Carbon sequestration and soil nitrogen enrichment in Robinia pseudoacacia L. post-mining restoration plantations

Robinia pseudoacacia L. (black locust) has been extensively used for restoring degraded lands, following anthropogenic interventions like coal mining. Here we have addressed the contribution of black locust restoration plantations, established on overburden post-mining material, to carbon storage and to soil nitrogen enrichment at the largest lignite center in Greece. Carbon stocks and fluxes in all pools of the ecosystem, as well as the foliar nitrogen resorption efficiency and soil N stocks were quantified and the effect of plantations’ age was tested. The young age of the plantations (4–24 years) resulted in a relatively low total ecosystem C stock (56.7 t ha−1), which was partitioned among the different pools in the following order: above-ground biomass (50%) > black locust-derived SOC (24%) > coarse roots (14%) > deadwood (6%) > forest floor (5%) > fine roots (less than 1%). Litterfall started early in the growing season and together with fine roots that had a turnover rate of 0.62 yr−1, fueled soil organic carbon. SOC accrual, referring to the accumulation of SOC derived by black locust, declined with age. However, further SOC accumulation is expected, based on the potential SOC storage capacity of soil at the area. C stocks in above- and below-ground biomass increased linearly with age. The same response was observed for soil N stock and NRE, indicating that despite the N2-fixing capacity of black locust, there was still a poor pedospheric N supply and a need for efficient N cycling. Overall, the studied restoration plantations have a considerable contribution to C and N accumulation at the degraded post-mining sites. These positive effects are expected to further increase at least until the plantations reach maturity

Productivity Linear Regression Models of Tree-Length Harvesting System in Natural Coastal Aleppo Pine (Pinus halepensis L.) Forests in the Chalkidiki Area of Greece

Time studies of harvesting and skidding tree-length logs in Aleppo pine (Pinus halepensis L.) natural coastal forests of Chalkidiki area in northern Greece were carried out to formulate linear regression models and to evaluate productivity. The harvesting system consisted of a feller with chainsaw for felling, delimbing and crosscutting, and a four wheel drive farm tractor, with a 74 kW engine, equipped with a special winch attached to the tractor three point hitch for the extraction of tree length logs. Operational factors such as distance, slope, volume and the time required for harvesting and extracting tree length logs were measured and recorded. The results illustrate that the calibrated linear regression models show strong correlation between the time needed for harvesting operations and the extraction distance from the stump to the forest road

Ένα πρότυπο αύξησης για την quercus frainetto (Ten) στην Ελλάδα

The general objective of this study was to introduce the contemporary technology and state of the art in individual tree growth models as a new tool for forest management in Greece. Specific objectives of this work were: (1) To study the existing modelling theory and define the proper theoretical modelling framework for the Quercus frainetto stands. (2) To develop individual tree distance-dependent growth and mortality models for pure, even-aged coppice Q. frainetto stands and stands under conversion into high forests. (3) To develop form factor and taper equation models that can be used for volume calculations and production of assortment tables for Q. frainetto stands. (4) To adapt the MOSES software to a new prototype forest simulator capable of quantifying the stand growth characteristics, relationships and dynamics in natural Q. frainetto stands in Greece. Data for this study came from 18 permanent experimental plots established in even-aged stands with age variations at the year of establishment from 16 to 80 years. The development of diameter and height increment models was based on the assumption that the potential increment for a given tree is reduced by a function of crown ratio as the allometric multiplier representing the past growing conditions and the overstocking multiplier representing the current competition status. For the prediction of the future crown length, a dynamic crown height increment model was developed by estimating the periodical recession of the height to the base of live crown in dependence on total tree height, crown ratio, competition index after crown release and the breast height diameter at the beginning of the each growing period. For the estimation of the probability between dead and live trees a logistic model was applied to the data. The final model predicts the probability of individual tree mortality in dependence of the competition index after crown release, crown ratio and breast height diameter. The validation of the models should be done using a validation procedure on an independent dataset. Three permanent experimental plots for Q. frainetto have been used for the model validation. For the stand treatment studies, DRYMOS version 1.0, a computer simulation software for modelling oak stand response was developed. DRYMOS is a derivative software program of the Austrian forest simulator MOSES. The objective of this program is to function interactively with the system of equations and visualise the evolution of the forest in time. Growth can be projected up to 30 five-year periods. The user has the option to choose various silvicultural scenarios and get respective outputs. At the end of a simulation period the program can give stand diagrams and tabular data (yield tables)Ο γενικός στόχος αυτής της διατριβής ήταν να εισαχθεί η σύγχρονη τεχνογνωσία της τεχνολογίας των ατομικών προτύπων δέντρων ως ένα νέο εργαλείο για τη διαχείριση των δασών στην Ελλάδα. Συγκεκριμένα οι στόχοι αυτής της εργασίας ήταν: (1) Να μελετήσει την διεθνώς υπάρχουσα θεωρία ανάπτυξης προτύπων και να καθορίσει το κατάλληλο θεωρητικό πλαίσιο προτυποποίησης για τις συστάδες πλατύφυλλης δρυός. (2) Να αναπτύξει τα εξαρτώμενα από αποστάσεις ατομικά πρότυπα αύξησης και θνησιμότητας δέντρων για αμιγείς, ομήλικες πρεμνοφυείς συστάδες πλατύφυλλης δρυός και συστάδες υπό αναγωγή. (3) Να αναπτύξει πρότυπα μορφαρίθμου και μορφής κορμού, τα οποία θα χρησιμοποιηθούν για τους υπολογισμούς όγκου και την παραγωγή πινάκων κατάταξης προϊόντων των συστάδων πλατύφυλλης δρυός. (4) Να προσαρμόσει το λογισμικό “MOSES” σε έναν νέο πρωτότυπο για τα Ελληνικά δεδομένα προσομοιωτή δάσους ικανό να ποσοτικοποιεί και να προσομοιώνει συσταδικά χαρακτηριστικά και σχέσεις της αύξησης και τη δυναμική των φυσικών δασών πλατύφυλλης δρυός. Τα δεδομένα για αυτήν τη διατριβή προήλθαν από 18 μόνιμες πειραματικές επιφάνειες εγκατεστημένες σε ομήλικες συστάδες. Η ηλικία των συστάδων τη χρονική στιγμή της εγκατάστασης των επιφανειών κυμαινόταν από 16 έως 80 έτη. Δέκα τρεις από τις επιφάνειες ήταν εγκατεστημένες σε πρεμνοφυείς συστάδες ενώ πέντε απόαυτές σε σπερμοφυείς Η ανάπτυξη των ατομικών προτύπων αύξησης διαμέτρου και ύψους βασίστηκε στην παραδοχή ότι η εν δυνάμει αύξηση για ένα δεδομένο δέντρο μειώνεται από ένα αλλομετρικό πολλαπλασιαστή του λόγου της πράσινης κόμης ο οποίος αντιπροσωπεύει τις συνθήκες αύξησης του παρελθόντος και από ένα πολλαπλασιαστή ξυλοβρίθειας που αντιπροσωπεύει την τρέχουσα κατάσταση ανταγωνισμού. Για την πρόβλεψη του μελλοντικού μήκους κόμης, αναπτύχθηκε ένα δυναμικό πρότυπο μεταβολής ύψους κόμης. Ο υπολογισμός της περιοδικής υποχώρησης του ύψους στη βάση της ζωντανής κόμης έγινε σε εξάρτηση με το συνολικό ύψος του δέντρου, την αναλογία κόμης, το δείκτη ανταγωνισμού μετά από την απελευθέρωση κόμης και τη στηθιαία διάμετρο στην αρχή της κάθε αυξητικής περιόδου. Η αφετηρία για την ανάπτυξη ενός κατάλληλου προτύπου θνησιμότητας ήταν οατομικός προσδιορισμός της πιθανότητας θνησιμότητας δέντρων ως συνάρτηση των μεταβλητών μεγέθους των δέντρων, οι οποίες ήταν διαθέσιμες στο τέλος κάθεαυξητικής περιόδου. Η Αξιολόγηση των προτύπων πρέπει να γίνεται χρησιμοποιώντας μια διαδικασία αξιολόγησης η οποία θα χρησιμοποιεί “ανεξάρτητα” δεδομένα, δηλαδή δεδομένα που δεν χρησιμοποιήθηκαν για την παραμετροποίηση των προτύπων. Τρεις μόνιμες πειραματικές επιφάνειες για την πλατύφυλλη δρυ χρησιμοποιήθηκαν για την αξιολόγηση των προτύπων. Για τη μελέτη και ανάλυση των χειρισμών των συστάδων, αναπτύχθηκε ο DRYMOS 1.0, ένα λογισμικό προσομοίωσης μέσω υπολογιστή της μελέτης αντίδρασης αύξησης συστάδων πλατύφυλλης δρυός στις αραιώσεις. Ο DRYMOS είναι ένα παράγωγο πρόγραμμα λογισμικού του Αυστριακού προσομοιωτή δάσους MOSES. Ο στόχος αυτού του λογισμικού είναι να λειτουργήσει αμφίδρομα με το σύστημα των εξισώσεων και να απεικονιστεί η μελλοντική εξέλιξη του δάσους. Η αύξηση μπορεί να προβληθεί μέχρι 30 πενταετείς περιόδους. Ο χρήστης έχει την επιλογή να διαλέξει διάφορα δασοκομικά σενάρια χειρισμών και μέσω της προσομοίωσης να πάρει τα αντίστοιχα αποτελέσματα. Στο τέλος μιας περιόδου προσομοίωσης το πρόγραμμα μπορεί να παράγει συσταδικά διαγράμματα και πινακοποιημένα αποτελέσματα (πίνακες παραγωγής

Assessing Black Locust Biomass Accumulation in Restoration Plantations

Forests (either natural or planted) play a key role in climate change mitigation due to their huge carbon-storing potential. In the 1980s, the Hellenic Public Power Corporation (HPPC) started the rehabilitation of lignite post-mining areas in Northwest Greece by planting mainly black locust (Robinia pseudoacacia L.). Today, these plantations occupy about 2570 ha, but the accumulation of Above Ground Biomass (AGB) and deadwood has not been assessed to date. Therefore, we aimed at estimating these biomass pools by calibrating an allometric model for AGB, performing an inventory for both pools and predicting the spatial distribution of AGB. 214 sample plots of 100 m2 each were set up through systematic sampling in a grid dimension of 500 × 500 m and tree dbh and height were recorded. AGB was estimated using an exponential allometric model and performing inventory measurements and was on average 57.6 t ha−1. Kriging analysis reliably estimated mean AGB, but produced errors in the prediction of high and low biomass values, related to the high fragmentation and heterogeneity of the studied area. Mean estimated AGB was low compared with European biomass yield tables for black locust. Similarly, standing deadwood was low (6–10%) and decay degrees were mostly 1 and 2, indicating recent deadwood formation. The overall low biomass accumulation in the studied black locust restoration plantations may be partially attributed to their young age (5–30 years old), but is comparable to that reported in black locust restoration plantation in extremely degraded sites. Thus, black locust successfully adapted to the studied depositions of former mines and its accumulated biomass has the potential to improve the carbon footprint of the region. However, the invasiveness of the species should be considered for future management planning of these restoration plantations

Where are we now with European forest multi-taxon biodiversity and where can we head to?

International audienceForestry implementation significantly impacts forest biodiversity. Despite the promotion of Sustainable Forest Management (SFM) in Europe, sustainability assessments hardly account for direct biodiversity indicators. We aim to i) gather and map the existing information on forest multitaxon biodiversity associated with stand structure and management in Europe; ii) identify knowledge gaps for forest biodiversity research; and iii) discuss the research potential associated with multitaxon biodiversity data. We established a research network focused on multi-taxon biodiversity, stand structure and management data of European forests; and fitted species records, standing trees, lying deadwood, and sampling unit metadata from 34 local datasets. Suitable information was available for 3,591 sampling units, each surveyed for on average 4.6 taxonomic groups. Standing tree diameters, tree height deadwood and tree-related microhabitats were sampled in respectively 2,889; 2,356; 2,309 and 1,388 sampling units. Sampling unit metadata includes spatial coordinates, and compositional and management descriptors. Available data cover all the 14 European forest compositional categories but are unevenly distributed among them, with European beech forests being over-represented as compared to thermophilous and boreal forests. Overall, the available information has the potential to inform the development of conservation and SFM strategies for European forests by supporting: (i) methodological harmonization and coordinated monitoring; (ii) the definition and testing of SFM indicators and thresholds; (iii) datadriven assessment of the effects of environmental and management drivers on multi-taxon forest biological and functional diversity, (iv) multi-scale forest monitoring integrating in-situ and remotely sensed information