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1.
W. E. Hillis 《Wood Science and Technology》1998,32(2):139-143
Summary Crystalline or almost pure organic compounds can be formed either alone or with two or three related compounds in juxtaposition in shakes in central heartwood. The compounds may not always be present in the more complex extractives formed at the heartwood periphery. The largest amounts of deposits are in the innermost or widest portion of the shake. No evidence could be found of a source of substrate, energy or specific enzymes necessary for the selective biosynthesis of these deposits. They are considered to be formedin situ by an undetermined mechanism during enlargement of the shake. 相似文献
2.
Examination of callus micro-grafts in Uapaca kirkiana Müell Arg. was carried out with the objective of determining early signs of graft compatibility. Leaves from U. kirkiana, U. nitida and Jatropha curcas trees were used for callus induction. Two pieces of callus were co-cultured on Murashige and Skoog (MS) medium with different
supplements. Co-cultured calli were embedded in paraffin wax and dissected. The specimens were stained in safranin and fast
green before viewing under a light microscope. Results showed that MS medium with 0.1 mg l−1 thidiazuron (TDZ) and 0.5 mg l−1 naphthaleneacetic acid (NAA) or 1.0 mg l−1 dichlorophenoxyacetic acid (2,4-D) and 0.5 mg l−1 NAA was effective for callus induction. There were no necrotic layers at the unions within U. kirkiana clones and provenances, but a differential growth (irregularity) between U. kirkiana and U. nitida co-cultured calli. Phenol deposits were observed at the union interfaces of U. kirkiana combinations and were high on calli derived from mature trees. Phenol deposits were absent at the union of J. curcas heterografts. Necrotic layers developed at the unions of U. kirkiana and J. curcas micro-grafts and indicating an outright graft incompatibility. Accumulation of phenol deposits at the union interfaces inhibited
graft compatibility in many U. kirkiana combinations. Callus fusion technique can be used to identify partners with an outright graft incompatibility, especially
for distant related plant species. 相似文献
3.
Hollie Hall Yuncong Li Nicholas Comerford Enrique Arévalo Gardini Luis Zuniga Cernades Virupax Baligar Hugh Popenoe 《Agroforestry Systems》2010,80(3):447-455
In many tropical soils, excessive weathering of primary minerals confounded by intense agricultural production has resulted
in the depletion of organic matter and plant available forms of phosphorus (P). Long-term growth of cover crops in tropical
agroforestry systems have been shown to influence nutrient cycling, and soil organic matter pools. The objective of this experiment
was to assess the affect of 2 years of cover-crop cultivation on organic matter accumulation and P bioavailability using Mehlich
I and sequential fractionation methods. The experiment included six treatments in the understory of a cacao-plantain agroforestry
system adjacent to lower montane tropical forests of the San Martin district of Eastern Peru. Cacao and plantain formed the
primary canopy on otherwise abandoned agricultural land. The treatments consisted of four perennial leguminous cover crops
(Arachis pintoi, Calopogonium mucunoides, Canavalia
ensiformis, and Centrosema macrocarpum), a non-legume cover crop (Callisia repens), and a control treatment (no cover crop). After only 2 years of cultivation, results suggest that all cover crop species
accessed residual P pools in 0–5 cm soil depths as indicated by a decrease in the 0.5 M HCl extractable P pools when compared
to control. Additional use of residual P pools by A. pintoi and C. macrocarpum were indicated by significant reduction in the 6.0 M HCl extractable P pool. Relative to control, there was no treatment
effect on soil organic matter content; however significant differences occurred between treatments. The C. ensiformis, C. mucunoides and C. repens treatments in 5–15 cm soil depths contained significantly more organic matter than the A. pintoi treatment. In 15–30 cm soil depths the C. ensiformis treatment contains significantly more organic matter than the A. pintoi treatment. Continued research should focus on monitoring the long-term effects of cover crop cultivation on the bioavailability
of soil P pools in surface soil horizons, development of organic matter pools and the productivity of the agroforestry species. 相似文献
4.
Greater organic matter inputs in agroforestry systems contribute to the long-term storage of carbon (C) in the soil, and the
use of simulation models provides an opportunity to evaluate the dynamics of the long-term trends of soil organic carbon (SOC)
stocks in these systems. The objective of this study was to apply the Century model to evaluate the long-term effect of agroforestry
alley crop and sole crop land management practices on SOC stocks and soil C fractions. This study also evaluated the accuracy
between measured field data obtained from a 19-year old tropical (TROP) and 13-year old temperate (TMPRT) alley crop and their
respective sole cropping systems and simulated values of SOC. Results showed that upon initiation of the TROP and TMPRT alley
cropping systems, levels of SOC increased steadily over a ~100 year period. However, the sole cropping systems in both tropical
and temperate biomes showed a decline in SOC. The active and passive C fractions increased in the TROP agroforestry system,
however, in the TMPRT agroforestry system the active and slow fractions increased. The input of organic matter in the TROP
and TMPRT agroforestry systems were 83 and 34% greater, respectively, compared to the sole crops, which likely contributed
to the increased SOC stock and the C fractions in the alley crops over the 100 year period. Century accurately evaluated levels
of SOC in the TROP (r
2 = 0.94; RMSE = 226 g m−2) and TMPRT (r
2 = 0.94; RMSE = 261 g m−2) alley crops, and in the TROP (r
2 = 0.82; RMSE = 101 g m−2) and TMPRT (r
2 = 0.83; RMSE = 64 g m−2) sole crops. Century underestimated simulated values in the alley cropping systems compared to measured values due to the
inability of the model to account for changes in soil bulk density with increasing organic matter inputs with tree age from
prunings or litterfall. 相似文献
5.
A long-term (20 months) bulk litter decomposition experiment was conducted in a subtropical plantation in southern China in
order to test the hypothesis that stable isotope discrimination occurs during litter decomposition and that litter decomposition
increases concentrations of nutrients and organic matter in soil. This was achieved by a litter bag technique. Carbon (C),
nitrogen (N) and phosphorus (P) concentrations in the remaining litter as well as δ13C and δ15N during the experimental period were measured. Meanwhile, organic C, alkali-soluble N and available P concentrations were
determined in the soils beneath litter bags and in the soils at the control plots. The dry mass remaining (as % of the initial
mass) during litter decomposition exponentially declined (y = 0.9362 e−0.0365x
, R
2 = 0.93, P < 0.0001), but total C in the remaining litter did not decrease significantly with decomposition process during a 20-month
period. By comparison, total N in the remaining litter significantly increased from 5.8 ± 1.7 g kg−1 dw litter in the first month to 10.1 ± 1.4 g kg−1 dw litter in the 20th month. During the decomposition, δ13C values of the remaining litter showed an insignificant enrichment, while δ15N signatures exhibited a different pattern. It significantly depleted 15N (y = −0.66x + 0.82, R
2 = 0.57, P < 0.0001) during the initial 7 months while showing 15N enrichments in the remaining 13 months (y = 0.10x − 4.23, R
2 = 0.32, P < 0.0001). Statistically, litter decomposition has little impact on concentrations of soil organic C and alkali-soluble N
and available P in the top soil. This indicates that nutrient return to the topsoil through litter decomposition is limited
and that C cycling decoupled from N cycling during decomposition in this subtropical plantation in southern China. 相似文献
6.
Fundamental to the success of forest restoration following major disturbances such as mining is development of a functioning soil, including the amount, properties and rates of accumulation of soil organic matter (SOM). SOM enters mineral soil through leaching of dissolved organic matter from the forest floor; macrofaunal processing of above-ground litter and mixing with soil (bioturbation); and direct deposition of root litter and rhizodeposits. Our study focused on how SOM accumulation in reclaimed mineral soils was affected following re-vegetation with three vegetation treatments: deciduous trees (Populus tremuloides Mitchx. and Populus balsamifera L.), spruce trees (Picea glauca (Moench) Voss.) and grasses (Festuca sp., Bromus inermis), compared to the natural boreal forest. Seventeen sites were studied: 4 reclaimed Deciduous, 5 reclaimed Spruce, 4 reclaimed Grass, and 4 Natural forest. Concentrations of soil organic matter in the upper 30 cm of soil were highest at the Deciduous sites and lowest at Natural sites. SOM concentrations in the top 10 cm of soil were elevated relative to 10–30 cm soil at the Deciduous and Grass sites. The elevated SOM in the upper soil at Deciduous and Grass sites was associated with greater macrofauanal activity and higher root biomass at these sites. The higher macrofaunal activity in the surface organic layer and greater amounts of faunal fecal material in the uppermost cm of soil at Deciduous and Grass sites indicate greater enrichment of upper soil by macrofauna at these sites. SOM concentrations were significantly positively related to root abundance at Grass sites (indicating a contribution of roots to SOM), and a similar trend was apparent at the Deciduous sites. The elevated organic matter concentrations in the upper 10 cm of soil at the Deciduous and Grass sites suggest that planting of aspen following reclamation would hasten C sequestration into soil organic matter.
相似文献7.
The impact of Erythrina poeppigiana on soil characteristics, at three different positions relative to the shade tree and from three different soil depths, was
evaluated in pairs of comparable Costa Rican coffee farms (organic and conventional) in 2000 and 2004. In the conventional
system at 0–5 cm, higher C and N concentrations were found close to the shade tree versus the positions 2 m from the trunk
(5.04 vs. 4.18%). This positive effect could influence only 20% of the farm area when high population of E. poeppigiana were used. This finding highlighted the importance of E. poeppigiana in maintaining SOM levels. In contrast, the organic system showed similar C and N concentrations for all positions probably
due to an even distribution of pruning residues and to the use of organic amendments. A trend to higher total C and N concentrations
for organic farms in comparison to conventional farms was found. No significant temporal changes in soil C or N concentrations
were found between 2000 and 2004. 相似文献
8.
Gudeta W. Sileshi Festus K. Akinnifesi France M. Gondwe Oluyede C. Ajayi Simon Mng’omba Konisaga Mwafongo 《Agroforestry Systems》2011,83(3):361-372
The production of paprika (Capsicum annum L.) under small-scale farm conditions in southern Africa is constrained by low soil fertility and lack of appropriate cultivars.
The objective of this study was to determine the growth responses and fruit yields of six cultivars of paprika to organic
and inorganic nutrient sources. The study was conducted in 2007 and 2008 at Chitedze Agricultural Research Station in Malawi.
A combination of six paprika cultivars and four nutrient sources, namely (1) organic input from Gliricidia, (Gliricidia sepium) biomass, (2) inorganic fertilizer, (3) integrated nutrient input (Gliricidia biomass + inorganic fertilizer), and (4) control
(no nutrient input) were compared. Each combination was replicated five times. A split-plot design was used where nutrient
sources formed the main plot and cultivars the sub-plots. Plant height differed due to nutrient source in 2007 and 2008, while
differences due to cultivar were minor. The control plots produced the shortest plants (height < 50 cm), while plots receiving
the integrated nutrient input produced the tallest plants (height > 60 cm). Numbers of branches and fruits per plant differed
due to nutrient source and cultivar during most of the study period. Plants receiving either organic inputs (Gliricidia biomass)
alone or the integrated nutrient input alone had significantly higher stem, leaf and fruit weight compared with the control.
Average fruit yield was lower in control plots than in plots receiving the organic input alone or the integrated nutrient
input. Among cultivars, Papri-King, Papri-Supreme and Papri-Queen produced higher dry fruit yield. The ASTA and RAL colour
rating was within the internationally accepted range for fruit from the treatments. 相似文献
9.
Adele Muscolo Maria Sidari Silvio Bagnato Carmelo Mallamaci Roberto Mercurio 《European Journal of Forest Research》2010,129(3):355-365
Changes in soil properties related to natural regeneration of silver fir (Abies alba, Mill.) in small (185 m2) and medium (410 m2) gaps, in the Calabria Apennines (Southern Italy), were studied 2 years after gap creation. The organic matter within the
medium gaps decayed more rapidly than those in the small gaps. Among the microenvironmental variables and soil properties,
soil temperature was most strongly positively related to organic matter decomposition rates. Medium gaps had high soil temperature
and photosynthetically active radiation (PAR) transmittance, and low soil moisture. Within medium gaps, we found a great amount
of phenolic compounds and a low content of organic matter and humic acids. These results indicate that in the medium gaps
mineralization of organic matter was more important than humification. In contrast, in small gaps, the great amount of organic
matter, the high content of humic acid and the values of humification index suggested that in these gaps the humification
process of organic matter prevailed. Within small gaps, we observed more silver fir regeneration than medium gaps. Difference
in organic matter content, particularly in the amount of phenolic compounds, may account for differences observed in natural
regeneration of silver fir between small and medium gaps. 相似文献
10.
Lorena Soto-Pinto Manuel Anzueto Jorge Mendoza Guillermo Jimenez Ferrer Ben de Jong 《Agroforestry Systems》2010,78(1):39-51
The importance of agroforestry systems as carbon sinks has recently been recognized due to the need of climate change mitigation.
The objective of this study was to compare the carbon content in living biomass, soil (0–10, 10–20, 20–30 cm in depth), dead
organic matter between a set of non-agroforestry and agroforestry prototypes in Chiapas, Mexico where the carbon sequestration
programme called Scolel’te has been carried out. The prototypes compared were: traditional maize (rotational prototype with
pioneer native trees evaluated in the crop period), Taungya (maize with timber trees), improved fallow, traditional fallow
(the last three rotational prototypes in the crop-free period), Inga-shade-organic coffee, polyculture-shade organic coffee,
polyculture-non-organic coffee, pasture without trees, pasture with live fences, and pasture with scattered trees. Taungya
and improved fallow were designed agroforestry prototypes, while the others were reproduced traditional systems. Seventy-nine
plots were selected in three agro-climatic zones. Carbon in living biomass, dead biomass, and soil organic matter was measured
in each plot. Results showed that carbon in living biomass and dead organic matter were different according to prototype;
while soil organic carbon and total carbon were influenced mostly by the agro-climatic zone (P < 0.01). Carbon density in the high tropical agro-climatic zone (1,000 m) was higher compared to the intermediate and low
tropical agro-climatic zones (600 and 200 m, respectively, P < 0.01). All the systems contained more carbon than traditional maize and pastures without trees. Silvopastoral systems,
improved fallow, Taungya and coffee systems (especially polyculture-shade coffee and organic coffee) have the potential to
sequester carbon via growing trees. Agroforestry systems could also contribute to carbon sequestration and reducing emissions
when burning is avoided. The potential of organic coffee to maintain carbon in soil and to reduce emissions from deforestation
and ecosystem degradation (REDD) is discussed. 相似文献
11.
Ginkgo (Ginkgo biloba L.) is a traditional economic tree species in China, and often cultivated in agroforestry systems. The objective of the study
was to examine the effects of different Ginkgo and crop species combinations on soil fertility. We established two Ginkgo
and crop species systems: Ginkgo + wheat + soybean (G+W+S), Ginkgo + rape + soybean (G+R+S), and one Ginkgo + mulberry (G+M)
system, one pure mulberry plantation (M), and one crop systems of rape + soybean (R+S) in the field. Soil chemical properties
and enzymes activities were measured 4 years after planting. These soil chemical properties and enzyme activities were used
as soil fertility indicators (FI). Soil fertility of the five planting systems was finally evaluated by using improved Analytic
Hierarchy Process (AHP). The result showed that soil chemical properties (including pH, organic matter, total N, hydrolysable
N, available P and K, total K) and soil enzyme activities (including catalase, sucrase, urease, dehydrogenase, phosphatase,
polyphenol oxidase and protease) in the five planting systems were significantly different from each other (P = 0.0237). The above parameters were also different at different soil depths. The concentration of total N, P, organic matter,
available P and K of soil decreased significantly with soil depth (P = 0.0146), however, pH increased. The concentrations of organic matter, total N, hydrolysable N, available P and K of soil
under rape + soybean (R+S) was lowest among the five planting systems. The activities of sucrase, urease, dehydrogenase, phosphatase
and protease decreased with soil depth, however, the activity of catalase and polyphenol oxidase increased. Except for catalase,
the activities of these enzymes in the R+S system were the lowest among the five planting systems. The integrated evaluation
of soil fertility showed that soil fertility indicators (FI) were significantly different, and the FI values for the five
systems followed order: G+M (0.847) > G+W+S (0.446) > M (0.399) > G+R+S (0.343) > R+S (0.211). These results indicated that
adoption of a Ginkgo-crop combination could lead to increased long-term sustainability of soil fertility by improving levels
of soil organic matter, pH, available nutrient and soil enzyme activity. 相似文献
12.
Patrícia A. B. Barreto Emanuela F. Gama-Rodrigues A. C. Gama-Rodrigues Alexandre G. Fontes José C. Polidoro Maria Kellen S. Moço Regina C. R. Machado V. C. Baligar 《Agroforestry Systems》2011,81(3):213-220
Agroforestry systems can play a major role in the sequestration of carbon (C) because of their higher input of organic material
to the soil. The importance of organic carbon to the physical, chemical, and biological aspects of soil quality is well recognized.
However, total organic carbon measurements might not be sensitive indicators of changes in soil quality. Adoption of procedures
that can extract the more labile fraction preferentially might be a more useful approach for the characterization of soil
organic carbon resulting from different soils. This study aimed to evaluate organic carbon (C) fractions distribution in different
soil layers up to 50 cm depth in two soil orders under cacao (Theobroma
cacao) agroforestry systems (AFS) in Bahia, Brazil. Soil samples were collected from four depth classes (0–5, 5–10, 10–30 and 30–50 cm)
under two cacao agroforestry systems (30-year-old stands of cacao with Erythrina glauca, as shade trees) in Latosol and Cambisol, in Bahia, Brazil. The determination of oxidizable carbon by a modified Walkley–Black
method was done to obtain four C fractions with different labile forms of C (fraction 1: labile fraction; fraction 2: moderate
labile fraction; fraction 3: low labile fraction and fraction 4: recalcitrant fraction). Overall, at two cacao AFS, the C
fractions generally declined with increase in soil depth. The C fractions 1 and 2 were 50% higher on upper layers (0–5 and
5–10 cm). More than 50% of organic C was found in more labile fraction (fraction 1) in all depths for both soils. High value
of C fraction 1 (more labile C)-to-total organic C ratio was obtained (around 54–59%, on Latosol and Cambisol, respectively),
indicating large input of organic matter in these soils. 相似文献
13.
Changes in soil properties and nematode population status under Flemingia macrophylla [(Willd.) Merrill], Pueraria phaseoloides (Roxb.) Benth, and natural bush fallows were assessed in three villages in southern Cameroon. In each village, experiments
were set up in a 4–5 year-old bush fallow dominated by Chromolaena odorata (L.) R. M. King and H. Rob and a more than 20 year-old secondary forest. Total aboveground biomass production of P. phaseoloides was 7.45 Mg ha−1, 4.2 times higher than F. macrophylla (1.78 Mg ha−1; P < 0.05). In two years (24 MAP), the soil bulk density under P. phaseoloides, F.macrophylla and the natural regrowth in both bush and forest land use systems decreased (P < 0.05). Within the same period, there was a general improvement in aggregate stability. The particle size distribution changed
over 3 years (36 MAP), such that at 0–10 cm depth, the percent sand content had reduced whiles the percent clay content had
increased under all the fallow systems in both bush and forest land use systems (LUSs). Soil N also increased significantly
(P < 0.05) after cropping under all the fallow systems in both LUS. In contrast, soil organic carbon decreased, but the extent
was lower under P. phaseoloides and F. macrophylla compared to the natural regrowth. Soil P also decreased after cropping under all the fallow systems in both LUS whereas decrease
in Mg was only observed under P. phaseoloides. F. macrophylla had Mg content after cropping similar to the initial in both LUS. Soil contents of K and Ca were not significantly different
over time under all the fallow systems. Comparing the initial Helicotylenchus multicinctus population to that at 12 MAP, both P. phaseoloides and F. macrophylla reduced density of H. multicinctus (P < 0.05). However, when the initial population density was compared to that at 24 MAP only under P. phaseoloides was the reduction maintained. The study concluded that the general improvement in the soil physical properties, impacted
positively on the N and organic carbon contents which were sustained to a larger extent under the planted fallows than the
natural regrowth. Furthermore, P. phaseoloides could be used as one component for the biological control of Helicotylenchus multicinctus, a phytopathogenic nematode. 相似文献
14.
Soil properties under an exotic plantation (Pinus caribaea) and an indigenous plantation (Podocarpus imbricatus) were compared with adjacent secondary forests and abandoned land in the tropical forest areas of Jianfengling National Nature
Reserve in Hainan province, southern China. The surface soil (0–0.2 m) under Pi. caribaea has higher bulk density, lower soil organic carbon, total N, total K, available N, microbial biomass carbon, and smaller
soil microbial communities (as indicated by soil Biolog profiles) than under Po. imbricatus. Both land use types showed negative cumulative soil deterioration index (DI) compared to secondary forests. However, compared
to abandoned land (DI = –262), the soil quality of Po. imbricatus showed improvement (DI = –194) while that of Pi. caribaea showed deterioration (DI = –358). These results demonstrated that these exotic pine plantations can significantly and negatively
influence soil properties. By contrast, our results showed that adoption of indigenous species in plantations, or natural
regeneration, can improve soil quality. 相似文献
15.
Summary Morphological and chemical examinations of the extractives of the tissues and shake contents of eight Dacrydium and one Podocarpus species have been made. The whitish deposits in heart-shakes are without exception mainly podocarpic acid (PCA). This compound occurs also in the tissue of samples but only when shakes are found nearby. Accordingly PCA is regarded as an anomalous extractive, synthesized in response to those conditions resulting in shake formation. In samples with shakes PCA is present in very small amounts at the sapwood-heartwood boundary and in one sample there were traces even in the innermost sapwood. It was notable that shakes containing deposits can arise in those Dacrydium species with coloured heartwood and with a known tendency for wetwood formation. On the other hand Dacrydium franklinii does not develop coloured heartwood or wetwood or shakes, and the lack of these features may have taxonomic significance.The third author expresses his gratitude to the Division of Building Research, CSIRO, Highett, Vic., for a visiting Fellowship during 1974. 相似文献
16.
Bareroot Changbai larch (Larix olgensis Henry.) seedlings were reared with inorganic fertilizer (nitrogen (N):phosphorus (P) = 1:1, W/W) applied at a rate of 100
(F100) or 200 kg N ha−1 (F200) with (+) or without (−) chicken manure as a soil amendment (O) in north-eastern China. An unfertilized control treatment
was included. Inorganic and organic fertilizer treatments tended to increase soil ammonium, nitrate, available P, total P,
organic carbon content and electrical conductivity, and biomass and N concentration in seedlings. Organic amendment improved
first order lateral root number, tap root length, fine root morphology (length, surface area, volume) in seedlings, while
the F100 treatment increased N accumulation in needles and stems compared to the F200 treatment, on average. Most fertilizer
treatments tended to increase P content in combined stems and roots, but F200 − O and F100 + O treatments diluted P in needles.
Organic amendment combined with inorganic fertilizer at a rate of 100 kg N and P ha−1 is recommended to improve seedling growth and N reserves in woody tissues. 相似文献
17.
We selected sites of natural broad-leaved forests and adjacent coniferous plantations (Cunninghamia konishii and Calocedrus formosana of 30 and 80 years old, respectively) in central Taiwan to evaluate the effects of plantations on soil organic matter (SOM)
characteristics and composition. SOM was characterized by chemical analyses, solid-state 13C cross-polarization magic-angle nuclear magnetic resonance (CPMAS 13C NMR), and optical measurements. Semiquantitative analysis of CPMAS 13C NMR spectra showed the litter of broad-leaved forests to be less resistant to decomposition than that of coniferous forests.
The humification degree of SOM was higher under broad-leaved than coniferous forests because of the relatively high percentage
of aromatic C and carboxyl C in the humic acids (HAs) of A horizons under broad-leaved forests. Additionally, the E
4/E
6 ratio of HAs was lower in the A horizon under broad-leaved than coniferous forests, which reflected more condensation of
SOM. High alkyl C content under coniferous forests could be attributed to needle litter quality, which has a high content
of waxes or lipids. Afforestation with conifers induced accumulation of the litterfall layer, gradually increased SOM concentrations,
and changed the composition structures of SOM in the topsoils. 相似文献
18.
Federico Brilli Nicola Luchi Marco Michelozzi Luca Calamai Gabriele Cencetti Francesco Pecori Emanuele Nigrone Alberto Santini 《Forest Pathology》2020,50(4)
Ceratocystis platani causes canker stain of plane trees, and it represents a serious disease of Platanus spp. both in the United States and Europe. Current chemical or biological controls do not effectively manage C. platani, so new preventive methods need to be developed in order to limit this pathogen spreading. In this work, we have characterized the main volatile organic compounds (VOC) emitted in vitro from pure cultures of C. platani and other common pathogenic fungal species of hosts plants growing in the same ecosystems as plane trees. We found that C. platani emitted a similar blend of VOC compared with phylogenetically similar species C. populicola. In particular, C. platani was characterized by emission of isoamyl acetate and isobutyl acetate while C. populicola by ethyl acetate and isobutyl acetate, which were not released by any of the other out‐group fungal species grown on the same medium. Moreover, following a targeted approach based on the main VOC found in vitro, we have successfully validated in vivo that VOC uniquely emitted by C. platani (i.e. isobutyl acetate along with isoamyl alcohol) were released from the bark of plane trees following C. platani inoculation. Our results highlight the possibility to exploit VOC emitted specifically by C. platani as biomarkers to recognize Platanus x acerifolia plants infected by this pathogen. 相似文献
19.
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
20.
Labile C fractions: microbial biomass C (MBC), K2SO4 extractable C (
\textC\textK 2 \textSO 4 {\text{C}}_{{{\text{K}}_{ 2} {\text{SO}}_{ 4} }} ) and the cumulated mineralized C in 21 days incubation at 28°C (C–CO2(21d)), were compared as land use indicators in a calcareous soil under three different management systems: native Querqus ilex forest (under and outside tree cover), a Pinus halepensis plantation, and cropped land (with cereals). Microbial biomass and activity were found to be low and coincided with high
carbonate contents. As indicators of land use,
\textC\textK 2 \textSO 4 {\text{C}}_{{{\text{K}}_{ 2} {\text{SO}}_{ 4} }} and C–CO2(21d) showed the same sensitivity as MBC. C–CO2 emissions were measured in an incubation experiment in order to study C mineralization kinetics. The data for cumulative
amounts of C–CO2 released showed a good fit (R
2 > 0.94) to the first-order kinetic model C
m = C
o(1 − e−kt
). The kinetic parameters C
o and C
o
k were affected by land use and especially by tree cover. Principal components analysis was applied to the data and the relationship
among microbial metabolic quotient (qCO2), labile C pools, and MBC revealed a decrease in efficiency of organic substrate utilization with an increase in availability
and lability of the organic matter. 相似文献