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1.
G. B. Douglas A. S. Walcroft S. E. Hurst J. F. Potter A. G. Foote L. E. Fung W. R. N. Edwards C. van den Dijssel 《Agroforestry Systems》2006,66(2):165-178
Silvopastoral systems involving poplars are widespread in rural landscapes in a number of regions of New Zealand. The effect
of widely spaced trees of Populus nigra × P. maximowiczii, aged 8–11 years, on the growth and botanical composition of understorey pasture mixes was determined over 3 years at a southern
North Island hill country site. Pasture mixes comprised existing pasture, and two introduced test swards comprising new grass
(Agrostis capillaris, Dactylis glomerata, Lolium perenne) and legume (Lotus uliginosus, Trifolium repens) cultivars. Pasture accumulation beneath trees (6.6 t DM ha−1 year−1) was 23% less than open (unshaded, no trees) pasture (8.6 t DM ha−1 year−1) and differences in accumulation occurred between tree aspects (North and South sides of trees) when trees were foliated.
In early spring, North plots produced 11–14% more herbage than South plots whereas in late summer, South plots produced up
to 44% more herbage than North plots. Yield of both test swards (6.4 and 8.0 t DM ha−1 year−1) was not significantly different from that of the existing sward (7.4 t DM ha−1 year−1) but productivity varied between swards in spring and summer. One test sward included Lotus uliginosus cv. Grasslands Maku, and the sward produced 30% more DM than the other swards in mid-summer. Dactylis glomerata cv. Grasslands Wana comprised 37% of the DM of swards in which it was sown and was the most successful cultivar, followed
by Grasslands Maku. Both cultivars are recommended for silvopastoral systems where pasture is lightly grazed. 相似文献
2.
Validation of a canopy photosynthesis model for cocksfoot pastures grown under different light regimes 总被引:3,自引:0,他引:3
Daily net canopy photosynthesis (P
n) was predicted for cocksfoot (Dactylis glomerata L.) canopies grown under different light regimes by integration of a leaf photosynthesis model developed for the light-saturated
photosynthetic rate (P
max), photosynthetic efficiency (α) and the degree of curvature (θ) of the leaf light–response curve. When shade was the only
limiting factor, the maximum P
n (P
nmax) was predicted to decrease approximately linearly from 33.4 g CO2 m−2 d−1 to zero as photosynthetic photon flux density (PPFD) fell from full sunlight (1800 μmol m−2 s−1 PPFD) to 10% of this in a fluctuating light regime. It was also predicted that at 50% transmissivity P
nmax was higher for a continuous light regime (10.4 g CO2 m−2 d−1) than for a fluctuating light regime with the same intensity (8.4 g CO2 m−2 d−1). The canopy photosynthesis model was then used to predict dry matter (DM) production for cocksfoot field grown pastures
under a diverse range of temperature, herbage nitrogen content and water status conditions in fluctuating light regimes. This
prediction required inclusion of leaf area index and leaf canopy angle from field measurements. The model explained about
85% of the variation in observed cocksfoot DM production for a range from 6 to 118 kg DM ha−1 d−1. The proposed model improves understanding of pasture growth prediction through integration of relationships between shade
limitations in fluctuating light regimes and other environmental factors that affect the canopy photosynthetic rate of cocksfoot
pastures in silvopastoral systems. 相似文献
3.
A. C. Varella D. J. Moot K. M. Pollock P. L. Peri R. J. Lucas 《Agroforestry Systems》2011,81(2):157-173
Shade cloth is commonly used in agroforestry research. It produces a continuous, uniform reduced light environment. Shade
cloth and a slatted structure were compared in relation to the inability to represent the light regime and plant responses
of an agroforestry system. The split-split-plot randomised block experiment had main plots as covering status (with or without
radiata pine trees), subplots as artificial shade (none, shade cloth or wooden slats) and sub-subplots as growth rotation,
over sown alfalfa, in three replicates. The quantity of light transmittance was 49% under trees, 41% under cloth and 44% under
slats. Temporal changes and spectral composition under trees were more accurately reproduced under the slats than shade cloth.
The red to far red ratio was 0.64 under tree shade and 0.74 during the shaded period under slats. This compared with 1.31
in open pasture, 1.28 under shade cloth in open and 1.26 under slats during sunny periods. To compensate for low light quantity
and quality, alfalfa had elongated stems and internodes. In open pasture and under cloth in the open, it produced short stems.
The mean dry matter yield under trees was 68% of the 30.3 t ha−1 in open pasture, 56% under cloth and 57% under slats. The slats induced similar morphological responses in alfalfa to those
in the agroforestry system. The magnitude of changes had little effect on growth and yield responses. The artificial slatted
structure approximated the intermittent light environment and consequent plant responses observed in an agroforestry system. 相似文献
4.
An integrated model for predicting maximum net photosynthetic rate of cocksfoot (Dactylis glomerata) leaves in silvopastoral systems 总被引:1,自引:0,他引:1
Net light-saturated photosynthetic rate (Amax) of field grown cocksfoot (Dactylis glomerata L.) leaves in a radiata pine (Pinus radiata D. Don) silvopastoral system (Canterbury, New Zealand) was measured at different times under severe shade (85–95 μmol m–2 s–1 photosynthetic photon flux density, PPFD) and in full sunlight (1900 μmol m–2 s–1 PPFD). The aim was to integrate individual functions for Amax against air temperature (2 to 37 oC), water status, expressed as pre-dawn leaf water potential (ψlp) (-0.01 to −1.6 MPa), herbage nitrogen (N) (1.5 to 5.9%), regrowth duration (20 to 60 days) and time under shade (1 to 180
min) into a multiplicative model. The highest Amax value obtained was 27.4 μmol CO2 m–2 s–1 in non-limiting conditions with full sunlight. This value was defined as standardised dimensionless Amaxs = 1 for comparison of factor effects. The canopy temperature of the cocksfoot sward was up to 7.4 oC cooler than air temperature
for plants under shade. Therefore, canopy temperature was used to predict Amax. The only interaction was between time under severe shade (5% of the open PPFD) and water stress (ψlp = −0.4 to −1.3 MPa) and this was included in the model. Validation of this model indicated 78% of the variation in Amax could be accounted for using these five factors by the addition of the interaction function. This model could be used to
assist the prediction of pasture growth in silvopastoral systems through incorporation into a canopy photosynthesis model.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
This long term experiment provides production data for evaluation of combined forestry and livestock systems. Five systems
were established in Pinus radiata planted in 1981 (620 mm average annual rainfall). Sheep were introduced in 1984 and trees were pruned in several lifts. Adjusted
tree stockings were (1) 60 widely spaced trees ha−1, (2) 200 widely spaced trees ha−1, (3) 200 trees ha−1 in five-row belts, (4) 1,090 trees ha−1 (unpruned) and 815 trees ha−1, and (5) no trees (open pasture). Tree growth, wool production, liveweight gain and pasture production were measured. At
year 25, tree diameter under bark at 1.3 m (DBHUB) in Systems 1, 2, 3 and 4 (unpruned) was 46.0, 39.2, 33.5 and 24.1 cm, while
volume of bark-free 6-m butt-logs was 49, 117, 86 and 233 m3 ha−1. Inner rows of System 3 belts contained smaller trees than outer rows. Pruned System 4 trees had slightly greater diameter
than unpruned trees. Pasture production declined with tree stocking and time, due to shading and competition. Wool production
(WP ha−1) and liveweight gain (LWG ha−1) declined linearly from year 9 to 17 with increasing disparity among systems. In 1998 (year 17) WP ha−1 in Systems 1, 2 and 3 was 64, 16 and 43% of that in open pasture. Further analysis is needed to evaluate the financial costs
and returns of various systems under particular rotation lengths and market prices. 相似文献
6.
G. B. Douglas A. S. Walcroft S. E. Hurst J. F. Potter A. G. Foote L. E. Fung W. R. N. Edwards C. van den Dijssel 《Agroforestry Systems》2006,67(2):177-186
Silvopastoral systems involving poplars are common to rural landscapes in many parts of New Zealand. The effect of widely
spaced trees of Populus nigra × P. maximowiczii, aged 8–11 years, on the surrounding micro-environment in a tree-pasture system was determined over 3 years at a southern
North Island hill country site. Relative to open (unshaded, no trees) pasture, understorey pasture received 33% less radiation
while radiation on the north side of trees (North) was similar to that on the south side of trees (South). Around one tree,
soil temperature averaged 14.9°C annually on the North and 13.8°C on the South. Soil water content was highest in spring and
winter (0.35–11;0.39 m3 m−3) and lowest in summer and autumn (0.21–11;0.26 m3 m−3), and differences occurred between plots in open pasture and those beneath trees in all seasons except spring. Soil water
content of tree aspects differed slightly (<10%) in summer (South > North) and autumn (North > South), but not in spring and
winter, when contents were similar. Soil pH was 0.2 units higher beneath trees than in open pasture in one of 2 years. Concentrations
of Ca, K, Mg, P, and S were similar in tree and open environments. The study results complement those collected for mature
trees, and will be useful in developing tree-pasture models. 相似文献
7.
Photosynthetic induction responses of Pinus koraiensis seedlings grown in different light environments 总被引:2,自引:0,他引:2
The time processes of photosynthetic induction responses to various irradiances in Korean pine (Pinus koraiensis) seedlings grown in open-light environments and in understory of forest were studied in an area near the Research Station
of Changbai Mountain Forest Ecosystems, Jilin Province, China from July 15 to August 5, 1997. The results showed that at 200
μmol·m−2·s−1 photosynthetic photon flux density (PPFD) and 500 μmol·m−2·s−1 PPFD, the induction time for the photosynthetic rates of understory-grown seedlings to reach 50% and 90% steady-state net
photosynthetic rates was longer than that of the open-grown seedlings. The induction responses of open-growth seedlings at
500 μmol·m−2·s−1 PPFD were slower than those at 200 μmol·m−2·s−1 PPFD, but it was the very reverse for understory-growth seedlings, which indicates that the photosynthetic induction times
of Korean pine seedlings grown in the understory depended on the sunfleck intensity.
Biograph: ZHOU Yong-bin (1970-), female, associate professor of Shenyang Agricultural University, Shenyang 110161, P.R. China.
Responsible editor: Song Funan 相似文献
8.
Information is lacking on the potential of leguminous fodder trees such as Leucaena leucocephala as a feed resource to supplement the native forages in traditional grazing management systems in the tropics. Two studies
were conducted (1) to assess traditional fodder banks’ forage nutritive potential on animal production, and (2) to investigate
the effect of Leucaena leucocephala leaf meal (LLM) supplementation on growth of steers grazing standing hay basal forages in the dry season. The traditional
forages had low nutritive values indicated by low mean crude protein (CP) of 23 g kg−1 dry matter (DM), and high fibre contents of 717, 546 and 153 g kg−1 DM for neutral detergent fibre (NDF), acid detergent fibre (ADF) and acid detergent lignin (ADL), respectively. The forages
were poorly degraded in sacco and had low metabolisable energy (ME) (4.2–4.6 MJ kg−1 DM). Mean washing losses A, slowly degradable DM fraction, B, potential degradability, (A+B) and mean 48 h DM degradability
(DMD) of grazing land forages were 70, 471, 541 and 326 g kg−1 DM, respectively. In the supplementation study, 16 growing steers (160.8±0.24 kg) were randomly allocated into four groups,
in a completely randomized design. Four LLM treatment diets (T1, T2, T3 and T4), with four levels: 0, 0.4, 0.6 and 0.8 kg
DM for control, low, medium and high LLM levels, respectively, were randomly allocated to the animals in the four groups for
70 days (d). LLM supplementation (p<0.05) improved mean weight gain from −0.30 to 0.26 kg steer−1 d−1, for T1 and T4, respectively. Steers on T4 gained (p<0.05) more weight compared to the animals in T1 and T2, though there was no (p>0.05) difference in weight gains between animals on T3 and T4 (0.14 vs. 0.26 kg steer−1 d−1, respectively). Standing hay basal forages alone could not sustain animal productivity during dry seasons unless corrected
for protein. Higher levels of LLM supplementation prevented weight losses and improved the performance of grazing steers,
a management practice thought appropriate to low income pastoralists in semiarid western Tanzania. 相似文献
9.
Small Appalachian hill farms may benefit economically by expanding grazing lands into some of their under-utilized forested
acreages. Our objective was to study the forage production potential of forest to silvopasture conversion. We thinned a white
oak dominated mature second growth forested area establishing two orchardgrass-perennial ryegrass-white clover silvopasture
replications for comparison with two nearby open pasture replications. After thinning trees, silvopastures were limed, fertilized
and seeded. Sheep were fed hay and corn scattered across the area to facilitate removal of residual understory vegetation,
disruption of litter layer and incorporation of applied materials into surface soil. Each area was divided into multiple paddocks
and rotationally grazed by sheep. Two 1 m2 herbage mass samples were taken from each paddock prior to animal grazing. There was no significant difference in soil moisture
between silvopastures and open pastures however, there was adequate rainfall to prevent drought all 3 years. The two silvopastures
received 42 and 51% of total daily incident PAR compared to the open field. Total dry forage mass yield from open pasture
over the 3 years averaged 11,200 kg ha−1 y−1 and from silvopasture 6,640 kg ha−1 y−1. Silvopastures, however, had a higher PAR use efficiency (PARUE) than open pasture. Hill farms could increase grazing acreages
without sacrificing all benefits from trees on the landscape by converting some areas to silvopasture. 相似文献
10.
M. J. Rozados-Lorenzo M. P. González-Hernández F. J. Silva-Pando 《Agroforestry Systems》2007,70(1):53-62
We studied the effect of six tree species planted at six different densities on pasture production seven years after establishment.
Annual and seasonal pasture production was studied every six months, over three years. Pasture production was lower under
conifer trees (Pseudotsuga menziesii (Mirb.) Franco, Pinus pinaster Aiton, Pinus radiata D. Don) than under broadleaved trees (Betula alba L., Quercus rubra L. and Castanea sativa Mill.). Annual pasture production under Pseudotsuga menziesii and Pinus pinaster decreased progressively starting from 952 trees ha−1, while decline in herbage production under Pinus radiata began to occur at 427 trees ha−1. Tree density effect on pasture production was detected at 2,000 trees ha−1 for all of the deciduous species studied. This effect on pasture production was more important in the first six months of
the year (June sampling), while from June to December herbage production was less affected by tree density. The tree effect
became more noticeable over time, with the last sampling showing the inverse relationship between tree density and herbage
production most clearly. Seven years after tree establishment, pasture production was quite consistent under tree densities
between 190 trees ha−1 and 556 trees ha−1 and declined remarkably from 556 trees ha−1 to 2,500 trees ha−1. The study also indicated that by the sixth growing season, annual pasture production under different tree species is inversely
correlated with tree leaf area index. 相似文献
11.
Agroforestry trees are now well known to play a central role in the build up of nutrients pools and their transformations
similar to that of forest ecosystem, however, information on the potential of homegarden trees accumulating and releasing
nitrogen (mineralization) is lacking. The present study reports seasonal variations in pool sizes of mineral N (NH4+-N and NO3−-N), and net N-mineralization rate in relation to rainfall and temperature under coconut (Cocos nucifera L.), clove (Eugenia caryophyllata Thunb) and nutmeg (Myristica fragrans Houtt. Nees) trees in a coconut-spice trees plantation for two annual cycles in the equatorial humid climate of South Andaman
Island of India. Concentration of NH4+-N was the highest during wet season (May–October) and the lowest during post-wet season (November–January) under all the
tree species. On the contrary, concentration of NO3−-N was the lowest in the wet season and the highest during the post-wet season. However, concentrations of the mineral N were
the highest under the nutmeg and the lowest under the coconut trees. Like the pool sizes, mean annual mineralization was the
highest under the nutmeg (561 mg kg−1 yr−1) and the lowest under the coconut trees (393 mg kg−1 yr−1). Rate of mineralization was the highest during the post-wet season and the lowest during the dry season (February–April)
under all the tree species. High rainfall during the wet season, however, reduced the rate of nitrification under all the
tree species. The mean annual mineralization was logarithmically related with rainfall amount and mean monthly temperature. 相似文献
12.
A. Rigueiro-Rodríguez M. R. Mosquera-Losada E. Gatica-Trabanini 《Agroforestry Systems》2000,48(3):245-256
The use of organic waste materials such as milk sewage as an organic fertilizer could have the dual advantages of organic-waste
disposal and reduced dependence on inorganic fertilizers. The effects of fertilization with (1) conventional mineral fertilization,
(2) milk sewage sludge at 40 kg N ha−1 target rate and (3) no fertilization on pasture production and tree growth were examined in an experiment consisting of two
pasture mixtures under a one-year-old Pinus radiata plantation with a density of 2500 trees ha−1. The two pasture mixtures were: (1) Dactylis glomerata L. var. saborto (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1); (2) Lolium perenne L. var. Tove (25 kg ha−1) + Trifolium repens L. group Ladino (4 kg ha−1) + Trifolium pratense L. var. Marino (1 kg ha−1). The experiment began in the spring of 1995 using a randomized block design with three replicates in Castro Riberas de Lea
(Lugo, Galicia, north-western Spain). Plot size was 12 × 8 m2, with a 1 m buffer strip between plots. Two-year data showed that fertilization with either material had a positive effect
on pasture production, with no significant difference between the two fertilization treatments. Tree growth in the milk sewage
sludge plot was significantly higher than in the control plots. Inorganic fertilization increased pasture production, but
affected tree growth negatively. The results show that milk sewage sludge could be used as a fertilizer in silvo-pastoral
systems.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
13.
We have studied the percentage of radiation transmitted through the tree canopy to the underlying pasture and crops in dehesas
of Southwest Spain by means of fish-eye photographs taken at different distances from the tree. Thirty-six trees were studied
covering all the diametric classes (0.1–14 m canopy width) of two stands, with mean density of 19 mature trees ha−1. Intercepted light decreased with distance following an logistic curve, indicating a rapid increase in the light availability
with distance from the tree. For mature trees, radiation was constant beyond 20 m. Applying a multivariable regression light
equation, distance, stem diameter and canopy width explained more than 88% of the light variability for each orientation studied.
A simple model was built up from light equations, tree growth curves and allometric relationships. From this model, we have
estimated that radiation available for crops and pasture decreased up to 21% due to the presence of trees in a standard dehesa
with 24 mature trees ha−1 and 13% of canopy cover. In addition, we have generated different radiation maps of virtual dehesas differing in tree age,
density and arrangement, which could be useful to determine optimal tree planting schemes and consequent pruning and thinning
regimes. 相似文献
14.
Tree Performance and Root-Zone Salt Accumulation in Three Dryland Australian Plantations 总被引:3,自引:0,他引:3
Robert D. Archibald Richard J. Harper John E. D. Fox Richard P. Silberstein 《Agroforestry Systems》2006,66(3):191-204
Doubts exist about the effectiveness of establishing trees near saline discharge areas on farmland to manage dryland salinity.
These centre on low rates of water uptake from saline water tables, salt accumulation in tree root zones and the consequent
poor growth and survival of trees. Despite this, trees still survive in many plantations established adjacent to saline discharge
areas and land-holders often favour such locations, as they do not compete for arable land such as that occurs with plantings
in recharge areas. Tree performance and salt accumulation were assessed in three experimental plantations established adjacent
to saline discharge areas 20–25 years ago. These were all in the 400–600 mm rainfall zone of south-western Australia. Mean
soil salinity, within 1 m of the surface, ranged from 220 to 630 mS m−1, while permanent ground-waters occurred within 2–5 m of the surface and had electrical conductivities ranging from 175 to
4150 mS m−1. The study confirmed the low growth rates expected for trees established over shallow, saline water tables in a relatively
low rainfall environment, with estimated wood volumes in Eucalyptus cladocalyx, E. spathulata, E. sargentii, E. occidentalis and E. wandoo of between 0.5 and 1.5 m3 ha−1 yr−1. Values of up to 3 m3 ha−1 yr−1 were obtained on soils with low salinity (<200 mS m−1). The excellent survival (>70%) of several Eucalyptus species confirms that discharge plantations species can persist, despite increasing soil salinity. However, the long-term
sustainability of such plantings (50–100 years) without broader landscape treatment of the present hydrological imbalance
must be questioned. 相似文献
15.
Species composition, biomass, and productivity patterns of three types of traditional agroforestry systems, namely, agrisilvicultural,
agrihorticultural, and agrihortisilvicultural, commonly practiced in the western Himalaya, were studied. Species composition
in the systems varied depending upon the size of the land holdings, and the basic requirements of the farmer. Among three
systems agrihortisilvicultural was highly diverse in vegetation, with as many as 13 tree and 5 agricultural crops mixed together.
This system showed the highest productivity up to 25.8 t ha−1 yr−1, out of which 68 percent was contributed by the trees and the remainder by the annuals. Agrisilvicultural system having predominantly
annuals had the lowest productivity of 20.4 t ha−1 yr−1 with only 27 percent contribution by the trees. Total aboveground biomass in agrihortisilvicultural or agrihorticultural
system was around 48 t ha−1 and it was about 2-fold higher than agrisilvicultural system. In fodder trees, a significant percentage of annual production,
up to 48 percent, was allocated in current twigs, while in horticultural trees a major portion, up to 63 percent was partioned
towards fruits. Implications of the results have been discussed in context with the growing problems of fuel, fodder, and
packaging material in the western Himalaya. 相似文献
16.
Aurelio Guevara-Escobar Peter D. Kemp Alec D. Mackay John Hodgson 《Agroforestry Systems》2007,69(3):199-213
Traditionally, poplar (Populus spp.) have been planted to control erosion on New Zealand’s hill-slopes because of their capacity to dry out and bind together
the soil. Two systems: (1) widely spaced, planted poplar for soil conservation, and (2) non-eroded open pasture were compared
to determine the relative effect of the poplar–pasture system on the production, nutritive value and species composition of
the pasture, and on the water balance. Measurements were made at three sites with mature poplar (>29 years and 37–40 stems ha−1) and at a replicated experiment with young poplar (5 years, 50–100 stems ha−1). Soil water relations did not suggest strong competition for water between poplar and pasture. Pasture accumulation under
mature poplar was 40% less than in the open pasture, but under young poplar was similar to that in the open pasture. Chemical
composition of pasture suggested that feed quality of pasture in the open was better than under the poplar canopy, except
during spring, when most chemical components were similar. At the most, in vitro digestibility of pasture dry matter was 8.9%
lower and metabolisable energy of pasture dry matter was 1.5 MJ kg lower under the poplar canopy than in the open pasture.
Shade tolerant species were not dominant in the plant community under the poplar canopy with grasses such as browntop (Agrostis capillaris, L.) and ryegrass (Lolium perenne, L.) being a high proportion of the plant community. Differences in chemical composition were related to differences in the
botanical composition between the open pasture and the poplar understorey. It was concluded that the greatest effect of poplar
was on pasture production due to shading, and that management of this silvopastoral system needs to focus on control of the
tree canopy to lessen the decrease in pasture production. 相似文献
17.
Quantitative field measurements of biological nitrogen fixation (BNF) and biomass production by four different understorey pastures in a Pinus radiata-pasture agroforestry system were determined over a period of one year. The trees were two years old at the beginning of this study and the understorey pastures were being cut and removed for silage. The BNF was determined using the 15N dilution technique. Pastures of ryegrass+clover, cocksfoot+clover, phalaris+clover and lucerne were used. Substantial amounts of BNF were found (71 to 230 kg N ha–1 year–1) with lucerne showing the highest N fixation. However, lucerne derived only 71 to 72% of its N from the atmosphere (%Ndfa) during the spring/summer period compared to 83–97% with clovers, thus the net N demand from the soil was substantially higher with lucerne. This caused increased N stress to the trees. Clover in ryegrass+clover pasture fixed more N than the other grass+clover pastures. Although pasture position in relation to trees did not affect annual pasture total DMY and %Ndfa, pastures north of tree row grew better than those in other positions. Trees significantly affected the BNF of legumes and the botanical composition of pastures with highest BNF and legume production occurring in pastures midway between two rows of trees. These results suggest that it would be advantageous to evaluate different legumes and grasses for tolerance of shade and moisture stress in future studies. As the trees studied were only 1.5 to 3 m in height, their effects on BNF, seasonal pasture biomass production and botanical composition are expected to increase with tree dominance in the ecosystem with time. Amounts of N fixed were related to the productivity (i.e. dry matter and N yield) and seasonal persistence of the legumes. The productivity was high in spring and summer and low in autumn and winter. 相似文献
18.
Veiko Uri Krista Lõhmus Ivika Ostonen Hardi Tullus Renal Lastik Merit Vildo 《European Journal of Forest Research》2007,126(4):495-506
The above-ground biomass and production, below-ground biomass, nutrient (NPK) accumulation, fine roots and foliar characteristics
of a 8-year-old silver birch (Betula pendula) natural stand, growing on abandoned agricultural land in Estonia, were investigated. Total above-ground biomass and current
annual production after eight growing seasons was 31.2 and 11.9 t DM ha−1, respectively. The production of stems accounted for 62.4% and below-ground biomass accounted for 19.2% of the total biomass
of the stand. Carbon sequestration in tree biomass reaches roughly 17.5 t C ha−1 during the first 8 years. The biomass of the fine roots (d < 2 mm) was 1.7 ± 0.2 t DM ha−1 and 76.2% of it was located in the 20 cm topsoil layer. The leaf area index (LAI) of the birch stand was estimated as 3.7 m2 m−2 and specific leaf area (SLA) 15.0 ± 0.1 m2 kg−1. The impact of the crown layer on SLA was significant as the leaves are markedly thicker in the upper part of the crown compared
with the lower part. The short-root specific area (SRA) in the 30 cm topsoil was 182.9 ± 9.5 m2 kg−1, specific root length (SRL), root tissue density (RTD) and the number of short-root tips (>95% ectomycorrhizal) per dry mass
unit of short roots were 145.3 ± 8.6 m g−1, 58.6 ± 3.0 kg m−3 and 103.7 ± 5.5 tips mg−1, respectively. In August the amount of nitrogen, phosphorus and potassium, accumulated in above ground biomass, was 192.6,
25.0 and 56.6 kg ha−1, respectively. The annual flux of N and P retranslocation from the leaves to the other tree parts was 57.2 and 3.7 kg ha−1 yr−1 (55 and 27%), respectively, of which 29.1 kg ha−1 N and 2.8 kg ha−1 P were accumulated in the above-ground part of the stand. 相似文献
19.
Ecological studies on subtropical evergreen broad-leaved forest in Okinawa, Japan: Litter production and nutrient input 总被引:1,自引:1,他引:0
Xiaoniu Xu Yoshihiro Tokashiki Eiji Hirata Tsutomu Enoki Kangoro Nogami 《Journal of Forest Research》2000,5(3):151-156
Patterns of litterfall and nutrient input in a subtropical evergreen broad-leaved forest in northern Okinawa, Japan, were
studied during May, 1996–April, 1999. The mean annual rate of litterfall in the five sampling plots ranged from 6.84 to 8.93
Mg ha−1 yr−1, of which 63.3–68.5% were leaves; 22.4–29.1% woody parts (including branches < 5.0 cm in diameter and bark); 2.8–5.0% sexual
organs and 4.6–6.3% miscellaneous material. Significant differences were found among plots and among years. Significantly
monthly differences pronounced seasonal patterns in litterfall were observed. Total litterfall and leaf litter showed negative
correlations with relative basal area of the dominant species,Castanopsis sieboldii; and showed positive correlations with mean height of the stands. The dominant species,C. sieboldii produced an average of 2.36 Mg ha−1 yr−1 of leaf litter, which covered 30.5% of the annual litter production, and the nutrient input from those litterfall contributed
32.3, 28.3, 30.2, 22.2, 32.5, and 30.5% of total N, P, K, Ca, Mg, and Na, respectively. Nutrient use efficiency in litter
production was high, especially for P and K compared with other broad-leaved forests in Japan indicating that P and K may
be limiting in Okinawan evergreen broad-leaved forest. 相似文献
20.
Goddert von Oheimb Christina Westphal Werner Härdtle 《European Journal of Forest Research》2007,126(3):359-370
The diversity, spatial patterns and temporal dynamics of dead wood were examined within the near-natural beech forests (Fagus sylvatica) of Serrahn (North-eastern Germany). Data were collected in an 8 ha sample plot and in two permanent plots (0.36 and 0.25 ha)
that had been established at the end of the 1960s. The mean volume of dead wood was 94 m3 ha−1, amounting to 14% of the total volume of all trees. The dead wood displayed a large variation in dead wood type, tree size
and decay class. Standing dead wood accounted for about one-third of the total dead wood volume. The densities of standing
dead trees were about 10% of the densities of the living trees over a wide range of diameters. The overall spatial distribution
of dead trees exhibited a random pattern. Among the different dead wood types, standing entire dead trees and uprooted trees
deviated from this pattern by displaying a significantly aggregated pattern. In the permanent plots a high mortality of overstorey
trees was observed (1.3% year−1) and the average amount of dead wood increased greatly from 2.9 to 111.6 m3 ha−1 over the 35-year observation period. The near-natural beech forests of Serrahn have experienced a long period of low human
interference. Nevertheless, our results suggest that the structure and dynamics of dead wood are strongly affected by the
last major disturbance events that took place at the end of the Middle Ages. Information about the forest history is therefore
a basic requirement when interpreting the results obtained in near-natural forests. 相似文献