Gap evapotranspiration and drainage fluxes in a managed and a virgin dinaric silver fir–beech forest in Slovenia: a modelling study

The monthly water balance in gaps in a managed Dinaric silver fir–beech forest and a virgin forest remnant located in SE Slovenia was modelled using a capacity water balance model for two growing seasons. Two gaps of different size (ca. 0.07 and 0.15 ha) were selected in each forest and plots for soil moisture monitoring were established in each gap (2–4) and in the surrounding forest (2–3). We report on the modelled actual evapotranspiration (AET) and potential evapotranspiration (PET) and drainage fluxes (DF) from the rooting zone at the plots. Precipitation over the 2001 growing season (May–October) was considerably drier than average and that for 2002 growing season was wetter than average. Modelled AET for the 2001 growing season varied between 88% and 96% of PET for the managed forest plots and between 90% and 100% for the virgin forest plots. The values for the gap plots varied between 87% and 100% at the managed forest site and between 92% and 96% for the gaps in the virgin forest site. Monthly AET values declined to 57–59% of PET at plots in the centre of the gaps in the managed forest site and to 63–74% in the gaps in the virgin forest site (July), indicating that the highest drought stress occurs in gap centres. For 2002 growing season, AET for all plots was 100% of PET. Modelled DF values in 2001 were 13–35% of rainfall for plots in the gap centres and 12–16% for plots in the forest at the managed forest site. On an average, gap DF values were 20% (154 mm) higher than the forest plot values. DF values in 2002 were similar for all plots at the managed forest site, 31–33% of rainfall. At the virgin forest site, 2001 growing season, DF values varied between 12% and 30% of rainfall at the forest plots and between 12% and 32% at the gap plots. In 2002, DF values for all plots in the virgin forest site varied between 24% and 38% of growing season rainfall. The varying development of vegetation and forest in the gaps of the virgin forest remnant resulted in more variable evapotranspiration and DF during the drought year 2001, with values not as clearly related to distance from the gap centre as in the managed forest site.     

The use of forest information in timber sales planning – a case study in a Swedish forest-owning company

Interactions between value-creating activities are vital to increasing product value. Information sharing is a cornerstone of such interactions. For a forest-owning company with the primary objective to be leading in selling roundwood to forest industries, it appears therefore crucial that the sales people within a forest company have up-to-date knowledge about the forest in planning their sales, and that the forest knowledge is presented in a format that is suitable for them. To investigate if this is the case, a study was conducted at Sveaskog, a large Swedish forest-owning company. Semi-structured interviews were conducted with respondents from different levels in the organization. The results show that most sales managers did not directly use the knowledge about the forests when planning their sales; instead, they relied on historical data and had low trust in the knowledge presented in the tactical forest plan. The study pinpoints the organizational obstacles for using forest information in sales planning. These obstacles need to be addressed if more sophisticated information made available through new technology is to be utilized.     

Fractal features and infiltration characteristics of the soil from different land uses in a small watershed in a rocky,mountainous area in Shandong Province

We studied infiltration and fractal mechanisms on sloping farmlands in a small watershed in Shandong Province in the rocky mountain areas of northern China.We studied soil fraction and soil water retention curves,and developed a soil infiltration model to analyze its quantitative relationship with soil particle size and pore dimensions under four types of land use,including sloping farmland,abandoned land,natural forest,and forest plantation(Malus pumila,Crataegus pinnatifida).Soil stability infiltration rate ranked as sloping farmland>abandoned land>natural forest>forest plantation.The sequence of soil particle size and pore dimension ranked as natural forest>forest plantation>abandoned land>sloping farmland.There were significant positive correlations between soil particle size and pore dimension,and both were positively correlated with the percent volume of silt and clay.They were negatively correlated with soil infiltration rate.The Horton model and the power function model were more suitable for simulating soil infiltration and the infiltration rate.We concluded that the soil in this area displayed typical fragments of rocky mountainous regions due to the loss of silt and clay caused by cultivation on sloping farmland.The uniformity and fractal dimensions of soil particle sizes and pore distribution decreased,thereby enhancing soil infiltration capacity and decreasing soil water retention capacity.     

Soil respiration in a natural forest and a plantation during a dry period in the PhilippinesOA

Climate change is forecast to increase the frequency of extreme hot temperatures and dryer days and is anticipated to have profound impacts on the global carbon budget.Droughts are expected to alter soil respiration(R_s) rates,but the scarcity of data preclude a reliable estimate of this response and its future trajectory.A field experiment using an automated soil respiration machinery(LI-8100A) was conducted in a natural forest and a plantation during a dry period in the Philippines,w...     

Soil quality in a pecan–kura clover alley cropping system in the Midwestern USA

Intercropping alleys in agroforestry provides an income source until the tree crop produces harvestable yields. However, cultivation of annual crops decreases soil organic matter and increases soil erosion potential, especially on sloping landscapes. Perennial crops maintain a continuous soil cover, increase water infiltration, reduce soil erosion, and improve overall soil quality. The objective of this on-farm study was to assess the effects of a perennial legume, kura clover (Trifolium ambiguum M. Bieb.), on soil quality in a recently established pecan (Carya illinoinensis Wangenh. C. Koch) orchard. The pecan-kura clover agroforestry practice was established on deep loess soils of the Missouri River hills landscape. These silt loams are on 2–20% slopes and can be highly erosive. Kura clover, introduced as the alley crop 5 years after pecan planting, was selected based on its perennial growth habit, nitrogen-fixing ability, winter hardiness, high forage quality, and soil conservation properties. Kura clover was seeded in 2001 and harvested for hay annually beginning 2003. Soil quality indicators of total organic C, total N, water-stable aggregates, and selected soil enzymes were determined on surface soil samples collected annually after kura clover establishment. Soil organic C and activities of soil enzymes increased compared with cultivated and grass pasture control soils by the eighth year of establishment. Water-stable aggregation improved by 50% and surface soil shear strength improved significantly (P < 0.05) in alleys compared with control sites. Results illustrate that kura clover as the alley-cropped component improved soil fertility and biological activity through increased organic matter and improved soil structure, and yielded high quality forage valuable for the cattle-feeding operation. Kura clover maintained or improved soil quality, reduced soil erosion potential, and benefited pecan growth by providing a source of soil nitrogen and improving soil structure for adequate water infiltration and aeration.     

Agroforestry systems in the rural landscape – a case study in Garhwal Himalaya, India

A mid altitude (700–1200 m amsl.) village in Garhwal Himalaya was analysed in terms of energy and economic efficiency of different land use-land cover types constituting the landscape. Simultaneous agroforestry, sequential agroforestry, home garden and community forests accounted for 27.47%, 27.47%, 1.1% and 43.96% of the total geographical area of the village. Simultaneous agroforestry is the traditional land use involving substantial input of manure derived from forest litter and animal excreta and was practised on terraced slopes in private ownership. Tree cover in this system was represented by nine species with total average density of 390 trees ha⁻¹, Grewia optiva and Boehmeria rugulosa being the most dominant. Sequential agroforestry system involving slash-burn practice and cultivation on unterraced slopes without tillage and manuring was an illicit land use on community lands where forestry land use is desirable as per the government policy. Per ha annual energy input in simultaneous agroforestry system was 305267 MJ compared to 279 MJ in sequential agroforestry and 27047 MJ in home garden. In monetary terms, highest per ha annual output was obtained from simultaneous agroforestry (Rs 25370, Rs 35 = US$1) followed by home garden (Rs 18200) and sequential agroforestry (Rs 9426). Local food, fodder and fuelwood production was in excess of the local consumption. While most of the surplus food was stored, surplus fodder and fuelwood were sold for cash. Production in simultaneous agroforestry system in private lands was sustained with substantial biomass and nutrient inputs from the community and government forests. Land use-land cover changes in the region are driven by the interaction of ecological, policy and human factors. It is concluded that present policy of treating forests and agriculture as closed and independent ecological or production systems needs to be replaced by an integrated land use policy. This revised version was published online in August 2006 with corrections to the Cover Date.     

Factors influencing the variability of Mg, Ca and K in waters of a mangrove creek in Bragança, North Brazil

Sodium, potassium, magnesium, calcium and physicochemical parameters were monitored for one year in a mangrove tidal creek near Bragança, North Brazil, to determine their tidally induced and seasonal variations and the main parameters controlling the concentration of these cations. On a daily basis, cation concentrations showed a strong tidal rhythm due to the mixing of estuarine and mangrove waters. Mean concentrations were highest at the end of the dry season (December 1996) and lowest (April 1997) towards the end of the rainy season. Average values over one year were: Na+ = 329± 118mM, K+ = 6.9±2.5mM, Mg++=37 ±14 mM and Ca++= 6.9±2.4mM. Dissolved oxygen concentration was higher during the dry season due to enhanced aquatic primary production, with a maximum daily average value of 8.5mg/L in July 1996, and a minimum value of 4mg/L in June 1997. Cation concentrations were transformed relating them to the respective average values in standard seawater at salinity 35. Although cation concentrations and salinity tightly correlated, this standardization showed that the concentrations of K+, Ca++ and Mg++ did not depend solely on salinity and reflected the seasonal variation in aquatic primary production. It also allowed the discrimination of their sources (marine, riverine and groundwater). Thermodynamic equilibrium calculations indicate that phytoplankton may be regulating the concentration of these cations in the water column indirectly by inducing precipitation through pH increase and directly through metabolic uptake.     

Expression of a Carrot Antifreeze Protein Gene in Escherichia coli

The recombinant expression vectorpET43. lb-AFP, which contains full encoding region of a carrot 36 kD antifreeze protein (AFP) gene was constructed. The recombinant was transformed into expression host carrying T7 RNA polymerase gene (DE3 lysogen) and induced by 1 mmol. L-1 IPTG (isopropyl-β-D-thiogalactoside) to express 110 kD polypeptide of AFP fusion protein.The analysis of product solubility revealed that pET43. 1b-AFP was predominately soluble, and the expressed amount reached the maximum after the IPTG treatment for 3 h.     

Water harvesting in a ‘runoff-catchment’ agroforestry system in the dry lands of Ethiopia

A major production constraint in arid and semiarid areas of Ethiopia is a lack of water for crop growth. Run off water can be harvested by channeling it into micro- catchments (MC) where it slowly infiltrates into the soil. The increased moisture provides more plant growth in these dry lands. An experiment using MC was conducted in eastern Ethiopia to study the growth of four multipurpose tree species intercropped with grass. Trees and grass were grown in 25 m² and 100 m² MC. Plant height, root collar diameter, and mortality rate of trees were determined 12 months after planting. Dry matter yield of grasses and trees were measured and nutrient analysis of plant tissues was determined. In a separate experiment the biomass of trees was determined after 2.5 years of continuous growth without grass competition. Soil moisture, organic matter, texture and bulk density of the soils were also determined. Mean tree height was 10% greater in the 100 m² than in the 25 m² MC. Root collar diameter and survival rate showed similar increase with 13% and 7.8% respectively. Acacia saligna and Leucaena leucocephala showed better growth in both plot sizes than the indigenous Acacia seyal and Acacia tortilis. The dry matter yield of grass (Panicum maximum) was over 12 tons/ha and 8 tons/ha in the 100 m2 and 25 m2 plots respectively. Soil moisture content was greater in MC than in control plots with no water harvesting structures with 31% and 24% during the wet and dry seasons respectively. The use of water harvesting can improve fodder production and carrying capacity of the dry lands of Ethiopia.     

Open woodland in Europe in the Mesolithic and in the Middle Ages: Can there be a connection?

In Grazing Ecology and Forest History F.W.M. Vera published his hypothesis that Europe's primeval vegetation was not closed forest but a more open, park-like landscape maintained by the grazing of large herbivores. The palaeoecological evidence has been re-examined a number of times, however, Vera's research and conclusions about more recent periods (ca. 500–1900 a.d.) have so far been neglected. These, nonetheless, are equally significant elements in the testing of the hypothesis, and deserve to be evaluated. It is argued in this paper that historical sources could be used in testing the hypothesis; however, analysis should concentrate on particular areas and periods and derive a synthesis from these. Vera mixes sources from many regions and periods in the same analysis, which therefore does not provide useful information about the hypothesis. Furthermore, Vera's analysis is based on the assumption that early medieval written sources depict a landscape that is in direct connection with the pre-Neolithic open vegetation, although in some early medieval landscapes domestic animals replaced the original large herbivores. He also claims that medieval coppices were formed straight out of this primeval vegetation. However, current landscape archaeological research shows that areas unaffected by human activity were virtually non-existent in the European lowlands by the Early Middle Ages, therefore early medieval Royal Forests and high medieval coppices were not formed out of primeval ‘wilderness.’ Because there is no direct connection between pre-Neolithic and medieval landscapes – although they can be analogous – the historical ecological evidence in Grazing Ecology and Forest History is irrelevant to the hypothesis. The hypothesis could only be tested if it were first proved that at a particular place the pre-Neolithic vegetation survived until the Early Middle Ages.     

Functional traits explain growth–mortality trade-offs in a mixed broadleaf-conifer forest in northeastern China

The trade-offs between tree growth and mortality are important indicators of the life-history strategies of species and have been demonstrated to be maintained by inherent fitness differences among species. There is a growing consensus that functional traits which inflect the ecological performances of individuals may be correlated with growth–mortality trade-offs within communities. In this study, the aforementioned trade-offs were detected and their relationships with the functional traits were examined, based on data collected in a typical temperate forested area in northeastern China. Principal components analyses were performed for growth–mortality trade-off relationships. The factor scores on the first principal component were used to represent the species’ positions at an axis of life-history variations among different species. Correlation and multiple regression analyses were performed for the purpose of detecting the relationships between functional traits and the growth–mortality trade-off. The results showed that there were significant trade-offs between the tree growth and mortality rates in the examined plot. Among the six functional traits which were considered, the H_max was found to have the strongest effects on the demographic rates and trade-offs. The observed negative effects on the tree growth and mortality rates suggested that the large species often grow more slowly and living longer, while species at small adult size grow fast but die easily. It was also observed that the specific leaf area and the leaf carbon content level were also very important to the growth and mortality trade-offs. The traits considered in this study explained 68% of interspecific variations in the species positions in the growth–mortality trade-off. In addition, wood density was found to show no effect on the trade-off. This was likely due to the fact that the density of the wood may influence the demographic rates more strongly during the early life stages of the trees. The results of discrimination analysis further confirmed the explanations abilities of the functional traits on the variations of life-history strategies among the species. Due to the fact that the relationships between the functional traits and the trade-offs were found to be relatively variable, it will be necessary to further consider other traits which are more closely and mechanistically linked to individual performances in future investigations, such as leaf life span, leaf tissue density, photosynthetic capacity, and dark respiration rates.

     

Fine roots refilling process in an artificial gap in a Picea mongolica forest

Picea mongolica is an endemic but endangered species in China. The spruce forest is only found in sandy forest-steppe ecotones. In this study, we examined the initial response of the quantity and refilling process of fine roots in an artificial canopy gap with a diameter of 36 m in a P. mongolica forest. Under the canopy, the fine root length densities of trees, shrubs and herbs were 2,622, 864 and 3,086 m·m–2, respectively. The fine root biomass of trees, shrubs and herbs were 148, 62 and 65 g·m–2, respect...     

Will changes in root-zone temperature in boreal spring affect recovery of photosynthesis in Picea mariana and Populus tremuloides in a future climate?

Future climate will alter the soil cover of mosses and snow depths in the boreal forests of eastern Canada. In field manipulation experiments, we assessed the effects of varying moss and snow depths on the physiology of black spruce (Picea -mariana (Mill.) B.S.P.) and trembling aspen (Populus tremuloides Michx.) in the boreal black spruce forest of western Québec. For 1 year, naturally regenerated 10-year-old spruce and aspen were grown with one of the following treatments: additional N fertilization, addition of sphagnum moss cover, removal of mosses, delayed soil thawing through snow and hay addition, or accelerated soil thawing through springtime snow removal. Treatments that involved the addition of insulating moss or snow in the spring caused lower soil temperature, while removing moss and snow in the spring caused elevated soil temperature and thus had a warming effect. Soil warming treatments were associated with greater temperature variability. Additional soil cover, whether moss or snow, increased the rate of photosynthetic recovery in the spring. Moss and snow removal, on the other hand, had the opposite effect and lowered photosynthetic activity, especially in spruce. Maximal electron transport rate (ETR(max)) was, for spruce, 39.5% lower after moss removal than with moss addition, and 16.3% lower with accelerated thawing than with delayed thawing. Impaired photosynthetic recovery in the absence of insulating moss or snow covers was associated with lower foliar N concentrations. Both species were affected in that way, but trembling aspen generally reacted less strongly to all treatments. Our results indicate that a clear negative response of black spruce to changes in root-zone temperature should be anticipated in a future climate. Reduced moss cover and snow depth could adversely affect the photosynthetic capacities of black spruce, while having only minor effects on trembling aspen.     

Analyses of stand structure as a tool for silvicultural decisions — a case study in a Quercus petraea — Sorbus torminalis stand

The study applies structural indices using the example of an oak (Quercus petraea (Matt.) Liebl.) — chequer tree (Sorbus torminalis (L.) Crantz) stand in order to derive recommendations for the silvicultural treatment of Chequer trees. The investigated stand, located in the northern part of Bavaria, comprises eight tree species and four shrub species. Various indices were used to analyse the stand structure and the crown coverage frequency. It was shown that chequer trees, which are presently of high economic interest, are strongly oppressed in the upper layer and almost completely missing in the lower layers of the stand. The possible reasons for this finding and alternatives for the further management of the stand are discussed. Persistent and repeated thinnings in order to ensure sufficient crown development of the chequer trees seem to be essential for their survival.     

Carbon stocks in a 50‑year‑old Eucalyptus camaldulensis stand in Sicily,Italy

Eucalyptus stands in semi?arid areas may contribute to enhance carbon (C) stocks in both biomass and soil. However, the limited information available is mainly focused on short?rotation plantations. In this study, the above? and below?ground C pools in five 50?year?old Eucalyptus camaldulensis Dehnh. stands planted on Miocenic evaporitic deposits in Sicily, Italy, with a xeric and thermic pedoclimate, were measured. Above?ground biomass was determined by partitioning and weighing branches, stem and leaves. Below?ground C pools included the determination of litter, root biomass, and soil organic and inorganic C. In terms of the above?ground biomass, the E. camaldulensis stand accumulated on average 116?Mg ha?1 corresponding to 55?Mg C ha?1. Below?ground biomass consisted mainly of larger roots, followed by fine and medium roots (33?Mg ha?1 corresponding to 14?Mg C ha?1). Litter accumulation on the soil surface accounted for 13?Mg ha?1 corresponding to 5?Mg C ha?1. The amount of C stored in soil was 554?Mg C ha?1, of which 75% was in organic form. Although E. camaldulensis is planted extensively throughout the Southern Hemisphere and tropics where it is managed over short rotations (c. 2–4 years), the results obtained from this study make this species important in terms of future afforestation planning for longer rotations due to its potential to sequester C, particularly in the below?ground components.     

Indigenous knowledge in a ‘modern’ sustainable agroforestry system—a case study from eastern Brazil

The case of an agroforestry farm in the coastal mountain area of the federal state of Bahia, Brazil, is used to highlight benefits of the integration of traditional knowledge into a scientifically based farming system. Special attention is given to the selection, combination and management of the crops cultivated. Working hypotheses on the rationale of some major measures are suggested and discussed from a synecological point of view. The results show that under the site conditions the forest garden provides cocoa yields without external inputs at a level which, in the surrounding cocoa plantations, can only be attained by the use of considerable amounts of fertilizer and pesticides.     

Biomass energy in industrialised countries—a view of the future

Biomass fuels currently (1994) supply around 14% of the world's energy, but most of this is in the form of traditional fuelwood, residues and dung, which is often inefficient and can be environmentally detrimental. Biomass can supply heat and electricity, liquid and gaseous fuels. A number of developed countries derive a significant amount of their primary energy from biomass: USA 4%, Finland 18%, Sweden 16% and Austria 13%. Presently biomass energy supplies at least 2 EJ year⁻¹ in Western Europe which is about 4% of primary energy (54 EJ). Estimates show a likely potential in Europe in 2050 of 9.0–13.5 EJ depending on land areas (10% of useable land, 33 Mha), yields (10–15 oven-dry tonnes (ODt) ha⁻¹), and recoverable residues (25% of harvestable). This biomass contribution represents 17–30% of projected total energy requirements up to 2050. The relative contribution of biofuels in the future will depend on markets and incentives, on continuous research and development progress, and on environmental requirements. Land constraints are not considered significant because of the predicted surpluses in land and food, and the near balance in wood and wood products in Europe.There is considerable potential for the modernisation of biomass fuels to produce convenient energy carriers such as electricity, gases and transportation fuels, whilst continuing to provide for traditional uses of biomass; this modernisation of biomass and the industrial investment is already happening in many countries. When produced in an efficient and sustainable manner, biomass energy has numerous environmental and social benefits compared with fossil fuels. These include improved land management, job creation, use of surplus agricultural land in industrialised countries, provision of modern energy carriers to rural communities of developing countries, a reduction of CO₂ levels, waste control, and nutrient recycling. Greater environmental and net energy benefits can be derived from perennial and woody energy cropping than from annual arable crops which are short-term alternative feedstocks for fuels. Agroforestry systems can play an important role in providing multiple benefits to growers and the community, besides energy. In order to ameliorate CO₂ emissions, using biomass as a substitute for fossil fuels (complete replacement, co-firing, etc.) is more beneficial from social and economic perspectives than sequestering the carbon in forests.Case studies are presented for several developed countries and the constraints involved in modernising biomass energy along with the potential for turning them into entrepreneurial opportunities are discussed. It is concluded that the long term impacts of biomass programmes and projects depend mainly on ensuring income generation, environmental sustainability, flexibility and replicability, while taking account of local conditions and providing multiple benefits, which is an important attribute of agroforestry-type systems. Biomass for energy must be environmentally acceptable in order to ensure its widespread adoptions as a modern energy source. Implementation of biomass projects requires governmental policy initiatives that will internalise the external economic, social and environmental costs of conventional fuel sources so that biomass fuels can become competitive on a ‘level playing field’.