Clear-felled Areas Research Articles

Impacts of Clear Cutting on Diversity of Ground Ants (Hymenoptera: Formicidae) in Pine Plantation Forest in Sukabumi Forest Management Unit, West Java

Clear cutting is the main source of timber production of plantation forest management in Indonesia, but this activity disrupts the lives of ground ants. It is rarely known how clear cutting affects the ground ant community in the Indonesian plantation forest. The study aimed to analyze the impacts of clear cutting on the diversity of ground ants in the pine plantation forest of Sukabumi, West Java. The study compared the community structure of ground ants before clear cutting and after clear cutting. Ground ants were collected using a pitfall trap. Trapping of ground ants was carried out six days before the clear cutting and six days after the clear cutting. The ground ants were identified to the morphospecies level and classified into their functional role. The results showed that clear cutting alters the community indices of ground ants. Abundance, morphospecies composition, diversity index, richness index, and evenness index of ground ants after clear cutting was lower compared with those before clear cutting. The clear-felled area due to clear cutting provided favorable habitat for the generalist groups of ground ants, but negatively affected the predator and forager groups of ground ants. These findings can be used as an important factor in the development of environmenllyt-friendly forest harvesting systems in Indonesian plantation forests.

An Assessment of Mangrove Management during the Colonial and Post-Colonial Periods

Mangroves of the east coast of India were brought under intensive management by the colonial authorities during the late 19th century. They were treated as forests rather than as wetlands, and hence management procedures developed for the terrestrial forests were applied to mangroves. Apart from this, the British foresters had limited mangrove tree mensuration data. This inadequacy in data led to the application of inappropriate silviculture methods such as clear felling to harvest mangrove wood products. This method triggered a chain reaction, that changed the biophysical condition of the clear-felled areas, which in turn prevented the regeneration of mangrove species. The same silvicultural system was followed during the post-colonial period leading to extensive degradation of mangroves.

Continuous-cover forestry maintains soil fungal communities in Norway spruce dominated boreal forests

Traditional clear-fell forestry greatly alters community structure and ecosystem function within boreal forests and alternative management practices may reduce these impacts. Continuous-cover forestry can maintain similar invertebrate and plant communities to unmanaged forest, but whether this extends to soil fungal communities remains unclear. Within four sites across the mid-boreal zone of Sweden, we conducted a comprehensive study to assess the impact of continuous-cover and clear-felling on soil fungi and chemical properties within Norway spruce dominated forests, using unmanaged forest as a control. We sampled soils for chemical properties (pH, carbon, nitrogen, C/N and Organic matter) and used both surveys of fungal fruiting bodies and state of the DNA metabarcoding techniques to assess treatment effects on soil fungal communities. We found that forest management practices had significant effects soil pH, C and C/N ratio and that continuous-cover forestry had more similar soil properties to unmanaged forest. Furthermore, the biodiversity of fruiting bodies, as expressed by species richness and Shannon’s diversity index, was higher in continuous-cover forestry and unmanaged forest compared to clear-felled areas. However, the opposite was true for the diversity of soil fungal communities, which was probably due to the high level of disturbance in clear-felled areas, and thus, ample habitat for early successional colonisers and some remnants of mature forest communities. However, in agreement with predictions we found that the composition of both fruiting body and soil fungal communities broadly similar in continuous-cover and unmanaged forest, but fundamentally different to clear-felled areas. Consequently, our findings highlight that continuous-cover forestry is an alternative to conventional practise, maintaining communities associated with unmanaged forest and mimicking natural disturbance regimes.

Can’t see the Woodlark for the trees? Commercial forests as a habitat for a bird of conservation concern

This study investigated the extent to which intensive forest management practices influence a widespread bird of conservation concern, the Woodlark Lullula arborea. We compared trends of the studied population in Notec Forest, Poland during 2010–2014 against country-wide monitoring data, and populations of the forest interior versus forest edge dominated landscapes (forest-agricultural area mosaic). We also studied the influences of forest management practice (clearing size, stand structure, forestry activities on restock sites, harvesting in the neighboring habitat, and retaining tree aggregates) on the population of this species. Changes in woodlark numbers, habitat availability, and quality differences among studied sites and years were assessed using ANOVA. The influence of habitat characteristics on woodlark occupancy and abundances were tested by Generalized Estimation Equations, while the magnitude of influences in the study years was compared by Random Forest algorithm (as were population trends). Over the four study years, 419 woodlark pairs occupied 336 patches, with a maximum of 127 pairs. The number of woodlark pairs fell by 40% on the studied areas over the period, in line with declines across Poland as a whole. In our study system, population trends did not differ between forest and forest- agro mosaic landscapes. Size, age and number of available habitats did not differ either temporally or spatially during the study. Retention of unfelled trees in clearfell areas and forest works in the nearby sites, however, showed slight differences among the sampling polygons. Larger habitat patch size and restock areas under five years favored woodlarks. Less important but still significant positive influences were a higher proportion of retained trees and elongated shape of the habitat patches. Forestry activities on the neighbor stands were correlated with increased woodlark abundances, which is an unexpected result. Moreover, forestry provides suitable habitats for woodlarks in a dynamically changing arrangement. The magnitude of the studied factors’ influences on woodlarks showed a very high difference between study years, with the highest values in the years where woodlarks are the most numerous. In conclusion, we found no evidence that contemporary forestry adversely affects Woodlark habitat occupancy. Our study suggests that while managing land for one ecosystem service (timber), an apparent dis-benefit (loss of recreational attractiveness) might benefit some semi-open habitat species.

Hypocrealean Fungi Associated with Hylobius abietis in Slovakia, Their Virulence against Weevil Adults and Effect on Feeding Damage in Laboratory

In temperate regions of Europe, the large pine weevil, Hylobius abietis, is a major pest of coniferous forests mostly at sites where clear-felling is followed by planting of saplings. Control measures against this pest are based on silvicultural techniques, an application of physical barriers on stems of saplings and insecticide treatments. To avoid the use of insecticides, alternative measures such as biological control have been investigated. The goal of the present study was to obtain local strains of entomopathogenic fungi (Ascomycota, Hypocreales) from natural populations of H. abietis, and to investigate their efficacy against the weevil. A survey on entomopathogenic fungi was undertaken at clear-felled areas of spruce forests in northern Slovakia. Two Beauveria species, B. bassiana and B. pseudobassiana, were identified, and 22 in vitro strains were obtained. Mean prevalence of infected adults was low (2.10% ± 0.67%) and the mycosis was mostly recorded during May and June. Virulence of Beauveria strains against the weevil was tested in laboratory. B. bassiana strain AMEP20 was significantly most virulent (LC50 of 0.65 ± 0.10 × 108 conidia mL−1). Treatment with conidia of AMEP20 strain affected feeding damage by the weevil on bark of Scots pine twigs. Daily bark consumption by B. bassiana-treated weevils was lower than by untreated individuals and decreased with increasing conidia concentration used for the treatment. In the outdoor experiment, AMEP20 strain killed weevils that fed on spruce saplings treated with conidia suspensions. Mortality due to mycosis on weevils exposed to the conidia-treated saplings reached 30.0%–76.5% and 55.0%–88.2% after 32 and 46 days, respectively.

Inner log temperatures vary with log direction and forest cover: Implications for predicting the phenology of saproxylic insects

Ambient temperature is frequently used to model the development of many herbivorous insects. Estimating development rates of cryptic saproxylic species in wood will be biased by the presence of differences between internal log temperatures, where larvae feed, and measured ambient conditions outside of logs. We tested for differences between ambient temperatures at the log surface and internal log temperatures as a function of habitat type (recent clearfell area and pine forest stands), log direction (north- and south-facing), depth (5–20 cm) and season (summer and winter). Internal log temperatures varied from log surface temperatures in all cases and were influenced by depth, depth × habitat, and depth × log direction interactions. A simple constant correction factor could not explain the relationship between log surface and internal log temperatures. Mean internal log temperatures were between 0.88 and 3.68 °C warmer in clearfells compared to forest stands irrespective of log direction or depth. During summer the average daily minimum temperatures were 2.3–4.1 °C warmer in logs compared to the log surface under a conifer canopy and up to 9.8 °C warmer in adjacent recently clearfelled areas. During winter the internal log minimum temperatures were 2.0–2.8 °C warmer under a conifer canopy and 2.6–5.2 °C warmer in recently clearfelled areas compared to log surface temperatures. Differences between log surface and internal minimum temperatures increased consistently with depth into the log. Accurate models that translate observed ambient temperatures to internal log temperatures that are representative of the location of feeding larvae are necessary to model saproxylic insect development at the landscape scale. Results from this study demonstrate that these translation models will have to consider depth, log orientation, and season.

Amount of nutrients extracted and left behind at a clear-felled area using the fresh-stacked and dried-stacked methods of logging residue extraction

ABSTRACTNutrient removal has been one of the key issues since the harvesting of logging residues started in Sweden. This study examined the actual removal of nutrients by measuring the amounts of biomass removed (from a forest products perspective) combined with their respective nutrient concentrations (N, P, Ca, K and Mg), from a clear-felled area when using the dried-stacked and fresh-stacked methods. The most important finding is that the two methods were very similar regarding nutrients remaining at the clear-felled area. Of the nutrients remaining there, most were found to be well distributed between the harvester heaps. Both methods fulfilled the requirements of the Swedish Forest Agency. A sensitivity analysis showed that even if the dried-stacked method left more needles, or the fresh-stacked method extracted more logging residues, there would only be a small impact on the levels of nutrients removed. The sensitivity analysis also showed that the amount of logging residues remaining between the harvester heaps seems to be much more important for nutrients left behind, regardless of extraction method. With this in mind, it is highly probable that improvements to the extraction of logging residues, without increasing nutrient removal, can be made.

Accompanying vegetation in young Pinus radiata plantations enhances recolonization by Ceroglossus chilensis (Coleoptera: Carabidae) after clearcutting

The replacement of native forests by Pinus radiata plantations modifies habitat availability and quality for wildlife, constituting a threat to species survival. However, the presence of understory in mature pine plantations minimizes the negative impacts of native forest replacement, rendering a secondary habitat for wildlife. Whether forest-dwelling species recolonize clear-felled areas pending on the spontaneous development of accompanying vegetation growing after harvesting is yet to be assessed. In this context, we analyze the abundance, movement and habitat selection of the endemic ground beetle Ceroglossus chilensis (Coleoptera: Carabidae) in an anthropic forest landscape consisting of native forest remnants, adult pine plantations (> 20 years) with a well-developed understory, and young (1–2 years) pine plantations with varying degrees of accompanying vegetation development. Particularly, we analyze the likelihood that C. chilensis would recolonize young pine plantations depending on the presence (> 70% cover) or the absence (< 20% cover) of this accompanying vegetation. C. chilensis shows a greater probability of selecting habitats with understory (pine plantations and native forest) and young plantations with accompanying vegetation (future understory) than habitats without such vegetation. Movement of C. chilensis also favors their permanence in habitats with understory vegetation, coinciding with higher abundances than in young pine plantations devoid of accompanying vegetation. Hence, the effect of clearcutting could be mitigated by allowing the development of accompanying vegetation into a future understory, which facilitates the recolonization of pine plantations and its use as secondary habitat for wildlife.

Arthropod assemblages deep in natural forests show different responses to surrounding land use

Many contemporary landscapes have vast areas of production land-uses within landscape mosaics, which may impact species dispersal and occurrence. Here, we determined the extent to which commercial exotic plantation forests affect arthropod diversity associated with natural Afrotemperate forests in the southern Cape Afrotemperate landscape mosaic, South Africa. Natural forests and fynbos vegetation naturally coexist here, with the addition of exotic plantation forests to form a heterogeneous landscape. Epigaeic arthropods were collected by means of pitfall trapping at stations along transects from inside natural Afrotemperate forest, across the edge and into the surrounding land use, which included natural fynbos vegetation, mature forestry plantation blocks (Pinus radiata) and areas where plantations have been clear-felled. Stations were set at 5, 10, 20, 30 and 50 m to both sides of the forest edge with the addition of 100 m stations situated in the natural forest. Arthropod assemblages were distinct in all land-use types. Natural edge effect between forest and fynbos, as measured by arthropod compositional changes, was 20 m into natural forests, yet when bordered by plantations this edge increased up to 30 m into the forest. Once plantations were clear-felled, edge effects increased up to 50 m into natural forests. Responses in terms of assemblage composition and species richness were however taxon specific. Results show that (1) pine plantations are not alternative habitat for native Afrotemperate forest arthropods, (2) there were stark changes in arthropod assemblage composition at edges between these land-use types and (3) that the effects of timber plantation practices (re: clear-felling) also penetrate deep into surrounding natural forests and need to be considered in regional landscape planning. The need for an effective rehabilitation strategy of clear-felled areas is identified as key priority for bordering natural forests. Ongoing monitoring in both the disturbed area and the adjoining natural forest should be undertaken to ensure sufficient recovery.

DESTRUCTION OF FOREST AREAS AS A RESULT OF LOGGING AND HARVESTING IN AFRICAN OR AMERICAN DENSE TROPICAL RAINFORESTS

Il est devenu habituel de lire dans les médias des articles accusant l’exploitation fores- tière d’être le moteur principal de la dispari- tion des forêts tropicales. Ce raccourci trom- peur est imputable à une méconnaissance des réalités forestières, d’une part, et à un amalgame entre l’exploitation forestière et le défrichement agricole, d’autre part. L’ob- jet de cet article rédigé par un praticien fami- lier du contexte forestier tropical était d’éva- luer l’impact de l’exploitation forestière sur les forêts denses tropicales humides, dans les deux continents africain et améri- cain. Par souci d’exactitude, les phases de l’exploitation ont été distinguées : installa- tion de la base vie, constitution du réseau routier de vidange des bois, réalisation des opérations d’exploitation proprement dites. Des scénarios ont été distingués en fonction de la richesse de la forêt, dont le volume ré- colté varie de 3 à 15 m3/ha. Ces estimations confirment que la destruction du couvert fo- restier demeure si faible qu’à l’exception de situations radicales l’exploitation forestière ne constitue pas une menace pour le main- tien durable des forêts tropicales. La mise en place des réseaux routiers et de pistes de débardage affecte de 4,5 à 5,5 % du couvert forestier. Les surfaces des trouées consé- cutives à l’abattage ne dépassent jamais 4 % du couvert, et restent inférieures à 2 % pour les forêts riches ou de richesse moyenne. L’exploitation forestière n’est donc direc- tement responsable que de la destruction de 5,5 à 8,5 % du couvert forestier. Dans le cas de forêts riches, des exploitations fores- tières successives peuvent certes atteindre 12 à 16 % du couvert forestier. Mais c’est alors sans compter sur la dynamique de reconstitution de la biomasse opérant natu- rellement entre deux séquences d’exploi- tation. En Asie du Sud-Est où l’exploitation est plus intensive en raison d’un potentiel commercial très élevé, la reconstitution du couvert est acquise en 20 ans. Si la valeur économique d’une forêt dense tropicale humide diminue avec l’exploitation, ses va- leurs biologique et écologique restent quant à elles sensiblement intactes.

Distributions and Losses of Logging Residues at Clear-Felled Areas during Extraction for Bioenergy: Comparing Dried- and Fresh-Stacked Method

It is well known that a large proportion of available logging residues intended for extraction will not reach the energy-conversion industry, because some are lost during transportation or left on the clear-felled area. However, there is little understanding of where logging residue losses occur in the supply chain. In this study, the distribution of logging residues for two methods (dried- and fresh-stacked method) to extract logging residues were studied in one clear-felled area. In addition, residue fractions were examined in a detailed comparison. Even though the fresh-stacked method left somewhat more logging residues at the clear-felled area, the differences are small between the methods. Approximately 30% of the total amount of logging residues was left behind between the harvester heaps, with an additional 10%–15% under these heaps and approximately 2%–3% beneath the windrows. The final product that was delivered to the energy-conversion industry was very similar, regardless of the extraction method used. The delivered chipped logging residues had moisture contents of 37% and 36% following fresh- and dried-stacked methods respectively, and in both cases the needle content in the processed logging residues was approximately 10%. However, the total amount of fine fractions (needles and fines) was slightly higher following dried-stacking.

Assessing the potential applications of Landsat image archive in the ecological monitoring and management of a production mangrove forest in Malaysia

This paper explores the suitability of remotely sensed data obtained from Landsat imaging sensors, in combination with ancillary forest inventory data, for the ecological monitoring and management of a production mangrove forest in Malaysia. An assessment is presented on the capabilities and limitations of utilizing Landsat Thematic Mapper data for mapping mangrove species and stand age structure in the Matang Mangrove Forest Reserve. The cloud-free subset satellite images used in this study were acquired in May 1988, February 1995, December 1999, March 2001, December 2009 and November 2013. The December 1999 Landsat 7 ETM+ image was used for the error and accuracy assessment because it coincided with the year the reference map was produced. The image classification process included both pixel-based and object-based approaches conducted on a combination of software which included ENVI, ArcGIS 10.1 and eCognition. Results revealed that the pixel-based approach was not effective in delineating species and stand age structure due to the presence of the ‘salt and pepper effect’ in the image output. The object-based approach accurately delineated between commercial and non-commercial mangrove species. It also produced a reliable and accurate stand-age structure map based on three designated classes: clear-felled areas; young mangrove forest (less than 13 years old); and mature mangrove forest (13 years or older). The analysis highlights that the mapping and analysis of mangrove species and stand age structure with Landsat Thematic Mapper image datasets can play a useful role in achieving cost-efficient and ecologically sustainable outcomes in a production mangrove forest.

Single large versus several small: The SLOSS debate in the context of bird responses to a variable retention logging experiment

The Variable Retention Harvest System (VRHS) is a silvicultural system designed to reduce logging impacts and enhance biodiversity conservation. VRHS has been widely applied worldwide but several important questions remain about its effectiveness for biodiversity conservation. A key issue is whether dispersed or aggregated retention is more effective for conservation, and hence what size of retained patches of forest should be maintained within logged areas. Many studies have indicated that increasing the amount of the original stand retained during harvesting increases the amount of biodiversity conserved. But in a form of the SLOSS (single large or several small areas for conservation) debate, a critical question is: does one large retained island better conserve forest biota than several small islands of the same aggregated area? We addressed this question in an experiment in the Mountain Ash (Eucalyptus regnans) forests of the Central Highlands of Victoria, south-eastern Australia. The experiment comprised seven blocks, each with four treatments – an unlogged control, a conventional 15–40ha clearfelled area, a 15–40ha harvest unit with a single 1.5ha retained “island”, and a 15–40ha harvest unit with three 0.5ha islands. A subset of the treatment plots and harvest units in our experiment were burned in a major wildfire in 2009. Given this, a subsequent further question we posed was: are there additional effects on birds resulting from logging operations that were followed by wildfires.We identified a significant gradient in species richness across treatments with lowest values in conventional clearfelled areas and highest values in unlogged controls. Unexpectedly, we identified no significant island size effects on bird species richness. We found no individual species that were significantly more likely to occur in a single large island than several small islands. Nonmetric multidimensional scaling revealed significant differences in the composition of the bird community between treatments, consistent with our findings for some of the more common species of birds. Several species were significantly less likely to be recorded in clearfelled areas, although the Flame Robin was more likely to be recorded in them. When we removed clearfelled areas from our analyses, some species were significantly less likely to occur in retained islands than unlogged controls. The application of VRHS did not appear to mediate bird responses to wildfire relative to effects for birds observed in clearfelled harvest units that were subsequently burned in 2009.Our results suggest that VRHS has positive effects on bird biota in Mountain Ash forests. However, this study found no advantage of setting aside a single large island versus several small islands within a given harvest unit for bird species richness nor the occurrence of individual bird species.

Změny prostředí lesa a biodiverzity v ekosystému smrku s holosečnou obnovou na původním stanovišti buku

The subject of the Rájec project (the Drahanská vysočina Upland) consists in the analysis of eco­lo­gi­cal impacts of intensive management in spruce monocultures growing on original sites of beech. Long-term studies were aimed at particular stand and environment stages after clear-felling regeneration and at the origin of a spruce monoculture of the 2nd generation. The establishment of the spruce monoculture can be considered to be most important. The highest attention was paid to the monoculture both from the aspect of carbon and nitrogen in particular components of the forest stand and their transport processes as well as from the aspect of water regime and biodiversity. The study was also aimed at the first stage of the clear-felled area development after felling a mature stand and also at functions of the herb vegetation, which reached its maximum production 4 to 7 years after felling. The paper objective was to assess spruce monocultures even outside their natural range from the aspect of changes in the forest environment as well as from the aspect of possible global changes of climate.

Nutrient leaching under zero tension in a subtropical clonal eucalypt plantation on a sandy soil in South Africa

Little is known about the effects of residue burning or retention on nutrient leaching during the inter-rotation of clonal Eucalyptus grown on the sandy soils of subtropical Zululand, South Africa. A study compared zero-tension nutrient leaching through the top metre of soil at depths of 0.15, 0.5 and 1.0 m in an undisturbed crop with adjacent clearfelled areas subjected to residue burning and residue retention. Leaching at 1.0 m in the undisturbed crop was 80% less than at 0.15 m leaching due to high water use of the mature trees. Loss of nutrients past 1.0 m in the undisturbed crop amounted to 7.0, 13.1, 6.6, 15.1 and 60.7 kg ha−1 of nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg) and sodium (Na) over the period between felling and new crop canopy closure (22 months). Annualised 1.0 m leaching amounted to 4.2, 7.8, 4.0, 9.0 and 36.3 kg ha−1 of N, K, Ca, Mg and Na, respectively. Clearfelling induced an increase in N and cation leaching that was apparent five months after clearfelling and persisted for nine months. Leaching loss declined rapidly in the new crop after planting to levels similar to the undisturbed crop by six months of age. Leaching past 1.0 m soil depth under residue retention amounted to 30.6, 132.0, 82.5, 108.7 and 299.1 kg ha−1 of N, K, Ca, Mg and Na, respectively, between felling and canopy closure. Although some weakly significantly differences were found between residue burning and retention, residue burning did not substantially alter leaching past 1 m soil depth. Burning rather induced a large loss of N (121 kg ha−1) through oxidisation, around half the residue N content. Residue retention or burning followed by rapid re-establishment can therefore be practiced to retain most nutrients on this site. Burning of residues should be practiced conservatively on low N soils or be followed by N fertilisation.

Soil and soil-solution chemistry after burning a clear-felled area in boreal Sweden

In Scandinavian forestry, prescribed burning is carried out to promote biodiversity. This study was initiated to examine how burning of a clear-felled area affected the soil and soil-solution chemistry in a nitrogen-limited coniferous forest in boreal Sweden. The stand was clear-felled and the logging residues were left on site. The harvested area was divided into two parts: one part was burnt within three months after clear-felling while the other part was left as a control. Soil and soil-solution samples were collected before and after felling and burning. In the FH layer, pH and the concentration of K and P tended to increase immediately after burning. Six years later, only small effects on soil chemistry were indicated, but the N concentration in the FH layer appeared lower in the burnt area even after 11 years. In the deep soil solution, the total organic carbon concentration was lower in the burnt area than in the unburnt area. The -N concentration in the burnt area peaked at 0.50 mg l−1 and the mean concentration during the first seven seasons was 0.13 mg l−1. In the unburnt area, the -N concentration peaked at 3.1 mg l−1 and the corresponding mean concentration was 1.0 mg l−1. Although the general level of -N was low in this study, burning largely counteracted the increase in -N concentration that usually follows final felling.

Analysing the effect of five operational factors on forest residue supply chain costs: A case study in Western Australia

In Australia the use of forest biomass has been developing in recent years and initial efforts are built on adopting and trialling imported European technology. Using a linear programming-based tool, BIOPLAN, this study investigated the impact of five operational factors: energy demand, moisture mass fraction, interest rate, transport distance, and truck payload on total forest residues supply chain cost in Western Australia. The supply chain consisted four phases: extraction of residues from the clear felled area to roadside by forwarders, storage at roadside, chipping of materials by mobile chippers, and transport of chips to an energy plant. For an average monthly energy demand of 5 GWh, the minimum wood supply chain cost was about 29.4 $ t−1, which is lower than the maximum target supply cost of 30–40 $ t−1, reported by many industry stakeholders as the breakeven point for economically viable bioenergy production in Australia. The suggested volume available for chipping in the second year was larger than in the first year indicating that the optimisation model proposed storing more materials in the first year to be chipped in the second year. The sensitivity analysis showed no strong correlation between energy demand and supply chain cost per m3. For higher interest rates, the total storage cost increased which resulted in larger operational cost per m3. Longer transport distances and lower truck payloads resulted in higher transport cost per unit of delivered chips. In addition, the highest supply chain costs occurred when moisture mass fraction ranged between 20% and 30%.

Does stump removal affect early growth and mycorrhizal infection of spruce (Picea abies) seedlings in clear-cuts?

Stump removal procedure increases the extent of exposed mineral soil in the clear felled areas. In this study, our aim was to find out whether the early growth and mycorrhization of Norway spruce (Picea abies (L.) Karst.) seedlings differ between stump removal and mounding sites. Stumps were harvested from five one-hectare study sites and other five sites were mounded after clear felling. Twenty seedlings were planted on mounds at each study site. Although the height of spruce seedlings did not differ between the treatments after three growing periods, their mean growth was ca. 10% higher at the stump removal sites. The community of ectomycorrhizal (ECM) in the seedling roots did not differ between the treatments. The high mycorrhization rate in the nursery still remained after two and three growing seasons in the field and diversity of ECM community slightly increased during the first years. Our results indicate some positive although rather small and transient effects of stump removal on the performance of planted spruce seedlings. Longer-term studies are needed to fully understand the effects of stump removal on the later seedling development and their symbiotic interactions with mycorrhizal fungi.

Rainfall-runoff-erosion relationships study for different land uses, in a sub-urban area

Rainfall-runoff-erosion relationships are poorly understood. The complexity introduced in hydrological properties and processes by land use changes as a result of urban sprawl further increases the unpredictability. To study the impact of urbanization, we selected a sub-urban catchment in Central Portugal, the “Ribeira dos Covoes”, where urban sprawl and land use changes are leading to changes in hydrological processes. This study surveys the hydrological response of different signifi cant land uses within the catchment, by performing rainfall simulations experiments at small plot scale (0.25 m2). The results show distinct overland fl ow responses for different land uses. The agriculture areas (including tilled and abandoned) showed no overland fl ow generation, after a rainfall of 43 mm h-1. In forest, clear felled areas and in build-up areas, overland fl ow ranged from 21 % to 83 % of total rainfall. However, parameters such as water repellence, soil moisture content, vegetation and litter surface soil cover were important to explain overland fl ow generation. The amount of sediments moved during the experiments was associated with overland fl ow generation. Values reached 172 g m-2 in hillslopes disturbed by construction sites. The high organic content of the sediments collected (more than 90 % in some cases), pinpoint the importance of nutrients relocation within different land uses.

Nation-Wide Clear-Cut Mapping in Sweden Using ALOS PALSAR Strip Images

Advanced Land Observing Satellite (ALOS) Phased Array L-band type Synthetic Aperture Radar (PALSAR) backscatter images with 50 m pixel size (strip images) at HV-polarization were used to map clear-cuts at a regional and national level in Sweden. For a set of 31 clear-cuts, on average 59.9% of the pixels within each clear-cut were correctly detected. When compared with a one-pixel edge-eroded version of the reference dataset, the accuracy increased to 88.9%. With respect to statistics from the Swedish Forest Agency, county-wise clear-felled areas were underestimated by the ALOS PALSAR dataset (between 25% and 60%) due to the coarse resolution. When compared with statistics from the Swedish National Forest Inventory, the discrepancies were larger, partly due to the estimation errors from the plot-wise forest inventory data. In Sweden, for the time frame of 2008–2010, the total area felled was estimated to be 140,618 ha, 172,532 ha and 194,586 ha using data from ALOS PALSAR, the Swedish Forest Agency and the Swedish National Forest Inventory, respectively. ALOS PALSAR strip images at HV-polarization appear suitable for detection of clear-felled areas at a national level; nonetheless, the pixel size of 50 m is a limiting factor for accurate delineation of clear-felled areas.