Fertilizer application in aid of plantation establishment in the savanna areas of Nigeria

Fertilizer trials were conducted to stimulate tree establishment and growth in the savanna region of Nigeria. The main nutrients investigated were N, P, K and B while the tree species included Azadirachta indica (Neem), Acacia auriculiformis, Eucalyptus spp., and Pinus spp. Borate application reduced the incidence of die-back of eucalypts and it also increased height growth. There was positive response to phosphate application by all species; phosphate reduced mortality considerably in pines on some sites. Response to N fertilizer by the species varied and related to type of N fertilizer. Urea was often found injurious to pines. There was strong interaction between N and P and usually response to N was not obtained on P-deficient sites. In all the cases where it was applied, there was no response to K. On more arid sites with poorly buffered soils, mineral fertilizers alone were insufficient to produce satisfactory tree growth. Application of animal manure on such sites increased survival and growth of Azadirachta indica, E. camaldulensis and A. auriculiformis.     

The influence of mycorrhizal associations on paper birch and jack pine seedlings when exposed to elevated copper,nickel or aluminum

Acid deposition may adversely affect northern forest ecosystems by increasing the concentration of metals in the soil solution. This study investigates the effects of ectomycorrhizal fungi on paper birch and jack pine seedlings exposed to elevated Cu, Ni, or Al in sand culture. One of four mycorrhizal fungi,Scleroderma flavidum, was able to reduce Ni toxicity to the birch seedlings. It did this by reducing transport of Ni to the stems. None of the fungi affected Cu toxicity in birch. In separate experiments, jack pine seedlings were exposed to combinations of Al and Ca. Infection withRhizopogon rubescens increased seedling susceptibility to A1. Seedlings inoculated withSuillus tomentosus showed a greater growth stimulation by Ca than uninoculated jack pines. Thus, for both tree species, the mycorrhizal association could alter the response of seedlings to high concentrations of certain metals, although this varied with fungal species.     

Increase in the abundance of cladocera at pH 5.1 in experimentally-acidified lake 223, Experimental Lakes Area,Ontario

Lake 223 in the Experimental Lakes Area, northwestern Ontario was experimentally-acidified with H₂SO₄ from 1976 to the present. Cladocerans increased in absolute and relative abundance and in total biomass when the pH of Lake 223 was lowered from 6.7 to 5.1. Comparing the cladoceran community at pH 6.7 (1974) with that at pH 5.1 (1981 to 1983), Daphnia galeata mendotae disappeared, Diaphanosoma birgei became rare, Holopedium gibberum increased in abundance and Daphnia catawba, recorded for the first time in 1980, became abundant. Bosmina longirostris became more abundant. Except for the decline in D. birgei, the changes in cladoceran species composition with acidification are consistent with known responses of these species to low pH. The increase in importance of cladocerans in 1981 to 1983 was at the expense of copepods. It was hypothesized to be caused by the decline in predation by small fish during 1981 to 1983 as acidification reduced minnow populations and inhibited reproduction in trout and sucker. The loss of the population of the invertebrate predator, the opposum shrimp, Mysis relicta, in 1979 had little effect on cladoceran biomass.     

Growth decline in red spruce and balsam fir relative to natural processes

Average annual growth of 3,001 red spruce (Picea rubens Sarg.) trees on plots randomly located across northern New England and upstate New York shows a regionally consistent decline starting soon after 1960. Depending on location, basal-area increment in 1980 was 13 to 40% less than in the peak growth year around 1960. The growth decline occurs in all size and age classes and is independent of elevation. Balsam fir (Abies balsamea (L.) Mill.) also shows a growth decline, but the start varies by tree age. The growth decline in both species is explainable at least in part by natural growth processes, complicating the task of evaluating the effects of atmospheric deposition.     

Influence of acidity and competition with fish on the development of ducklings in Quebec

In Quebec, in 1984 and 1985, a number of American Black Duck (Anas rubripes) and Common Goldeneye (Bucephala clangula) ducklings were reared on two acid lakes (pH 4.8 to 5.0) and one circumneutral lake (pH 6.0) in which the brook trout (Salvelinus fontinalis) populations had been manipulated. This allowed us to determine how acidity and competition with fish affected duckling feeding and growth. Strong acidity and the presence of fish were both required before the birds' development was restricted, the Black Duck being particularly affected. This result supports hypotheses on competition between fish and some waterfowl species.     

Patterns of plankton species,pH and associated water chemistry in Nova Scotia lakes

In order to assess the patterns of distribution of plankton species in relation to acidity, water chemistry, and physical characteristics, twenty lakes in Nova Scotia were selected for examination, with pH ranging from 3.5 to 7.6. Correlation and multiple regression analyses revealed associations between plankton and chemical variables. Patterns of plankton abundance and diversity were noted with respect to both pH and nutrient status, with occasionally conflicting effects of these two factors. Phytoplankton abundance was most closely associated with nutrient status, while zooplankton abundance was related to measures of primary production. pH tended to affect plankton diversity more than abundance or standing crop. Several lakes were outliers from overall patterns, with several possible explanations. Cluster and factor analyses were used to identify associations of plankton species, and to relate these associations to lake characteristics. Certain species were noted with relatively wide distribution, but which never occurred at low pH (<4.6). These were Chroococcus limneticus, Asterionella formosa, Cyclotella meneghiniana, Pinnularia braunii, and Surirella robusta for phytoplankton, and Polyphemus pediculus, Diaptomus oregonensis, and Tropocyclops prasinus for zooplankton.     

Nutritional stress inPicea sitchensis plantations in coastal British columbia: The effects ofGaultheria shallon and declining site fertility

Examples of nutritional stress in conifer seedlings caused by competing ericaceous species (e. g. Calluna andKalmia), have been reported in several parts of the world. Nutritional stress (primarily N deficiency) has been reported in Sitka spruce (Picea sitchensis) plantations growing in association with an ericaceous species, salal (Gaultheria shallon), in coastal British Columbia. Nutritional interference by salal was investigated on a chronosequence of sites up to 10 yr after clearcutting and slashburning. No direct evidence for an allelopathic contribution to the N stress was obtained. However, the rapid accumulation of salal fine roots and rhizomes, and the nutrients contained therein, provides a partial explanation for the observed stress symptoms. Soil analyses and seedling bioassays demonstrated a reduction in fertility in the period 8 to 10 yr after clearcutting and slashburning in comparison to the period 2 to 4 yr, which is believed to impose further nutritional stress on Sitka spruce. It is concluded that the nutritional stress in these Sitka spruce plantations is caused by a combination of (1) salal competition for nutrients and their subsequent immobilization in salal biomass, and (2) declining site fertility caused by the termination of the flush of nutrients (the “assart period”) that occurs in the immediate post-clearcutting and slashburning period. Sustaining good growth of plantations under such circumstances will require site nutrient management as well as vegetation management.     

Fish species distribution in relation to lake acidity in Ontario

Survey data from approximately 2,900 Ontario lakes were used to examine the distribution of 12 fish species with respect to lake pH. Yellow perch (Perca flavescens), white sucker (Catostomus commersoni), brook trout (Salvelinus fontinalis), pumpkinseed (Lepomis gibbosus), fathead minnow (Pimephales promelas) and redbelly dace (Phoxinus eos) proved to be tolerant of low pH (pH <6.4). Lake trout (Salvelinus namaycush), common shiner (Notropis cornutus), blacknose shiner (Notropis heterolepis), lake whitefish (Coregonus clupeaformis), walleye (Stizostedion vitreum vitreum) and northern pike (Esox lucius) showed limited distribution in low pH lakes (pH <6.4). The limited distribution of lake whitefish and northern pike likely relates to zoogeographic factors rather than their intolerance to low pH. Lake trout and common shiner occur in lakes susceptible to, and receiving high loadings of acidic deposition. However, without historical data, we cannot determine if their decreased distribution in low pH systems is due to intolerance to low pH.     

Simulation of nutrition of forests under stress using FORCYTE-11

Forest ecosystems are being subjected to an increasing variety of stresses for which we do not yet have rotation-length experience. Where we lack such experience, we cannot make experience-based predictions of the long-term effects of these stresses. While we are accumulating such experience, computer models can be used to make interim knowledge-based predictions. Most scientific knowledge has been produced by reductionist, disciplinary, process-based research. Such knowledge is a vital component of any explanation of natural or human-induced landscape phenomena, but cannot, in its reductionist, disciplinary form, provide an adequate basis on its own for long-term predictions about these phenomena. Such predictions require the development of computer models of ecosystem form and function based on the integration of knowledge from eco-physiology, autecology, community ecology, soil science, and climatology into ecosystem-level models that accurately describe the function and temporal dynamics of forest ecosystems. The ability of the ecosystem-level forest management simulation model FORCYTE-11 (FORest nutrientCycling andYieldTrendEvaluator) to simulate forest stresses is described briefly. The question of how to model other stresses, such as air pollution, acid rain, climate change, soil compaction and erosion, and moisture competition is discussed, and the outline of a new model (FORECAST:FORestry andEnvironmentalChangeASsessmenT) is presented.     

Role of air pollution in forest decline in Eastern North America

Evidence for and against three general mechanisms by which air pollution stress may cause or contribute to forest decline in eastern North America is examined. These mechanisms are (1) soil acidification, cation nutrient depletion, and subsequent Al toxicity, (2) direct and indirect effects of gaseous pollutants on the physiology and growth of forest trees; and (3) excess nitrogen deposition and subsequent soil acidification or physiological injury. Recent studies have revealed reductions in base saturation in some sites (both polluted and pristine), but the consequences of these changes to forest health and nutrition are not resolved. Aluminum toxicity may contribute to forest decline in red spruce (Picearubens L.) in high-elevation sites, but the data are contradictory. In forested landscapes in which regional decline (reduced tree growth and/or dieback) is reported, O₃ is the only gaseous pollutant documented as a contributing factor in the eastern North America. Whereas this secondary pollutant exhibits a regional distribution and occurs at potentially phytotoxic levels, a linkage between O₃ and forest decline is substantive only for loblolly pine (Pinustaeda Sarg.) in the southeast. Studies in high elevations do not support the hypothesis that O₃ or hydrogen peroxide directly affects the growth of red spruce or fraser fir (Abiesfraseri Poir.).However, preliminary data link chronic-level O₃ exposure with indirect effects, principally changes in drought tolerance in low-elevations (e.g., P. taeda) nd winter hardiness in high elevations (e.g., P. rubens).The emerging data on the role of air pollution as an environmental stress indicate that indirect effects (i.e., responses in which pollution alters the plant's ability to compete for limited resources or withstand other environmental stresses) are more important than direct effects (e.g., foliar necrotic lesions). Nitrogen saturation has been offered as an hypothesis for P. rubens decline, but no experimental data exist supporting this hypothesis.     

Mercury in plants,soil and atmosphere near a chlor-alkali complex

Data of atmospheric Hg concentrations measured near the chlor-alkali complex of Rosignano Solvay (Livorno, Italy) show that the impact of the industry on the terrestrial environment is restricted to a close area around; background values (3 to 5 ng m^?3) are reached within a radius of 4 to 5 km. Hg levels in plants (Poa sp. Pinus nigra and Solidago sp.) and in soil show the highest values in the sampling stations near the electrolytic cells.     

The use of organic and mineral fertilizers in reforestation and in revitalization of declining protective forests in the alps

BIOSOL BIOSOL and BACTOSOL are registered trademarks of Biochemie Ges.m.b.H., Kundl, Austria. and BACTOSOL BIOSOL and BACTOSOL are registered trademarks of Biochemie Ges.m.b.H., Kundl, Austria. organic fertilizers based on residue from commercial antibiotic production, were tested as an alternative to mineral fertilizers in reforestation and in revitalization of Norway spruce stands (Picea abies) affected by forest decline. Due to its slow release of N and its stimulation of root growth, the organic fertilizer was superior to mineral fertilizer in enhancing growth of spruce planted in nutrient poor soil with low nutrient retention capacity, especially when combined with magnesium carbonate fertilizer. In mature stands, basal area increment responded positively and significantly to both mineral fertilizer and BIOSOL. So far no pronounced effects of fertilizer treatment on seed production and viability were observed. Fertilization in the moderate amounts employed had no adverse effects on microbial activity in the soil and mycorrhizal status and thus seems to be a safe method to increase tree vigor without dramatically changing site parameters.     

Biological indicators of lake acidification

Indicator taxa are identified, based on both synoptic surveys and whole lake acidification experiments, for lake acidification in the pH 6.0 to 5.0 range. Acidobiontic diatoms (e.g Asterionella ralfsii, Fragillaria acidobiontica, etc.), periphyton (Mougeotia and related species), macroinvertebrates (e.g. Hyalella azteca, Orconectes sp., etc.), leeches, and cyprinid fishes (e.g. Pimephales promelas, Notropis cornutus, etc.) are identified as target organisms during early phases of lake acidification.     

Scattered CaSO4-crystallites on needle surfaces after simulated acid rain as an indicator of nutrient leaching

Two acid rain experiments were conducted, one at Oulu using transplanted seedlings of Picea abies and Pinus sylvestris, and the other with adult pines at Kevo where test plots were designated in a natural mixed stand of Pinus sylvestris and Betula tortuosa. The acid solution was made by adding H₂SO₄ and HNO3 (vol:vol 2:1, pH adjusted to 3 and 4) to clean water.The Oulu experiment was carried out from 1986 to 1989, and Kevo from 1985 to 1989. No visible injuries related directly to the acid rain treatment could be observed after 3 yr of the experiments, but microscopic examination revealed significant changes in the structure and morphology of the needles. The conifer seedlings treated at pH 3 had significant amounts of scattered CaSO₄ crystallites and characteristic piles and bows on the needle surfaces, as detected with EDS. The number of CaSO₄ crystallites was higher on the surfaces of the spruce needles than those of the pine needles. The current needles had more crystallites than the previous year's needles.     

Foliar sensitivity of eight eastern hardwood tree species to ozone

As part of a larger 3-yr study, container-grown seedlings of black cherry (Prunus serotina) red maple (Acer rubrum), red oak (Ouercus rubra), sweetgum (Liquidambar styraciflua), white ash (Fraxinus americana), white oak (Ouercus alba), yellow-poplar (Liriodendron tulipifera), and yellow birch (Betula allegheniensis) were exposed to 0,0.075, or 0.15 μL L-¹ O₃ in laboratory controlled-environment chambers for 6 hr d^?1 on 2 consecutive days for 12 weeks. On the third consecutive day of each week, plants were treated for 45 min with precipitation at pH 3.0 or 4.2. The only significant foliar symptoms were induced by the O₃ treatments, and the severity of symptoms was not influenced by precipitation pH. The most common symptom was a dark, adaxial stipple which was most severe on the oldest leaves. Equations were developed to express the influence of leaf position on percent leaf injury following 4, 8, and 12 weeks of treatment. Based on percent leaf tissue showing stipple and defoliation following exposure to 0.15 μL L^?1 O₃, the most sensitive species to O₃ was black cherry, followed by sweetgum, yellow-poplar, white ash, red maple and yellow birch. Red oak and white oak foliage did not exhibit stipple.     

Comparison of the macrophyte communities of a clearwater and a brownwater oligotrophic lake in Kejimkujik National Park,Nova Scotia

Beaverskin and Pebbleloggitch Lakes are small, proximate, acidic, oligotrophic, headwater lakes located in southwestern Nova Scotia. Beaverskin Lake has clear water, its euphotic zone is deep, and it has extensive beds of macrophytic vegetation that cover most of its bottom to a depth of 6.5 m. In contrast, the water of Pebbleloggitch Lake is highly colored by dissolved humic substances, and macrophytes are restricted to a narrow littoral fringe in depths of less than about 1.8 m. The most widespread macrophyte community in Beaverskin Lake occurs at depths of 2.0–6.5 m and is dominated by Sphagnum macrophyllum and Utricularia vulgaris, while the second most prominent community is littoral and is dominated by Eriocaulon septangulare, Lobelia dortmanna, and Eleocharis acicularis. The most prominent community in Pebbleloggitch Lake is dominated by the floating-leaved Nuphar variegatum rooted as deep as 1.8 m, while communities dominated by E. septangulare and Sphagnum spp. occur in water less than about 0.7 m deep.     

Simulation of nutrition of forests under stress using forgyte-11

Forest ecosystems are being subjected to an increasing variety of stresses for which we do not yet have rotation-length experience. Where we lack such experience, we cannot make experience-based predictions of the long-term effects of these stresses. While we are accumulating such experience, computer models can be used to make interim knowledge-based predictions. Most scientific knowledge has been produced by reductionist; disciplinary, process-based research. Such knowledge is a vital component of any explanation of natural or human-induced landscape phenomena, but cannot, in its reductionist, disciplinary form, provide an adequate basis on its own for long-term predictions about these phenomena. Such predictions require the development of computer models of ecosystem form and function based on the integration of knowledge from eco-physiology, autecology, community ecology, soil science, and climatology into ecosystem-level models that accurately describe the function and temporal dynamics of forest ecosystems.The ability of the ecosystem-level forest management simulation model FORCYTE-11 (FORest nutrient Cycling and Yield Trend Evaluator) to simulate forest stresses is described briefly. The question of how to model other stresses, such as air pollution, acid rain, climate change, soil compaction and erosion, and moisture competition is discussed, and the outline of a new model (FORECAST: FORestry and Environmental Change ASsessmenT) is presented.     

Fish species distribution in relation to water chemistry in selected Maine lakes

We examined the possible effects of acidity on the number of fish species in 22 lakes in Maine, ranging in pH from 4.4 to 7.0 (mean values). We caught no fish in three lakes with pH <5.0, but collected 1 to 9 species in the remaining 19 lakes (pH 5.4 to 7.0). Brook trout (Salvelinus fontinalis), golden shiners (Notemigonus crysoleucas), and white suckers (Catostomus commersoni) were ubiquitous, but no common shiners (Notropis cornutus) or creek chubs (Semotilus atromaculatus) were collected from lakes with pH below 6.0 and 5.9, respectively. The fishless lakes differed from the others primarily in water chemistry variables related to acidity, i.e., pH, Al, and concentration of divalent cations. Among lakes that contained fish, the factors related to the number of species collected were lake surface area and maximum depth, which may be related to habitat quantity and diversity. Cluster analysis identified two distinct fish species groups — depauperate and cyprinid-sucker — but multiple comparison analysis failed to relate any measured chemical or physical variable to these two groups, probably because water chemistry was suitable for reproduction by these species.     

The effect of simulated acid rain on feather mosses and lichens of the boreal forest

Permanent field plots containing a dominant ground cover of feather moss (Pleurozium schreberi) and the forage lichen, (Cladina), were established in mature, boreal forest jack pine stands to monitor the effects of simulated acid precipitation. For a five-year period commencing in 1981, bimonthly sprays (pH range 2.5 to 5.6) were given throughout the growing season. The feather moss wefts were extremely sensitive to simulated rains of pH 2.5 and 3.0; but loss of cover and frond blackening were also observed at pH 3.5. The pH 2.5 treatment killed almost all of thePleurozium, while the cover remaining in the pH 3.0 treatment after 5 years was reduced by 44%. In laboratory studies designed to compare the effects of H₂S0₄, HN03 and a 2:1 mixture of both, microcosms sprayed with H₂S0₄ alone (pH 3.0) were more significantly affected than fronds treated with HN0₃ alone or pH 5.6 sprays of any ratio. Although less sensitive thanPleurozium, field-sprayed lichens were also visibly damaged. At pHs less than 3.5,C. stellaris andC. rangiferina had reduced podetial height and dry weight; whileC. mitis was affected by a combination of the acid rain treatment and other associated factors. While ambient rains of pH 4.2 may not in themselves be harmful to the boreal ground flora, it is apparent that the feather mosses and lichens, lacking a cuticle and true roots, are very sensitive to occasional, extremely acidic rain events.     

Population dynamics of yellow perch (Perca flavescens) and pumpkinseed (Lepomis gibbosus) in two acid-stressed lakes

Fish population parameters: abundance, age-class composition, and size-at-age, which respond to environmental stresses, were investigated in two lakes showing chemical and biological evidence of acidification. Plastic Lake, Muskoka District of Ontario, shows spring pH depression and A1 toxicity in surface waters, with an associated annual fish kill. In Crosson Lake, pH 5.2 to 5.3, there has been a dramatic decline in abundance of the white sucker (Catostomus commersoni). In Platic Lake the abundance of pumpkinseed (Lepomis gibbosus) has declined and that of rock bass (Ambloplites rupestris) has increased. In Crosson Lake size-at-age has increased in yellow perch (Perca flavescens), pumpkinseed abundance has increased but with no change in growth rate.