species in forest practice is not reached by far and the nursery production does not back up the need for NNTS use. Paper also provides a comprehensive overwiev of different aspects and benefits of the use of NNTS in Croatia. For example, increased wood production and non-wood forest products; production of high quality timber in short–time periods; use of fast-growing tree species for bioenergy production in higher proportion and enhancement of ecosystem services. Increase of stability and adaptive capacity of forest stands by the use of NNTS is highlighted as new silvicultural option for facing climate change. Their use in reforestation or conversion of degraded forest to more valuabe and more resistant/resilient stands offers new possibilities. Integrated and site-specific management is a strategy, which seems to be an appropriate approach for guidelines for the introduction and management of NNTS in Croatia. The use of high productive, resistant NNTS presents new silvicultural solution especially important in terms of site amelioration and enhancement of resistance and resilience of forest stands, which is the most important component of adaptive forest management strategies.Gospodarenje alohtonim vrstama ima tradiciju u hrvatskome šumarstvu, ali njihov potencijal se treba ponovno razmotriti i ocijeniti u novonastalim okvirima klimatskih promjena te rastućim potrebama društva za šumskim proizvodima i uslugama. Unatoč činjenici da svaka država ima svoj popis introduciranih vrsta, uključujući i Hrvatsku, autori prihvaćaju definiciju COST Akcije FP1403 NNEXT te rad baziraju na šumskim vrstama drveća kojima se prirodni areal nalazi izvan granica Europe. Ovaj pregledni rad doprinos je saznanjima o introdukciji i aktivnoj uporabi alohtonih vrsta u zemlji, a obuhvaća dostupne znanstvene i stručne studije te primjere uspješne uporabe u gospodarenju šumama. Zbog složenosti ove problematike autori će objaviti pregled rizika i izazova uporabe alohtonih vrsta u zasebnome radu. Dostupni podaci o prisutnosti alohtonih vrsta na pokusnim objektima te u šumarskoj praksi ukazuju kako se u praksi koristi tek manji broj vrsta (Tablica 1), dok su stvarni potencijal i njihove koristi daleko veće. Analiza podataka ukazuje kako su najzastupljenije alohtone vrste u šumarskoj praksi: Robinia pseudoacacia L. (12003.88 ha), Pinus strobus L. (3218.69 ha), Juglans nigra L. (2376.66 ha), F. pennsylvanica Marshall. i Fraxinus americana L.(1099.77 ha), Pseudotsuga menziesii (Mirb.) Franco. (393,05 ha) i L Quercus rubra. (51,99 ha). Podaci o proizvodnji šumskoga reprodukcijskog materijala navedenih vrsta ukazuje da rasadnička proizvodnja nije usklađena s potencijalom njihove uporabe u praksi. U radu se daje i iscrpan pregled različitih gledišta i koristi uzgoja alohtonih vrsta u Hrvatskoj. Samo neke od njih su (Slika 1, Tablica 2): nove mogućnosti proizvodnje visoko kvalitetnog drveta u kraćim ophodnjama, kao i drveta za bioenergiju, novih drvnih proizvoda i tehnologija; socijane koristi (mali i srednji poduzetnici, privatni šumoposjednici); povećanje stabilnosti i adaptabilnosti šumskih sastojina, ali samo u slučajevima velikih šteta i male plastičnosti i otpornosti domaćih vrsta; smanjenje intenziteta šumskouzgojnih radova, kao i uloženih sredstava na pripremi staništa prilikom pošumljavanja; ostvarivanje većih mogućnosti uporabe zapuštenoga poljoprivrednog zemljišta i ostalih prikladnih površina; sanacija progala ili većih površina nakon šteta u sastojinama domaćih vrsta (npr. obične smreke); supstitucija osjetljivih vrsta otpornijim i plastičnijim vrstama (mogućnosti mješovitih ili obogaćenih sastojina otpornijim alohtonim vrstama) te umanjenje negativnog djelovanja biotskih i abiotskih čimbenika. Njihova uporaba u sanaciji površina te konverziji degradiranih i devastiranih šuma pruža nove mogućnosti posebice na područjima s nepovoljnim ekološkim uvjetima, za koja se predviđa da će biti najpogođenija područja Hrvatske u budućnosti. Alohtone vrste mogu osigurati i niz opće korisnih funkcija šuma (npr. povećanje vezanja ugljika, fitoremedijacija zagađenih tala). Zbog složenosti problematike preporučujemo da se odluke o uporabi alohtonih vrsta donose na osnovi usporedbe s domaćim vrstama za svako stanište te na osnovi pregleda potencijalnih koristi, ali i rizika i izazova. Ističemo kako pojedine alohtone vrste treba poticati, dok neke zbog svoga invanzivnog potencijala trebaju biti strogo ograničene. Uporaba visokoproduktivnih, otpornijih i plastičnijih alohtonih vrsta predstavlja nova šumskouzgojna rješenja, koja su posebice važna u smislu pripreme staništa za prihvat autohtonih vrsta te povećanja otpornosti i plastičnosti šumskih sastojina, što je neizostavna komponenta adaptacijskih strategija gospodarenja šumama. Ipak, daljnja znanstvena istraživanja potrebna su kako bi se kvantificirala uporabljivost svake alohtone vrste, ali i olakšalo donošenje odluka u praksi

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in Europe: an overview of management practices

Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), one of the most commercially important tree species in western North America and one of the most valuable timber trees worldwide, was introduced to Europe in 1827. It became a major species for afforestation in Western Europe after WWII, currently grows in 35 countries on over 0.83 million ha and is one of the most widespread non-native tree species across the continent. A lower sensitivity to drought makes Douglas-fir a potential alternative to the more drought-sensitive Norway spruce so its importance in Europe is expected to increase in the future. It is one of the fastest growing conifer species cultivated in Europe, with the largest reported dimensions of 2.3 m in diameter and 67.5 m in height. Pure stands have high productivity (up to 20 m3 ha-1a-1) and production (over 1000 m3 ha-1). The species is generally regenerated by planting (initial stocking density from less than 1000 seedlings ha-1 to more than 4000 ha-1), using seedlings of European provenance derived from seed orchards or certified seed stands. As the range of end-uses of its wood is very wide, the rotation period of Douglas-fir is highly variable and ranges between 40 and 120 years. When the production of large sized, knot-free timber is targeted, thinnings are always coupled with pruning up to 6 m. There is an increasing interest in growing Douglas-fir in mixtures and managing stands through close-to-nature silviculture, but the species’ intermediate shade tolerance means that it is best managed through group selection or shelter-wood systems

Ecology, growth and management of black locust (Robinia pseudoacacia L.), a non‑native species integrated into European forests

Black locust (Robinia pseudoacacia L.), a species native to the eastern North America, was introduced to Europe probably in 1601 and currently extends over 2.3 × 106 ha. It has become naturalized in all sub-Mediterranean and temperate regions rivaling Populus spp. as the second most planted broadleaved tree species worldwide after Eucalyptus spp. This wide-spreading planting is because black locust is an important multipurpose species, producing wood, fodder, and a source of honey as well as bio-oil and biomass. It is also important for carbon sequestration, soil stabilization and re-vegetation of landfills, mining areas and wastelands, in biotherapy and landscaping. In Europe, black locust is drought tolerant so grows in areas with annual precipitation as low as 500–550 mm. It tolerates dry, nutrient poor soils but grows best on deep, nutrient-rich, well-drained soils. It is a fast-growing tree and the height, diameter and volume growth peak before the age of 20. It mostly regenerates vegetatively by root suckers under a simple coppice system, which is considered the most cost-effective management system. It also regenerates, but less frequently, by stool sprouts. Its early silviculture in production forests includes release cutting to promote root suckers rather than stool shoots, and cleaning-respacing to remove low-quality stems, reduce the number of shoots per stool, and adjust spacing between root suckers. In addition, early, moderate and frequent thinning as well as limited pruning are carried out focusing on crop trees. The species is regarded as invasive in several European countries and its range here is expected to expand under predicted climate changes

Non-Native Forest Tree Species in Europe: The Question of Seed Origin in Afforestation

Non-native forest tree species have been introduced in Europe since the 16th century, but only in the second half of the 20th century the significance of the seed source origin for their economic use was recognized, resulting in the establishment of numerous provenance trials at a national, regional, European and International level, as those led by IUFRO. Breeding programs have also been launched in the continent for the most economically important species. Aim of this work is the formulation of provenance recommendations for planting of five non-native tree species in Europe (Douglas fir, grand fir, Sitka spruce, lodgepole pine and black locust), based on the information obtained from twenty countries, in the frame of the EU FP-1403 NNEXT Cost Action. The survey revealed that official and non-official national recommendations, based on provenance research results, have been elaborated and followed at a different level and extend for the above five species, but only for Douglas fir recommendations exist in almost all the participating to the survey countries. The compilation of provenance recommendations across Europe for each species is presented in the current work. Besides the recommended introduced seed sources, European seed sources are also preferred for planting, due to ease of access and high availability of forest reproductive material. European breeding programs yielding genetic material of high productivity and quality constitute currently the seed source of choice for several species and countries. Consolidation of trial data obtained across countries will allow the joint analysis that is urgently needed to draw solid conclusions, and will facilitate the development of ‘Universal-Response-Functions’ for the species of interest, rendering possible the identification of the genetic material suitable for global change. New provenance trial series that will test seed sources from the entire climatic range of the species, established in sites falling within and outside the environmental envelopes of their natural ranges, are urgently needed to pinpoint and understand the species-specific climate constraints, as well as to correlate functional traits to the seed origin and the environmental conditions of the test sites, so that the selection of suitable forest reproductive material of non-native tree species in the face of climate change can be feasible.publishedVersio

A review of black walnut (Juglans nigra L.) ecology and management in Europe

Black walnut (Juglans nigra L.) is a light-demanding, competition-intolerant, and tall forest tree species, introduced in Europe from North America at the beginning of the seventeenth century. It has an important economic role in Europe for producing wood and fruits, in agroforestry systems, as an ornamental tree for parks and avenues, for rehabilitation/restoration of degraded lands. The best sites for black walnut growth have warm and mild climates, with frequent and well-spread precipitation, and rich, deep, near neutral, well-drained and moist soils. Black walnut is a fast grower in youth and its height and diameter growth reach their peaks before age 30–35 years. It is globally the best known allelopathic species due to the juglone substance present in all parts of black walnut trees. The species is storm-resistant and not affected by any major pest or disease in Europe. It is regenerated by planting or direct seeding on bare land, in monocultures and mixed stands. The management of stands with black walnut, with a rotation period generally up to 80 years, include weeding (mandatory), cleaning-respacing (in dense stands), thinning (mostly from above), high and formative pruning (mandatory), with the aim of producing valuable wood for sliced veneer, solid furniture, flooring/parquet, cabinetry, panelling, sculpture, musical instruments, gunstocks