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1.
The effect on litter decomposition rates was studied after annual additions for four years to the forest floor of sulfuric acid (64 kg S.ha?1), sulfur powder (64 kg S.ha?1), and in the first year limestone (dolomite) powder (412 kg Ca+230 kg Mg.ha?1). The litter was Norway spruce needles which were incubated in the field in litter‐bags. Drastic reductions in decomposition rates were observed and the addition of diluted acid caused a rate reduction to 66% of that in control and the additions of sulfur powder a reduction to 80%. The effect of the sulfur powder on litter mass‐loss rate appeared to be delayed and could not be noted until one year after the first addition. No effect could be seen of the limestone powder.  相似文献   

2.
This study evaluated the effects of site-specific, soil-testing-based fertiliser recommendations on maize yields using the transdisciplinary (TD) process. The TD process utilizes knowledge from science and practice. Farmers, extension officers, local financial institutions, and other practitioners collaborated with local scientists from the University of Eldoret in the process of financing, purchasing, and applying fertilisers in adequate amounts and composition. A total of 144 farmers participated in the study, which lasted for two seasons. The data sampling was based on a randomized 2?×?3?×?4?×?2 factorial complete block design, including the following factors: TD (non-participation vs participation in the TD process); ST (soil testing in the following categories: fertiliser application with no soil testing, fertiliser application following government recommendations, and application of site-specific, soil-testing-based fertiliser recommendations), and location (Kapyemit, Kipsomba, Ng’enyilel, and Ziwa). The “no soil testing” (ST1) category refers to farmers’ own practices at an average fertilisation of about 60?kg?N?ha?1 and 15?kg?P?ha?1. The government recommendation (ST2) calls for 75?kg?N?ha?1, 25?kg?P?ha?1, and 6?t?ha?1 manure, and site-specific fertiliser recommendations (ST3) were based on actual soil-testing results; generally, this resulted in the recommendation of 90?kg?N?ha?1, 30?kg?P?ha?1, 25 kg K ha?1, 2?t?ha?1 lime, and 1?t?ha?1 manure. Highly significant effects were seen where farmers participated in the TD process (TD) for soil testing (ST). The farmers’ yields in Uasin Gishu County of 4.5?t?ha?1 increased by approximately 1.5?t?ha?1 based on site-specific, soil-testing fertilisation recommendations and by approximately 1.0?t?ha?1 based on participation in the transdisciplinary process. However, as indicated by a significant interaction of the variables ST and TD—and while there is a significant main effect of participating in a TD process—the latter increase occurs only if site-specific, soil-testing-based recommendations can be used in the transdisciplinary process with farmers.  相似文献   

3.
The Y Ikatu Xingu Campaign brought together indigenous people, farmers, researchers, governmental, and non-governmental organizations seeking riparian forest restoration in the Xingu watershed, in west-central Brazil. Forest restoration is challenging in the region because of scarce nurseries, long distances, and high costs associated with the usual technique of planting nursery-raised seedlings. This article describes mechanized direct seeding and compares it with the planting of seedlings, in terms of cost and tree densities at ages of 0.5 until 5.5 yr after planting. Direct-seeding was mechanized using common agricultural machines designed for sowing cereals or grasses, which were loaded with 200,000 seeds of native trees and 150,000 seeds of annual and sub-perennial legumes, plus 50–150 kg sand ha?1. The Campaign restored more than 900 ha by direct-seeding and 300 ha by planting seedlings. The great demand for native seeds was met by the Xingu Seed Network, formed by Indians, small landholders, and peasants, which commercialized 98 tons of native seeds and earned US$500,000 since 2006. Direct-seeding costs less per hectare than planting seedlings (US$1,845 ha?1 against US$5,106 ha?1), results in higher tree densities (2,500–32,250 trees ha?1 against 1,500–1,650 trees ha?1), is more practical, and creates layers of dense vegetation that better resembles natural forest succession.  相似文献   

4.
The effect of ash fertilization on height growth and volume production of Scots pine (Pinus sylvestris L.) was studied on oligotroph peatland in southeast Norway. In the year 1944, plots 15 m × 15 m size were fertilized with 0, 4, 7, and 10 tons ha?1 of wood or peat ash. The area was treeless, but a satisfactory number of pine seedlings were present. All measurements were confined to the central inner plot, 10 m × 10 m area. Most plots were re-fertilized with 10 tons of wood ash ha?1 in the year 1993. Wood ash had higher content of nutrients, and generally, it had greater growth enhancement effect than peat ash. When the amount of ash was increased, volume production significantly increased for the age period 38–50 years and the total production at age 50 years. The mean annual increment during the first 50 years was about 6 m3 ha?1 for the plots applied with 10 tons of ash ha?1. Trees on plots fertilized with 7 or 10 tons in 1944 and replenished with 10 tons ha?1 at age 50 years (1993) had a mean annual increment of 14 m3 ha?1 for the stand age period 51–68 years. Over time some tree roots from control plots and plots fertilized with 4 tons ha?1 have captured nutrients from richer plots. Such effect is to a smaller extent relevant for treatment 7 tons. It is concluded that the content of mineral nutrients of wood and peat ash makes these ashes well suited as fertilizers on peatland.  相似文献   

5.
Numerous studies have quantified the responses to vegetation management in Eucalyptus plantations but most publications have reported early responses in tree growth and a gap in knowledge exist about the magnitude and duration of growth responses throughout the whole rotation. We evaluated the long-term response (9 years-old) of E. globulus across a gradient of sites to different intensity levels of free area of competing vegetation around individual tree seedlings. Competing vegetation intensity levels considered free areas ranging between 0 (control) to 2.54 m2 plus a treatment with total weed control. Competing vegetation biomass production during the first growing season was 2.9, 6.5, 2.2 and 12.9 Mg ha?1, for sites ranging from low to high annual rainfall. Across sites, maximum response in stand volume ranged between 58 and 262 m3 ha?1 at age 9 years and was proportional to the amount of competing biomass controlled during the first growing season. Total competing vegetation control showed the largest response in stand volume at sites with 2.9 and 12.9 Mg ha?1 of competing vegetation. However, the 2.54 m2 vegetation control treatment showed the maximum response for sites with 2.2 and 6.5 Mg ha?1 of competing vegetation. The duration of response for vegetation control treatments ranged between 5 and 9 years. However, at the site with the largest accumulation of competing vegetation biomass the response to vegetation control showed a sustained and divergent response. Our results suggest that vegetation control improved site resources acquisition increasing long-term stand productivity by reducing environmental limitations to tree growth differentially at each site.  相似文献   

6.
Growth and nutrition of hydroponically cultivated pine seedlings (Pinus pinaster Ait.) were investigated at various phosphorus (P) availabilities. P was added either with free access or at a relative addition rate of 0.02 and 0.04 day?1. Laboratory observations were compared with adult growth performances in the field in two sets of experiments: the first with three contrasting populations, the second with seven full-sib families within a population. Significant differences in P productivity (growth rate per unit P in the plant) and in maximal relative growth rate were observed in both experiments, but correlation with adult performances was restricted to populations. Selection for nutrient-related traits would thus be possible, but understanding of the relationship between growth and nutrition needs further evaluation. The minimum P concentration in the seedlings supporting maximum growth ([P]optimum) varied from 2.2 to 3.8 mg g?1 DM, which is in agreement with values obtained in other species. The root/shoot ratio increased with P limitation, with a marked tendency for the population with the highest adult height performance. Inversely, within families, seedlings identified as the best performers for adult growth invested more biomass in shoots than in roots with P stress.  相似文献   

7.
ABSTRACT

Grey alder (Alnus incana) is a highly productive indigenous tree species, potential for short-rotation forestry in the Baltic and Nordic countries. The aim of the study was to investigate the development of a new forest generation, as well as the nitrogen (N) and carbon (C) storages and fluxes in a grey alder regenerating coppice (COP) after clear-cut and in an adjacent unharvested 21-year-old stand (MAT), which had reached its bulk maturity. The regeneration of COP was rapid and 5 years after clear-cut, stem mass was 6.4?t?ha?1. The nitrogen demand of the aboveground part of the 5-year-old COP trees was estimated to be roughly half of the corresponding value for MAT, depending mostly on leaf production. The annual N leaching flux in MAT was in the range of 16–29?kg?ha?1, the corresponding values for COP were roughly half of that. Net nitrogen mineralization did not differ significantly between MAT (117?kg?ha?1) and COP (129?kg?ha?1). For the soil respiration study, a 32-year-old grey alder stand growing at a similar site was included; soil respiration was significantly higher in MAT compared to COP in all study years in both studied stands.  相似文献   

8.
On three sites in coastal northwestern Oregon, USA, seedling root and shoot development were assessed for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), western hemlock (Tsuga heterophylla (Raf.) Sarg.), and western red-cedar (Thuja plicata Donn ex D. Don) container seedlings under varying sulfometuron methyl (Oust XP®) herbicide application treatments. Treatments consisted of application of 0.16 kg active ingredient (ai) ha?1 as a site preparation in fall 2003, a release application in fall 2004, or a control treatment with no application. Seedlings were planted in winter 2004 and measurements recorded in summer 2004, winter 2005, and summer 2005. During first season growth, western red-cedar seedlings showed the greatest negative impact to site preparation compared to the control with overall average new root length outside the root plug reduced by 67%. Significant reductions in root length also occurred for western hemlock (47%) and Douglas-fir (40%) seedlings. About 9 months after the release treatment, and 21 months after the site preparation application, there were no significant differences between treatments for any measured parameter. These findings suggest that seedlings under the site preparation treatment recovered from initial damage incurred to the root system. Lack of seedling response under the release treatment may be the result of opposing influences from the herbicide application associated with seedling phytotoxicity and enhanced seedling development resulting from effective vegetation control. Although our study was limited to 21 months following planting, reduced vegetation cover in the site preparation and release treatments suggests that these treatments may benefit future seedling growth.  相似文献   

9.
《Southern Forests》2013,75(3):201-212
Forest plantation growers in Vietnam commonly burn residues after harvesting and often apply suboptimal amounts of nutrients during plantation establishment. We examined whether the retention of forest residue, and application of phosphorus fertiliser at higher rates, can increase rates of growth. A factorial combination of residue management (burning vs retention) and phosphorus fertiliser application at planting (15 vs 100 kg ha?1) treatments were applied at a steeply sloping site in northern Vietnam. Two adjacent experiments were established, one with Acacia mangium and the other with a Eucalyptus hybrid (Eucalyptus urophylla × Eucalyptus pellita). Standing volume and leaf area index in A. mangium were greater following burning; this was mostly attributable to the significantly higher survival rate of seedlings. Burning of residues was associated with increases in the number of large branches per tree, and a higher crown damage index (CDI). In the Eucalyptus hybrid, diameter and height responses to the higher rate of fertiliser were observed at age 6 and 12 months, but not beyond. High phosphorus application also led to higher CDI. Standard fertiliser treatment, applied in amounts equivalent to 17, 15 and 8 kg ha?1 of nitrogen, phosphorus and potassium, respectively, was adequate to meet the early growth requirement of eucalypt and acacia plantations at this site. The relatively low amounts of harvest residue and high fertility levels at the site may have masked more significant responses of trees to the silvicultural treatments applied in this study. On steep slopes, especially if soil is poorly fertile, harvest residue retention with adequate weed and termite control may be preferential to burning as it is closely correlated with reducing factors that negatively impact productivity, i.e. water run-off and soil erosion.  相似文献   

10.
More than 300 wild edible mushrooms are consumed in Mexico. They have been reported mainly from temperate forests in the center and southeast of the country. However, these valuable non-timber forest products are under-utilized because a lack of knowledge on their ecology and productivity. The objectives of this work were to compare the richness and fruit body production of wild edible mushrooms in temperate forests with a distinct vegetation composition in Amanalco, to describe species availability, and to test a new sampling approach in a heterogeneous environmental context. We designed a sampling method with random transects rather than traditional fixed sampling sites. Our method permits the acquisition of data from the highest number of environmental conditions. In 2009 and 2010, we collected and counted mushrooms in 248 transects distributed in five vegetation types (Abies, Abies–Pinus, Pinus, Pinus–Quercus and Quercus). We calculated the ecological importance value of each species as a function of its relative abundance and relative spatial frequency and relative temporal frequency. Abies religiosa pure stands and A. religiosa–Pinus forests had the greatest richness of edible fungi (43.1 and 21.3 species ha?1, respectively) and produced most of the fruit bodies (1,160 and 820 ha?1, respectively). The most abundant species in Amanalco region (combining all the vegetation types), Clavulina cinerea, Clitocybe gibba and Russula brevipes, also had the highest ecological importance value (0.2312, 0.1709 and 0.1516, respectively). These temperate forests maintain a considerable diversity of valuable wild edible mushrooms that are heterogeneously distributed according to the type of vegetation.  相似文献   

11.
The objective of this study was to quantify the effects of high nitrogen (N) inputs on N cycling in a 35–45-yr-old Scots pine (Pinus sylvestris L.) forest. Nitrogen was added annually (single doses) as NH4NO3 in doses of 0 (N0), 30 (N1) and 90 (N2) kg N ha?1 yr?1. The only N input to the N0 plots was atmospheric deposition of 10 kg N ha?1 yr?1. The N cycle in these plots was tight, with almost complete retention of the incoming N. In the N1 plots the N retention was 83% after 9 yrs of N addition. The trees were the major sink, but the soil also contributed to the N retention. In the N2 plots the N retention was 63%, being mainly accounted for by accumulation in the soil. The leaching of N from the N2 stands was as high as 35 kg N ha?1 yr?1. The N2 system was N saturated.  相似文献   

12.
This study assessed the amount of carbon stored and the economic viability of the small-scale Clean Development Mechanism (CDM) carbon offsets in Pinus caribaea and Eucalyptus grandis plantations under varying rotations. Volume equations were used to estimate carbon stocks and merchantable wood volume in the plantations, while net present value (NPV) and annual equivalent value (AEV) were used as measures of profitability at the optimum economic rotation age as well as at the CDM-defined crediting period of 20 years. The findings show that over a 20-year rotation, E. grandis and P. caribaea plantations sequestered 638 and 418 t CO2-e ha?1, respectively. The NPVs of E. grandis and P. caribaea with carbon credits over the CDM carbon-crediting period of 20 years were US$2 540 ha?1 and US$1 814 ha?1, respectively. This is higher than the NPVs without carbon credits of US$1 543 ha?1 and US$1 390 ha?1 for E. grandis and P. caribaea, respectively. The AEV of E. grandis harvested at its optimal economic rotation of 10 years was US$316 ha?1. This is slightly higher than the AEV of US$298 ha?1, utilising the CDM carbon-crediting period of 20 years. In contrast, the AEV of P. caribaea under the 20-year CDM carbon-crediting period was higher than harvesting at the optimal economic rotation of 16 years without carbon credits. When the average CDM contract establishment costs exceed US$500 ha?1 and US$1 000 ha?1 for P. caribaea and E. grandis woodlots, respectively, it is not economically viable for one to participate in the CDM forest carbon offsets programme. In conclusion, the study results indicate that whereas E. grandis has a higher biological potential to sequester carbon than P. caribaea, it is currently not economically viable for participation in the CDM forest carbon offset scheme. In contrast, it is economically viable for P. caribaea plantations to participate in the CDM, if the CDM contract establishment costs are low.  相似文献   

13.
Five herbicides were evaluated for their potential to reduce reliance on directed white (mineral) spirits applications and hand weeding for grass control in P. caribaea var. hondurensis nurseries. Post-emergent applications of haloxyfop-methyl, fluazifop-P, fenoxaprop-ethyl and sethoxydim were identified as being selective to P. caribaea var. hondurensis seedlings whilst providing effective grass control. Ametryn was toxic to P. caribaea var. hondurensis seedlings at 1 kg ha–1.  相似文献   

14.
《Southern Forests》2013,75(3-4):193-206
Atmospheric deposition was assessed at two sites over a four-year period in post-canopy-closure (mature) Eucalyptus stands in the northern Dukuduku and southern KwaMbonambi commercial plantation forestry areas of Zululand, South Africa. The aim of this study was to determine the magnitude and relevance of nutrient addition with rainfall, throughfall and stemflow to commercial forestry in this region. Canopy cation exchange was used with rainfall and canopy drainage to derive wet, dry and total atmospheric deposition. Nutrient concentrations measured in the rainfall, throughfall and stemflow varied widely throughout the study period, and between sources and sites. Rainfall was slightly acidic at both sides, but became less acidic upon passing through the tree canopies. Canopy exchange and collection of dry deposition resulted in increased cation concentrations under the tree canopy, while the canopy generally absorbed nitrogen (N), from the rainfall, reducing the below canopy concentrations. Atmospheric deposition was shown to be responsible for large quantities of nutrients added to the eucalypt stands at each site. Annualised deposition averaged across all years at each site amounted to N, calcium, magnesium, and potassium (K) fluxes of 11.0, 6.0, 2.7 and 10.2 kg ha?1 y?1 at Dukuduku and 10, 10.6, 7.5 and 18.8 kg ha?1 y?1 at KwaMbonambi, respectively. Organic N fluxes contributed a further 8.1 kg ha?1 y?1 at Dukuduku and 7.1 kg ha?1 y?1 at KwaMbonambi to the total N deposition. Although K deposition values were high, additions of all other nutrients, although also high, were within the ranges reported in local and international research. Over the course of a full rotation, the atmospheric deposition levels recorded at these sites may have potential to supply a large proportion of the nutrients that are lost during stem-wood harvesting. This study adds value to understanding of nutritional sustainability of fast-growing plantation forests, demonstrating the importance of atmospheric deposition as a nutrient addition source to plantation-grown eucalypts along the Zululand coastal plain.  相似文献   

15.
An experiment was conducted in Nobéré, Burkina Faso to assess the effect of shade of two indigenous fruit trees, Adansonia digitata (Baobab) and Parkia biglobosa (Néré), on a shade-tolerant crop called taro (Colocasia esculenta) in comparison with millet (Pennisetum glaucum) a shade-intolerant crop. Photosynthetically active radiation (PAR) and performance of crops under trees and in the open field were assessed during three cropping seasons. Millet performed better under baobab (806.1?±?121.48?kg?ha?1) compared to the control plot (595.8?±?83.43?kg?ha?1) and néré (320.2?±?59.91?kg?ha?1). In contrast, the yield of taro was higher under néré (4124.0?±?469.05?kg?ha?1) compared to the control plot (2336.9?±?617.04?kg?ha?1) and baobab (2738.3?±?595.61?kg?ha?1). There was a strong relationship between the amount of PAR intercepted by trees and crop yields under trees. As PAR decreased the yield of millet decreased whereas the yield of taro increased. Hence, it was concluded that parkland productivity could be enhanced by cropping taro under néré where light reduction was 83, 56 and 18% in zones A, B and C, respectively. An efficient association of baobab with crops could be the production of taro in zone A and millet in zones B and C where PAR reduction was 62, 38 and 15%, respectively.  相似文献   

16.
Accumulation of carbon (C) in biomass and soil, and using forest residues for bioenergy are examples of forestry’s contribution to reducing the enhanced concentration of greenhouse gases in the atmosphere. The aim of this report was to study the effect of rotation length on carbon accumulation in biomass and soil, and on the amount of forest residues that could substitute fossil fuel during 2000–2100. Two models, based on inventory data from the Swedish National Forest Inventory, were used to simulate the effects of a changed rotation length in the region of Dalarna (1.8 × 106 ha), in central Sweden. During the studied period, the accumulation of carbon in biomass was 32 kg C ha?1 yr?1 larger for the prolonged rotation period and 105 kg C ha?1 yr?1 smaller for the shortened rotation period compared with the base scenario. The build-up of carbon in forest soil was 23 kg C ha?1 yr?1 larger for the prolonged rotation than for the base scenario, whereas the shortened rotation was 24 kg C ha?1 yr?1 smaller than the base scenario. The potential to substitute fossil fuel was 37 kg C ha?1 yr?1 larger for the shortened rotation and 17 kg C ha?1 yr?1 smaller for the prolonged rotation compared with the base scenario. The annual accumulation of carbon in biomass decreased in all scenarios, which resulted in a prolonged rotation scenario possibly being a poor long-term solution (> 100 yrs). The amount of forest residues that could substitute fossil fuel increased in all scenarios during the studied period.  相似文献   

17.
To determine if inoculation increases nodulation and yield of bare-root red alder (Alnus rubra Bong.), fumigated nursery plots were treated with inoculum and ammonium sulfate (28 kg N ha–1) in a factorial experiment. Inoculum was alder soil with 100 infective units of Frankia g–1. Seedlings were evaluated for nodulation at age 10 wk and when lifted, at age 9 mo. Inoculation produced earlier and more extensive nodulation and increased seedling root collar diameter, height, and dry weight. Fertilization decreased seedling height, but did not decrease nodulation. No interaction of fertilization with inoculation was found. Inoculated unfertilized plots had the highest yield of packable seedlings (257 m–2), and uninoculated fertilized seedlings had the lowest yield (126 m–2).  相似文献   

18.
Seedling growth and gas exchange responses were measured for two potted seedling trials testing herbicide phytotoxicity to three important tree species of the Inland Northwest, USA. Media-filled pots were treated with sulfometuron methyl (Oust?) in varying concentrations and planted with seedlings of Larix occidentalis Nutt., Pseudotsuga menziesii var. glauca (Beissn.) Franco, and Pinus monticola Dougl. ex D. Don. Seedlings were grown in two trials to determine the effects of two important residue breakdown factors, substrate moisture and pH, relative to that of herbicide application rate on seedling health. Changes in seedling height, root-collar diameter, and root volume were morphologic variables of interest, and physiological variables measured were net photosynthetic assimilation, stomatal conductance, and transpiration rate. While three levels of media moisture and four levels of media pH had no effect on seedling performance, most growth and leaf function variables were hindered across application rate treatments of all three species. Label-recommended dosages resulted in growth suppression levels potentially detrimental to seedling establishment for all three species. This was most pronounced for Pinus monticola, in particular for root growth, where untreated control seedlings showed 109% more root volume growth than treated seedlings. We conclude that when possible, a species-specific application rate might be found that balances the benefits of vegetation control with the phytotoxicity to promote optimal growth gains.  相似文献   

19.
  • ? Fall fertilization may increase plant nutrient reserves, yet associated impacts on seedling cold hardiness are relatively unexplored.
  • ? Bareroot red pine (Pinus resinosa Ait.) seedlings in north-central Minnesota, USA were fall fertilized at the end of the first growing season with ammonium nitrate (NH4NO3) at 0, 11, 22, 44, or 89 kg N ha?1. Seedling morphology and cold hardiness [assessed by freeze induced electrolyte leakage (FIEL)] were evaluated six weeks after fertilization and following the second growing season.
  • ? Seedling height and number of needle primordia increased with fertilizer rate for both sampling years. Seedlings fertilized with 44 and 89 kg N ha?1 attained target height (15 cm) after the second growing season. Shoot and root N concentration increased after the first growing season in fall fertilized seedlings compared to controls. Fall fertilized seedlings had lower FIEL (i.e., increased cold hardiness) compared to controls when tested at ?40 °C after the first growing season, but no significant differences in FIEL of control and fertilized seedlings were observed after the second growing season.
  • ? Results suggest that fall fertilization of red pine seedlings can help render desired target height in the nursery, while maintaining or increasing cold hardiness levels.
    •   相似文献   

    20.
    During the spring of 2006, three willow varieties (SV1, SX67 and 9882-41) were established on marginal land in an agroforestry tree-intercropping arrangement where plots of short rotation willows were planted between rows (spaced 15?m apart) of 21-year-old mixed tree species. As a control, the same varieties were established on an adjacent piece of land without established trees (conventional willow system). This study investigated the magnitude of carbon pools, fine root and leaf biomass inputs and clone yields in both the tree-based intercropping (agroforestry) and conventional monocropping systems. Willow biomass yield was significantly higher in the agroforestry field (4.86?odt?ha?1?y?1) compared to the conventional field (3.02?odt?ha?1?y?1). In both fields, varieties SV1 and SX67 produced higher yields than the variety 9882-41. Willow fine root biomass in the top 20?cm of soil was significantly higher in the intercropping system (3,062?kg?ha?1) than in the conventional system (2,536?kg?ha?1). Differences in fine root biomass between clones were similar to that observed for differences in biomass yield: SV1?>?SX67?>?9882-41. Leaf input was higher in the intercropping system (1,961?kg?ha?1) than in the conventional system (1,673?kg?ha?1). Clonal differences in leaf inputs followed the same trends as those for root biomass and yield: SV1?>?SX67?>?9882-41. Soil organic carbon was significantly higher in the agroforestry field (1.94?%) than in the conventional field (1.82?%). A significant difference in soil organic carbon was found between the three clones: soils under clone 9882-41 had the lowest soil organic carbon at 1.80?%.  相似文献   

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