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1.
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
2.
In sodic soils, excessive amounts of salts have an adverse effect on soil biological activity and stability of soil organic
matter. The study analyzes the role of silvopastoral systems to improve soil organic matter and microbial activity with a
view for effective management of soil fertility. The silvopastoral systems for the present study (located at Saraswati Reserved
Forest, Kurukshetra; 29°4′ to 30°15′ N and 75°15′ to 77°16prime; E) are characterized by tree species of Acacia nilotica, Dalbergia sissoo and Prosopis juliflora along with grass species of Desmostachya bipinnata and Sporobolus marginatus. Soil microbial biomass carbon was measured using the fumigation extraction technique and nitrogen mineralization rates using
aerobic incubation method. The microbial biomass carbon in the soils of D. bipinnata and S. marginatus treatments were low. In silvopastoral systems, microbial biomass carbon increased due to increase in the carbon content in
the soil – plant system. A significant relationship was found between microbial biomass carbon and plant biomass carbon (r = 0.83) as well as the flux of carbon in net primary productivity (r = 0.92). Nitrogen mineralization rates were found greater in silvopastoral systems compared to 'grass-only' system. Soil
organic matter was linearly related to microbial biomass carbon, soil N and nitrogen mineralization rates (r = 0.95 to 0.98, p < 0.01). On the basis of improvement in soil organic matter, enlarged soil microbial biomass pool and greater soil N availability
in the tree + grass systems, agroforestry could be adopted for improving the fertility of highly sodic soil.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
3.
A study was conducted in the semi-arid regions of Haryana, in Northern India, to see the effect of Azadirachta indica, Prosopis cineraria, Dalbergia sissoo and Acacia nilotica on the yield of irrigated wheat crop. Data on crop yield for each tree species at different distances (1, 3, 5 and 7 m) and four directions (east, west, north and south) from the tree bases and control (no trees) were collected. Results indicate that A. indica and P. cineraria did not show any significant difference in the wheat yield while the other two species (D. sissoo and A. nilotica) showed a reduction in wheat yield. A. nilotica had the most significant and prominent effect, and a reduction of nearly 40 to 60% wheat yield was observed. The effect of this tree species was observed even beyond the spread of the crown. D. sissoo reduced yield by 4 to 30% but the reduction was only up to a distance of 3 m. In general, the impact of trees on wheat yield was observed up to 3 m distance and there is little, if any, impact up to 5 m distance and almost no impact at 7 m distance. In all the tree species, the wheat yield was reduced to a maximum on the north side of the trees and had almost no effect in the southern direction. Crop maturity was observed to be delayed by three weeks under A. nilotica, by 9–10 days under D. sissoo, and only by 6–7 days under P. cineraria and A. indica. 相似文献
4.
Soil properties under Acacia nilotica trees in a traditional agroforestry system in central India 总被引：2，自引：0，他引：2
Acacia nilotica (L.) Willd. ex Del is an important multipurpose tree of traditional agroforestry system in the central belt of the Indian
sub-continent. The tree is reported to reduce crop yields under its canopy. However, information is lacking on the spatial
variation in soil physical characters, nutrient pool sizes and their availability to crops under its canopy. The present study
reports influence of three tree canopy positions, viz. mid canopy, canopy edge and canopy gap, of Acacia nilotica (≥ 12 years) on texture, organic C, total and mineral N and P, and soil pH, in 0 to 10, 10 to 20 and 20 to 30 cm depth of
the soil at ten sites in a traditional agroforestry system. Sand particles declined by 10% and 9% whereas clay particles increased
by 14% and 10% under mid canopy and canopy edge, respectively, compared to that under canopy gap. Clay particles did not decline
significantly with soil depth under all canopy positions. Proportion of silt particles was not influenced by the canopy position.
Soil organic C, total N, total P, mineral N (NO3
−-N and NH4
+-N) and P were greater under mid canopy and canopy edge positions compared to canopy gap. Soil organic C and N pool sizes
were maximum in 0 to 10 cm and declined with the depth of soil. Total and mineral P contents were nearly uniform across the
depths. C/N ratio tended to increase with the soil depth whereas C/P ratio declined.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
5.
Tree-based land-use systems could sequester carbon in soil and vegetation and improve nutrient cycling within the systems.
The present investigation was aimed at analyzing the role of tree and grass species on biomass productivity, carbon sequestration
and nitrogen cycling in silvopastoral systems in a highly sodic soil. The silvopastoral systems (located at Saraswati Reserved
Forest, Kurukshetra, 29°4prime; to 30°15prime; N and 75°15prime; to 77°16prime; E) consisted of about six-year-old-tree species
of Acacia nilotica, Dalbergia sissoo and Prosopis juliflora in the mainplots of a split-plot experiment with two species of grasses, Desmostachya bipinnata and Sporobolus marginatus, in the subplots. The total carbon storage in the trees + grass systems was 1.18 to 18.55 Mg C ha−1 and carbon input in net primary production varied between 0.98 to 6.50 Mg C ha−1 yr−1. Carbon flux in net primary productivity increased significantly due to integration of Prosopis and Dalbergia with grasses. Compared to 'grass-only' systems, soil organic matter, biological productivity and carbon storage were greater
in the silvopastoral systems. Of the total nitrogen uptake by the plants, 4 to 21 per cent was retained in the perennial tree
components. Nitrogen cycling in the soil-plant system was found to be efficient. Thus, It is suggested that the silvopastoral
systems, integrating trees and grasses hold promise as a strategy for improving highly sodic soils.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Dehydrogenase activity and VAM fungi in tree-rhizosphere of agroforestry systems in Indian arid zone
Biological activity in tree rhizosphere and association of VAM fungi with tree-roots could be used as selection criteria for
agroforestry trees in arid ecosystems. Dehydrogenase activity and VAM fungi association in rhizosphere of six agroforestry
trees (Azadirachta indica, Acacia tortilis, Eucalyptus camaldulensis, Prosopis cineraria and Tecomella undulata) were studied under irrigated and rainfed conditions in the arid zone of India. Higher dehydrogenase activity (9.5 to 16.8∼p kat g soil−1), root colonization (58.3 to 68.5%) and spore density (132.5 to 234.7 spores 100 g soil−1) were observed in tree rhizosphere as compared to that in non-rhizosphere (7.4, 37.7 and 44.4). Irrigation had increased
dehydrogenase activity by 22.1% while it reduced root colonization and spore density by 14.2% and 16.2%, respectively. Trees
of A. indica had registered maximum growth while E. camaldulensis the least. Findings suggest that selection of A. nilotica, A. indica, and T. undulata for plantations of agroforestry in arid region would reduce the risk and ensure sustainability of the agroforestry system. 相似文献
7.
Tree-crop interactions were monitored by measuring tree growth characters of Prosopis cineraria L. and Tecomella undulata L. and yields of Vigna radiata (L) in agroforestry systems in degraded lands of Indian Desert. Potential competition for resource between the trees and
associated crop was analyzed by measuring soil water contents, soil organic matters and NH4-N at different depths of soil layers i.e., 0–25 cm, 25–50 cm and 50–75 cm in the experimental plots. The plots size were
16 m × 18 m (D1), 20 m × 18 m (D2) and 32 m × 18 m (D3) with tree densities of 208, 138 and 104 trees·ha−1 after June 2002, respectively. Results showed that tree height increased by 3% to 7% during June 2002 to June 2004. Collar
diameter increased by 30% and 11% in D1, 23% and 19% in D2 and 18% and 36% in D3 plots, respectively, in P. cineraria and T. undulata in two years period. The increase in crown diameter was 9% to 18% in P. cineraria and 11% to 16% in T. undulata. Tree growth was relatively greater in 2002 than in 2003. Yield of V. radiata increased linearly from D1 to D3 plots. Lowest soil water content at 1 m distance from tree base indicated greater utilization of soil water within the tree
rooting zone. Concentrations of soil organic matters and NH4-N were the highest (p<0.05) in 0–25 cm soil layer. P. cineraria was more beneficial than T. undulata in improving soil conditions and increasing crop yield by 11.1% and thus more suitable for its integration in agricultural
land. The yield of agricultural crop increased when density of tree species was appropriate (i.e., optimum tree density),
though it varied with tree size and depended upon resource availability. The result indicated bio-economic benefits of optimum
density of P. cineraria and T. undulata over traditional practices of maintaining random trees in farming system in arid zones.
Biography: G. Singh (1961– ), male, Scientist E and Head, Division of Forest Ecology, Arid Forest Research Institute, New
Pali Road, Jodhpur-342005, India. 相似文献
8.
Root biomass and distribution of five agroforestry tree species 总被引：1，自引：0，他引：1
Knowledge of the quantitative assessment and structural development of root systems is essential to improve and optimize productivity
of agroforestry systems. Studies on root biomass recovery by sieves of different mesh sizes (2.0, 1.0, 0.5 and 0.25 mm) and
root distribution for four-year-old individuals of five agroforestry tree species viz.; Acacia auriculiformis A. Cunn. ex Benth, Azadirachta indica A. Juss, Bauhinia variegata L., Bombax ceiba L. and Wendlandia exserta Roxb. were conducted at the research farm of Rajendra Agricultural University, Pusa, Bihar, India. The results indicated
that the 0.5 mm sieve was adequate for recovery of the majority of roots. All the tree species exhibited a large variation
in root depth and horizontal root spread four years after planting. The maximum root depth was recorded in W. exserta (2.10 m) and minimum in B. variegata (1.00 m). Horizontal root spread was 2.05 m in B. ceiba and 8.05 m in A. auriculiformis. Root spread exceeded crown cover for all species. The primary roots were more horizontal than the secondary roots. The length
and diameter of the main root were highest in A. indica (108.3 cm) and B. ceiba (23.2 cm), respectively. Highest length and diameter of lateral roots were recorded in B.
variegata (201.6 cm) and A. indica (1.8 cm), respectively. Total root biomass among different species accounted for 18.2–37.9% of the total tree biomass. Results
of this study infer that although all the species have potential to conserve moisture and improve fertility status of the
soil, A. auriculiformis is the most effective for promoting soil fertility. The deep rooted W. exserta and A. auriculiformis will be preferred for cultivation under agroforestry systems and could reduce competition for nutrients and moisture with
crops by pumping from deeper layers of soil. 相似文献
9.
M. A. U. Mridha P. P. Dhar 《林业研究》2007,18(2):91-96
从孟加拉国Dinajpur地区采集了不同农林复合区内树种和作物种,对采集植物的丛枝菌根多样性进行了研究.在3个取样地采集了18种植物的根和根际土,取样地和被采取植物分别为：取样地Dashmail为黄豆树 （Albizia procera Benth.）、小指椒 （Capsicum frutescens L）、姜黄（Curcuma domestica Vahl）、印度黄檀 （Dalbergia sissoo Roxb.） 和大叶桃花心木（Swietenia macrophylla）5种植物; 取样地Kantaji为姜黄（C.Domestica）、印度檀 （D.Sissoo）、赤桉 （Eucalyptus camaldulensis Dehnn.）、石梓（Gmelina arborea （Roxb） DC） 和水稻 （Oryza sativa L.） 5种植物; 取样地Ramsagar为姜黄（C.Domestica）, 印度檀 （D.Sissoo）, Litchi chinensis Sonn.和水稻.在取样地Dashmail,植物丛枝的分布范围在36%-79%,其中分布最高的是小指椒,达到79%,而C.Domestica仅占36%.取样地 Kantaji丛枝的分布范围在33%-70%之间,其中分布最高的是石梓,达到79%,而O.Sativa分布最低,仅36%.取样地 Ramsagar丛枝的分布范围在35%-70%之间,印度檀丛枝分布在该地最高, 达70%,而水稻丛枝在该地的分布最小,仅35%.在采样地Dashmail,每100克干土中所含采样植物丛枝菌根孢子群落54-140个;孢子群落最多的是印度檀（140/100g dry soil）,最低的是姜黄（C.Domestica） （40/100g dry soil）.在采样地Kantaji,孢子群落在63-221/100g dry soil,石梓具有的群落最高,为221/100g dry soil;印度檀为63/100g dry soil.在采样地Ramsagar, 所具有的最高和最低群落分别是 160/100g dry soil （D.Sissoo）和69/100g dry soil（L.Chinensis）.土壤Ph值与土壤中丛枝分布和菌根孢子群落无显著相关性.Simpson多样性指数和Shannon多样性指数在取样地Kantaji 的印度檀土壤中最高;而在取样地Ramsagar的水稻土壤中最低.研究表明孟加拉国Dinajpur地区丛枝菌根的存在、树种和作物种中的营养性质、丛枝菌根的必要性和贡献以及复合农林植物生长与丛枝? 相似文献
10.
Contribution of trees to soil carbon sequestration under agroforestry systems in the West African Sahel 总被引：1，自引：0，他引：1
Consequent to recent recognition of agricultural soils as carbon (C) sinks, agroforestry practices in the West African Sahel
(WAS) region have received attention for their C sequestration potential. This study was undertaken in the Ségou region of
Mali that represents the WAS, to examine the extent of C sequestration, especially in soils, in agroforestry systems. Five
land-use systems were selected in farmers’ fields [two traditional parkland systems, two improved agroforestry systems (live
fence and fodder bank), and a so-called abandoned land]. Soil samples taken from three depths (0–10 cm, 10–40 cm, and 40–100 cm)
were fractionated into three size classes (2,000–250 μm, 250–53 μm, and <53 μm) and their C contents determined. Whole-soil
C contents, g kg−1 soil, across three depths ranged from 1.33–4.69 in the parklands, 1.11–4.42 in live fence, 1.87–2.30 in fodder bank, and
3.69–5.30 in abandoned land; and they correlated positively with silt + clay content. Using the 13C isotopic ratio as an indicator of relative contribution of trees (C3 plants) and crops (C4 plants) to soil C, more tree-origin
C was found in larger particle size and surface soil and indicated that long-term tree presence promoted storage of protected
C in deeper soil. Existing long-standing agroforestry practices of the region such as the parklands seemed to have little
advantage for sequestering additional C, whereas improved agroforestry practices such as live fence and fodder bank introduced
in treeless croplands seemed to be advantageous. 相似文献
11.
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
12.
The advantages of associating shade trees in coffee agroforestry systems (AFS) are generally thought to be restricted mostly
to poor soil and sub-optimal ecological conditions for coffee cultivation whereas their role in optimal conditions remains
controversial. Thus, the objective of this study was to investigate, under the optimal coffee cultivation conditions of the
Central Valley of Costa Rica, the impact of Inga densiflora, a very common shade tree in Central America, on the microclimate, yield and vegetative development of shaded coffee in comparison
to coffee monoculture (MC). Maximum temperature of shaded coffee leaves was reduced by up to 5°C relative to coffee leaf temperature
in MC. The minimum air temperature at night was 0.5°C higher in AFS than air temperature in MC demonstrating the buffering
effects of shade trees. As judged by the lower relative extractable water (REW) in the deep soil layers during the dry season,
water use in AFS was higher than in MC. Nevertheless, competition for water between coffee and associated trees was assumed
to be limited as REW in the 0–150 cm soil layer was always higher than 0.3 in shaded coffee compared to 0.4 in monoculture.
Coffee production was quite similar in both systems during the establishment of shade trees, however a yield decrease of 30%
was observed in AFS compared to MC with a decrease in radiation transmittance to less than 40% during the latter years in
the absence of an adequate shade tree pruning. As a result of the high contribution (60%) of shade trees to overall biomass,
permanent aerial biomass accumulation in AFS amounted to two times the biomass accumulated in MC after 7 years. Thus provided
an adequate pruning, Inga-shaded plantations appeared more advantageous than MC in optimal conditions, especially considering the fact that coffee
AFS provides high quality coffee, farmers’ revenue diversification and environmental benefits. 相似文献
13.
Soil hydro-physical behaviour was studied under a 20-year old agroforestry plantation consisting of five multipurpose tree
species (Pinus kesiya Royle ex-Gordon, Alnus nepalensis D.Don, Parkia roxburghii G.Don, Michelia oblonga Wall. and Gmelina arboria Roxb.) maintained under normal recommended practices at Indian Council of Agricultural Research (ICAR) Complex, Umiam, Meghalaya,
India. The aim was to select tree species, which could act as better bio-ameliorant as well as provides higher economic return
in highly degraded soil of northeastern hill region of India. A site without vegetation (no tree) nearby the plantation was
also selected as control for comparison. Soil samples for various hydro-physical analysis, were taken from 0–15 and 15–30 cm
soil depth at a distance of 1 m from respective tree species during wet and dry season of 2003–2004. No appreciable differences
in relative contents of textural separates of sand, silt and clay were observed among various tree covers. Surface cover with
constant leaf litter fall and extensive root system increased soil organic carbon, helped in better soil aggregation, improved
water transmissivity and infiltrability and in turn, reduced soil erosion in the present study. However, due to variation
in quantity of leaf litter fall and root biomass, these parameters differed among tree species. Of the tree species, P. kesiya, M. oblonga and A. nepalensis were found to be rated best for bio-amelioration of soils as these tree covers had more root and shoot biomass and more litter
fall compared to other species. However, considering both timber production and improvement in hydro-physical behaviour, M. oblonga was found best among the tested tree species. The study, thus, suggested that inclusion of tree species M. oblonga in agroforestry system is a viable option for natural resource management and could sustain long-term soil productivity in
a highly degraded soil of this region as well as for food security of the resource poor people of North East India. 相似文献
14.
Tal Ilany Mark S. Ashton Florencia Montagnini Constanza Martinez 《Agroforestry Systems》2010,80(3):399-409
This study assessed the use of agroforestry to improve soil nutrient properties in plantations containing Ilex paraguariensis St. Hilaire (yerba mate). Intercropping within tree plantation systems is widely practiced by farmers around the World, but
the influence of different species combinations on system performance still requires further investigation. I. paraguariensis is a major South American crop commonly cultivated in intensive monocultures on low activity clay soils, which are highly
prone to nutrient deficiencies. Study plots were established in 20 plantations in Misiones, Argentina. These involved two
species combinations (I. paraguariensis monoculture and I. paraguariensis intercropped with the native tree species Araucaria angustifolia) and two age classes (30 and 50 years old). Chemical soil samples were analysed to determine Ca, Mg, K, P, N, C and Al concentrations,
effective CEC (eCEC) and pH at two soil depths (0–5 cm and 5–10 cm). In the younger plantations, the agroforestry sites had
lower nutrient levels than I. paraguariensis monoculture sites. However, the monoculture plantations were more susceptible than agroforestry sites to a decline in soil
nutrient status over time, particularly with respect to Ca, eCEC, N and C for both soil depths. P concentrations were below
detection limits for all sites, potentially reflecting the high P-fixing capacity of the kaolinic soils of this region. While
agroforestry systems may be better at maintaining soil quality over time, significant growth increase of I. paraguariensis was apparent only for the monoculture sites. 相似文献
15.
Nitrogen inputs from biological nitrogen fixation contribute to productivity and sustainability of agroforestry systems but
they need to be able to offset export of N when trees are harvested. This study assessed magnitudes of biological nitrogen
fixation (natural 15N abundance) and N balance of Acacia mangium woodlots grown in farmer’s fields, and determined if N2 fixation capacity was affected by tree age. Tree biomass, standing litter, understory vegetation and soil samplings were
conducted in 15 farmer’s fields growing A. mangium as a form of sequential agroforestry in Claveria, Misamis Oriental, Philippines. The trees corresponded to ages of 4, 6,
8, 10 and 12 years, and were replicated three times. Samples from different plant parts and soils (0–100 cm) were collected
and analyzed for δ15N and nutrients. The B-value, needed as a reference of isotopic discrimination when fully reliant on atmospheric N, was generated by growing A. mangium in an N2-free sand culture in the glasshouse. Isotopic discrimination occurring during N2 fixation and metabolic processes indicated variation of δ15N values in the order of nodules > old leaves > young leaves > stems > litterfall and roots of the trees grown in the field,
with values ranging from −0.8 to 3.5‰ except nodules which were enriched and significantly different from other plant parts
(P < 0.0001). Isotopic discrimination was not affected by tree age (P > 0.05). Plants grown in N free sand culture exhibited the same pattern of isotopic discrimination as plants grown in the
field. The estimated B-value for the whole plant of A. mangium was −0.86‰. Mature tree stands of 12 years accumulated up to 1994 kg N ha−1 in aboveground biomass. Average proportion of N derived from N2 fixation of A. mangium was 54% (±22) and was not affected by age (P > 0.05). Average yearly quantities of N2 fixed were 128 kg N ha−1 in above-ground biomass amounting to 1208 kg N fixed ha−1 over 12 years. Harvest of 12-year old trees removed approximately 91% of standing aboveground biomass from the site as timber
and fuel wood. The resulting net N balance was +151 kg N ha−1 derived from remaining leaves, twigs, standing litter, and +562 kg N ha−1 when tree roots were included in the calculation. The fast growing A. mangium appears to be a viable fallow option for managing N in these systems. However, other nutrients have to be replaced by using
part of the timber and fuel wood sales to compensate for large amounts of nutrient removed in order for the system to be sustainable. 相似文献
16.
The present study deals with root architecture of 6-year-old trees of 9 indigenous and 3 exotic species growing in arid climate of north-western India. Observations, made on excavated root systems (3 tree replicates of each species) showed large variation in horizontal and vertical spread of roots. In Morus alba, Melia azedarach and Populus deltoides, the roots were confined to 80 cm, while in Prosopis cineraria, Acacia nilotica and Eucalyptus tereticornis, roots penetrated more deeply to 233 cm. The number of total roots ranged from 103 in Acacia catechu to 1932 in Eucalyptus tereticornis, and 62 to 80% of the roots were less than 2 mm in diameter. The primary roots were more horizontal than the secondary roots. The total root biomass varied from 2.2 kg in Acacia catechu to 30.6 kg–1 tree in Populus deltoides, and top 30 cm soil contained 42 to 78% of the total biomass. The implications of the results are discussed in the context of the ecological niche of the species, and its usefulness in agroforestry systems. 相似文献
17.
Seedling indices of four tree species in nursery and their correlations with field growth in Tamil Nadu, India 总被引：1，自引：0，他引：1
Selection of quality seedlings in nursery is important for raising fast-growing trees for production of fuelwood and other products. In order to identify the morphophysiological variables that can be used in nursery for selection purpose, a study on growth, drymatter production, and rate of photosynthesis was undertaken with seedlings of four tree species, viz, Acacia nilotica, Albizzia lebbeck, Dalbergia sissoo and Eucalyptus camaldulensis. The species varied significantly in growth, drymatter production and photosynthetic rate in nursery. E. camaldulensis was the fastest in growth and A. nilotica had maximum number of leaves. Total drymatter production was maximum in D. sissoo followed by A. lebbeck. The rate of photosynthesis was maximum in D. sissoo followed by A. nilotica and lowest in A. lebbeck. Among the various seedling attributes, height, number of leaves per plant, rootweight and photosynthetic rate exhibited significant correlations with seedling drymatter. Seedling diameter showed weak positive correlations with drymatter of both seedlings as well as two-year old field trees. However, number of leaves per plant, rootweight, shootweight and leafweight showed significant correlations with two-year field tree drymatter, the strongest correlation (r = 0.96, P = 0.001) was found between number of leaves per plant and field tree drymatter. Although plant height and leaf photosynthetic rate showed a positive correlation with two-year field growth, the relationship was statistically non-significant. The study reveals that maximum value for leaf number and dryweight of seedling components such as root, shoot and leaf can be used as criteria for selecting nursery stocks for field planting in semiarid conditions.This revised version was published online in November 2005 with corrections to the Cover Date. 相似文献
18.
Anthony A. Kimaro Vic R. Timmer Ancelm G. Mugasha Shaban A. O. Chamshama Deborah A. Kimaro 《Agroforestry Systems》2007,71(3):175-184
Frequent nutrient removals accompanying wood and crop harvests from rotational woodlot systems may contribute to declining
site productivity and sustainability because of soil nutrient depletion. However, selecting for nutrient-efficient tree species
may well sustain productivity under this system. To test this hypothesis, a randomized complete block experiment was adopted
to assess effects of five tree species on soil nutrients status, nutrient use efficiency and wood yield in semi-arid Tanzania.
After 5 years rotation, top soils under Gliricidia sepium (Jaqua), Acacia polyacantha Willd. and Acacia mangium Willd. were the most fertile with soil organic carbon and exchangeable cation status raised close to those in natural Miombo
systems. Soil inorganic N and extractable P levels reached sufficiency levels for subsequent maize culture. Wood productivity
in tree fallows averaged three times higher than that of Miombo woodlands indicating the high potential of the woodlot system
to supply fuelwood, and consequently relieve harvesting pressures on the natural forests. Acacia crassicarpa A. Cunn. ex Benth. produced the most wood (51 Mg ha−1) at low nutrient “costs” presumably due to high nutrient use efficiency. Wood yield of this species was 42 and 120% greater
than that of A. polyacantha and A. nilotica, respectively, but contained comparatively less nutrients (42–60% less for P, K, and Ca). Gliricidia sepium and A. polyacantha returned the largest amount of nutrients through slash at harvests. Of all test species, A. crassicarpa exhibited the most promise to sustain wood production under rotational woodlot systems due to relatively high productivity
and low nutrient export at harvest. 相似文献
19.
Mahmood Hossain Mohammad Raqibul Hasan Siddique Md. Saidur Rahman Md. Zaber Hossain Md. Mahedi Hasan 《林业研究》2011,22(4):577-582
Azadirachta indica A. Juss, Dalbergia sissoo Roxb., and Melia azedarach L. are little studied species in nutrient return capabili- ties from leaf litter decomposition to maintenance of the soil fertility despite their importance in agroforestry practices of Bangladesh. A leaf litter decomposition experiment was conducted using a litterbag tech- nique to assess the nutrient return efficiency of these species. The de- composition rate of leaf litter was highest for M. azedarach and lowest for D. sissoo. Rainfall and temperature of study sites showed a signifi- cant (p<0.05) positive relationship with the rate of leaf litter decomposi- tion. The highest decay constant was observed for M. azedarach (6.67). Nitrogen and Phosphorus concentration in leaf litter showed a decreased trend sharply at the end of the first month, whereas rapid decrease of Potassium concentration was reported within 10 days. Conversely, higher concentration of nutrient was observed at the later stages of decomposi- tion. All three species showed a similar pattern of nutrient release (K > N > P) during the decomposition process of leaf litter. Among the studied species, D. sissoo was best in terms of N and P return and A. indica was best in terms of K return. 相似文献
20.
Effects of different vegetation restoration models on soil microbial biomass in eroded hilly Loess Plateau, China 总被引：2，自引：0，他引：2
Vegetation restoration is a key measure to improve the eco-environment in Loess Plateau, China. In order to find the effect
of soil microbial biomass under different vegetation restoration models in this region, six trial sites located in Zhifanggou
watershed were selected in this study. Results showed that soil microbial biomass, microbial respiration and physical and
chemical properties increased apparently. After 30 years of vegetation restoration, soil microbial biomass C, N, P (SMBC,
SMBN, SMBP) and microbial respiration, increased by 109.01%–144.22%, 34.17%–117.09%, 31.79%–79.94% and 26.78%–87.59% respectively,
as compared with the farmland. However, metabolic quotient declined dramatically by 57.45%–77.49%. Effects of different models
of vegetation restoration are different on improving the properties of soil. In general, mixed stands of Pinus tabulaeformis-Amorpha fruticosa and Robinia pseudoacacia-A. fruticosa had the most remarkable effect, followed by R. pseudoacacia and Caragana korshinkii, fallow land and P. tabulaeformis was the lowest. Restoration of mixed forest had greater effective than pure forest in eroded Hilly Loess Plateau. The significant
relationships were observed among SMBC, SMBP, microbial respiration, and physical and chemical properties of soil. It was
concluded that microbial biomass can be used as indicators of soil quality.
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Translated from Journal of Natural Resources, 2007, 22(1): 20–27 [译自: 自然资源学报] 相似文献