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1.
Effects of harvest residues on nutrient leaching and soil chemical properties were studied in a lysimeter experiment. Treatments
were: (A) forest floor litter and harvest residues, other than branches, incorporated into the soil, (B) as A, but with branches
cut in 20 cm long bits and placed on the soil surface, (C) as B, but with bits incorporated into the soil, (D) as B, but with
branches chopped into chips, (E) as C, but with branches chopped into chips, (F) forest floor litter and harvest residues
on the soil surface, with branches cut in 20 cm long bits, (G) as F, but with branches chopped into chips, and (H) absence
of harvest residues (control). Treatments were applied in zero-tension lysimeters containing 25 kg of soil. Leachates were
collected for a 6-year period. At the end of the experiment, lysimeters were dismantled and soil was divided in four layers.
Residues, other than branches, increased N leaching, as compared with the control. Branches on the soil surface reduced N
leaching when cut in chips. Branches incorporated into the soil reduced leaching independently of their size. Organic residues
on the soil surface showed similar effect to those incorporated into the soil. However, harvest residues on the soil surface
increased leachate volume, and reduced Ca and P losses. Such a placement of residues led to high contents of Ca and P in the
0–5 cm top soil layer. Contents of organic C, total N and base cations were not affected by the treatments. 相似文献
2.
3.
Athina A. Pappa Nikolaos E. Tzamtzis Sofia E. Koufopoulou 《Annals of Forest Science》2008,65(2):210-210
The application of Long Term fire Retardants (LTRs) for forest fire prevention and/or suppression purposes can result in chemicals leaching, from soil to the drainage water, during the annual rain fall period. In leachates, large concentrations of nitrogen (N), one of the major components of LTRs, could affect the groundwater quality. N leaching due to the application of a nitrogen phosphate based LTR was studied in laboratory microcosms. The concentrations of nitrate (NO 3 ? -N) and ammonium nitrogen (NH 4 + -N) were measured in the resulting leachates from pots with forest soil and pine seedlings (Pinus halepensis) alone and in combination with fire. Up to 30% of the total N in the retardant was lost to leaching, primarily as NO 3 ? -N. The vegetation seems to decrease to some extent the N leaching. The N leaching from treated pots with a burnt tree is lower compared with that from treated pots with a living tree, due to the partial N volatilization during the fire. Although this is a laboratory study, these results may be considered as rough indications of LTR environmental implications, due to the leaching of a significant part of the retardant’s N into groundwater. 相似文献
4.
Aims
This study aims to evaluate the effects of wood ash application on nutrient dynamics and soil properties of an acidic forest soil (Arenosol).Methods
Treatments were loose and pelleted ash application (11?Mg?ha?1), alone or together with N fertiliser, and control treatment in a lysimeter experiment. Nutrient leaching was followed during a 2-year period and soil chemical and biological properties were evaluated at the end of the experiment.Results
Wood ash increased leaching of total N, NH 4 + -N, base cations and P, mainly during the first months, the effect being more pronounced for the loose formulation. At the end of the study period, a positive effect on soil nutrient availability and soil acidity reduction was seen. The application of loose and pelleted ash alone decreased N leaching and increased N microbial biomass at the end of the experiment. The C dynamics was weakly affected.Conclusion
Wood ash can be used to improve nutrient availability and balance nutrient exported by tree harvesting in acid forest soils, the effects at short-term being stronger for loose than for pelleted ash. However, their application should be carried out when vegetation is established to minimise nutrient losses at short-term and reduce the potential risk for water bodies. In N-limited soils, wood ash should be applied with N fertilisers to counteract N immobilisation. 相似文献5.
The fate of high and equally distributed ammonium and nitrate deposition was followed in a 72-year-old roofed Norway spruce forest at Solling in central Germany by separately adding 15NH4+ and 15NO3− to throughfall water since November 2001. The objective was to quantify the retention of atmospheric ammonium and nitrate in different ecosystem compartments as well as the leaching loss from the forest ecosystem. δ15N excess in tree tissues (needles, twigs, branches and bole woods) decreased with increased tissue age. Clear 15N signals in old tree tissues indicated that the added 15N was not only assimilated to newly produced tree tissues but also retranslocated to old ones. During a period of over 3-year 15N addition, 30% of 15NH4+ and 36% of 15NO3− were found in tree compartments. For both 15N tracers, 15% of added 15N was found in needles, followed by woody tissues (twigs, branches and boles, 7–13%) and live fine roots (7%). The recovery of 15NH4+ and 15NO3− in the live fine roots differed with soil depth. The recovery of 15NH4+ tended to be higher in the live fine roots in the organic layer than in the upper mineral soil. In the live fine roots in deeper soil, the recovery of 15NO3− tended to be higher than that of 15NH4+. Soil retained the largest proportion of 15N, accounting for 71% of 15NH4+ and 42% of 15NO3−. Most of 15NH4+ was recovered in the organic layer (65%) and the recovery decreased with soil depth. Conversely, only 8% of 15NO3− was found in the organic layer and 34% of 15NO3− was evenly distributed throughout the mineral soil layers. Nitrate leaching accounted for 3% of 15NH4+ and 19% of 15NO3−. Only less than 1% of the both added 15N was leached as DON. These results suggested that trees had a high contribution to the retention of atmospheric N and soil retention capacity determined the loss of atmospheric N by nitrate leaching. 相似文献
6.
Nutrient stocks of short-term fallows on a high base status soil in the humid tropics of Papua New Guinea 总被引：1，自引：0，他引：1
Alfred E. Hartemink 《Agroforestry Systems》2004,63(1):33-43
In order to understand nutrient dynamics in tropical farming systems with fallows, it is necessary to assess changes in nutrient
stocks in plants, litter and soils. Nutrient stocks (soil, above ground biomass, litter) were assessed of one-year old fallows
with Piper aduncum, Gliricidia sepium and Imperata cylindrica in the humid lowlands of Papua New Guinea. The experiment was conducted on a high base status soil (Typic Eutropepts), and
in Papua New Guinea such soils are intensively used for agriculture. Soil samples were taken prior to fallow establisment
and after one year when the fallows were slashed and above ground biomass and nutrients measured. The above ground and litter
biomass of piper was 13.7 Mg dry matter ha-1, compared to 23.3 Mg ha-1 of gliricidia and 14.9 Mg ha-1 of imperata. Gliricidia produced almost 7 Mg ha-1 wood. Total above ground biomass returned to the soil when the fallows were slashed was the same for piper and gliricidia
(8 Mg ha-1). Gliricidia accumulated the largest amounts of all major nutrients except for K, which was highest in the above ground piper
biomass. Imperata biomass contained the lowest amount of nutrients. The largest stocks of C, N, Ca and Mg were found in the
soil, whereas the majority of P was found in the above ground biomass and litter. Almost half of the total K stock of piper
and gliricidia was in the biomass. During the fallow period, soil organic C significantly increased under gliricidia fallow
whereas no net changes occurred in piper and imperata fallows. The study has shown large differences in biomass and nutrient
stocks between the two woody fallows (piper, gliricidia) and between the woody fallows and the non-woody fallow (imperata).
Short-term woody fallows are to be preferred above grass (imperata) fallows in the humid lowlands of Papua New Guinea because
of higher nutrient stocks. 相似文献
7.
杉木纯林、混交林土壤微生物特性和土壤养分的比较研究 总被引：6，自引：0，他引：6
本文于2005年5月份,在中国科学院会同森林生态实验站选择了一块15年生的杉木纯林和两块15年生杉阔混交林作为研究对象,调查了林地土壤有机碳、全氮、全磷、硝态氮、有效磷和土壤微生物碳、氮、磷、基础呼吸以及呼吸熵,比较了纯林和混交林土壤微生物特性和土壤养分.结果表明,杉阔混交林的土壤有机碳、全氮、全磷硝态氮和有效磷含量高于杉木纯林;在混交林中,土壤微生物学特性得到改善.在0(10 cm和10(20 cm两层土壤中,杉阔混交林土壤微生物氮含量分别比杉木纯林高69%和61%.在0(10 cm土层,杉阔混交林土壤微生物碳、磷和基础呼吸分别比杉木纯林高11%、14%和4%;在10(20 cm土层,分别高6%、3%和3%.但是,杉阔混交林土壤微生物碳:氮比和呼吸熵较杉木纯林低34%和4%.另外,土壤微生物与土壤养分的相关性高于土壤呼吸、微生物碳:氮比和呼吸熵与土壤养分的相关性.由此可知,在针叶纯林中引入阔叶树后,土壤肥力得以改善,并有利于退化森林土壤的恢复. 相似文献
8.
Megumi Kuroiwa Keisuke Koba Kazuo Isobe Ryunosuke Tateno Asami Nakanishi Yoshiyuki Inagaki Hiroto Toda Shigeto Otsuka Keishi Senoo Yuichi Suwa Muneoki Yoh Rieko Urakawa Hideaki Shibata 《Journal of Forest Research》2011,16(5):363-373
Measurements of gross NH 4 + and NO 3 ? production in forest soils were conducted using the 15N pool dilution method. Mineral topsoils (0?C10?cm depth) were collected from four forests from northern to southern Japan with a natural climate gradient to elucidate the mechanisms regulating gross nitrification rates in forest soils. Additionally, we attempted to evaluate the relative importance of heterotrophic nitrification in gross total nitrification using acetylene as a specific inhibitor of autotrophic nitrification. Distinct differences were found among sites in the gross rates of NH 4 + production (3.1?C11.4?mg?N?kg?1?day?1) and gross total nitrification (0.0?C6.1?mg?N?kg?1?day?1). The rates of gross heterotrophic nitrification were low in this study, indicating that heterotrophic nitrification is of minor importance in most forest mineral topsoils in Japan. Significant relations were found between gross autotrophic nitrification and gross NH 4 + production, soil N, and soil C concentrations, but none was found between gross autotrophic nitrification and soil pH. We determined the critical value of the gross NH 4 + production rates for gross autotrophic nitrification under which no gross autotrophic nitrification occurred, as well as the critical soil C/N ratio above which gross autotrophic nitrification ceased. Results show that tight coupling of production and consumption of NH 4 + prevents autotrophic nitrifiers from utilizing NH 4 + as long as NH 4 + availability is low. 相似文献
9.
Fast-growing poplar plantations on agricultural land require intensive management activities, often involving fertilization. The present paper aims at investigating the effect of fertilization on growth and on groundwater quality, by examining four trials established in commercial poplar plantations in central and south Sweden. The treatments consisted of nitrogen applications (Urea N46, Tot. N: 46%) in two different dosages, 75 and 150?kg?ha?1 for two years, and a control, in three replicates (plot size: 20?×?20?m) following a randomized block design. Diameters were measured at each plot at the end of each growing season for the period 2012–2015. At the same time, groundwater pipes were installed in the center of each plot, at ca. 1.5?m depth. Samples were regularly collected and analyzed for NO3-N and PO4-P. The results show a large variation in the diameter growth response to nitrogen fertilization and the leaching of poplar plantations after canopy closure. In young plantations, the effect on growth was clear with moderate fertilization rates although it was not observed on sandy soils with already good growth, leading to high nitrogen leaching. 相似文献
10.
Nitrogen (N) is usually the most limiting nutrient in degraded agricultural soils and affects the growth and ecological function
of poplar (Populus spp.) plantations. We hypothesized that application of organic mulch would improve soil nitrogen availability and increase
tree growth, while the quality of mulching materials would alter the supply of essential nutrients. In this study, poplar
plantations were established in 2004 and two experiments were established in the field. The fresh above-ground biomass of
cogongrass (Imperata cylindrica (L.) P. Beauv.), oak (Quercus fabri Hance), Chinese coriaria (Coriaria nepalensis Wallich) and brackenfern (Pteridium aquilinum (L.) Kuhn. var. latiusculum (Desv.) Underw. ex Heller) in the current year was selected as mulching materials, and mulches were annually applied at the
rate of 5.0 kg/m2 in the N mineralization experiment and 20,000 kg/ha in growth and nutrient availability experiment. Additions of fresh biomass
significantly improved annual net N-mineralization estimates and the mulching treatments increased the cumulative N mineralized
over the incubation period by 22–30%. However, a significant difference in the cumulative N mineralized was not observed among
the mulched treatments, even if the cumulative N mineralized in the treatment mulched with oak (QF) was 5.9, 3.3 and 2.2%
greater than that of treatments with brackenfern (PA), Chinese coriaria (CN) and cogongrass (IC), respectively. Application
of fresh biomass mulch markedly affected soil available N contents and growth performance of poplar plantations. The mulching
treatments with QF, IC, PA and CN increased annual means of available N concentration by 39.0, 29.0, 29.6 and 39.7% respectively.
At the end of the fifth growing season, the average height of poplar plantations in treatments mulched with QF, IC, PA and
CN was 46.8, 14.9, 42.6 and 57.4% greater than that in Check (CK-no mulch), while mean DBH increased by 35.4, 12.5, 33.3 and
52.1%, respectively. Overall, the productivity was enhanced in mulched plots at the end of the third growing season. Compared
with CK, the treatments mulched with QF, IC, PA and CN increased total biomass by 97.4, 96.4, 63.1 and 81.6%, respectively.
Based on the results of this study, annual application of 20,000 kg/ha fresh woody biomass would be recommended for soil improvement
in young poplar plantations growing on a degraded agricultural soil. 相似文献
11.
Carbon,nitrogen and phosphorus leaching after site preparation at a boreal forest clear-cut area 总被引：1，自引：0，他引：1
Clear-cutting followed by mechanical site preparation is the major disturbance influencing nutrient and water fluxes in Fennoscandian boreal forests. The effects of soil harrowing on the fluxes of dissolved organic carbon (DOC), dissolved nitrogen compounds (organic N, NH4+ and NO3−) and water soluble phosphorus (PO43−) through a podzolic soil were studied in a clear-cut in eastern Finland for 5 years. The old, mixed coniferous stand was clear-cut and stem only harvested in 1996 followed by soil harrowing in 1998 and planting in June 1999. Zero-tension lysimeters were used to collect soil water from below different soil horizons in the three types of microsites that resulted from site preparation treatment: low ridges (25% of clear-cut area), shallow furrows (30%) and the undisturbed soil (45%). After soil harrowing, the leaching of DOC, N and P from below the B-horizon increased compared to pre-treatment levels. However, the increases were short-lasting; 1–2 years for inorganic N and P, and 5 years for DOC and organic N. The highest concentrations were associated with the ridges and lowest with the furrows, reflecting the differences in amount of organic matter present in each microsite type and, for N, to enhanced mineralization and nitrification. Leaching from below the B-horizon over the 5 years following soil harrowing for the whole clear-cut area was 36.5 kg ha−1 for DOC, 0.88 kg ha−1 for NH4-N, 0.46 kg ha−1 for NO3-N, 1.24 kg ha−1 for organic N and 0.09 kg ha−1 for PO4-P. Site preparation increased temporarily the risk for nutrient leaching into watercourses and groundwater from the clear-cut area but soil fertility was not affected since the leached amounts remained small. The main reasons for the observed low leaching values were the rapid recovery of ground vegetation and low N deposition loads. 相似文献
12.
Eduardo S. Matos Dirk Freese Eduardo S. Mendonça Anna Slazak Reinhard F. Hüttl 《Agroforestry Systems》2011,81(3):203-211
The conversion of silvopasture to different land use systems cause effective changes in soil carbon distribution, due to disturbances
in soil aggregation promoted by soil management and changes in crop residues inputs and decomposability. We evaluate the C
and N stocks, and organic C fractions in soils under continuous arable land (AR) and silvopasture with apple trees and grass
(SP); and after 4 years of conversion from silvopasture to arable land (SP-AR) and grassland (SP-GL). Total N (TN) and organic
C (TOC), as well as microbial biomass carbon (CMB), light fraction (CLF) and heavy fraction (CHF) were evaluated at two different depths (0–10 and 10–20 cm). After 4 years of conversion, SP-AR and SP-GL presented C and
N stocks similar to the observed for SP when the 0–20 cm depth was considered. However, AR presented TOC and TN stocks around
21 and 10% lower than SP, respectively. SP-AR tended to present the lowest CMB stocks and was positively correlated with salt extractable organic C (r
2 = 0.60, P < 0.001). CLF values declined by 62% from 0–10 to the 10–20 cm at SP and SP-GL, however there was no variation with increasing depth for
AR and SP-AR. CHF represented the highest C fraction in soil, corresponding to 82% of TOC. Except for AR, δ13C values of the light fraction increased with increasing depth. In general, heavy fraction tended to be more enriched in δ13C than light fraction. In a long-term, conventional tillage can significantly contribute to reduce TOC and TN stocks when
compared to the silvopastoral system. 相似文献
13.
The removal or maintenance of harvest residues in eucalypt plantations may influence site quality and productivity. Removal of slash from the site may facilitate further management operations and provide a valuable energy resource, but effects on site productivity and sustainability for a rotation time span were not yet assessed under Mediterranean conditions. Therefore, a study was carried out to assess the effects of slash (harvest residues plus forest floor litter) management and soil preparation options on stand productivity and understory vegetation dynamics, hypothesizing that those options influence tree growth, forest floor dynamics and understory biomass and diversity. An experiment was installed in West Central Portugal, consisting on: removal of slash without soil preparation (R); broadcast of harvest residues on the soil surface without soil disturbance (S); as in S, but concentrating the woody debris between tree rows (W); incorporation of slash into the soil by harrowing (I); removal of slash followed by harrowing (RH); and as in I followed by ripping (IS). The experiment was monitored for a rotation time span (140 months). Maintenance of slash followed by deep soil disturbance led to the highest wood production, but differences between treatments were not significant (p > 0.05). Forest floor load and understory biomass were also similar between treatments. Ground vegetation played an important role on nutrient cycling in early rotation stages, such effect being irrespective on slash management options. Incorporation of slash into the soil followed by ripping is probably the best option to match production and environmental sustainability of eucalypt plantations in Mediterranean conditions. 相似文献
14.
Naoyuki Yamashita Seiichi Ohta Hiroyuki Sase Jesada Luangjame Thiti Visaratana Bopit Kievuttinon Hathairatana Garivait Mamoru Kanzaki 《Forest Ecology and Management》2010
Seasonal and spatial variability of litterfall and NO3− and NH4+ leaching from the litter layer and 5-cm soil depth were investigated along a slope in a tropical dry evergreen forest in northeastern Thailand. Using ion exchange resin and buried bag methods, the vertical flux and transformation of inorganic nitrogen (N) were observed during four periods (dry, early wet, middle wet, and late wet seasons) at 15 subplots in a 180-m × 40-m rectangular plot on the slope. Annual N input via litterfall and inorganic N leached from the litter layer and from 5-cm depth soil were 12.5, 6.9, and 3.7 g N m−2 year−1, respectively, whereas net mineralization and the inorganic N pool in 0–5-cm soil were 7.1 g N m−2 year−1 and 1.4 g N m−2, respectively. During the early wet season (90 days), we observed 82% and 74% of annual NO3− leaching from the litter layer and 5-cm soil depth, respectively. Higher N input via leaf litterfall in the dry season and via precipitation in the early wet season may have led to higher NO3− leaching rate from litter and surface soil layers during the early wet season. Large spatial variability in both NO3− vertical flux and litterfall was also observed within stands. Small-scale spatial patterns of total N input via litterfall were significantly correlated with NO3− leaching rate from the surface soil layer. In tropical dry evergreen forests, litterfall variability may be crucial to the remarkable seasonal changes and spatial variation in annual NO3− vertical flux in surface soil layers. 相似文献
15.
Bernd Zeller Sylvie Recous Morgan Kunze Judicaël Moukoumi Micheline Colin-Belgrand Séverine Bienaimé Jacques Ranger Etienne Dambrine 《Annals of Forest Science》2007,64(2):151-158
We compared N fluxes in a 150-year-old Fagus sylvatica coppice and five adjacent 25-year-old plantations of Fagus sylvatica, Picea abies, Quercus petraea, Pinus laricio and Pseudotsuga menziesii. We measured net N mineralization fluxes in the upper mineral horizon (A1, 0–5 cm) for 4 weeks and gross N mineralization fluxes for two days. Gross rates were measured during the 48-h period after addition of 15NH4 and 15NO3. Mineralization was measured by the 15NH4 dilution technique and gross nitrification by 15NO3 production from the addition of 15NH4, and by 15NO3 dilution. Net and gross N mineralization was lower in the soil of the old coppice, than in the plantations, both on a soil weight and organic nitrogen basis. Gross nitrification was also very low. Gross nitrification measured by NO3 dilution was slightly higher than measured by 15NO3 production from the addition of 15NH4. In the plantations, gross and net mineralization and nitrification from pool dilution were lowest in the spruce stand and highest in the beech and Corsican pine stands. We concluded that: (1) the low net mineralization in the soil of the old coppice was related to low gross rate of mineralization rather than to the concurrent effect of microbial immobilisation of mineral N; (2) the absence of nitrate in the old coppice was not related to the low rate of mineralization nor to the absence of nitrifyers, but most probably to the inhibition of nitrifyers in the moder humus; (3) substituting the old coppice by young stands favours nitrifyer communities; and (4) heterotrophic nitrifyers may bypass the ammonification step in these acid soils, but further research is needed to check this process and to characterize the microbial communities. 相似文献
16.
Nothofagus antarctica forests in south Patagonia are usually used as silvopastoral systems but how grasses and trees compete for specific resources, such as nitrogen in these systems is unknown. To understand interactions between grasses and N. antarctica trees for N, an experiment with 15N labeled fertilizer was carried out comparing N absorption by grasses growing under trees (silvopastoral system) with an open site. Labeled 15NH 4 15 NO3 fertilizer at 10 % atom excess was added in spring at both sites and 15N was measured in herbage, soil and trees every 30 days during the growing season. Soil was the component that containing the greatest amount of N and greatest 15N recovery. Grasses growing in the silvopastoral system absorbed almost double of the fertilizer applied than grasses in the open site (32.4 kg N ha?1derived from fertilizer based on 15N recovery). Roots were also an important fate for N absorbed, representing 50 and 63 % of total 15N recovered in grass roots of open and silvopastoral sites, respectively. Trees absorbed 69 % less applied N than grasses in the silvopastoral system; being mainly allocated in small branches, sapwood and fine roots. Overall, 15N recovery was 65 % higher in the silvopastoral system (tree + grasses) than in the open site (grasses). Silvopastoral system made more efficient use of the 15N added. These results indicated that N. antarctica trees in the silvopastoral system may “facilitate” fertilizer N absorption of grasses by improving environmental conditions like water availability or by reducing competition for inorganic N between soil microorganisms and plants. 相似文献
17.
Pastures store over 90% of their carbon and nitrogen below-ground as soil organic matter. In contrast, temperate conifer forests
often store large amounts of organic matter above-ground in woody plant tissue and fibrous litter. Silvopastures, which combine
managed pastures with forest trees, should accrete more carbon and nitrogen than pastures or timber plantations because they
may produce more total annual biomass and have both forest and grassland nutrient cycling patterns active. This hypothesis
was investigated by conducting carbon and nitrogen inventories on three replications of 11 year-old Douglas-fir (Pseudotsuga menziesii)/perennial ryegrass (Lolium perenne)/subclover (Trifolium subterraneum) agroforests, ryegrasss/subclover pastures, and Douglas-fir timber plantations near Corvallis, Oregon in August 2000. Over
the 11 years since planting, agroforests accumulated approximately 740 kg ha–1 year –1 more C than forests and 520 kg ha–1 year–1 more C than pastures. Agroforests stored approximately 12% of C and 2% of N aboveground compared to 9% of C and 1% of N above
ground in plantations and less than 1% of N and C aboveground in pastures. Total N content of agroforests and pastures, both
of which included a nitrogen-fixing legume, were approximately 530 and 1200 kg ha–1 greater than plantations, respectively. These results support the proposition that agroforests, such as silvopastures, may
be more efficient at accreting C than plantations or pasture monocultures. However, pastures may accrete more N than agroforests
or plantations. This apparent separation of response in obviously interrelated agroecosystem processes, points out the difficulty
in using forest plantation or pasture research results to predict outcomes for mixed systems such as agroforests.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
18.
Cristina Fernández José A. Vega Salvador Bará Carmen Beloso Margarita Alonso Teresa Fonturbel 《Annals of Forest Science》2009,66(8):807-807
19.
A major limitation to efficient forage-based livestock production in Appalachia is asynchrony of forage availability and quality
with nutritional requirements of the grazer. Producers require dependable plant resources and management practices that improve
the seasonal distribution and persistence of high quality herbage, sustainability and environmental integrity of the agricultural
landscape. It was hypothesized that inorganic N and fecal coliform concentrations delivered in leachate to the soil/bedrock
interface would be lowest in deciduous forest (HF) and highest in pasture (CP) with HF converted to silvopasture (SP) between
the two. Piezometers were used to monitor water quality at the soil/bedrock interface under conventional pasture, SP, and
hardwood forest. The pasture and SP were rotationally grazed by sheep during the spring to fall grazing season (2004–2008).
Geometric mean fecal coliform bacteria concentrations (FC) were greatest in SP (18 FC 100 mL−1) with no difference between CP (7.5 FC 100 mL−1) and HF (5.6 FC 100 mL−1). Mean NO3-N concentration was lowest in SP (2.3 mg L−1) and greatest in CP (4.4 mg L−1) and HF (4.1 mg L−1), which were not significantly different. Mean NH4-N concentrations showed different trends with the lowest mean concentration in CP (0.5 mg L−1) and the greatest in SP (2.5 mg L−1) and HF (2.6 mg L−1), which were not significantly different. SP was shown to be a management option in the study area that reduces nitrate leaching,
but should be considered cautiously in near-stream areas and near wells where fecal bacteria pollution can be problematic.
This study makes an important contribution to our knowledge about interactions between landscape management and environmental
quality of the Appalachian region. A diversity of land and forage management options are needed to maximize forage and livestock
productivity while protecting surface and groundwater quality of the region. 相似文献
20.
《Scandinavian Journal of Forest Research》2012,27(1):38-47
The objective of this study was to quantify the effects of high nitrogen (N) inputs on N cycling in a 35–45-yr-old Scots pine (Pinus sylvestris L.) forest. Nitrogen was added annually (single doses) as NH4NO3 in doses of 0 (N0), 30 (N1) and 90 (N2) kg N ha?1 yr?1. The only N input to the N0 plots was atmospheric deposition of 10 kg N ha?1 yr?1. The N cycle in these plots was tight, with almost complete retention of the incoming N. In the N1 plots the N retention was 83% after 9 yrs of N addition. The trees were the major sink, but the soil also contributed to the N retention. In the N2 plots the N retention was 63%, being mainly accounted for by accumulation in the soil. The leaching of N from the N2 stands was as high as 35 kg N ha?1 yr?1. The N2 system was N saturated. 相似文献