Omvandling av granskog till ädellöv i södra Sverige – fallstudier från Söderåsens nationalpark och Raslångens ekopark

I Sverige och stora delar av Europa har det planterats gran, Picea abies, på marker som tidigare varit lövdominerade. Idag restaureras ädellövskog på dessa marker i ökad omfattning, bland annat för att gynna skogens biologiska mångfald och rekreationsvärden. Syftet med detta arbete var att undersöka överlevnad och tillväxt av ek, Quercus robur, och bok, Fagus sylvatica, som planterats efter gran i Söderåsens nationalpark och i Raslångens ekopark i södra Sverige. I Söderåsens nationalpark undersöktes plantutvecklingen tio år efter plantering på öppna hyggen (ek och bok) eller under björkskärm (bok). För Raslångens ekopark var syftet att undersöka om inversmarkberedning och hägn påverkar initial etablering och överlevnad hos bokplantor på öppna hyggen. Resultaten från Söderåsen visar att ek och bok tio år efter plantering kan nå en hög överlevnad och god tillväxt med hjälp av fungerande hägn och regelbundna röjningar. Utebliven röjning kan dock snabbt leda till undertryckta träd och ökad dödlighet. Konkurrens från tät fältskiktsvegetation kan även leda till ökad dödlighet av bok under de första åren efter plantering. I Raslångens ekopark testades därför effekten av inversmarkberedning och hägn för bokens överlevnad och tillväxt efter två växtsäsonger. Medan markberedningen hade en signifikant positiv effekt på både överlevnad och planthöjd, fanns det ingen effekt av hägnen på dessa variabler. Sammanfattningsvis tyder resultaten på att boken är känsligare än eken för konkurrerande markvegetation efter plantering medan eken är mer beroende av regelbunden röjning av konkurrerande träd och buskar.In Sweden and in large parts of Central Europe spruce, Picea abies, has been planted on land that previously had been dominated by broadleaves. Today an increasing amount of land is being restored back to broadleaved forest to enhance biodiversity and recreation values. The aim of this study was to investigate the survival and development of oak Quercus robur, and beech, Fagus sylvatica that has been planted in Söderåsens national park and Raslångens ecopark in the south of Sweden. At Söderåsens national park, the survival and development of oak Quercus robur, and beech, Fagus sylvatica was studied ten years after planting on open clear cuts (oak and beech) and under a shelter of birch (beech). For Raslångens ecopark the aim was to determine if soil scarification and fencing affected initial plant establishment and survival rate of beech on open clear cuts. The results from Söderåsen show that oak and beech, ten years after planting, had a high survival rate and a good growth with functional fences and frequent cleanings. If the cleaning is neglected it can quickly lead to suppressed trees and increased mortality. In addition, competing vegetation may lead to increased mortality of beech during the first years after planting. Therefore, in Raslångens ecopark the effects of soil scarification and fencing were tested on the survival rate and growth of beech after two growing seasons. While scarification had a significant positive effect on both survival and plant height, there was no effect of fences on these variables. In summary, the results indicate that beech is more sensitive than oak for competing ground vegetation after planting, while oak is more dependent on regular thinning of competing trees and shrubs

Physico-chemical characteristics and heavy metal concentrations of copper mine wastes in Zambia: implications for pollution risk and restoration

Soil characterization is a vital activity to develop appropriate and effective restoration protocols for mine wastelands while insights into the total content of heavy metals in the soil is an important step in estimating the hazards that the metals may pose to the vital roles of soil in the ecosystem. This study addressed the following research questions: (1) To what extent do the physico-chemical characteristics vary between mine waste sediments and the nearby forest soil? (2) Are the concentrations of heavy metals high enough to be considered as toxic? and (3) Are heavy metals present in mine waste sediments potential sources of pollution? We hypothesized that the physico-chemical characteristics of mine waste sediments are less favorably for plant establishment and growth while the concentrations of heavy metals are very high, thus restricting the success of revegetation of mine waste lands. Mine waste sediments were sampled following a diagonal transect across tailings dams, overburden dump sites and the local forest soil from the top layer (0-20 cm) using a closed auger. Samples were analyzed for arsenic, barium, lead, cadmium, cobalt, copper, chromium, nickel, vanadium, and zinc as well as for soil physico-chemical properties. The mine waste sediments were dominated by silt whilst the forest soil by sand particles, with significantly high bulk density in the former. Both the forest soil and overburden sediments were acidic than the alkaline tailings dam sediment. Total organic carbon and nitrogen contents were significantly low in mine wasteland substrates but the concentration of Ca and Mg were significantly higher in tailings dam substrate than the forest soil. The concentrations of available P, K and Na were similar across sites. The mean concentrations of heavy metals were significantly (p < 0.01) higher in mine waste sediments than the forest soil; except for cadmium (p = 0.213). The order of contamination by heavy metals on the tailings was Cu > Co > Ba > Ni > As > Zn > Pb > Cr > V > Cd, and that on the overburdens was Cu > Co > Ba > Ni > Zn > Cr > Pb > V > As > Cd. The pollution load index (PLI) was nearly twice higher for the tailings dam (8.97) than the overburden (5.84). The findings show that the copper mine wastes (the tailings dams and overburden waste rock sites) are highly contaminated by heavy metals; which, in turn, might pose serious hazards to human health and agricultural productivity. In addition, poor macro-nutrient availability, substrate compaction and soil acidity (particularly on overburden sites) coupled with toxic level of heavy metals would be the main challenges for successful phytostabilization of copper mine wastelands

Restoring mixed forests through conversion of Norway spruce stands: effects of fencing and mechanical site preparation on performance of planted beech and natural tree regeneration

Conversion of Norway spruce (Picea abies) plantations to more diverse and resilient forest types is an important task for European forest managers in the face of climate change and increased focus on ecosystem services beyond timber production. However, there is a lack of knowledge on how to cost-effectively restore such forests. This study reports the influence of vicinity (distance) of forest type (mixed or spruce), fencing and mechanical site preparation (MSP) on the early performance of planted beech (Fagus sylvatica) seedlings and natural regeneration of other tree species following clear-cuts of Norway spruce in southern Sweden. After 6 years, we found clear effects of fencing and MSP, but not of vicinity of forest type. Fencing had a positive effect on height growth of Scots pine (Pinus sylvestris) but not on height of planted beech and naturally regenerated birch (Betula pendula, B. pubescens). There was a positive effect of MSP on survival and height growth of planted beech, and on the amount of natural regeneration of Scots pine. We conclude that establishment of beech forest is greatly accelerated by active regeneration approaches such as planting. In addition, the combination of planting beech, natural regeneration of other species, fencing and MSP is effective to promote the transition to mixed and diverse stands with both broadleaves and conifers. Fencing represented the highest cost among the treatments, and its cost-effectiveness depends on the local ungulate browsing pressure. In our study, fencing was critical to protect natural regeneration of Scots pine from browsing. Finally, natural regeneration of birch was abundant in our study and relatively unaffected by fencing and MSP treatments. With time, pre-commercial thinning of the naturally regenerated birch will be needed to maintain a diverse mixture of tree species