Browsing by Subject "415 Other agricultural sciences"

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  • Ingutia, Rose Anyiko (2020)
    The Sustainable Development Goals target of leaving no one behind has stalled because out-of-school children (OOSC) in Africa are generally poor, disabled, orphaned, minority, working, overaged, child-brides and are remote. Descriptive statistical analysis of quantitative secondary data was applied to investigate education issues. Comparisons across gender, residence and regions indicate marginalisation in education systems characterised by low preschool education, inefficient primary schools evidenced by insufficient inputs, untrained, poorly paid teachers and biased public expenditure. OOSC face a range of circumstances: to meet Sustainable Development Goals targets requires solutions to specific cases; one size will not fit all, since OOSC are trapped in a web of multiple problems.
  • Sheehy, Jatta; Nuutinen, Visa; Six, Johan; Palojarvi, Ansa; Knuutila, Ossi; Kaseva, Janne; Regina, Kristiina (2019)
    By processing large quantities of crop residues, earthworms enhance the mineralization of organic matter but have also been shown to stabilize soil organic carbon (SOC) into soil fractions like microaggregates (53-250 mu m) within macroaggregates (> 250 mu m) especially in no-till soils. Our objective was to find direct evidence on the impact of an anecic, soil surface-feeding earthworm, Lumbricus terrestris L., on the redistribution of SOC and soil nitrogen (N) into macroaggregate-occluded soil fractions of boreal soils. We sampled soil (0-5 cm depth) from the middens of L. terrestris (mounds of collected residue and surface casts at the openings of its permanent burrows) and the adjacent non-midden (bulk) soil at three no-till sites in southern Finland: two clayey sites (sites 1-2) and one coarse textured site (site 3). Compared to bulk soil, the soil in L. terrestris middens featured general increase in aggregate size and content of SOC and N within the large macroaggregates (> 2000 mu m) at the clayey sites. The microaggregates within the large macroaggregates had accumulated more SOC and N in the midden soil especially at site 1 where 99% of the difference in total SOC between midden and bulk soil was associated with this type of SOC stabilization. At site 2, the increase in SOC found in the large macroaggregates was counteracted by a decrease in SOC in microaggregates within the small macroaggregates (250-2000 mu m). No differences in SOC stored in soil fractions were found between midden and non-midden soil at the coarse soil site 3 with higher top soil decomposition rate compared to sites 1 and 2. Across the study sites, the total amount of SOC was 6% higher in midden soil compared to the bulk soil. These results suggest L. terrestris mediates the storage of SOC and N into better protected soil fractions in clay soils under boreal conditions.
  • Meyer, N.; Welp, G.; Amelung, W. (2019)
    Knowledge about spatial patterns of soil respiration (SR) and its temperature sensitivity (Q10) is of emerging relevance for assessing carbon fluxes across the landscape. Related experiments are often conducted under controlled laboratory conditions and usually rely on soil samples, which are sieved and stored. Here, we investigated the effect of sieving and storage on SR and Q10. We took 14 samples from different land use types and soil textures. Samples were sieved to 2 mm at field-moist conditions and split into four treatments: sieved/no-storage, sieved/freeze-storage (−18  °C), sieved/cold-storage (+ 4 °C), and sieved/dry-storage (+ 40 °C). The storage time was 7 weeks. Intact soil cores were used as a control. The SR was not significantly affected by sieving/no-storage, sieving/freeze-storage, and sieving/cold-storage compared with the control. Yet, sieving/dry-storage significantly increased SR but all samples were similarly affected (r = 0.81 for the correlation between SR after sieving/dry-storage and SR in the control). The Q10 of sieving/no-storage (1.94 ± 0.28), sieving/freeze-storage (1.94 ± 0.23), sieving/cold-storage (2.37 ± 0.29), and sieving/dry-storage (2.29 ± 1.35) did not differ significantly from the control (2.12 ± 0.23). All samples responded similar to sieving and storage (r = 0.68–0.73 for the correlation between Q10 in each respective treatment and Q10 in the control), with the exception of sieved/dry-storage (r = 0.09). We conclude that sieving at field-moist conditions and subsequent freeze- or cold-storage is acceptable to derive SR and Q10 for the here reported storage time. Although dry-storage may be acceptable for the comparison of SR between samples, it should be avoided for realistic estimates of SR and for the determination of Q10.
  • Manninen, Noora Johanna; Soinne, Helena Susanna; Lemola, Riitta; Hoikkala, Laura Kristiina; Turtola, Eila (2018)
    Dissolved organic carbon (DOC) load in discharges from cultivated soils may have negative impacts on surface waters. The magnitude of the load may vary according to soil properties or agricultural management practices. This study quantifies the DOC load of cultivated mineral soils and investigates whether the load is affected by agricultural practices. Discharge volumes and concentrations of DOC and dissolved organic nitrogen (DON) were continually measured at three sites from surface runoff and artificial subsurface drainage or from combined total discharge over a two-year period (2012-2014). Two experimental sites in South-West Finland had clayey soils (with soil carbon contents of 2.7-5.9% in the topmost soil layer), and the third site in West-Central Finland had sandy soil (soil carbon contents of 4.3-6.2%). Permanent grassland, organic manure application, mineral fertilization, and conventional ploughing or no-till activities were studied. Furthermore, the biodegradable DOC pool of surface runoff and subsurface drainage water from no-till and ploughed fields was estimated in a 2-month incubation experiment with natural bacterial communities collected from the Baltic Sea seawater. The annual DOC and DON loads were affected by discharge volume and seasonal weather conditions. The loads varied between 25-52 kg ha(-1) and 0.8-3.2 kg ha(-1), respectively, and were comparable to those from boreal forests with similar soil types. The DOC load increased with increasing topsoil carbon content at all sites. There were slightly higher DOC concentrations and DOC load from permanent grassland, but otherwise we could not distinguish any clear management-induced differences in the total DOC loads. While only 6-17% of the DOC in discharge water was biologically degraded during the 2-month incubation, the proportion of biodegradable (labile) DOC in surface runoff appeared to increase when soil was ploughed compared to no-till. (c) 2017 Elsevier B.V. All rights reserved.
  • Yu, Lei; Song, Mengya; Lei, Yanbao; Korpelainen, Helena; Niinemets, Ulo; Li, Chunyang (2019)
    Leaf and root systems are known to show a high degree of developmental plasticity in response to the local environment. However, few studies have investigated simultaneously the leaf and root traits as affected by competition and phosphorus (P) fertilization, especially in connection with the primary succession. We investigated morphological and physiological responses to different competition treatments (infra- vs. interspecific competition) and P regimes in seedlings of Abies fabri and Picea brachytyla, collected from the late succession stage Hailuogou glacier retreat area. A. fabri had a greater total chlorophyll content and specific leaf area (SLA), higher leaf nitrogen (N) and P concentrations, as well as a higher water use efficiency (assessed by the carbon isotope composition, delta C-13) and N absorption relative to P. brachytyla under P fertilization conditions, and its total biomass responded more strongly to P fertilization, especially under interspecific competition. P fertilization decreased the specific root length (SRL) and ectomycorrhizal infection in both species and specific root tip density in P. brachytyla but it had no effect on the average root diameter. We concluded that similar changes in root characteristics, but the superior performance of above-ground traits in A. fabri in response to P availability, especially under competition, explain the greater competitive capacity of A. fabri at final stages of succession. These findings highlight the influence of soil nutrition availability and competition on the functional traits of plants and contribute to the understanding of the role of relative modifications in leaf and root traits during succession.
  • Hytönen, Timo Petteri; Pinho, Paulo; Rantanen, Marja; Kariluoto, Maria Susanna; Lampi, Anna-Maija; Edelmann, Johanna Minnamari; Joensuu, K.; Kauste, K; Mouhu, Katriina; Piironen, Vieno Irene; Halonen, Liisa; Elomaa, Paula Riitta (2018)
    Year-round greenhouse production in northern latitudes depends on the use of artificial lighting. Light emitting diodes provide a promising means to save energy during cultivation as well as to modify the light spectrum to regulate the growth and quality of the crop. We compared the effects of light emitting diode lighting with different spectral compositions on the growth, development and nutritional quality of lettuce (Lactuca sativa L. ‘Frillice’). We show that warm-white and warm-white supplemented with blue spectra provide equal growth and product quality compared to conventional high-pressure sodium lighting in the absence and presence of daylight. Our data indicate that for biomass accumulation, the far-red component in the light spectrum is more critical than green light or the red/blue ratio. Furthermore, we demonstrate that a red + blue spectrum increases the concentration of several vitamins in lettuce. However, biomass accumulation using this spectrum was insufficient when daylight was excluded.
  • Rajaniemi, Mari; Jokiniemi, Tapani; Alakukku, Laura; Ahokas, Jukka (2017)
    The aim of this study was to examine the electric energy consumption of milking process on dairy farms and to evaluate the methods to improve the energy efficiency. The electricity consumption of the milking process was measured on three dairy farms in Southern Finland, and it varied between 37-62 Wh kg(-1) milk. The largest energy saving potential was identified in milk cooling and the heating of cleaning water. Even simple methods, such as placing the condenser of the refrigeration system outside, may reduce the energy consumption of milk cooling by 30%. Efficient milk pre-cooling can reduce the energy consumption of the whole milking process by more than 25%. Even larger energy savings are possible with a sophisticated milk cooling - water heating systems. It was concluded that there is a significant potential to reduce the energy consumption and energy costs of the milking process, and thus to improve the profitability and sustainability of the sector at the same time.
  • Palonen, Pauliina; Kemppinen, Johanna; Karhu, Saila (International Society for Horticultural Science, ISHS, 2020)
    Acta Horticulturae
  • Mikkonen, Kirsi S.; Kirjoranta, Satu; Xu, Chunlin; Hemming, Jarl; Pranovich, Andrey; Bhattarai, Mamata; Peltonen, Leena; Kilpeläinen, Petri; Maina, Ndegwa; Tenkanen, Maija; Lehtonen, Mari; Willför, Stefan (2019)
    Wood biorefining currently involves large-scale industrial processes where a notable portion of raw materials, namely hemicelluloses and lignin, are either lost with the process water, degraded, or burnt for energy. Value added utilization of polymeric hemicelluloses is challenging due to their intermediate molar mass and the presence of other wood components, such as phenolic residues or wood extractives. Oil-in-water (O/W) emulsions represent a diverse and abundant class of applications in which the natural properties of wood hemicelluloses are beneficial. In the current work, we present highly promising new technical alkyd paint emulsion systems stabilized with hardwood glucuronoxylans (GX) and softwood galactoglucomannans (GGM). Samples from three isolation methods and their further fractionation by ethanol precipitation were systematically compared with regard to hemicellulose composition, interfacial activity, and functionality in emulsions. Emulsification of alkyd resins was successful with both GX and GGM obtained by various biorefining strategies. The highest emulsion stability over storage was achieved using crude non-purified GX and GGM fractions, and was correlated with the presence of phenolic compounds and extractives, interfacial activity, and small droplet size. Hardwood GX and softwood GGM are envisioned as natural emulsifiers of alkyd O/W emulsions, which are examples of diverse and abundantly-used technical dispersions. This study can be utilized as a guideline for targeted extraction of hemicelluloses with desired functionality, and as a protocol for developing environmentally-compatible industrial dispersions.
  • Birge, Traci Lynn; Herzon, Irina (2019)
    Results-oriented payment approaches are a means to deliver ecological results in agri-environment schemes. The results-based approach requires that farmers understand the meaning of the expected ecological results, and the approach and goals should be culturally acceptable. We interviewed 20 farmers in Finland about a hypothetical results-based payment scheme for biodiversity conservation that builds on an existing grassland fallow scheme. We explored i) how the ‘managing for nature values’ approach fits with ‘good farming’ ideal, ii) whether farmers would be able to operationalize ecological results, for which they would be rewarded, and iii) whether the results-based payment approach enhances or dilutes the current ‘good farmer’ ideal held by the farmers. We used ‘good farming’, cultural scripts, and the visibility of nature to farmers to explore these questions. The ‘tidy farm’ cultural script dominated, but farmers also described their farms as having space for non-production elements. Visibility of nature to farmers varied, field visits with farmer and researchers together resulted in increased enthusiasm for farmers seeing biodiversity as an outcome that they can produce. The grassland fallow fits farmers’ conceptualisations of ‘good farming’, and the results-based payment approach is culturally acceptable. Farmers’ activities show nature values have a place in their conceptualisation of ‘good farming’. We identified four categories of farmers based on their integration of ecological results into farming. These are nature values: 1) central to farmer thinking, 2) well-integrated, 3) viewed positively, but with limited actions and, 4) mainly absent.
  • Mäkelä, Minna; Kabir, Kazi Md. Jahangir; Kanerva, Sanna; Yli-Halla, Markku; Simojoki, Asko (2022)
    Factors limiting the production of the greenhouse gases nitrous oxide (N2O) and carbon dioxide (CO2) were investigated in three incubation experiments conducted with soil from top- and subsoil horizons of a peatland which had an acid sulphate mineral subsoil derived from black schists. The effect of moisture was investigated by equilibrating undisturbed soil samples from three horizons (H-2, Cg and Cr) at -10, -60 or -100 cm matric potential and measuring the gas production. In the second experiment, the effects of temperature and various substrates were studied by incubating disturbed soil samples in aerobic conditions at 5 or 20 degrees C, and measuring basal respiration and N2O production before and after adding water, glucose or ammonium into the soil. In the third experiment, the effects of added glucose and/or nitrate on the denitrification in soil samples from four horizons (H1, H2, Cg and Cr were investigated by acetylene inhibition and monitoring of N2O production during a 48-h anaerobic incubation. The production of CO2 in the topmost peat horizon was largest at -10 cm matric potential, and it was larger than those in the mineral subsoil also at -60 and -100 cm potentials. In contrast, drainage seemed to increase N2O production, whereas in the wettest condition the production of N2O in the mineral subsoil was small and the peat horizon was a sink of N2O. Lowering of temperature (from 20 degrees C to 5 degrees C) decreased CO2 production, as expected, but it had almost no role in the production of N2O in aerobic conditions. Glucose addition increased the aerobic production of CO2 in peat, but it had a minor effect in the mineral horizons. Lack of C source (glucose) was limiting anaerobic N2O production in the uppermost peat horizon, while in all other horizons, nitrate proved to be the most limiting factor. It is concluded that peatlands with black schist derived acid sulphate subsoil horizons, such as in this study, have high microbial activity in the peaty topsoil horizons but little microbial activity in the mineral subsoil. These findings are contrary to previous results obtained in sediment-derived acid sulphate soils.
  • Ponstein, Helena; Meyer-Aurich, Andreas; Prochnow, Annette (2019)
    In the light of a dire need to reduce greenhouse gas emissions (GHG) from food value chains, this paper analyses GHG emissions from wine production based on primary data from 5 wineries, one wine cellar and 9 grape producers in Germany and explores main emission sources based on their contributions to variance. Considering system boundaries from cradle to gate we found a 90% confidence interval for results between 0.753 and 1.069 kg CO2e per bottle of wine. Main contributors to variance were bottle weight (31%), electricity usage (18%), heat (11%), yield (−9%), and diesel use in vineyards (9%). Looking at production process phases, 19% of emissions resulted from the production of wine grapes, while 81% were attributable to the winery phase, mainly to the packaging materials (57%). Exploring the mitigation potential of a reduction in bottle weight, reuse of glass bottles, increase in packaging volume and renewable energies, we found that the reuse of glass bottles deserves close attention from wine producers, consumers, and policy makers who strive for an effective decarbonization of the wine value chain. The mitigation potential of the reuse of an average bottle exceeds the mitigation potential from a reduction in bottle weight by more than threefold. A combination of the replacement of grid electricity by renewable energies, bottle weight reduction and reuse can curb GHG emissions per bottle of wine by 47%.
  • Palonen, Pauliina; Laine, Tuomo Kalevi (International Society for Horticultural Science, ISHS, 2020)
    Acta Horticulturae
  • Wasonga, Daniel; Kleemola, Jouko; Alakukku, Laura; Mäkelä, Pirjo (2020)
    Cassava (Manihot esculenta Crantz) experiences intermittent water deficit and suffers from potassium (K) deficiency that seriously constrains its yield in the tropics. Currently, the interaction effect between deficit irrigation and K fertigation on growth and yield of cassava is unknown, especially during the early growth phase. Therefore, pot experiments were conducted under controlled greenhouse conditions using cassava cuttings. Treatments initiated at 30 days after planting included three irrigation doses (30%, 60%, 100% pot capacity) and five K (0.01, 1, 4, 16, and 32 mM) concentrations. The plants were harvested 90 days after planting. Decreasing irrigation dose to 30% together with 16 mM K lowered the leaf water potential by 69%, leaf osmotic potential by 41%, photosynthesis by 35%, stomatal conductance by 41%, water usage by 50%, leaf area by 17%, and whole-plant dry mass by 41%, compared with full-irrigated plants. Lowering the K concentration below 16 mM reduced the values further. Notably, growth and yield were decreased the least compared with optimal, when irrigation dose was decreased to 60% together with 16 mM K. The results demonstrate that deficit irrigation strategies could be utilized to develop management practices to improve cassava productivity by means of K fertigation under low moisture conditions.
  • Hakkila, Matti; Abrego, Nerea; Ovaskainen, Otso; Monkkonen, Mikko (2018)
    Protected areas are meant to preserve native local communities within their boundaries, but they are not independent from their surroundings. Impoverished habitat quality in the matrix might influence the species composition within the protected areas through biotic homogenization. The aim of this study was to determine the impacts of matrix quality on species richness and trait composition of bird communities from the Finnish reserve area network and whether the communities are being subject of biotic homogenization due to the lowered quality of the landscape matrix. We used joint species distribution modeling to study how characteristics of the Finnish forest reserves and the quality of their surrounding matrix alter species and trait compositions of forest birds. The proportion of old forest within the reserves was the main factor in explaining the bird community composition, and the bird communities within the reserves did not strongly depend on the quality of the matrix. Yet, in line with the homogenization theory, the beta-diversity within reserves embedded in low-quality matrix was lower than that in high-quality matrix, and the average abundance of regionally abundant species was higher. Influence of habitat quality on bird community composition was largely explained by the species' functional traits. Most importantly, the community specialization index was low, and average body size was high in areas with low proportion of old forest. We conclude that for conserving local bird communities in northern Finnish protected forests, it is currently more important to improve or maintain habitat quality within the reserves than in the surrounding matrix. Nevertheless, we found signals of bird community homogenization, and thus, activities that decrease the quality of the matrix are a threat for bird communities.
  • Ylinen, Vappu; Pylkko, Paivi; Peura, Jussi; Valaja, Jarmo (2020)
    To formulate low-protein diets for blue foxes with sufficient amounts of amino acids (AA), AA digestibility and AA requirements of the animals are crucial information. Therefore, a digestibility and nitrogen (N) balance trial was conducted with 20 blue foxes to determine the macronutrient and AA digestibility and N utilisation in low-protein diets supplemented with DL-methionine (Met) and L-histidine (His). In addition, plasma urea and plasma AA were measured. The diets were designated as P24 (control), P20, P20M, P16M and P16MH and contained energy from digestible crude protein (DCP) at 24%, 20% or 16% of total dietary metabolisable energy (ME). The 20% protein level was fed with or without Met and the 16% protein level was fed with Met and with or without His. The apparent total-tract digestibility (ATTD) of crude protein linearly decreased with decreasing dietary protein level. The ATTD of dry matter, organic matter and crude carbohydrates increased when wheat starch was added as a replacement for protein. The apparent ileal digestibility (AID) and ATTD methods were compared to determine the AA digestibility. The decreasing dietary protein supply decreased the ATTD of most of the AA: threonine, tryptophan (Trp), valine, alanine (Ala), aspartic acid (Asp), glutamic acid, glycine (Gly), proline (Pro), serine (Ser) and total AA. The AID of the AA was constant between diets. Diverging AA showed higher or lower digestibility when determined in the AID or ATTD methods. Isoleucine, lysine, Met, Ala and tyrosine showed higher levels of AID. Arginine, His, cysteine (Cys), Trp, Asp, Gly, Pro and Ser showed higher levels of ATTD, which may reflect the net loss of these AA in the large intestine. Met and His supplementation improved the ATTD and AID of the AA in question, respectively, but did not affect the other variables examined. N retention did not differ between diets and renal N excretion decreased with decreasing protein level; thus N utilisation improved. It was concluded that the protein supply and AA composition in low-protein diets with supplemented Met were adequate for adult blue foxes, since the lower protein supply improved N utilisation and did not affect N retention. However, His supplementation failed to reach the designed level and therefore showed no clear results.
  • Haggblom, Olle; Salo, Heidi; Turunen, Mika; Nurminen, Jyrki; Alakukku, Laura; Myllys, Merja; Koivusalo, Harri (2019)
    In northern clay soils, field drainage is needed to ensure suitable moisture conditions for crop growth and farming operations. Supplementary drainage installations improve the efficiency of old drainage systems, but the hydrological impacts of the drainage procedures are not comprehensively understood or quantified. The objective was to simulate the hydrological behavior of a clay field section and to quantify the effects of a supplementary drainage on the water balance of the field section. The study site, in southern Finland, was originally subsurface drained in 1952 with 32 m drain spacing. Supplementary drainage was installed in 2014, decreasing the drain spacing to 10.7 m. Simulations were carried out with a dual-permeability hydrological model and two model parametrizations describing the field hydrology (1) before and (2) after the supplementary drainage installation. The parameterizations were used for simulations of a nine-year period to quantify the hydrological impacts of the supplementary drainage. For the periods without snow on the ground, the modified Nash-Sutcliffe efficiency for daily drain discharge and topsoil layer runoff values ranged from 0.43 to 0.53 and from 0.44 to 0.53, respectively. During the original drainage setup scenario, the average annual drain discharge was lower (7.8% of precipitation) than topsoil layer runoff and groundwater outflow (10.3% and 26.4%, respectively). For the supplementary drainage scenario, most of the water outflow was through drain discharge and groundwater outflow (20.4% and 21.9%, respectively). The supplementary drainage installation increased the average annual drain discharge by a factor of 2.6, while the annual average topsoil layer runoff and groundwater outflow decreased by 75% and 18%, respectively. The supplementary drainage setup was found to expedite the drying of the field section in spring by 8 days on average compared to the original drainage setup.
  • Gu Yunfu,; Wang, Yingyan; Xiang, Quanju; Yu, Xiumei; Zhao, Ke; Zhang, Xiaoping; Lindstrom, Kristina; Hu Yufu,; Liu, Songqing (2017)
    Alpine wetland in the Zoige Plateau has suffered from serious degradation during"the last 30 years due to global climate change and anthropogenic impact. Denitrification is a key nitrogen removal process which can be performed by different microorganisms, including bacteria harboring ttirS-genes. In this study, a degradation succession was used to study the effect on potential denitrification activity (PDA) and on bacterial communities harboring nirS genes. Based on the determination of the PDA, the abundance, structural diversity, and phylogenetic identity of the soil bacteria with nirS genes were further assessed by qPCR, terminal restriction fragment length polymorphism (T-RFLP), and DNA-sequencing, respectively. The results showed that soil PDA ranged from 8.78 to 52.77 ng N20-N g(-1) dry soil h(-1), being lowest in sandy soil and highest in swamp soil. The abundance of nirS genes (copies g(-1) soil) were also the lowest in the sandy soil while highest in the swamp soil. The average Shannon-Wiener diversity index of the nirS denitrifying bacterial structural ranged from 2.20 in the meadow soil to 3.07 in the swamp soil. Redundancy analysis (RDA) showed that the nirS denitrifying bacterial community correlated with soil water content and available phosphorus, with water content as the major factor in shaping the nirS denitrifying bacterial community. The results of this study suggest that the wetland degradation would decrease soil PDA, and abundance and structural diversity of the denitrifying bacteria with nirS genes. These findings can contribute to support a theoretical foundation for predicting the potential influences of wetland degradation on soil denitrifying bacteria in alpine wetlands. (C) 2017 Elsevier Masson SAS. All rights reserved.
  • Karhu, Saila; Bles, C.; Laine, Kalle; Palonen, Pauliina (International Society for Horticultural Science, ISHS, 2020)
    Acta Horticulturae
  • Song, Mengya; Yu, Lei; Jiang, Yonglei; Korpelainen, Helena; Li, Chunyang (2019)
    The stress gradient hypothesis predicts that plant-plant interactions switch between facilitation (positive) and competition (negative) along environmental gradients, with facilitation being more common under high abiotic stress conditions relative to more moderate abiotic stress conditions. Our aim was to reveal, whether the interactions between Populus purdomii Rehder and Salix rehderiana Schneider switch from positive to negative during the early stages of primary succession in the Gongga Mountain glacier retreat region. We also investigated, whether soil age is a major driving factor for the transformation of interactions between neighboring plants. We analyzed differences between intraspecific interactions and interspecific interactions of Populus and Salix under 20- and 40-year-old soil conditions, including plant biomass accumulation and allocation, nutrient absorption and utilization, relative competition intensity, non-structural carbohydrates, foliar carbon and nitrogen isotope composition, mesophyll cell ultrastructure, soil microbial biomass and community structure, extracellular enzyme activities, and soil organic carbon (SOC), soil total nitrogen (TN), soil ammonium (NH4+-N), and soil nitrate (NO3--N) contents. We found that P. purdomii and S. rehderiana growing under interspecific interactions had greater contents of aboveground dry matter, belowground dry matter and total dry matter compared to intraspecific interactions in 20-year-old soil. Furthermore, in 40-year-old soil conditions, the phospholipid fatty acid (PLFA) analysis showed that Populus and Salix exposed to interspecific interactions exhibited lower amounts of gram-positive bacteria, fungi (18,1 omega 9c) and actinomycetes, and lower levels of total PLFAs than those growing under intraspecific interactions. The redundancy analysis (RDA) results demonstrated that soil N was the most important parameter contributing to the composition of microbial communities. In addition, the N-15 stable isotope labeling method showed that Populus and Salix growing under interspecific interactions had higher foliage delta N-15 derived from NO3- (delta N-15-NO3-) than those growing under intraspecific interactions in 20-year-old soil. In summary, our results demonstrated that Populus-Salix interactions exhibited positive effects on survival in 20-year-old soil. Conversely, under 40-year-old soil conditions, Populus-Salix interactions presented negative effects in relation to nutrients and elimination by neighboring plants. Moreover, soil age is a major driving factor for plant-plant interactions that shift from positive to negative with an increasing soil age in the Gongga Mountain glacier forefield. In all, our results support the stress gradient hypothesis. Our findings improve understanding of plant-plant interactions and plant-soil feedbacks during the early stages of soil development, and of the construction of vegetation communities.