Five native tree species and manioc under slash-and-mulch agroforestry in the eastern Amazon of Brazil: plant growth and soil responses

Throughout the Amazon of Brazil, manioc (Manihot esculenta) is a staple crop produced through slash-and-burn agriculture. Nutrient losses during slash-and-burn can be large and nutrient demand by food crops so great that fields are often abandoned after two years. In recent decades, farmers have reduced the fallow phase from 20 to ~5 years, limiting plant nutrient accumulation to sustain crop yields. Improved fallows through simultaneous planting of trees with food crops may accelerate nutrient re-accumulation. In addition, slash-and-mulch technology may prevent loss of nutrients due to burning and mulch decomposition may serve as a slow-release source of nutrients. This study in Pará, Brazil, in a 7-year-old secondary forest following slashing and mulching of the vegetation, involved two main plot treatments (with and without P and K fertilizers) and two sub-plot treatments (with or without a N₂-fixer Inga edulis). A mixed-culture of trees and manioc was planted in all plots. P and K fertilizer increased tree mortality due to weed competition but growth of surviving trees in four of the five tree species tested also increased as did biomass production of manioc. In the N₂-fixer treatment trends of greater growth and survival of four of five tree species and manioc biomass were also observed. Fertilization increased the biomass of competing vegetation, but there was a fertilizer by N₂-fixer interaction as I. edulis caused a reduction in competing biomass in the fertilized treatment. After one year, fertilization increased decomposition of the mulch such that Ca, Mg, and N contents within the mulch all decreased. In contrast, P and K contents of mulch increased in all treatments. No influence of the N₂-fixer on 0–10 cm soil N contents was observed. Two years after establishment, this agroforestry system succeeded in growing a manioc crop and leaving a well-maintained tree fallow after the crop harvest.     

Partitioning of soil water among tree species in a Brazilian Cerrado ecosystem

Source water used by woody perennials in a Brazilian savanna (Cerrado) was determined by comparing the stable hydrogen isotope composition (deltaD) of xylem sap and soil water at different depths during two consecutive dry seasons (1995 and 1996). Plant water status and rates of water use were also determined and compared with xylem water deltaD values. Overall, soil water deltaD decreased with increasing depth in the soil profile. Mean deltaD values were -35 per thousand for the upper 170 cm of soil and -55 per thousand between 230 and 400 cm depth at the end of the 1995 dry season. Soil water content increased with depth, from 18% near the surface to about 28% at 400 cm. A similar pattern of decreasing soil water deltaD with increasing depth was observed at the end of the 1996 dry season. Patterns consistent with hydraulic lift were observed in soil profiles sampled in 1995 and 1997. Concurrent analyses of xylem and soil water deltaD values indicated a distinct partitioning of water resources among 10 representative woody species (five deciduous and five evergreen). Among these species, four evergreen and one deciduous species acquired water primarily in the upper soil layers (above 200 cm), whereas three deciduous and one evergreen species tapped deep sources of soil water (below 200 cm). One deciduous species exhibited intermediate behavior. Total daily sap flow was negatively correlated with xylem sap deltaD values indicating that species with higher rates of water use during the dry season tended to rely on deeper soil water sources. Among evergreen species, minimum leaf water potentials were also negatively correlated with xylem water deltaD values, suggesting that access to more readily available water at greater depth permitted maintenance of a more favorable plant water status. No significant relationship between xylem water deltaD and plant size was observed in two evergreen species, suggesting a strong selective pressure for small plants to rapidly develop a deep root system. The degree of variation in soil water partitioning, leaf phenology and leaf longevity was consistent with the high diversity of woody species in the Cerrado.     

试论黑龙江省西部城市引栽绿化树种的抗寒性

用树木抗寒等级标准对黑龙江省西部170个绿化树种进行平均抗寒指数测定,结果抗寒树种有116种,较抗寒树种30种,其余为不抗寒树种。提出了绿化树种选择的抗寒性定量指标。     

Leaf water status and stem xylem flux in relation to soil drought in five temperate broad-leaved tree species with contrasting water use strategies

? Five temperate broad-leaved tree species were compared with respect to their water consumption strategies under ample and restricted water supply. We measured synchronously leaf conductance (g _L) in the sun canopy, xylem sap flux (J _s) and leaf water potential (predawn, ψ_pd and noon, ψ_noon) in adult trees in a mixed stand and related them to the fluctuations in vapor pressure deficit (D) and soil moisture.

? Maximum g _L was particularly high in F. excelsior, C. betulus and T. cordata and revealed a higher D sensitivity. ψ_pd remained constantly high in A. pseudoplatanus, C. betulus and F. excelsior, but decreased in T. cordata and F. sylvatica with decreasing soil moisture.

? J _sddecreased linearly with decreasing soil matrix potential in all species except for F. excelsior. Apparent hydraulic conductance in the soil-to-leaf flow path (L _c) was higher in A. pseudoplatanus than in the other species.

? F. sylvatica maintained a low maximum g _L and reduced J _sd markedly upon drought, but faced severe decreases in ψ_pd and ψ_noon. F. excelsior represents an opposite strategy with high maximum g _L and stable ψ_pd.

? The species drought sensitivity increases in the sequence F. excelsior < C. betulus < T. cordata < A. pseudoplatanus < F. sylvatica.

     

大力提倡发展乡土树种——东北地区城市绿化乡土树种推荐

在全球气候总体变暖的大背景下,我国北方地区冬春季气候异常波动现象频繁发生,常常导致园林树木生长异常,主要表现为边缘树种树木春季发芽推迟、枯黄及死亡。由于东北地区的乡土树种在本地区经历了长期的演化过程,与边缘树种相比,对气候的异常变化适应性较强。东北地区城市绿化应大力推广应用椴树、蒙古栎、色木槭、朝鲜槐等乡土树种。       

Components of the water balance for tree species under evaluation for agroforestry to control salinity in the wheatbelt of Western Australia

The soil water balance technique was used to study evaporation from two fodder tree species, tenEucalyptus species and annual pasture over a three year period after planting in the Western Australian wheatbelt. Evaporation is the total water loss by the processes of transpiration, evaporation from the soil surface and evaporation of water intercepted by plant canopies.Evaporation from both fodder trees and from seven of theEucalyptus species was greater than from pasture for one or more of the study years. The maximum difference in evaporation between trees and pasture was 82, 84 and 70 mm in the first, second and third study years, respectively. Higher evaporation from trees was associated with greater depletions in soil water than occurred beneath pasture. Upward movement of water from wet soil beneath the root zone was found under trees, with a maximum flux of 30 mm observed over a one year period beneathE. camaldulensis.The water use efficiency of fodder trees was significantly higher than for mostEucalyptus species, due to greater yields from fodder trees. Biomass production was found to be a good indicator of the water use of eucalypts over the first two years of growth, but the relationship between productivity and water use was found to differ for species with tree and mallee forms. In the third year of study, obvious differences in the relation between water use and yield were observed for some species of eucalypts with high evaporation.     

Growth of native forest species planted on abandoned pasture land in Costa Rica

Many forest plantations in the humid neo-tropics are established on degraded soils in abandoned pasture land and, with some exceptions, the species planted have not grown successfully. Studies of adaptability and growth under these conditions are scarce, particularly for native species. In this paper we present data on growth and tree form at 3 years of age for 11 species planted in abandoned pastures. The research plantation was established at La Selva Biological Station, in the Atlantic lowlands of Costa Rica (10° 26′N, 83° 59′W). Survival, diameter at breast height (DBH), total height, basal area, volume index and tree form were used to evaluate the species performance. After 3 years, Vochysia guatemalensis displayed a survival significantly higher (98%) than that of the other species. The lowest survival was 75% for Pinus tecunumanii. There were significant differences in growth measures among species. Acacia mangium exhibited significantly higher growth rates than the other species. Although this species grew rapidly, it did not develop straight single stems. About 14% of trees of A. mangium had bifurcation below DBH and more than 50% showed multiple axes or branches as large in diameter as the principal axis. The native species with the highest growth rate was Vochysia guatemalensis (DBH 12.7 cm, total height 7.5 m, volume index 55 m³ ha⁻¹ at 3 years of age). Vochysia ferruginea exhibited a slightly lower growth rate. Both Vochysia species were ranked highly with regard to tree form, with more than 80% straight single stemmed trees. The lowest growth rates were exhibited by Pentaclethra macroloba, Pithecellobium macradenium and Virola koschnyi; however, the latter two species formed straight single terms. Pentaclethra macroloba and Inga edulis failed to form straight single stems. In general, the growth rates of the species studied were high in comparison with results reported from other tree plantations in the tropics. In spite of this, it is not prudent to draw final conclusions on the basis of these 3 year measurements.     

Retranslocation of foliar nutrients in evergreen tree species planted in a Mediterranean environment

Internal nutrient recycling through retranslocation (resorption) is important for meeting the nutrient demands of new tissue production in trees. We conducted a comparative study of nutrient retranslocation from leaves of five tree species from three genera grown in plantation forests for commercial or environmental purposes in southern Australia--Acacia mearnsii De Wild., Eucalyptus globulus Labill., E. fraxinoides H. Deane & Maiden, E. grandis W. Hill ex Maiden and Pinus radiata D. Don. Significant amounts of nitrogen, phosphorus and potassium were retranslocated during three phases of leaf life. In the first phase, retranslocation occurred from young leaves beginning 6 months after leaf initiation, even when leaves were physiologically most active. In the second phase, retranslocation occurred from mature green leaves during their second year, and in the third phase, retranslocation occurred during senescence before leaf fall. Nutrient retranslocation occurred mainly in response to new shoot production. The pattern of retranslocation was remarkably similar in the leaves of all study species (and in the phyllodes of Casuarina glauca Sieber ex Spreng.), despite their diverse genetics, leaf forms and growth rates. There was no net retranslocation of calcium in any of the species. The amounts of nutrients at the start of each pre-retranslocation phase had a strong positive relationship with the amounts subsequently retranslocated, and all species fitted a common relationship. The percentage reduction in concentration or content (retranslocation efficiency) at a particular growth phase is subject to many variables, even within a species, and is therefore not a meaningful measure of interspecific variation. It is proposed that the pattern of retranslocation and its governing factors are similar among species in the absence of interspecies competition for growth and crown structure which occurs in mixed species stands.     

Carbon and nitrogen in forest floor and mineral soil under six common European tree species

The knowledge of tree species effects on soil C and N pools is scarce, particularly for European deciduous tree species. We studied forest floor and mineral soil carbon and nitrogen under six common European tree species in a common garden design replicated at six sites in Denmark. Three decades after planting the six tree species had different profiles in terms of litterfall, forest floor and mineral soil C and N attributes. Three groups were identified: (1) ash, maple and lime, (2) beech and oak, and (3) spruce. There were significant differences in forest floor and soil C and N contents and C/N ratios, also among the five deciduous tree species. The influence of tree species was most pronounced in the forest floor, where C and N contents increased in the order ash = lime = maple < oak = beech ? spruce. Tree species influenced mineral soil only in some of the sampled soil layers within 30 cm depth. Species with low forest floor C and N content had more C and N in the mineral soil. This opposite trend probably offset the differences in forest floor C and N with no significant difference between tree species in C and N contents of the whole soil profile. The effect of tree species on forest floor C and N content was primarily attributed to large differences in turnover rates as indicated by fractional annual loss of forest floor C and N. The C/N ratio of foliar litterfall was a good indicator of forest floor C and N contents, fractional annual loss of forest floor C and N, and mineral soil N status. Forest floor and litterfall C/N ratios were not related, whereas the C/N ratio of mineral soil (0–30 cm) better indicated N status under deciduous species on rich soil. The results suggest that European deciduous tree species differ in C and N sequestration rates within forest floor and mineral soil, respectively, but there is little evidence of major differences in the combined forest floor and mineral soil after three decades.     

几种常见喀斯特森林树种种子发芽对水分胁迫的反应

本文采用不同浓度的PEG对16个不同喀斯特森林树种种子萌发进行人工水分胁迫处理，结果表明，随着水势的下降，除少数树种发芽率在轻度胁迫下有所上升外，总体呈下降趋势，发芽速度、胚轴、胚根长下降，不同喀斯特森林树种种间变化趋势相似，但变化幅度差异显著。樟树、香椿、女贞、刺槐和火棘等在-0．6Mpa下仍有较高的发芽率，且胚根长、胚轴长下降幅度较小，综合评价初步认为耐早性较强；而细叶榕、鹅掌柴、盐肤木、朴树等发芽率、胚根长、胚轴长下降幅度显著，综合评价初步认为耐早性较弱；荆节花、械树、粗叶木、小果蔷薇、云南鼠刺等耐早性居中。     

Changes in soil properties and nematode population status under planted and natural fallows in land use systems of southern Cameroon

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.     

印度恒河平原苏打土壤种植的10个多功能树种生物量和生物能产量(英文)

评价了10个多功能树种--阿江榄江树(Terminalia arjuna)、印楝(Azadirechta indica)、牧豆树(Prosopis juliflora)、水黄皮(Pongarnia pin-nata)、木麻黄(Casuarina equisetifolia)、角豆树(Prosopis alba )、阿拉伯金合欢(Acacia nilotica)、细叶桉(Eucalyptus tereticornis)、牛蹄豆(Pithecellobium dulce)、铁刀木(Cassia siamea )等10年间的生物量和生物能产量,这些树种采用单种栽培的农作方式种植于印度北部恒河平原苏打土壤。该地区土壤紧密、盐碱化、透水性差、营养匮乏。10个树种中,细叶桉植株最高,牧豆树和木麻黄次之。阿拉伯金合欢林分基面积为3.04m2·hm-2,植株胸径优于其他树种,牧豆树和木麻黄植株胸径次之。10年间,牧豆树和Acacia nilotica分别产出生物量56.50和50.75 Mg·hm-2,而阿拉伯金合欢、水黄皮和角豆树生物量产出量较小。牧豆树的营养需求和净生物量产出均最大,而且叶片中营养元素(N,P,K,Ca和Mg)含量较高。然而,树种间木质成分差异较小。以每吨木材营养元素产出量计算,氮素在阿拉伯金合欢中产出量最低,磷和钾分别在阿江榄仁树和牛蹄豆中产出最低,钙和镁在牧豆树中产出最低。牧豆树生物质能产量最高1267.75 GJ·hm-2,阿拉伯金合欢次之1206 GJ·hm-2,印楝最低(520.66GJ·hm-2)。图2表7参31。     

杨粮间作林内土温及水分因子的变化

根据江苏省泗阳县境内南方杨树杨粮间作林内土温及水分因子４ａ定位观测资料,系统地分析了杨粮间作林中土温及水分因子的变化规律。间作地年均温度低于对照,且温度变化缓慢;各原土壤含水量均低于对照,减少了对间作物的水分供应,但林粮间作可降低风速,减少蒸发,提高相对湿度。     

Responses of the seedlings of five dominant tree species in Changbai Mountain to soil water stress

Soil water stress was studied on the potted seedlings of five dominant tree species (Pinus koraienes Sieb.et Zucc.,Fraxinus mandshurica Rupr., Juglans mandshurica Maxim, Tilia amurensis Rupr. and Quercus mongolica Fisch.ex Turcz) from the broadleaved/Korean pine forest in Changbai Mountain. Leaf growth, water transpiration and photosynthesis were compared for each species under three soil moisture conditions: 85%-100% (high water, CK), 65%-85% (Medium water, MW) and 45%-65% (low water, LW) of 37.4% water-holding capacity in field. The results showed that the characteristic of typical drought-resistance of the leaves is significantly developed. The net photosynthetic rate and water use efficiency of Fraxinus mandshurica were higher in MW than those in CK. But for the other four species, the net photosynthetic rate and water use efficiency in CK were lower than those in MW and LW. The transpiration rate responding to soil moistures varied from species to soecies.     

Litter dynamics and soil properties under different tree species in a semi-arid region of Rajasthan,India

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.     

Leaf gas exchange and growth of flood-tolerant and flood-sensitive tree species under low soil redox conditions

Seedlings of Taxodium distichum L., Quercus lyrata Walt. and Q. falcata var. pagodaefolia Ell. were grown for 22 days in a rhizotron system providing two soil redox potential regimes, +170 mV (low Eh) and +560 mV (high Eh). Leaf chlorophyll concentration and gas exchange, root alcohol dehydrogenase (ADH) activity, root and leaf ethylene production, and growth and biomass partitioning were measured. In response to the low Eh soil treatment, stomatal conductance was reduced in Q. falcata and Q. lyrata but not in T. distichum, whereas net photosynthesis was reduced significantly in all species; however, net photosynthesis in T. distichum began to recover within 2 weeks of treatment initiation. Within each treatment, mean stomatal conductance and net photosynthesis were significantly greater in T. distichum than in the oak species. Leaf chlorophyll concentration was not affected by the soil treatments. All species showed significant reductions in root and leaf dry weights in response to the low Eh soil condition. The low Eh soil treatment resulted in increased root ADH activity and ethylene production in T. distichum, but had no effect on root ADH activity and ethylene production in the oak species.     

Impact of tree species on soil carbon stocks and soil acidity in southern Sweden

Abstract

The impact of tree species on soil carbon stocks and acidity in southern Sweden was studied in a non-replicated plantation with monocultures of 67-year-old ash (Fraxinus excelsior L.), beech (Fagus silvatica L.), elm (Ulmus glabra Huds.), hornbeam (Carpinus betulus L.), Norway spruce (Picea abies L.) and oak (Quercus robur L.). The site was characterized by a cambisol on glacial till. Volume-determined soil samples were taken from the O-horizon and mineral soil layers to 20?cm. Soil organic carbon (SOC), total nitrogen (TN), pH (H₂O), cation-exchange capacity and base saturation at pH 7 and exchangeable calcium, magnesium, potassium and sodium ions were analysed in the soil fraction?<?2 mm. Root biomass (<5 mm in diameter) and its proportion in the forest floor and mineral soil varied between tree species. There was a vertical gradient under all species, with the highest concentrations of SOC, TN and base cations in the O-horizon and the lowest in the 10–20?cm layer. The tree species differed with respect to SOC, TN and soil acidity in the O-horizon and mineral soil. For SOC and TN, the range in the O-horizon was spruce?>?hornbeam?>?oak?>?beech?>?ash?>?elm. The pH in the O-horizon ranged in the order elm?>?ash?>?hornbeam?>?beech?>?oak?>?spruce. In the mineral soil, SOC and TN ranged in the order elm?>?oak?>?ash?=?hornbeam?>?spruce?>?beech, i.e. partly reversed, and pH ranged in the same order as for the O-horizon. It is suggested that spruce is the best option for fertile sites in southern Sweden if the aim is a high carbon sequestration rate, whereas elm, ash and hornbeam are the best solutions if the aim is a low soil acidification rate.     

贵州乡土植物及其在园林绿化中的应用

针对贵州境内植物资源十分丰富、珍稀特有植物众多、而城镇绿化植物种类贫乏、缺少地方特色的状况，提出了将乡土植物作为园林绿化植物开发应用的意义及技术路线。