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1.
A. Moulaert J.P. Mueller M. Villarreal R. Piedra L. Villalobos 《Agroforestry Systems》2002,54(1):31-40
A silvopastoral model that combines the production of pasture herbage with valuable native timber species has potential to
simultaneously address the multiple goals of reforestation, conservation of native species and enterprise intensification.
The objective of this study was to design, establish and monitor early growth of a silvopastoral experiment on a dairy farm
in the north Atlantic zone of Costa Rica. Two indigenous timber species, Vochysia guatemalensis and Hyeronima alchorneoides were planted with and without the tropical pasture legume, Arachis pintoi in a split plot design, (2 × 2) factorial arrangement of treatments with four replications. After the first two years, V. guatemalensis was significantly taller (3.1 m) than H. alchorneoides (2.5 m). The mean root collar diameter for V. guatemalensis was significantly larger (6.5 cm) than H. alchorneoides (4.5 cm). Two-year establishment was acceptable for the tree component (83 to 85% survival) but poor for A. pintoi (2 to 8% of the sward). The most important pest affecting the establishment of the timber species was the leaf cutter ant,
Atta cephalotes. An insect larvae, Cosmopterix sp., severely damaged 39% of the V. guatemalensis trees by repeatedly attacking their apical meristems. The two-year establishment data was insufficient to accurately predict
future wood volume. A hypothetical economic analysis concluded that the silvopastoral system must average at least 1.2 m3 wood volume/paddock/year (20 m3/ha/year) throughout the first ten years of growth to assure a positive economic return from timber. The experiment is planned
for a ten year period, which corresponds to the estimated rotation length for harvesting the timber species.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
2.
Fourth year results are presented from a species screening trial established at the La Selva Biological Station in northeastern Costa Rica. Of the 14 tropical hardwood species evaluated on survivorship, growth, form, and volume the most promising were (survival, diameter and height): Vochysia guatemalensis (84%, 12.2 cm, 10.5 m); Vochysia ferruginea (79%, 9.7 cm, 7.8 m); Hyeronima alchorneoides (83%, 8.1 cm, 7.9 m); Dipteryx panamensis (78%, 5.5 cm, 7.2 m); and Calophyllum brasiliense (80%, 6.3 cm, 6.2 m).
Resumen Se presentan resultados a los cuatro años de edad de un ensayo de adaptabilidad establecido en la Estación Biológica La Selva ubicado en el noreste de Costa Rica. Las variables evaluadas para todas las especies fueron: sobrevivencia, crecimiento (altura total, diámetro a la altura del pecho), forma, y volumen. Las siguientes especies presentaron los mejores resultados (sobrevivencia, diámetro y altura): Vochysia guatemalensis (84%, 12.2 cm, 10.5 m); Vochysia ferruginea (79%, 9.7 cm, 7.8 m); Hyeronima alchorneoides (83%, 8.1 cm, 7.9 m); Dipteryx panamensis (78%, 5.5 cm, 7.2 m); y Calophyllum brasiliense (80%, 6.3 cm, 6.2 m).相似文献
3.
Research for developing silvopastoral systems includes tree species selection and management, and interactions of trees with
pastures. In the Caribbean humid lowlands of Costa Rica, total height, diameters at breast height (DBH), survival, basal area
and bole volume were compared among three plantations with four species each, in pure stands as well as in the mixture of
the four species. In Plantation 1, at 86 months old the pure plantations of Jacaranda copaia and Vochysia guatemalensis, and the mixed plantations (Jacaranda copaia + Vochysia guatemalensis + Calophyllum brasiliense + Stryphnodendron microstachyum) had the largest DBH. Vochysia guatemalensis is one of the most preferred species in the region for reforestation of degraded pastures, while Jacaranda copaia is not preferred because it has low local economic value. In Plantation 2, at 81 months, the greatest DBH was found in Virola koschnyi, Terminalia amazonia and the mixed plantations (Virola koschnyi + Terminalia amazonia + Dipteryx panamensis + Pseudosamanea guachapele). Dipteryx panamensis has good economic value and has a relatively open canopy that produces moderate shade. Virola koschnyi and Terminalia amazonia have denser canopies, are preferred by farmers, and they could be planted in low density in silvopastoral systems. In Plantation
3, at 70 months, the greatest DBH was found in Vochysia ferruginea, Hieronyma alchorneoides and the mixed plantation (Vochysia ferruginea + Hieronyma alchorneoides + Genipa americana + Balizia elegans). Most of these species are currently used in silvopastoral systems in the region. Mixed plantations may combine beneficial
effects of the different species' characteristics, with the additional advantage of product diversification.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
《Forest Ecology and Management》1999,113(1):91-103
Aboveground biomass and nutrients and soil chemical characteristics were examined in young plantations of four indigenous tree species: Hieronyma alchorneoides, Vochysia ferruginea, Pithecellobium elegans, and Genipa americana, growing in mixed and pure stands at La Selva Biological Station, Costa Rica. Total tree biomass production rates ranged from about 5.2 Mg ha−1 year−1 for G. americana to 10.3 Mg ha−1 year−1 for H. alchorneoides pure stands, and for the species mixture it was about 8.9 Mg ha−1 year−1. Branches and foliage formed 25–35% of total tree biomass but they represented about 50% of total tree nutrients. H. alchorneoides, the four species mixture, and P. elegans had the greatest accumulations of total aboveground nutrients per hectare. The importance of the plantation floor as a nutrient compartment varied temporally. When forest floor litter biomass was at its peak, plantation floor litter N, Ca, and Mg were roughly equal to, or greater than stem nutrients for all species except for P. elegans. For P. elegans, the plantation floor consistently represented a very low proportion of total aboveground nutrients. G. americana and V. ferruginea trees showed 55–60% less biomass accumulation in mixed than in pure stands while H. alchorneoides and P. elegans trees grew 40–50% more rapidly in mixture. P. elegans foliage had 60% lower Ca but higher P concentrations in mixed than in pure stands, and G. americana had higher foliar Mg in mixed than in pure stands. V. ferruginea stands had the highest concentrations of soil Ca, Mg, and organic matter, particularly in the top layers. Relative to pure plantations, soil nutrient concentrations in mixed plantations were intermediate for N, P, and K, but lower for Ca and Mg. The results of this study can be used in the selection of tree species and harvest designs to favor productivity and nutrient conservation. 相似文献
5.
《Journal of Sustainable Forestry》2013,32(4):115-139
Aboveground-tree biomass and nutrient content (nitrogen, phosphorus, calcium, magnesium and potassium) were measured in 4-year-old stands of four indigenous tree species: Stryphnodendron microstachyum Poepp. et Endl. (ex S. excelsum Harms), Vochysia guatemalensis Donn. Smith (ex V. hondurensis Sprague), Vochysia ferruginea Mart and Hyeronima alchorneoides (0), growing on infertile soils in an experimental plantation in the Atlantic humid lowlands of Costa Rica. Biomass and nutrient content among the species, and among aboveground tree parts, forest-floor litter and understory vegetation were compared, as key factors that can be manipulated with different effects on site nutrient conservation. Biomass and stemwood annual increments of the four species were similar to those reported for other tropical tree plantations in the humid tropics. S. microstachyum had the highest accumulation of N in stem, branch and total aboveground tree biomass. V. guatemalensis had the highest accumulation of Ca and Mg in the biomass, while H. alchorneoides had the highest stem K and P. In spite of heir relatively lower N tissue collcentrations. V. ferruginea and H. alchorneoides showed a high potential for N recycling due to its more even distribution in stems, branches and leaves. Nument accumulation by the understory in S. microstachywn and H. alchorneoides plots was 0.8-7.746 of aboveground see biomass numents. The forest floor litter repsented a major compartment for nutrient accumulation and recycling under the four species, especially for N, Ca, Mg and P. 相似文献
6.
Generic or default values to account for biomass and carbon accumulation in tropical forest ecosystems are generally recognized
as a major source of errors, making site and species specific data the best way to achieve precise and reliable estimates.
The objective of our study was to determine carbon in various components (leaves, branches, stems, structural roots and soil)
of single-species plantations of Vochysia guatemalensis and Hieronyma alchorneoides from 0 to 16 years of age. Carbon fraction in the biomass, mean (±standard deviation), for the different pools varied between
38.5 and 49.7% (±3 and 3.8). Accumulated carbon in the biomass increased with the plantation age, with mean annual increments
of 7.1 and 5.3 Mg ha−1 year−1 for forest plantations of V. guatemalensis and H. alchorneoides, respectively. At all ages, 66.3% (±10.6) of total biomass was found within the aboveground tree components, while 18.6%
(±20.9) was found in structural roots. The soil (0–30 cm) contained 62.2 (±13) and 71.5% (±17.1) of the total carbon (biomass
plus soil) under V. guatemalensis and H. alchorneoides, respectively. Mean annual increment for carbon in the soil was 1.7 and 1.3 Mg ha−1 year−1 in V. guatemalensis and H. alchorneoides. Allometric equations were constructed to estimate total biomass and carbon in the biomass which had an R
2aj (adjusted R square) greater than 94.5%. Finally, we compare our results to those that could have resulted from the use
of default values, showing how site and species specific data contribute to the overall goal of improving carbon estimates
and providing a more reliable account of the mitigation potential of forestry activities on climate change. 相似文献
7.
Litterfall and decomposition were studied in agroforestry systems involving large cardamom (Amomum subulatum) and mandarin (Citrus reticulata) in the Sikkim Himalaya, India. There were stands with N2-fixing trees (Alnus nepalensis over large cardamom, and Albizia stipulata over mandarin agroforestry) or without them (native non-symbiotic mixed tree species) in both systems. The total annual litter (litter + crop residue) production was higher in the Alnus-cardamom than in the forest-cardamom stand and in the mandarin than in the Albizia-mandarin stand. The ratio of litter production to floor litter was higher in the N2-fixing stands than in the non-N2-fixing stands, indicating a faster litter turnover in the former. Tree litterfall occurred throughout the year, but with marked peaks during November to April. Total soluble polyphenolics of fresh litter were higher in N2-fixing species than in mixed tree species and crops. Half-life values for ash-free mass were shortest in the leaves of N2-fixing species. N loss was higher from N2-fixing Alnus and Albizia leaves, whereas P loss was faster and nearly equal in Alnus leaf litter and cardamom residue in cardamom, and Albizia leaf litter and crop residue in mandarin agroforestry systems. The P turnover in N2-fixing Alnus and Albizia twigs was faster than in the twigs of mixed tree species. The N2-fixing tree species increased the N and P cycling through production of more above-ground litter and influenced greater release of these nutrients. 相似文献
8.
Litterfall and decomposition are the two main processes accounting for soil enrichment in agroforestry. The extent of enrichment
in soil properties depends on the tree species, management practices and the quantity and quality of litter. A field investigation
was carried out to study litterfall production, decay rates, release of nutrients and consequent changes in soil physicochemical
properties under crowns of four multipurpose tree species (MPTs) in irrigated conditions in farm fields. The species were
Prosopis cineraria (L.), Dalbergia sissoo (Roxb.) ex DC, Acacia nilotica (L.) Del. and Acacia leucophloea (Roxb.) Willd. Annual accretion of litter ranged from 36 to 54 kg tree−1 year−1 and was highest under D. sissoo and lowest under A. nilotica. Total litterfall production was in the order: P. cineraria > A. leucophloea > A. nilotica > D. sissoo. P. cineraria showed the highest NPK concentration in litter. For all MPTs, a large pulse of litterfall coincided with the winter season
(November to February). Litter of P. cineraria decomposed fastest while that of A. nilotica was slowest. More than 95% of the leaf litter of P. cineraria decomposed in 6 months, of D. sissoo in 7 months and A. leucophloea and A. nilotica in 9 months. Decomposition rate of litter was highly correlated with neutral detergent fibre (NDF) (r = −0.94) and P (r = −0.91) concentration. N, P and K release were best correlated with NDF, acid detergent fibre (ADF), P, lignin, lignin/N
and C/P ratios and NDF alone explained 88% to 94% of the variability in litter decomposition and nutrient release rates. There
was significant build up of soil organic carbon and available NPK in the agrisilvicultural systems but also a decrease in
soil pH. Build up in soil fertility was significantly correlated with litterfall and soil improvement was greatest under P. cineraria. 相似文献
9.
A preliminary nutrient cycling study quantified total and temporal nutrient inputs via litterfall and pruning residues in two agroforestry systems: (1) Coffea arabica (perennial crop)-Erythrina poeppigiana (leguminous shade tree); and (2) C. arabica-E. poeppigiana-Cordia alliodora with emphasis on the effect of the timber tree C. alliodora. The total annual input of litterfall plus pruning residues was similar in both associations. Total annual input from E. poeppigiana was less than half in the association with C. alliodora than without, but the litterfall from this latter species compensated for the loss. Large differences in the total annual nutrient input of K, Ca and Mg was found between associations, but not for N or P. The amount of nutrients recycled by the associated trees reached the recommended level of fertilizer required for coffee production. The inclusion of C. alliodora within the C. arabica-E. poeppigiana association resulted in a more evenly distributed annual nutrient input. 相似文献
10.
M. Prez-Surez J.T. Arredondo-Moreno E. Huber-Sannwald J.J. Vargas-Hernndez 《Forest Ecology and Management》2009,258(7):1307-1315
Litterfall is an important ecological process in forest ecosystems, influencing the transfer of organic matter, carbon (C), nitrogen (N), phosphorous (P) and other nutrients from vegetation to the soil. We examined the production of different litterfall fractions as well as nutrient content and nutrient inputs by senesced and green leaf-litter in a semiarid forest from central Mexico. From September 2006 to August 2007, monthly litter sampling was carried out in monospecific and mixed stands of Quercus potosina and Pinus cembroides. Litterfall displayed a marked bimodal pattern with the largest annual amount (5993 ± 655 kg ha−1 yr−1) recorded in mixed stands, followed by Q. potosina (4869 ± 510 kg ha−1 yr−1), and P. cembroides (3023 ± 337 kg ha−1 yr−1). Leaves constituted the largest fraction of total litterfall reaching almost 60%, while small branches contributed with 20–30%. Overall, N content in leaf-litter was higher while lignin content was significantly lower for Q. potosina than for P. cembroides. Thus, greater litter quality together with higher litter production caused the largest C, N and P inputs to forest soils to occur in monospecific Q. potosina stands. Green leaf fall displayed significantly lower lignin:N and C:N ratios in Q. potosina than P. cembroides suggesting faster decomposition and nutrient return rates by the former. Although we recorded only two green leaf fall events, they accounted for 18% and 11% of the total N and P input, respectively, from leaf-litter during the study period. Apart, from the large spatiotemporal heterogeneity introduced by differences in litter quantity and quality of evergreen, deciduous and mixed stands, green litterfall appears to represent a much more important mechanism of nutrient input to semiarid forest ecosystems than previously considered. 相似文献
11.
A study on dry matter production and nutrient cycling in agroforestry systems of mandarin grown in association with N2-fixing Albizia and mixed tree species (non-N2-fixing) was carried out in the Sikkim Himalaya. A site with Albizia was referred asAlbizia-mandarin stand and the other site with mixed tree species as mandarin stand. The stand total biomass, net primary productivity and mandarin fruit production was higher under the influence of Albizia. Agronomic yield of crops remained nearly the same in both the stands. Nitrogen and phosphorus concentrations of different components of Albizia were higher than those of mixed tree species, whereas their back translocation from leaf to branch before abscission was lower inAlbizia. The mandarin-based agroforestry is a highly nutrient-exhaustive system evaluated in terms of nutrient exit through the removal of agronomic yield. This system, under the influence of Albizia, was more productive with faster rates of nutrient cycling. Nutrient use efficiency increased under the influence of Albizia, in contrary to the hypothesis that efficiency should decrease with increasing rate of uptake. The poor nutrient conservation of Albizia, and malleability of nutrient cycling under its influence make it an excellent association which promotes higher availability and faster cycling of nutrients.Albizia should be utilised more extensively in the management of mandarin-based agroforestry systems. 相似文献
12.
Dry matter production and nutrient cycling in agroforestry systems of cardamom grown underAlnus and natural forest 总被引：4，自引：0，他引：4
A study on dry matter production and nutrient cycling in agroforestry systems of cardamom grown under N2-fixingAlnus and mixed tree species (non-N2-fixing) was carried out in the Sikkim Himalaya. The stand total biomass, and tiller number, basal area and biomass of cardamom crop was much higher under the influence ofAlnus. Annual net primary productivity ofAlnus trees was slightly higher than mixed tree species in spite of lower stand density ofAlnus. The agronomic yield of cardamom increased by 2.2 times under the canopy ofAlnus. Litter production and its disappearance rates were also higher in theAlnus-cardamom stand. Nitrogen and phosphorus concentrations of different components ofAlnus were higher than those of mixed tree species, whereas their back translocation from leaf before abscission was lower inAlnus. The cardamom based agroforestry system under the influence ofAlnus was more productive with faster rates of nutrient cycling. The poor nutrient conservation and low nutrient use efficiency ofAlnus, and malleability of nutrient cycling under its influence make it an excellent association which promotes higher availability and faster cycling of nutrients. 相似文献
13.
《Journal of Sustainable Forestry》2013,32(3-4):95-118
Abstract Rates of litter decomposition and nutrient release from litter provide valuable information on the capacity of different tree species to replenish soil nutrients in degraded tropical areas. Leaf litter decomposition, leaf litterfall, plantation floor leaf litter, and mulch performance were studied for four indigenous timber species, Virola koschnyiWarb, Dipteryxpanamensis(Pittier) Record and Mell, Terminalia amazonia(J.F. Gmel.) Exell., and Albizia gua-chapele(H.B.K.) Little, grown in mixed and monospecific plantations in the Atlantic humid lowlands of Costa Rica. Terminalia amazonialitter decomposed the fastest: no litter remained after 6 months. After 12 months, D. panamensis, A. guachapele, and the mixed litter decomposed completely, while 15% of the original weight of V. koschnyilitter remained. Differences in decomposition rates were closely related to leaf nutrient content. Total annual leaf litterfall was highest in T. amazonia(872.9 g/m2), followed by D. panamensis, V. koschnyi, and the mixed plots. A. guachapelehad the lowest leaf litterfall (236.0 g/m2). The highest plantation-floor leaf litter was found in V. koschnyiand D. panamensis.Both litterfall and plantation-floor litter accumulation fluctuated least in the mixed plots. A. guachapeleand D. panamensismulch most positively affected maize seedling growth, followed by the mixed mulch. Recommendations are drawn from the results to suggest species choice for sustainable land management in the region. 相似文献
14.
The response of corn (Zea mays) to incorporated leaf and twig mulches ofLeucaena leucophala, Gliricidia sepium andCassia siamea, andGrevillea robusta as a non-legume comparison was investigated in a 10-week pot trial and a concurrent soil incubation study to evaluate the suitability of various agroforestry trees as mulch sources.Leucaena contributed to the highest N uptake and biomass production of these corn plants, reflecting the benefits of organic mulching.Cassia-treated plants also performed better than the unmulched controls, butGrevillea incorporation suppressed corn growth probably because of the relatively high Mn status of this mulch. Manganese toxicity was confirmed by comparative vector diagnosis of plant nutrient status.Cliricidia mulching resulted in seedling mortality after germination possibly from high soil pH and ammonium toxicity. Mineral N production in mulched soils during the laboratory incubation was well correlated with N uptake in corn shoots. The results suggest that the nutritional effects of agroforestry tree mulches on growth of companion crops may be effectively screened by a combined soil test, pot trial, and plant analysis approach. 相似文献
15.
J. Lehmann D. Günther M. Socorro da Mota M. Pereira de Almeida W. Zech K. Kaiser 《Agroforestry Systems》2001,53(2):113-124
In the central Amazon basin, the effects of secondary vegetation and primary forest on inorganic and organic P and S pools
were compared with those of different fruit and timber tree species in a multistrata agroforestry system. The soils (Xanthic
Ferralsols) were low in readily available P and S. Fertilizer applications increased the less accessible nutrient pools more
than the plant available pools. For example, dilute-acid extractable P increased substantially (from 2 to 76 mg P kg−1), whereas Mehlich P (plant available) increased less (from 3 to 19 mg P kg−1). In contrast, the recalcitrant soil P pools, such as the residual P, did not increase on the short term, but only after
more than six years following application. The proportion of less available ester-sulfate S was significantly higher in fertilized
sites than in unfertilized sites, in contrast to soluble inorganic sulfate S or carbon-bonded S. The marked increase of successively
available soil P and S pools through fertilization was advantageous with respect to the long-term effect of nutrient applications.
Soil nutrient availability was not only related to the amount of nutrients applied but was also influenced by tree species.
Nutrient return by litterfall and litter quality played an important role in soil P and S dynamics. Incorporation of applied
nutrients into successively available organic nutrient pools will decrease potential P fixation and S losses by leaching and
increase long-term nutrient availability. Therefore, tree species with rapid above-ground nutrient cycling and high quality
litter (such as annato [Bixa orellana] and peach palm [Bactris gasipaes]) should constitute the majority of crops in multistrata agroforestry systems on infertile soils to ensure adequate medium
to long term availability of P and S.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
John Beer 《Agroforestry Systems》1988,7(2):103-114
The relative importance of N fixation, organic material inputs and nutrient inputs in litterfall, as justifications for including shade trees in plantations of coffee or cacao, is discussed. According to existing data, N fixation by leguminous shade trees does not exceed 60 kg.N/ha/a. However, these trees contribute 5,000–10,000 kg. organic material/ha/a.Comparisons are made between the leguminous shade tree Erythrina poeppigiana and the non-leguminous timber tree Cordia alliodora. The former, when pruned 2 or 3 times/a., can return to the litter layer the same amount of nutrients that are applied to coffee plantations via inorganic fertilizers, even at the highest recommended rates for Costa Rica of 270 kg.N, 60 kg.P, 150 kg.K/ha/a. The annual nutrient return in this litterfall represents 90–100 percent of the nutrient store in above-ground biomass of E. poeppigiana, and hence the consequences of competition with the crop should not be a serious limitation. In the case of C. alliodora, which is not pruned, nutrient storage in the tree stems, especially of K, is a potential limiting factor to both crop and tree productivity.It is concluded that, in fertilized plantations of cacao and coffee, litter productivity is a more important shade tree characteristic than N fixation.An early version of this review was presented at the CATIE-IUFRO meeting Los Arboles de Uso Multiple en Sistemas Agroforestales, June 1985, Turrialba, Costa Rica. 相似文献
17.
[目的]探讨南亚热带西南桦和尾巨桉人工纯林的凋落叶分解动态及其与土壤化学性质之间的相关关系.[方法]采用原位分解袋法研究凋落叶的分解过程.[结果]表明:西南桦、尾巨桉人工林凋落叶分解系数分别为0.96 a-1和0.88 a-1.在为期12个月的分解试验中,2种凋落叶有机C含量在整个分解过程中呈逐渐下降趋势;全K含量和C/N比在分解前期迅速下降,之后趋于平缓;全N含量和全P含量在整个分解过程中呈逐渐上升趋势;2种凋落叶N/P比则呈先升高后下降的趋势.无论是分解前期还是分解后期,凋落叶质量损失与N含量均呈显著正相关(前期R=0.877;后期R=0.855),与C/N均呈显著负相关(前期R=-0.735;后期R=-0.697).与尾巨桉林地土壤性质相比,西南桦凋落叶分解提高了林地0~10、10~20 cm土壤的有机C、全N、全P、全K、N/P,对2030 cm土壤有机C、全K、pH值、C/N、N/P则未产生显著影响.相关分析表明:凋落叶初始有机C含量与土壤有机C、全N、全P、全K、N/P显著相关;凋落叶初始全N含量与土壤全N、pH值、C/N显著相关.[结论]凋落叶的养分含量与土壤养分的关系紧密;与尾巨桉相比,西南桦凋落叶的养分含量明显较高,分解速率更快,释放到土壤中的养分也更多. 相似文献
18.
Based on farmers’ knowledge and laboratory studies, the nutrient accumulation in the topsoil (0–20 cm) under Cordia africana Lam (Cordia), Millettia ferruginea Hochst (Millettia) and Eucalyptus camaldulensis Dehnhardt (Red gum) managed under two agroforestry practices on different farms at three sites was evaluated. The number
of these trees on individual farms has increased during the last two decades. The number of stems ha−1 of Red gum was higher on farms of wealthier households than on farms of poor and medium households at two of the sites, but,
at one site the number of stems ha−1 on farms of poor households was higher than on farms of wealthier households. Apart from the concentration of Na in the topsoil,
there were significant variations in the analysed soil nutrients between the tree species. At all study sites, significantly
higher concentration of P was observed under Millettia and Cordia than under Red gum. At one site, concentrations of available
P under Cordia were nearly two-fold, and four and half-fold greater than under Millettia and Red gum, respectively. At one
site, total N under Red gum was 14% and 24% lower than under Cordia and Millettia, respectively. In contrast, organic C content
under Red gum was 11.6% greater than under Millettia and 23.8% greater than under Cordia. The pH under Millettia and Cordia
were significantly higher than concentrations under Red gum at one site. Topsoil under Millettia and Cordia also had significantly higher levels of exchangeable Ca and Mg than Red gum. 相似文献
19.
[目的]探讨竹林与其林下植被凋落物叶之间相互影响的潜在机制,为合理经营管理毛竹林林下植被提供理论参考。[方法]采用原位分解袋法研究了四川长宁毛竹与林下植被芒箕凋落物叶分解和养分释放过程。[结果](1)芒箕凋落物叶初始C、N、P含量和羟基碳高于毛竹(P 0. 05),而C∶N、C∶P、烷基碳、氧烷基碳和芳香碳低于毛竹(P 0. 05)。(2)凋落物叶分解和养分释放速率芒箕整体高于毛竹,芒箕和毛竹分解常数(k)分别为0. 58±0. 03和0. 73±0. 02,C、N、P养分释放均表现为净释放。(3)凋落物叶混合对分解速率没有显著影响,但抑制了N、P元素整个分解周期和C元素中后期的释放。(4)凋落物叶分解过程中元素含量变化格局表现为C含量和C∶N比整体呈下降趋势,N含量和N∶P比有小幅上升,P含量有微弱的下降趋势,C∶P比呈波动性变化。(5)凋落物叶分解速率与土壤温度、初始凋落物叶N和P含量呈显著正相关(P 0. 01),与初始凋落物叶的C∶N和C∶P呈极显著负相关(P 0. 01),与土壤含水量相关不显著。[结论]单独分解过程中,毛竹凋落物叶分解速率低于林下植被芒箕,养分释放特征均表现为直接释放;混合分解过程中,毛竹和芒箕凋落物叶分解速率无显著混和效应,但养分释放的混合效应表现出一定负效应和不同阶段性。 相似文献
20.
Leaf litter decomposition and nutrient release patterns from five common multipurpose tree species—viz., Artocarpus heterophyllus, Mangifera indica, Areca catechu, Citrus sp., and Tamarindus indica, found in homegardens of Mizoram—were evaluated using a litter bag technique. The result of the study indicates a varying pattern of decomposition and nutrient release (N&P) among the species. Citrus sp. and T. indica were found to be the most labile species with comparatively much higher decay constant and faster nutrient release. Initial nitrogen concentration, lignin content, and lignin/N ratio of foliage litter showed significantly higher (p < .01) correlation with the decay coefficient and were found to be the important determinants in the decay process. The initial slow release and immobilization of N in A. heterophyllus and M. indica leaf litter reflect their potential as a source of nitrogen storage and effective mulching material. While litter from T. indica and Citrus sp. can provide the short-term nutrient need, foliage for the other three species may supply the long-term nutrient requirement for the understory crops in such agroforestry systems. 相似文献