Jouni Siipilehto

Effect of retained trees on the development of young Scots pine stands in Southern Finland

Abstract The purpose of the study was to examine the effect of retained Scots pine (Pinus sylvestris L.) trees in the context of even-aged management systems on height, diameter growth, and branching of individual Scots pine seedlings and seedling stands in Southern Finland. A modeling and simulation approach was applied. Empirical models were constructed using data sets acquired from temporary sample plots in nine stands. The models were used to simulate tree height, diameter, and branch diameter growth. Results indicate that Scots pine trees retained in Scots pine seedling stands had not brought about unstocked or very poorly stocked patches around their bases in the study stands. Each retained tree of 25–40xa0cm in diameter reduced the height growth potential of Scots pine seedlings about 9–17% within a circle of 10xa0m radius. Retained tree competition did not result in reduced tree diameter for a given height. Retained tree influence on the diameter of the thickest branch of a seedling was rather small for practical applications, but the sum branch cross-sectional area was reduced, especially on fertile sites. In stand level simulations, the retention of 48xa0ha−1 trees of 25xa0cm average diameter and 21xa0m height on a rather poor site resulted in 15 years in about 5–7% decrease in seedling height, 6–8% decrease in diameter, and 2–5% decrease in maximum branch diameter compared to no retention, varying with the seedling stand density. The effect of the spatial pattern of retention in random, regular, or clustered structures on seedling growth was marginal.

Long-term impacts of forest management on biomass supply and forest resource development: a scenario analysis for Finland

AbstractnA national-level scenario analysis was conducted to comprehensively assess the long-term impacts of alternative forest management strategies on potential Finnish forest resource use. Four scenarios with varying management intensities were defined. The future development of forest resources under specific forest management schedules in accordance with the given scenarios was subsequently predicted over a 100-year period using the MOTTI stand simulator. The 10th Finnish National Forest Inventory data served as the initial simulation data, which included data from a network of 46,295 inventory sample plots that covered commercial forest areas across the country. The results suggest that there is significant potential to increase annual removals in a sustainable manner by applying more intensive forest management. In the intensive management scenarios, annual removals increased by approximately 40xa0% compared with actual removals. Moreover, annual areas of forest regeneration and pre-commercial thinning were 35 and 70xa0% larger than current treatment areas, respectively. Therefore, intensive management improves the profitability of forest management by nearly 50xa0%. However, there is significant variation in profitability between geographical regions because of differences in climate, forest site production potential and current forest structures. There were notable differences between scenarios in growing stock volumes and the amount of carbon stocks in forests. Extensive management increased growing stock from 2 to 3.5xa0billionxa0m3, while intensive management slightly decreased growing stock volumes and carbon stocks in forests. The results indicate that intensively managed forests are more efficient in capturing carbon from the atmosphere than extensively managed forests.n

Effect of edge stands on the development of young Pinus sylvestris stands in southern Finland

Abstract The quantitative effect of pine-dominated edge stands in southern Finland on the density and growth of pine saplings was addressed in the study. The cumulative effect of a mature edge stand on the development of a pine sapling stand with variable cutblock sizes was also estimated. The data were acquired from 10 study sites with a Scots pine sapling stand with a current dominant height of 1–6 m and an adjoining middle-aged to mature edge stand dominated by Scots pine. Tree level models were constructed to describe and simulate the structure and development of the sapling stands. The results indicated that dividing an average regeneration area (2 ha) into smaller cutblock units (1.0–0.5 ha) appreciably increased the edge stand effect. Total stand volume growth was 6% lower on 1 ha cutblocks, and 31% lower on 0.5 ha blocks, than on 2 ha blocks.

Realised and projected gains in growth, quality and simulated yield of genetically improved Scots pine in southern Finland

Scots pine (Pinus sylvestris) seedlots of different genetic quality were compared in realised gain trials at six sites in southern Finland at an age of 14–15xa0years. Synthetic seedlot mixtures of 1.5-generation plus trees showed consistent superiority to both first-generation orchard seedlots and unimproved checklots in growth, slenderness and relative branch size. Open-pollinated offspring from first-generation orchards, in turn, outperformed unimproved trees in most growth and quality traits. The mean incidence of ramicorns and forks was similar between unimproved and first-generation orchard trees, but slightly elevated in the 1.5-generation stock. Stand-level yields were projected for two virtual sites in southern Finland using simulation software MOTTI. The development of improved stands was modelled by incorporating genetic gains in height and diameter growth in the asymptote parameter of the Chapman–Richards growth function. The mean annual yields of the first-generation and 1.5-generation orchard stock were, as an average over the two sites, 11.5 and 23.9xa0% above the unimproved stock, respectively. For juvenile, fully contaminated 1.5-generation orchards, the genetic gain was 15.9xa0%. The predicted reduction in the length of commercial rotation due to genetic improvement varied between 4 and 17xa0years depending on the site, orchard generation, level of pollen contamination and genetic thinning. The results indicated substantial returns on investments on improved reforestation stock in southern Finland. Increments in bare land value (using a 3xa0% interest rate) ranged from 529 to 1836xa0€xa0ha−1 (30.5–60.5xa0% above unimproved stock).

Restoring volume, diversity and continuity of deadwood in boreal forests

Abstract Restoration of boreal forests by emulating natural disturbances is used to bring back typical components of natural forests that are reduced by silvicultural management. The volume, diversity and continuity of deadwood are the most important factors determining the diversity of deadwood-dependent species. In a large-scale experiment consisting of 43 experimental stands and 15 controls we assessed how alternative restoration methods enhancing deadwood availability (felling and fellingxa0+xa0burning with two levels of felling: 20 and 40xa0% of initial volume of living trees, and a storm treatment) would affect short- and long-term deadwood volume and diversity using 7-year deadwood measurements and simulation modelling. In short-term, restoration by fellingxa0+xa0burning increased both the volume and diversity of deadwood, whereas felling only increased merely the volume of deadwood. The simulations of tree growth, mortality and wood decomposition indicated that in comparison to controls, felled and storm-treated stands have greater deadwood volumes up to 40xa0years and felledxa0+xa0burned stands more than 60xa0years after restoration. Our results suggest that felling with 20xa0% of initial tree volume does not harm the future deadwood continuity, whereas intensive burning may imperil the deadwood continuity in a stand level. In conclusion, restoration clearly speeds up the development of the deadwood volumes needed to host large portions of biodiversity, and burning is the most effective restoration method in short- and long term. In practice, several restoration methods could be used concurrently in the landscape to obtain the best results.

Cost-Efficiency of Alternative Forest Conservation Targets, a Case Study from Finland

Temporal contracts to protect biodiversity in forests are a recent approach which has shown to be a promising and cost-efficient procedure. With respect to cost-efficiency of temporal contracts the relevant issue is the goal of conservation: for instance, are we interested in enhancing CWD index (coarse woody debris) or increasing the amount of dead wood in forests? This study focuses on demonstrating the effect of conservation goal (either enhancing CWD index or increasing the amount of dead wood) on costefficiency by optimization. Further, we analyze whether both the length of temporal conservation (10 or 30 years) and discount rate (2% or 4%) would have an effect on optimal solutions. The data consisted of 20 measured forest sites with stand age between 60 and 160 years. Majority of the stands (80%) fulfilled the biological conservation criteria of the Finnish Forest Biodiversity Programme METSO and a few of the stands were managed commercial forests. For temporal conservation (either 10 or 30 years), stand growth and dynamics of decaying wood were forecasted with a stand simulator (Motti) by prolonging the clear-cut with 10 or 30 years. The results for the two alternative conservation periods were compared to business-as-usual, BAU, with respect to income losses. Then, for ecological responses the initial, measured stand characteristics were set for the baseline to which temporal conservation alternatives (10 or 30 years) were compared to. The results of optimization distinctively demonstrated that the conservation goal has a relevant effect on the cost-efficiency. Further, the length of the conservation period has also an important role in cost-efficiency whereas the discount rate plays only a minor role in this study context. In the optimal solutions the forest sites with distinctively above-average initial amount of dead wood and excellent growth predictions which imply lower than average income losses due to conservation shone through with respect to cost-efficiency. As a word of caution, it should be pointed out that if one merely chooses the most cost-efficient sites for conservation, there is a possibility that a desirable level of biodiversity might not be fulfilled. To test this, the study needs to be next extended to landscape level with larger data input.

Männyn- ja kuusentaimikoiden kehitys erilaisia metsänuudistamisketjuja käytettäessä

Tutkimuksessa tarkasteltiin mäntyja kuusitaimikoiden tiheyttä ja pituuskehitystä. Tutkimus perustui käytännön uudistusaloilta koko maan alueelta kerättyyn kertamittausaineistoon, joka käsitti 68 männynja 19 kuusentaimikkoa. Mänty oli uudistettu luontaisesti, kylvetty tai istutettu tuoreelle ja kuivahkolle kankaalle ja kuusi oli istutettu lehtomaiselle ja tuoreelle kankaalle. Uudistusala oli joko muokkaamaton tai muokattu äestämällä, laikuttamalla, mätästämällä tai auraamalla. Joitakin uudistusaloja oli lisäksi kulotettu. Taimikot olivat mittaushetkellä 6–34 vuotta vanhoja ja valtapituudeltaan 2–11 m. Aineistoon sovitettiin lineaarisia malleja selittämään pääpuulajin osalta sekä yksittäisen taimen pituutta, että taimikon keskija valtapituutta sekä runkolukua. Lisäksi tarkasteltiin siemenja vesasyntyisen lehtipuuston määrää. Erityisen kiinnostavia selittäviä tekijöitä olivat erilaiset muokkausmenetelmät. Keskija valtapituutta selittivät taimikon ikä, lämpösumma, pääpuulaji, uudistamismenetelmä ja kasvupaikka. Keskipituuteen ja runkoluun vaikuttivat myös erilaiset muokkausmenetelmät, mutta niillä ei ollut vaikutusta valtapituuteen. Maanmuokkaus lisäsi lehtipuuston määrää, mutta muokkausmenetelmät eivät eronneet merkitsevästi toisistaan. Yksittäisen taimen pituutta selitti syntytapa, asema muokkausjäljessä ja terveydentila. Metsikkötason mallit selittivät 48–66 % runkoluvun ja 81–87 % pituustunnusten vaihtelusta. Maanpinnan käsittelyistä kulotus, auraus ja mätästys nopeuttivat keskipituuden kehitystä äestetyn uudistusalan perustasoon verrattuna. Vesakon tiheys ei vaikuttanut merkitsevästi kasvatettavien taimien pituuskehitykseen, mutta vesakon pituus suhteessa kasvatettavan havupuun taimen pituuteen oli merkitsevä selittäjä.