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1.
《Scandinavian Journal of Forest Research》2012,27(2):113-121
Scots pine (Pinus sylvestris) and lodgepole pine (Pinus contorta) needle litters were compared in terms of nutrient composition and its change during decomposition. Initial nutrient composition differed between the species, with lodgepole pine needle litter having significantly higher concentrations of P, Mg and Mn. However, no difference was found for concentrations of N, Ca or K. Increases in concentrations of N, P and K during decomposition were significant in both litter types. For Ca the pattern of concentration changes followed a quadratic function as decomposition proceeded. Concentrations of Mg and Mn decreased in lodgepole pine needle litter. In Scots pine litter there was also an initial decrease, but it was followed by an increase in most incubations. For both Mg and Mn, changes in concentrations during decomposition differed significantly between species. In the late decomposition stages, concentrations of Mg and Mn became similar in both litter types. Nutrient concentrations generated by the models were compared with those of the humus (F and H) layer in the stands. The model was quite accurate in predicting concentrations of N and P for both species and the concentration of Mg for lodgepole pine. By contrast, it was not accurate in predicting concentrations of Ca and Mn. Nutrient release was estimated for the two species using both measured litterfall data and long‐term estimates, and regression models were used to predict concentration changes. Rates of release of P, Mg and Mn in the lodgepole pine stands were found to be about twice as high compared with those in Scots pine. Calcium was also released to a greater extent although the difference was not significant. 相似文献
2.
《Scandinavian Journal of Forest Research》2012,27(6):582-592
Abstract Swedish forest commons are collectively owned and managed by shareholders who always also own other forest holdings. The majority of them are non-industrial private forest (NIPF) owners. The objective of this study was to assess differences, with respect to harvesting intensity and related business activities on their individually managed forest properties, between non-shareholders and shareholders in a Swedish forest common. Forest commons are intended to promote local agriculture and forestry and to serve as a model for forestry activities. On this basis, the hypotheses examined in this study were that the shareholders’ harvesting and business activities, as well as their contributions to the local economy, are greater than those of non-shareholders. An apparent difference between shareholders and non-shareholders was found, but it was unexpected since non-shareholders undertook more harvesting and business activities than shareholders, and contributed more to the local economy through taxes. Since no evidence was found for a significant difference between the two categories in their potential to undertake forestry activities, one provisional conclusion is that the outcome is partly due to differences between the institutional frameworks in which shareholders and non-shareholders operate and the impact of these frameworks on incentives to maximize forest production. 相似文献
3.
Frederick Gyasi Damptey Emmanuel Opuni-Frimpong Collins Ayine Nsor James Addai Daniel Kwame Debrah Benjamin Schnerch Felicity Bentsi-Enchill Henn Korjus 《林业研究》2023,(3):641-653
Tropical forests provide several ecosystem services and functions and support approximately two-thirds of the world’s biodiversity but are seriously threatened by deforestation.Approaches to counteract this menace have revolved around afforestation with several or a single tree species.We thus investigated how plantation forests with either a single or several tree species influenced arthropod taxonomic and community composition using pitfall traps to sample selected groups of epigeal arthropods... 相似文献
4.
Long range (or strategic) planning is an important tool for forest management to deal with the complex and unpredictable future.
However, it is the ability to make meaningful predictions about the rapidly changing future that is questioned. What appears
to be particularly neglected is the question of the length of time horizons and the limits (if any) to these horizons, despite
being considered one of the most critical factors in strategic planning. As the future creation of values lies within individual
responsibility, this research empirically explored the limits (if any) of individual foresters’ time horizons. To draw comparisons
between countries with different traditions in forest management planning, data were collected through telephone surveys of
forest managers in the state/national forest services of the Netherlands and Germany. In order to minimize other cultural
differences, the research in Germany concentrated on the federal state of Nordrhein-Westfalen, which has considerable similarities
with the Netherlands, e.g. in topography, forest types and forest functions. The results show that, in practice, 15 years
appears to be the most distant horizon that foresters can identify with. This is in sharp contrast to the time horizons spanning
decades and even generations that are always said to exist in forestry. The “doctrine of the long run”—the faith in the capacity
of foresters to overcome the barriers of the uncertain future and look ahead and plan for long-range goals—which in many countries
still underlies traditional forest management, can therefore be rejected.
相似文献
| Heiner SchanzEmail: |
5.
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. 相似文献
6.
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. 相似文献
7.
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. 相似文献
8.
A complete diallel cross was made among nine Betula pendula trees growing in a natural population and a trial was planted on agricultural soil at one site. This exceptional trial has provided estimates of genetic parameters that can only be estimated in complete diallels. Traits measured were height and diameter during a period of 37 years, and assessments were made of bud burst, leaf abscission and rust infection at the early ages. All traits showed genetic variation and the variance components of general combining ability (GCA) effects were dominating, with heritability estimates of 0.16 and 0.23 for height and diameter at age six years. The best-growing families could be identified at that age. At age 37 years, when the trial had been thinned twice, the offspring from the highest and lowest ranked parent for growth contributed with 19% and 6% of the total volume of the stand, respectively. The GCA effects were also highly significant for the assessment traits, but with an interaction with year for bud burst. High values of estimates of genetic correlations proved that bud burst, leaf abscission and rust infection are interrelated, and also to some extent with growth traits. Families with an early bud burst were tallest, were less affected by the rust fungus and kept their leaves later in the autumn. 相似文献
9.
This paper presents a review of agroforestry in Africa from a gender perspective. It examines women’s participation relative
to men and the challenges and successes they experience. Particular agroforestry practices examined include fodder production
and utilization, soil fertility management, woodlots and indigenous fruit and vegetable production and processing. The review
shows that agroforestry has the potential to offer substantial benefits to women; however, their participation is low in enterprises
that are considered men’s domain, such as timber and high in enterprises that have little or no commercial value, such as
collection of indigenous fruits and vegetables. Furthermore, the degree of women’s involvement relative to men in technologies
such as soil fertility management, fodder production and woodlots is fairly high in terms of proportion of female-headed households
participating but is low as measured by the area they allocate to these activities and the number of trees they plant. Data
on whether women are able to manage agroforestry practices as well as men are mixed, although it is clear that women do most
of the work. In cases where they do not perform well, the reasons are mostly due to scarcity of resources. In marketing, women
are confined to the lower end of the value chain (retailing), which limits their control over and returns from the productive
process. In order to promote gender equity in agroforestry and to ensure that women benefit fully, the paper recommends various
policy, technological and institutional interventions. These include (1) facilitating women to form and strengthen associations,
(2) assisting women to improve productivity and marketing of products considered to be in womens’ domain and (3) improving
women’s access to information by training more women extension staff, holding separate meetings for women farmers, and ensuring
that women are fully represented in all activities. 相似文献
10.
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11.
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. 相似文献
12.
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(Rs) 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... 相似文献
13.
Fallowing can improve crop yields as a result of improved soil fertility and nutrient status. The objective of this work was
to determine the effects of fallows and pruning regimes in coppicing fallows on soil moisture and maize yields under conventional
tillage (CT) and no tillage (NT). Fallows that were evaluated were coppicing Acacia angustissima, non coppicing Sesbania sesban, natural fallow (NF) and continuous maize. In 2000/2001 season, maize yields were significantly different (P < 0.05) among treatments and were; 1.8, 1.2, 0.7 and 0.5 tonnes per hectare (t ha−1) under CT, while under NT yields were 1.3, 0.8, 0.7 and 0.2 t ha−1 for A. angustissima, maize, S. sesban and NF plots respectively. In 2001/2002 season, yields decreased in the order S. sesban > continuous maize > NF > A. angustissima, for both CT and NT. The 2-week pruning regime had significantly higher maize yields when compared to the 1 and 3 week pruning
regime during the 2002/2003 cropping season. For the three seasons, CT had significantly higher yields than NT. A. angustissima had significantly higher mean available water at suctions <33 kPa for the 0–25 cm depth when compared to other fallow treatments.
The bulk of the available water (47–80%) was retained at suction <33 kPa for all treatments and depths. There were no treatment
differences in water retention at suctions >33 kPa for all treatments. It was concluded that improved fallowing increased
yields when compared to NF. However, in coppicing fallows competition for water can result in reduced yields when there is
rainfall deficiency, thus the need for pruning to manage the competition. 相似文献
14.
Patricia María Rodríguez-González John Christopher Stella Filipe Campelo Maria Teresa Ferreira António Albuquerque 《Forest Ecology and Management》2010
In forested wetlands, hydrology exerts complex and sometimes compensatory influences on tree growth. This is particularly true in semi-arid ecosystems, where water can be both a limiting resource and a stressor. To better understand these relationships, we studied hydrologic and edaphic controls on the density, growth, tree architecture and overall productivity of forested wetlands dominated by the tree species Alnus glutinosa and Salix atrocinerea in Southern Europe. We sampled 49 plots set within 21 stands in the Atlantic coastal zone of the Iberian Peninsula, and quantified woody composition, size structure (diameter and height), and radial growth using dendrochronology. Plots were grouped into three saturation classes to compare tree growth characteristics (tree density, degree of sprouting, live basal area and productivity) across levels of saturation. We used Principal Component Analysis (PCA) to create integrated explanatory factors of hydrology, soil nutrient status and soil texture for use in linear mixed models to predict stand characteristics. Increased site saturation favoured a shift in species dominance from Alnus to Salix and resulted in a higher degree of multi-stemmed tree architecture (‘shrubbiness’), particularly for Alnus. Radial growth was negatively correlated with long-term soil saturation; however, annual productivity on a per-tree basis varied by species. Alnus growth and tree density were negatively correlated with waterlogging and fine-textured soils, possibly due to anaerobiosis in the rooting zone. In contrast, Salix growth was more influenced by nutrient limitation. Overall site productivity as measured by annual basal area increment decreased with prolonged saturation. In summary, soil saturation appears to act as a chronic stressor for tree species in this ecosystem. However, these species persist and maintain a dominant canopy position in the most permanently flooded patches through increased sprouting, albeit at a reduced rate of overall biomass accumulation relative to well-drained sites. The diversity in functional responses among wetland forest species has important implications for the conservation and management of these ecosystems. The sustainable management of these ecosystems is directly tied to their vulnerability to changing hydrological conditions. Non-equilibrium modifications to the hydrologic regime from land use and climate change, which are particularly severe in semi-arid regions, may further decrease productivity, integrity and resilience in these stress-adapted communities. 相似文献
15.
The C-isotopic composition (δ13C) of leaf respiration (δ(LR)) has previously been shown to vary among functional groups, plant organs and times of day. We here investigated vertical and seasonal variation in δ(LR) through deep (~35 m) forest canopies. We measured δ(LR), δ13C of leaf bulk organic matter (δ(LB)), specific leaf area, net photosynthesis (A) and dark respiration in shade, middle and sun foliage in four conifer species from May to August. We used Keeling plots to estimate δ(LR); we developed a novel technique for ensuring that the respiratory substrate was not changing over the course of the measurement. Variables δ(LR) and δ(LB) displayed a vertical pattern in Abies grandis, Pseudotsuga menziesii and Thuja plicata, but were independent of canopy position in Larix occidentalis. Vertical gradients in δ(LB) (3.6‰) and δ(LR) (2.8‰) were similar. The respiratory enrichment (δ(LR)-δ(LB)) was smaller in expanding (3‰) than mature (4-8‰) foliage. There was a linear relationship between the respiratory enrichment and A. Our data support the hypothesis that δ(LR) values are related to patterns of C allocation among metabolic pathways. We demonstrated that considerable variation in δ(LR) occurs vertically through the canopy (3‰ gradient) and seasonally (3-7‰). Understanding sources of variation in respiratory signals is fundamental to comprehending C dynamics and for global model applications. 相似文献
16.
Carbon sequestration in the woody biomass of shelterbelts has been investigated but there have been no measurements of the
C stocks in soil and tree litter under this agroforestry practice. The objective of this study was to quantify C stored in
surface soil layers and tree litter within and adjacent to a 35-year-old shelterbelt in eastern Nebraska, USA. The 2-row shelterbelt
was composed of eastern red cedar (Juniperus virginiana) and scotch pine (Pinus sylvestris). A sampling grid was established across a section of the shelterbelt on Tomek silt loam (fine, smectitic, mesic Pachic Argiudolls).
Four soil cores were collected at each grid point, divided into 0–7.5 and 7.5–15 cm depth increments, and composited by depth.
Soil samples were analyzed for total, organic, and inorganic C, total N, texture, pH, and nutrient content. Under the shelterbelt,
all surface litter in a 0.5 × 0.5 m2 area at each grid point was collected prior to soil sampling, dried, weighed, sorted, and analyzed for total C and N. Average
soil organic carbon (SOC) in the 0–15 cm layer within the shelterbelt (3,994 g m−2) was significantly greater than in the cultivated fields (3,623 g m−2). The tree litter contained an additional ∼1,300 g C m−2. Patterns of litter mass and soil pH and texture suggested increased organic inputs by tree litter and deposition of wind-blown
sediment may be responsible for greater SOC beneath the shelterbelt. Further research is needed to identify the mechanism(s)
responsible for the observed patterns of SOC within and adjacent to the shelterbelt and to quantify the C in biomass and deeper
soil layers.
相似文献
| Thomas J. SauerEmail: |
17.
18.
Manuela Panzacchi John D.C. Linnell Claudia Melis Morten Odden John Odden Lucrezia Gorini Reidar Andersen 《Forest Ecology and Management》2010
During the last century the boreal forests of south-eastern Norway have been converted into patchworks of agricultural areas, clear-cuts and even-aged conifer monocultures. Even though Scandinavian forest ecosystems are strongly influenced by small mammals’ dynamics, the effects of anthropogenic changes on these communities are still debated. We conducted an extensive capture–mark–recapture study to examine the relative abundance and distribution of 11 species of small mammals during the reproductive season with respect to all available landscape-scale habitat types and fine-scale vegetation characteristics. 相似文献
19.
Xin Li Haosheng Pang Minglong Sun Xiuli Zhang Nan Xu 《Scandinavian Journal of Forest Research》2018,33(2):103-113
The aim of this study was to compare soil bacterial communities in the Great Xing’an Mountains that represent three dominant vegetation types (Quercus mongolica forest, shrub mixed with herb and grassland). Soil bacterial communities were analyzed by both culture-dependent physiological profiling (Biolog) and culture-independent DNA-based approaches. The Q. mongolica forest and shrub mixed with herb had higher average well color development than the grassland, and the Q. mongolica forest and shrub mixed with herb soil bacterial communities easily utilized miscellaneous and amines/amides. The bacterial community structure was distinct across the three sites. Most of Acidobacteria, Proteobacteria and Bacteroidetes were found in grassland soil, while Firmicutes was present at a higher percentage in the Q. mongolica soil. Extracellular enzyme assays indicated that the soil ecosystem in the grassland experienced altered N and P nutrient cycling dynamics. pH, available phosphorus, potassium and nitrogen were important in shaping bacterial community structure. These results suggest that vegetation type was a strong determinant of the structure and function of bacterial communities, which may subsequently lead to significant changes in ecosystem functioning. 相似文献