Forestry Sites Research Articles

Relationship between soil water repellency and some of soil properties in northern Iran

Abstract The occurrence and consequences of soil water repellency (SWR) have been reported in many parts of the world, but little is known on the existence of SWR in Iran. The purpose of the present study was to investigate the persistence of SWR in 10 forestry sites under different plant species (Pinus taeda, Alnus subcordata, Pterocarya fraxinifolia, Sambucus ebulus, Boxus sempervirens, Parotia persica, Quercus castanefolia, Fagus orientalis, Acer sp. and sparse grass) in North of Iran at Guilan province. The soils examined in this study include a broad range of textures, organic matter contents and pH levels. The persistence of SWR at the surface of the soil in the undisturbed samples (0–5 cm, n = 256) was collected at the areas, was measured using the Water Drop Penetration Time Test (WDPT). In the field, the actual water repellency was determined using the WDPT test but the same test was used to determine the potential water repellency after drying process for several days at 25 °C in the laboratory. A wide range of SWR classes (hydrophilic to extreme water-repellent soils) has been found in sandy soils under pine, Alnus vegetation and broadleaves forests with silty loam, silty clay loam and clay loam texture, while inexistent or slight water repellency has been observed in soils under pine forest with clay contents > 35%. Sampling was performed within 2 seasons (Autumn and Summer) and actual water repellency was only observed in forests in the Summer. The results showed a positive correlation between LogWDPT and organic matter content with r = 0.41 (p = 0 · 01, n = 256). Comparing all soil samples together, low coefficients, r = − 0.35 and 0.27 (p = 0.01) between LogWDPT with clay and sand percentage were determined respectively. Soil pH had no significant effect on soil water repellency when all soil samples were compared together but when sites were compared separately, a negative and significant relation was detected between pH and LogWDPT. In this research, maximum water repellency was found in sandy soil samples with 5.26–11.5% organic matter. Field observations imply that SWR is not a static soil property and could be observed in field when soil becomes so dry. The results show that soil organic matter content, texture and pH are important factors for developing SWR in soil.

Project of “three networks greening” based on optimal allocation in the Yellow River Delta, China (Dongying section)

We have used the Yellow River Delta (Dongying section) as our study area to address the project of “Three Networks Greening” (TNG). With the use of GIS technology and from an ecological point of view, an optimal allocation scheme of land resources is constructed and applied to guide the adjustment of land resources. Given this scheme, we have calculated that the area of land suitable for forest and shrubs without greening is 2256 km2. Simultaneously, acting on the layout of the TNG project, afforestation site types are prepared and improved. Soil types, microrelief, salinity and underwater levels are combined as major classification factors and irrigation conditions as a reference to classify sites into eight types. In this way, land suitable for forest and grass is afforested given particular planting patterns. Finally, by overlaying this forestry site type map with the TNG plan map, some suggestions and strategies are proposed and used to direct the TNG project. An ecological oasis of the Yellow River Delta should be the result.

Impact of climatic and soil conditions on environmental fate of atrazine used under plantation forestry in Australia

We studied the leaching and dissipation of atrazine (2-chloro-4-ethylamino-6-isopropylamino-1, 3, 5-s-triazine) and its two principal metabolites (desethylatrazine and desisopropylatrazine) for more than two years through soil profiles at five forestry sites across Australia (representing subtropical, temperate and Mediterranean climatic conditions with rainfall ranging from 780 to 1536 mm yr −1). Following atrazine applications at local label rates, soil cores were collected at regular intervals (up to depths of 90–150 cm), and the residues of the three compounds in soil were analysed in composite samples using liquid chromatography. Bromide was applied simultaneously with atrazine to follow the movement of the soil water. While bromide ion rapidly leached through the entire profile, in most cases the bulk of atrazine, desethylatrazine and desisopropylatrazine remained in the top 45 cm of the soil profile. However, a small fraction of residue moved deeper into the soil profile and at a subtropical site (Toolara) trace levels (ng L −1) of atrazine and one of its metabolites (DEA) were detected in perched groundwater located at a depth of 1.8 m. Data on the total residues of atrazine in soil profiles from all sites except the Tasmanian site fitted a first-order decay model. The half-life of atrazine in surface soils at the subtropical sites (Toolara and Imbil) ranged from 11 to 21 days. Four separate applications of atrazine at Toolara resulted in a narrow range of half-lives (16 ± 3.6 days), confirming relatively rapid dissipation of atrazine under subtropical conditions (Queensland). In contrast, a prominent biphasic pattern of initial rapid loss followed by very slow phase of degradation of atrazine was observed under the colder temperate climate of Highclere (Tasmania). The data showed that while its 50% (DT 50) loss occurred relatively rapidly (36 days), more than 10% of herbicide residue was still detectable in the profile even a year after application (DT 90 = 375 days). The rate of dissipation of atrazine at warm subtropical Queensland sites (Imbil and Toolara) was 2–3 times faster than sites located in colder climate of Tasmania. The marked contrast in DT 50 values between subtropical and temperate sites suggest that climatic conditions (soil temperature) is one of the key factors affecting atrazine dissipation. At the Tasmanian site, the combination of leaching of the herbicide in subsoil and slower microbial activity at cooler temperatures would have caused a longer persistence of atrazine.

The Effects of Forestry Site Preparation on Mountain Beaver Demographics and Associated Damage to Tree Seedlings

Abstract Timber resources are a vital part of the economy in the Pacific Northwest, yet reforestation efforts are often hampered by animal damage. Understanding the factors that influence seedling damage can assist managers in implementing appropriate techniques to reduce species-specific damage. I radio-collared and monitored mountain beavers (Aplodontia rufa) from preharvest to seedling planting to determine the impacts of forest management practices on demographics. In addition, I monitored Douglas-fir (Pseudotsuga menziesii) seedlings on 28 plots on two harvest units (Vesta and Schoolhouse) to determine the effects of chemical site preparation on mountain beaver foraging and subsequent seedling damage. Mountain beaver densities differed between silvicultural treatments (F3,39 = 3.58, P < 0.02), although reproductive success did not (χ2 = 0.14, df = 1, P = 0.70). Larger mountain beaver home ranges were documented in the mature timber compared with those following harvest. Home ranges were also larger in the chemical site preparation portion of the unit (mean = 3.37 ± 0.9 ha) than in the nontreated portion of the unit (mean = 0.82 ± 0.17 ha) on Vesta. Herbicide treatment did not promote seedling damage on either unit. Vegetation does not appear to be the only factor influencing mountain beaver movements and seedling damage. Availability of water is very important for mountain beavers and may also influence their foraging choice, as well as contributing to their increased movements in mature timber (reduced groundwater) versus clearcut areas. Understanding the effects of vegetation on population demographics and subsequent seedling damage may allow for initiating a nonlethal management method using alternative forage.

Influence of forest cover and herbaceous vegetation on the microbiological and biochemical properties of soil under Mediterranean humid climate

The effects of different Mediterranean vegetation cover on the biological and biochemical quality of soil is not well understood. The aim of this work is to evaluate the effects that different types of vegetation (forestry plots, mainly dominated by Spanish black pine ( Pinus nigra Arn. ssp salzmannii) and herbaceous plots, where overstorey density is lower and natural herbaceous percentage is higher than in forestry plots) have in the biological properties of soil in Mediterranean humid climate. The impact of these plant communities on the biological soil quality was determined by several sensitive parameters related to the microbial activity of the soil such as soil respiration and some enzyme activities (urease, phosphatase and dehydrogenase). Development of vegetation (herbaceous and pines) was also determined and correlated with microbiological and biochemical indicators. Organic matter content in herbaceous sites was significantly higher than in forestry sites, ranging from 5.27 to 6.70 g 100 g −1 in herbaceous sites to 1.64–2.81 g 100 g −1 in forested areas. Herbaceous sites showed higher values of basal respiration and dehydrogenase activity than pine areas. However, the decrease of organic carbon content in pine areas led microbial activity enrichment per unit of carbon. These results conclude that vegetation cover significantly impacts soil microbial processes in Mediterranean humid climates, herbaceous vegetation having a more positive influence than forest vegetation on the biochemical and microbial activity of the soil, principally due to the higher accumulation of organic matter from plant remains.

Approaches to utilising QuickBird data for the monitoring of NATURA 2000 habitats

The implementation of standardised methods for the monitoring of NATURA 2000 sites in Europe is still a key topic in environmental research. Effective, economically priced and, as far as possible, automated applications are required. Rapidly developing sensor technology together with advanced image processing methods offer new possibilities for application of remote sensing data to NATURA 2000 monitoring. The studies presented here combine commonly available GIS data, such as Biotope Type Maps or Forestry Site Maps with remote sensing classifications of the very high spatial resolution (VHSR) QuickBird sensor. Two knowledge-based approaches under inclusion of a priori object-based information are utilised to detect the extent of habitats as well as their quality according to the German NATURA 2000 mapping guidelines. While one method used a segmentation of forested sites in Bavaria (southern Germany), the second technique applied available objects to classify heathland habitats in the Brandenburg Region (northern Germany). The results were subsequently compared, in close cooperation with local environmental authorities, with habitats mapped terrestrially for NATURA 2000 management plans. These results indicate that different remote sensing methods can be a valuable support for terrestrial mapping. Woodland habitats can be detected and specific NATURA 2000 quality parameters (e.g., percentage of natural forest types) are recognisable. In the case of heath-dominated sites, terrestrial mapping can even be replaced by remote sensing of certain habitat types for which it is also possible to obtain adequate measures of quality. Having evaluated the quality of forest and heathland NATURA 2000 habitats, two general challenges when implementing the guideline regionally could be indicated. Firstly, the very general scope of the Habitats Directive contradicts to specific local protection purposes. Secondly, the protection aims given for NATURA 2000 areas are very static. The Directive could be improved by adapting existing management and conservation strategies to pro-actively respond on likely anthropogenic influences.

Hydraulic Core Extraction: Cutting Device for Soil–Root Studies

A critical objective of belowground research is to collect and process representative soil samples. Mechanical devices have been developed to quickly take soil cores in the field; however, techniques to rapidly process large‐diameter soil cores are lacking. Our objective was to design and construct a soil extraction–cutting system that could effectively reduce processing time. Soil cores were extracted from large diameter steel core tubes using a custom hydraulic cylinder device that vertically pushes the soil core to a desired depth increment before cutting in a horizontal direction with another hydraulically driven device. As many as eight large cores per hour could be processed with this system. This system has been effectively used in processing soil samples from both agricultural and forestry sites to meet desired experimental goals.

Exotic flora dependence of an unusual Brazilian propolis: The pinocembrin biomarker by capillary techniques

Significant amounts of pinocembrin (>10%), a dihydroxy-flavanone, was found in the composition of an unusual brand of a subtropical Brazilian propolis. Incidentally, this sealing material was obtained from hives surrounding a large forestry site based on a single exotic flora, namely poplar ( Populus sp.). Examination of the different botanical parts of poplar revealed the buds as the main source of the flavanone. Techniques used for the establishment of the chemical correlation between the propolis brand and the poplar buds were TLC/densitometry, capillary GC–MS in the e.i. mode, and CZE with DAD monitoring. Since color enhancement after Al 3+ complexation applies just for more hydroxylated flavonoids, the alternative techniques herein applied were of value for pinocembrin detection and estimation. Analytical data indicated the dominance of the main phenolic pinocembrin biomarker as well as the presence of other related flavonoids in the botanical source and in the propolis derived thereof.

Surveys for Phytophthora ramorum in the Czech Republic1

The State Phytosanitary Administration (SPA) of the Czech Republic has been conducting an official survey for Phytophthora ramorum since 2003. A single outbreak of P. ramorum was detected by the SPA on guelder rose (Viburnum bodnantense) in autumn 2003 during a phytosanitary inspection in an ornamental nursery made on the request of owner of the nursery as he had noticed plants of Viburnum bodnantense withering. The infested lot consisted of 15 plants, which were imported from Italy into the Czech Republic at the end of April in 2003. A post‐entry inspection was carried out at the place of destination just after arrival and no visual symptoms were seen at that time. The lot was destroyed by the owner of the nursery immediately after the sampling. A survey was carried out by the SPA in all nurseries in which host plants coming from the same origin as the infested plants had been planted. No other outbreak was found. Phytosanitary inspections were carried out in ornamental nurseries and garden centres, public parks and forestry sites. No outbreak was detected in 2004 (451 visual inspections) and 2005 (522 visual inspections). The status of Phytophthora ramorum in the Czech Republic is: absent, one isolated outbreak linked to an imported consignment was eradicated.

Poverty alleviation through community forestry in Cambodia, Laos, and Vietnam: An assessment of the potential

Abstract Introduced (as compared to traditional) models of community forestry have developed rapidly in Cambodia and Laos in the last decade, and were recently begun in Vietnam after a pilot phase. What is the potential of these community forestry models to deliver livelihood improvements to participants? This is an important question for two reasons. First, some donors are placing high hopes on community forestry to support poverty alleviation in the Mekong Region. Second, community forestry has generally under-performed in poverty alleviation worldwide. Existing and planned models must be examined to understand to what extent they can fulfill their goals and how they can be improved. Among various theoretical preconditions for successful poverty alleviation through community forestry, this article focuses on two: (1) the degree to which poverty alleviation is a guiding force in the establishment and implementation of community forestry; and (2) the compatibility of government commitment to poverty alleviation through community forestry with other goals being pursued by the government. How do the three case study countries perform with respect to these preconditions? With respect to the first precondition, it is found that although all three country programs now espouse poverty alleviation as a key goal, other state goals (e.g., compliance with donor organization recommendations, decentralization, devolution, resource conservation) were the guiding motivations in the establishment and early implementation of the programs. With respect to the second precondition, programs in all three countries are at least partly undermined by a tendency to favor government, the military, and concessionaires in the appropriation of timber rents, and to exclude people living in or near forests from access to these rents. However in each country there are factors that potentially enable a turn toward poverty alleviation through community forestry. In Cambodia there is less central government control than in Laos or Vietnam. Laos has a high level of forest resources per capita. Vietnam has an exceptionally strong record in poverty alleviation that can be linked to its emerging community forestry program. The article recommends three core policies to fully realize the potential of poverty alleviation through community forestry: (1) control illegal logging and forest sector corruption; (2) locate community forestry sites where there are abundant forests; and (3) boost forest income through improved access rights, tenure, and benefit sharing, and removal of anti-poor regulations.

Plow Power Requirements for Forestry Site Preparation

In this field study, data were collected to determine power requirements required by a trailing site preparation plow and the magnitudes of dynamic forces experienced by a plow during normal operation and during impact with stumps or other obstructions. Drawbar pull data were collected from five different tillage treatments on a recently harvested loblolly pine (Pinus taeda) site in central Alabama. The five treatments were: 1) a coulter, ripping shank, and four bedding disks; 2) a coulter, ripping shank, and two bedding disks; 3) a coulter and ripping shank; 4) a coulter alone; and 5) a ripping shank alone. A 330 kN [75 000 lb] capacity tension load cell was used to measure the drawbar load, a GPS receiver recorded tractor speed, four direct current displacement transducers (DCDT’s) monitored the depth of the disks, and two optical tachometers measured the speed of the tractor’s front and rear drive shafts. Each treatment produced significantly different drawbar loads (to alpha levels less than 0.001). The resulting mean loads were 46.0 kN [10 300 lb], 33.5 kN [7530 lb], 31.5 kN [7080 lb], 15.8 kN [3560 lb], and 43.4 kN [9760 lb] for treatments one through five, respectively. Maximum recorded drawbar load during a collision with a stump was 338.9 kN [76 188 lb].

Diversity of ectomycorrhizae on experimentally planted Douglas-fir seedlings in variable retention forestry sites on southern Vancouver Island

Studies were done on Vancouver Island of ectomycorrhizal (EM) communities at four distances (5–45 m) from isolated forest patches in three second-growth (SG) and three old-growth (OG) Douglas-fir sites subject to variable retention harvesting. We tested the hypothesis that retention of mature trees enhances colonization and diversity of EM fungi on seedlings planted in adjacent areas. In total 41 EM morphotypes were described, with mean diversity of 3.47 morphotypes and root colonization of 62% per seedling. Overall, root colonization declined with distance (72% at 5 m vs. 52% at 45 m), as did EM diversity (4.7 at 5 m vs. 2.9 at 45 m). For individual sites, the distance effect was significant for root colonization at four sites and for EM diversity at three to four sites. This suggests that variable retention is important for the recovery of ectomycorrhizal biota in harvested sites. Seedling root colonization was significantly lower in SG sites than in OG sites. Though EM diversity did not differ with stand age, OG sites had potentially more total (34) and unique (14) EM morphotypes than did SG sites (total 27, unique 7). Differences with stand age might be related to the relative abilities of EM fungi to disperse to regenerating second-growth forests.Key words: variable retention silviculture, ectomycorrhizae ecology, Douglas-fir seedlings, old growth, second-growth forests.

Armillaria Species Infesting Vineyards in Northwestern Spain

Twelve vineyards in northwestern Spain were studied to assess the incidence of white root rot during 1995 and 1997. In both years, diseased plant material was collected and the Armillaria species responsible was identified on the basis of compatibility testing. Subsequently, restriction fragment length polymorphism (RFLP) analysis of the intergenic spacer region of the nuclear ribosomal RNA gene cluster was used to identify Armillaria species in another 45 symptomatic samples submitted for diagnosis from this area. During 1995, 9 of the 12 vineyards showed white root rot, although in eight cases less than 2% of plants were affected; in the remaining vineyard 17% of plants were diseased. During 1997, 10 of the 12 vineyards were affected and three showed a marked increase in the number of plants with white root rot (to 43%, in the vineyard in which 17% were affected in 1995). The compatibility method detected Armillaria mellea in samples from 10 of the 12 vineyards, and Armillaria gallica in samples from two vineyards. RFLP–PCR analysis detected four restriction patterns corresponding to A. mellea, A. gallica and Armillaria cepistipes: patterns mel 1 (A. mellea, 71% of samples), mel 2 (A. mellea, 18%), gal 1 (A. gallica, 9%), and cep 1 (A. cepistipes, 2%, i.e. a single sample). This is the first report of A. gallica and A. cepistipes infecting Vitis spp. The presence of these two Armillaria species may be related to the fact that the vineyards from which they were isolated were located on cleared forestry sites.

Reclamation of roads and landings with balsam poplar cuttings

Balsam poplar ( Populus balsamifera L.) can easily be grown when planted as dormant, unrooted cuttings. The first part of this research project consisted of a greenhouse study to identify the best combination of pre-planting treatments to maximize rooting of hardwood cuttings for large-scale greenhouse propagation. Eighty-four treatment combinations were tested on 10 cm-long cuttings, including seven soaking lengths of time (0, 1, 2, 3, 4, 5 and 14 days), three dips (none, powder and liquid rooting hormone), two collection dates (fall and spring), and two cutting selections (average trees and a superior clone). Secondly, we tested the performance of unrooted cuttings on typical forestry sites lacking natural regeneration, using 30 cm-long cuttings and full-length whips (>60 cm). Three pre-planting treatment combinations were used (soaking for 1 or 3 days, or 3 days with a dip in rooting hormone). Other factors tested were two collection dates (fall and spring), two cutting selections (average trees and a superior clone), two storage methods (stored as full whips or cut to size), and two cutting locations (basal or top 30 cm of stools).

Atmospheric deposition at four forestry sites in the Alpine Region of Trentino- South Tyrol, Italy

The Trentino-South Tyrol Region is located in the southern part of the Alpine Chain. The territory is largely mountainous with crystalline rock formations dominant in the north and limestone in the south-east. Most of the land is open to the climatic and atmospheric influence of the River Po, via the mainly N-S oriented valley of the River Adige. The forestry authorities of the region have since the 80s been making an annual assessment of forest decline, particularly as regards parasite attacks, defoliation and crown discoloration, and have found the situation to be better than in most other parts of Europe. The region's forest protection policy is administered by the two provinces of Bolzano/Bozen and Trento in the framework of the European convention on Long Range Transboundary Air Pollution (UN-ECE LRTAP); each province operates two forestry sampling permanent plots. The sites are all constituted according to the standard recommendations, and are located in the central part of the region along the Adige Valley, where most of population live and where most of the agriculture and industry is. Two of the areas are in coniferous stands of the typical Alpine forest, mainly composed of Norway spruce; the other two are located in deciduous stands (both high forest and coppice) and are closer to the urban centres than the first two. Concentration and deposition values for the main ionic components in bulk, wet, throughfall, stemflow and soil water are given separately for the four monitoring sites, with reference to the period 1996- 1999. The major acidifying component in atmospheric precipitation is still sulphate, but as other investigations confirm, the relative importance of the nitrate input is increasing all the time. The effect of these changes is probably positive for terrestrial ecosystems in the short term because of the decrease in total acidifying input and the increase in inorganic fertilisation. The absence of major "forest" damage, outlined in the annual forest damage survey reports issued by the forestry authorities (internal reports since 1983), suggests that the current atmospheric acidic load is in balance with the stational and climatic conditions.

Public Preferences for Nontimber Benefits of Loblolly Pine (Pinus taeda) Stands Regenerated by Different Site Preparation Methods

Abstract This study assesses public preferences for nontimber benefits of loblolly pine (Pinus taeda L.) stands regenerated 15 yr earlier using different site preparation treatments at national forest and industrial forestry sites. Treatments tested on the Tuskegee National Forest were none, chainsaw felling, tree injection, and soil-active herbicide. At the industrial site, experimental treatments included chopping and burning, followed by no additional treatment, woody control, herbaceous control, and total control. Both sites were planted with loblolly pine seedlings. Two user surveys employing color photography were conducted to identify the respondents' ratings of the young stands in terms of perceived nontimber benefits, including aesthetics, picnicking, hiking/walking/cycling, camping, hunting, bird watching, wildlife habitat, and biodiversity. The site preparation treatments were rated without consideration of the treatment cost and its distribution. Results indicate that the respondents preferred the minimal or no treatment options at both study sites. The respondents' preferences were significantly affected by their age, education, income, employment status, and living distance from the experimental sites, but not gender. Respondents considered wildlife habitat as the most important benefit and hunting as the least important. Most of the respondents also felt that both national forests and industrial forests should be managed for nontimber as well as timber products. South. J. Appl. For. 24(3):145-149.

Soil wettability in forested catchments in South Africa; as measured by different methods and as affected by vegetation cover and soil characteristics

Earlier studies in South Africa had shown that water repellency in the soils of timber plantations was associated with a greater risk of overland flow and soil erosion on mountain slopes. This paper reports on a follow-up study to determine how prevalent water repellent soils are in the forestry areas of South Africa, and to what extent this phenomenon is associated with specific vegetation types. Soils from a representative series of forestry sites around South Africa were sampled from beneath each genus or plantation type and the range of local vegetation types. These soils were dried at low oven temperatures and then subjected to a series of tests of soil wettability, namely, water drop penetration time, infiltration rate, critical surface tension and apparent advancing contact angle as determined by the equilibrium capillary rise test.Water repellency is common in dried soils from timber plantations. The dominant variation in repellency is explained by the different vegetation types: soils beneath eucalypts are most repellent, followed by those beneath wattle (Acacia species), indigenous forest and pine. Soils beneath grassland and fynbos scrub were least likely to show repellency, perhaps because regular fires remove plant litter and thus the potential for hydrophobic substances to develop. Soil characteristics explained very little of the variation in repellency. Organic carbon content was weakly correlated with higher repellency, but organic carbon content and soil texture added little explanation to models that first accounted for variation in vegetation type and point of origin. These results are broadly the same regardless of which method of measuring repellency was used. However, the critical surface tension test was far superior to the others in terms of information gained, speed, efficiency and statistical utility of the resultant scores.

A field comparison of strategies for the control of Chilean needle grass in Hawke's Bay

Management strategies to control Chilean needle grass comprised two re-grassing regimes using the competitive pasture species cocksfoot, combined with lax grazing using sheep or young cattle, no attempted management, and forestry. The presence of Chilean needle grass and cocksfoot densities were assessed by examining 50 mm turf cores taken annually from 1994, and from the forestry site since 1997. There was a strong inverse relationship between Chilean needle grass frequency of occurrence and the sown cocksfoot density. The establishment of cocksfoot and its promotion by lax grazing reduced the frequency of occurrence of Chilean needle grass from 60% in October 1994 to 9% in 1998. Although cocksfoot suppressed Chilean needle grass, eradication appears unlikely or at least a long-time process. In the young pine plantation, Chilean needle grass grew unchecked with 24 and 27% of the cores containing Chilean needle grass in 1997 and 1998 respectively. Under forestry the Chilean needle grass seed bank is likely to develop until canopy closure. Keywords: Chilean needle grass, cocksfoot, Dactylis glomerata, forestry, grazing, Pinus radiata, Stipa neesiana, weed control

Simulation of CO 2 budget and ecological implications of sugi ( Cryptomeria japonica) man-made forests in Japan

A compartment model, including removal of organic matter in a forest ecosystem, is developed to describe matter cycling and net CO 2 flux of the ecosystem especially of managed forests. The model consists of five carbon stocks: atmosphere, foliage, woody matter, underground matter, and dead organic matter in the soil. Employing appropriate values of ecophysiological parameters in the model and simulation of man-made sugi ( Cryptomeria japonica D. Don) plantation forests shows that these forests have high growth potential with a maximum total phytomass of over 750 t ha −1 in dry matter basis. When the typical pattern of thinning regime for sugi plantation forests in Japan is applied to the present model, the simulated forest biomass developments compare well with mensuration data from various forestry sites. The CO 2 balance between the sugi forest ecosystem and the atmosphere reveals a net CO 2 fixation of 49.38 million ton CO 2 year −1 by all sugi forests of 4.509 million ha in Japan during 1986. Assuming that all the forest in Japan is to be changed to sugi plantation, the potential CO 2 sequestration by the forests will be improved 40% at most. Examining the forest development with various patterns of removal shows that a fixed rate of organic matter removal has a possibility to lead to extermination of the ecosystem, whereas proportional removal never cause ecosystem death. The present model makes it possible to examine forest development in terms of matter cycling with tree removal, and has further ecological implications for forest conservation and management.

Managing the threats of afforestation in reservoir catchments

Until recently the development of forestry sites in the United Kingdom paid little regard for their impact on the aquatic environment, with the result that there have been several instances of major damage to drinking water reservoirs, two of which are described briefly. In order to improve the formal planning of future forestry work the water industry initiated development of a joint Working Group, with the objective of producing Guidelines for use throughout the forest industry. Development of these Guidelines are described, as is the basic content of the final document which now forms an important reference work for the industry, both for the development of new forest sites and for restocking following felling of the first rotation. Concerns remain regarding the continuing management of sites, particularly with regard to artificial fertilisation and its potential to encourage algal blooms in standing waters: close liaison will be necessary between water and forestry interests.