Growth and nutrient uptake of coniferous seedlings: Comparison among 10 species at various seedbed densities

Summary The evaluation of biomass production and uptake of N, P, K, Ca, and Mg for various plant components (roots, stems, and foliage) and totals by 10 species of 2-0 coniferous seedlings grown at a controlled range of densities in a highly productive forest nursery documents considerable differences among species and seedling parameters. The species are ranked by biomass and nutrient-element relationships on a unit area of seedbed basis, quantifying the magnitude of the differences among the species at the various density levels. The 10 species include Abies balsamea, Larix leptolepis, Picea abies, Picea glauca, Picea mariana, Picea pungens, Pinus resinosa, Pinus strobus, Pinus sylvestris, and Pseudotsuga menziesii.Contribution of the Forest Resources Council, School of Environmental and Resource Management, State University of New York College of Environmental Science and Forestry, Syracuse, New York 13210.Contribution of the Forest Resources Council, School of Environmental and Resource Management, State University of New York College of Environmental Science and Forestry, Syracuse, New York 13210.     

The relative uptake of Ca and Sr into tree foliage using a whole-watershed calcium addition

The use of strontium isotopes and ratios of alkaline earth elements (i.e., ⁸⁷Sr/⁸⁶Sr and Ca/Sr) to trace Ca sources to plants has become common in ecosystem studies. Here we examine the relative uptake of Ca and Sr in trees and subsequent accumulation in foliage. Using a whole-watershed Ca addition experiment at the Hubbard Brook Experimental Forest in N.H., we measured the uptake of Ca relative to Sr in foliage and roots of sugar maple (Acer saccharum), yellow birch (Betula alleghaniensis), American beech (Fagus grandifolia), and red spruce (Picea rubens). Vegetation was analyzed for Ca and Sr concentrations and the ⁸⁷Sr/⁸⁶Sr ratio. A comparison of the Ca/Sr ratio in the vegetation and the Ca/Sr ratio of the applied mineral allows for the calculation of a discrimination factor, which defines whether Ca and Sr are incorporated and allocated in the same ratio as that which is available. A discrimination factor greater than unity indicates preferential uptake of Ca over Sr; a factor less than unity reflects preferential uptake of Sr over Ca. We demonstrate that sugar maple (SM) and yellow birch (YB) have similar and small discrimination factors (1.14 ± 0.12,1σ and 1.16 ± 0.09,1σ) in foliage formation and discrimination factors of less than 1 in root formation (0.55–0.70). Uptake into beech suggests a larger discrimination factor (1.9 ± 1.2) in foliage but a similar root discrimination factor to SM and YB (0.66 ± 0.06,1σ). Incorporation into spruce foliage occurs at a much slower rate than in these other tree species and precludes evaluation of Ca and Sr discrimination in spruce foliage at this time. Understanding the degree to which Ca is fractionated from Sr in different species allows for refinement in the use of ⁸⁷Sr/⁸⁶Sr and Ca/Sr ratios to trace Ca sources to foliage. Methods from this study can be applied to natural environments in which various soil cation pools have different ⁸⁷Sr/⁸⁶Sr and Ca/Sr ratios. The results reported herein have implications for re-evaluating Ca sources and fluxes in forest ecosystems.     

Stand treatment and sampling time of hardwood foliage

A 70-year-old thinned northeastern Fagus-Betula-Acer stand in the Adirondack Mountains of New York was fertilized with varying combinations of N, P, K and lime.Acer saccharum Marsh. andBetula alleghaniensis Brit. foliage was collected periodically during the frost-free season and analyzed for foliage areas and weights, and levels of ash, N, P, K, Ca, Mg. Comparisons were made within species, and among treatments, expressed as concentrations on dry weight and ash bases, and as contents on per leaf weight and area bases. Elemental composition trends over time were examined to determine treatment effects and optimum sampling period.     

Effect of soil K, Ca and Mg saturation and endomycorrhization on growth and nutrient uptake of sugar maple seedlings

Nutrient imbalances of declining sugar maple (Acer saccharum Marsh.) stands in southeastern Quebec have been associated with high exchangeable Mg levels in soils relative to soil K and Ca. A greenhouse experiment was set up to test the hypothesis that the equilibrium between soil exchangeable K, Ca, and Mg ions influences the growth and nutrient status of sugar maple seedlings. Also tested was whether endomycorrhization can alter nutrient acquisition under various soil exchangeable basic cations ratios. Treatments consisted of seven ratios of soil exchangeable K, Ca, and Mg making up a total base saturation of 58%, and a soil inoculation treatment with the endomycorrhizal fungus Glomus versiforme (control and inoculated), in a complete factorial design. Sugar maple seedlings were grown for 3 months in the treated soils. Plant shoot elongation rate, dry biomass and nutrient concentrations in foliage were influenced by the various ratios of soil cations. The predicted plant biomass and foliar K concentration were highest at a soil Ca saturation of 38%, a soil K saturation of 12%, and a soil Mg saturation of 8%. Potassium concentration in foliage was dependent on the level of Ca and Mg saturation in the soil when soil K saturation was close to 12%. Foliar Ca and Mg levels were more dependent on their corresponding levels in soil than foliar K. Colonization by G. versiforme did not influence seedling growth and macronutrient uptake. The results confirm that growth and nutrition of sugar maple are negatively affected by imbalances in exchangeable basic cations in soils.     

The effect of glucose-6-phosphate isomerase genotype onin vitro specific activity andin vivo flux inMytilus edulis

Four samples of the musselMytilus edulis were taken between 1984 and 1987 from Stony Brook, New York, and used to study the glucose-6-phosphate isomerase (GPI) polymorphism in this species.In vitro specific activity andin vivo flux measured in the same animals were found to be significantly correlated. A significant effect of GPI genotype on flux was observed in one of the samples; overall, significant evidence of effect of genotype on enzyme activity was also obtained. GPI activities of common genotypes tend to deviate less from the population mean than those of rare (frequency less than 5%) genotypes. This suggests the possibility that rare GPI genotypes are rare as a consequence of having biochemical properties that deviate from an optimum level and, therefore, having a lower fitness. In support of this hypothesis, we found in one of our samples that shell length is a concave function of GPI activity with an intermediate optimum activity level. The financial support provided to P.J.N.S. by the Luso-American Educational Commission (Fulbright Program), the Instituto Nacional de Investigacao Científica (Portugal), and the Faculdade de Ciências da Universidade de Lisboa during several stages of this research is gratefully acknowledged. Financial support from the Ministerio de Educatión y Ciencia (Spain) in the form of a postdoctoral Fulbright/MEC fellowship to M.S. is also gratefully acknowledged. Research was supported by National Science Foundation Grant BSR-8415060 to R.K.K. This is contribution No. 736 from the Program in Ecology and Evolution, State University of New York at Stony Brook. On leave from Departamento de Biologia Vegetal, Faculdade de Ciências, Universidade de Lisboa, Campo Grande C2, Lisboa, Portugal.     

Nitrogen cycling in a northern hardwood forest: Do species matter?

To investigate the influence of individual tree species on nitrogen (N) cycling in forests, we measured key characteristics of the N cycle in small single-species plots of five dominant tree species in the Catskill Mountains of New York State. The species studied were sugar maple (Acer saccharum), American beech (Fagus grandifolia), yellow birch (Betula alleghaniensis), eastern hemlock (Tsuga canadensis), and red oak (Quercus rubra). The five species varied markedly in N cycling characteristics. For example, hemlock plots consistently showed characteristics associated with "slow" N cycling, including low foliar and litter N, high soil C:N, low extractable N pools, low rates of potential net N mineralization and nitrification and low NO ₃ ^– amounts trapped in ion-exchange resin bags buried in the mineral soil. Sugar maple plots had the lowest soil C:N, and the highest levels of soil characteristics associated with NO ₃ ^– production and loss (nitrification, extractable NO ₃ ^– , and resin bag NO ₃ ^– ). In contrast, red oak plots had near-average net mineralization rates and soil C:N ratios, but very low values of the variables associated with NO ₃ ^– production and loss. Correlations between soil N transformations and litter concentrations of N, lignin, lignin:N ratio, or phenolic constituents were generally weak. The inverse correlation between net nitrification rate and soil C:N that has been reported in the literature was present in this data set only if red oak plots were excluded from the analysis. This study indicates that tree species can exert a strong control on N cycling in forest ecosystems that appears to be mediated through the quality of soil organic matter, but that standard measures of litter quality cannot explain the mechanism of control.     

Differentiation in DNA fingerprinting among species of the genus Acer L. in Campania (Italy)

Abstract

Natural populations of species in the Acer genus occurring in Campania (southern Italy) were surveyed by screening seven microsatellite loci. Primer pairs for Acer pseudoplatanus L. microsatellite loci were analysed in six different species: Acer lobelii Ten., Acer campestre L., Acer pseudoplatanus L., Acer obtusatum W. et K., Acer neapolitanum Ten. and Acer monspessulanum L. The aim of the present study was to survey the genetic variability and genetic structure of natural populations of the Acer genus in Campania. The high degree of polymorphism observed in six different species of Acer makes these markers useful for investigating genetic variation at various spatial scales, and for the analysis of gene flow and of the mating system.     

Use of foliar Ca/Sr discrimination and <Superscript>87</Superscript>Sr/<Superscript>86</Superscript>Sr ratios to determine soil Ca sources to sugar maple foliage in a northern hardwood forest

Calcium/strontium and ⁸⁷Sr/⁸⁶Sr ratios in foliage can be used to determine the relative importance of different soil sources of Ca to vegetation, if the discrimination of Ca/Sr by the plant between nutrient sources and foliage is known. We compared these tracers in the foliage of sugar maple (Acer saccharum) to the exchange fraction and acid leaches of soil horizons at six study sites in the White Mountains of New Hampshire, USA. In a previous study, sugar maple was shown to discriminate for Ca compared to Sr in foliage formation by a factor of 1.14 ± 0.12. After accounting for the predicted 14% shift in Ca/Sr, foliar Ca/Sr and ⁸⁷Sr/⁸⁶Sr ratios closely match the values in the Oie horizon at each study site across a 3.6-fold variation in foliar Ca/Sr ratios. Newly weathered cations, for which the Ca/Sr and ⁸⁷Sr/⁸⁶Sr ratios are estimated from acid leaches of soils, can be ruled out as a major Ca source to current foliage. Within sites, the ⁸⁷Sr/⁸⁶Sr ratio of the soil exchange pool in the Oa horizon and in the 0–10 cm and 10–20 cm increments of the mineral soil are similar to the Oie horizon and sugar maple foliar values, suggesting a common source of Sr in all of the actively cycling pools, but providing no help in distinguishing among them as sources to foliage. The Ca/Sr ratio in the soil exchange pool, however, decreases significantly with depth, and based on this variation, the exchange pool below the forest floor can be excluded as a major Ca source to the current sugar maple foliage. This study confirms that internal recycling of Ca between litter, organic soil horizons and vegetation dominate annual uptake of Ca in northern hardwood ecosystems. Refinement of our understanding of Ca and Sr uptake and allocation in trees allows improvement in the use of Ca/Sr and ⁸⁷Sr/⁸⁶Sr ratios to trace Ca sources to plants.     

Association of ectomycorrhizal mats with Pacific yew and other understory trees in coniferous forests

This study was designed to determine whether ectomycorrhizal mats (ECM) are more likely to be present in soils at the base of common understory trees than in soils distant from trees and to determine whether occurrence of ECM is related to tree size. Three understory trees were studied: Pacific yew (Taxus brevifolia Nutt.), western hemlock (Tsuga heterophylla (Raf.)Sarg), and vine maple (Acer circinatum Pursh). The 12 sites studied represent a range of climatic conditions and management histories. More than 2,900 plots were surveyed over 18 months. The incidence of ECM was higher at the base of all three species than in control plots. Incidence of mats was also positively correlated with tree size. Saplings consistently had a lower incidence of ECM than did larger trees.Paper 3028 of the Forest Research Laboratory, Oregon State University, Corvallis     

Hydraulic conductivity of branch junctions in three temperate tree species

Summary Hydraulic conductivities were measured in branch junctions and in the proximal segments of Quercus velutina Lam., Acer saccharum Marsh., and Tsuga canadensis (L.) Carr. In all three species, the basal proximal segment was more conductive than the junction by a factor of 1.1–1.5. There was no consistent pattern for the distal proximal segments, where the conductivities were higher, lower, or the same as the junction. These data are discussed in terms of Martin H. Zimmermann's concept of plant segmentation. It is concluded that junction constrictions to water flow contribute less to plant segmentation than the variation in leaf specific conductivity in the crown of these species.     

Nutrient requirements of exotic tree species in Zimbabwe

Pot and field experiments were conducted in the greenhouse and at three field sites (Marondera, Domboshawa and Makoholi) in Zimbabwe to examine the effects of soils and fertilizers on nutrient uptake and growth of 6 exotic tree species (Eucalyptus camaldulensis, E. grandis, E. tereticornis, Leucaena leucocephala, Casuarina cunninghamiana, and Acacia holosericea). Plant growth, N and P contents of all species were increased by the application of N, P, K and micronutrient fertilizers. The effect of individual nutrients (N, P, K and micronutrients) and their combination on Eucalyptus species was further investigated in a pot experiment using soil from Domboshawa. Eucalyptus species responded only to N application and no significant interactions were found between N and the other elements. Nutrient uptake results showed that E. camaldulensis and E. tereticornis removed more cations than the N-fixing trees but only in the fertilized treatments. L. leucocephala and C. cunninghamiana were higher in P, but no clear trends were observed for N. Plant growth and nutrient uptake by E. camaldulensis. C. cunninghamiana and A. holosericea were assessed in the field at the three sites. Plant species grown in the Marondera site had greater height and diameter at breast height (DBH) than those in the two other sites. These results followed trends in soil nutrient contents. The analysis of foliage revealed differences in the nutrient concentration of leaves from different trees, but no effect of site was found. The interrelationships between plant characteristics, soil and foliage nutrients were examined. In a pot experiment, mineral N was the only variable correlated with growth response and nutrient uptake, while in the field the only significant correlation was obtained with soil pH.     

Plant and soil natural abundance <Emphasis Type="Italic">δ</Emphasis><Superscript>15</Superscript>N: indicators of relative rates of nitrogen cycling in temperate forest ecosystems

Watersheds within the Catskill Mountains, New York, receive among the highest rates of nitrogen (N) deposition in the northeastern United States and are beginning to show signs of N saturation. Despite similar amounts of N deposition across watersheds within the Catskill Mountains, rates of soil N cycling and N retention vary significantly among stands of different tree species. We examined the potential use of δ ¹⁵N of plants and soils as an indicator of relative forest soil N cycling rates. We analyzed the δ ¹⁵N of foliage, litterfall, bole wood, surface litter layer, fine roots and organic soil from single-species stands of American beech (Fagus grandifolia), eastern hemlock (Tsuga canadensis), red oak (Quercus rubra), and sugar maple (Acer saccharum). Fine root and organic soil δ ¹⁵N values were highest within sugar maple stands, which correlated significantly with higher rates of net mineralization and nitrification. Results from this study suggest that fine root and organic soil δ ¹⁵N can be used as an indicator of relative rates of soil N cycling. Although not statistically significant, δ ¹⁵N was highest within foliage, wood and litterfall of beech stands, a tree species associated with intermediate levels of soil N cycling rates and forest N retention. Our results show that belowground δ ¹⁵N values are a better indicator of relative rates of soil N cycling than are aboveground δ ¹⁵N values.     

Canopy structure and vertical patterns of photosynthesis and related leaf traits in a deciduous forest

Canopy structure and light interception were measured in an 18-m tall, closed canopy deciduous forest of sugar maple (Acer saccharum) in southwestern Wisconsin, USA, and related to leaf structural characteristics, N content, and leaf photosynthetic capacity. Light attenuation in the forest occurred primarily in the upper and middle portions of the canopy. Forest stand leaf area index (LAI) and its distribution with respect to canopy height were estimated from canopy transmittance values independently verified with a combined leaf litterfall and point-intersect method. Leaf mass, N and A _max per unit area (LMA, N/area and A _max/area, respectively) all decreased continuously by over two-fold from the upper to lower canopy, and these traits were strongly correlated with cumulative leaf area above the leaf position in the canopy. In contrast, neither N concentration nor A _max per unit mass varied significantly in relation to the vertical canopy gradient. Since leaf N concentration showed no consistent pattern with respect to canopy position, the observed vertical pattern in N/area is a direct consequence of vertical variation of LMA. N/area and LMA were strongly correlated with A _max/area among different canopy positions (r²=0.81 and r²=0.66, respectively), indicating that vertical variation in area-based photosynthetic capacity can also be attributed to variation in LMA. A model of whole-canopy photosynthesis was used to show that observed or hypothetical canopy mass distributions toward higher LMA (and hence higher N/area) in the upper portions of the canopy tended to increase integrated daily canopy photosynthesis over other LMA distribution patterns. Empirical relationships between leaf and canopy-level characteristics may help resolve problems associated with scaling gas exchange measurements made at the leaf level to the individual tree crown and forest canopy-level.     

Successional trends and apparent <Emphasis Type="Italic">Acer saccharum</Emphasis> regeneration failure in an oak-hickory forest in central Missouri,USA

Permanent vegetation plots established in 1968 at the Baskett Research and Education Area (BREA) were remeasured in 2004/2005 to assess trends in canopy composition, vegetation–environment relationships, and regeneration patterns. Quercus spp. [particularly Quercus alba (white oak)] remained dominant in BREA forests. However, Nonmetric Multidimensional Scaling Ordination of a dataset composed of tree importance values from both samples indicated the two most common community types (Dry Ridge and Slope; Mesic Slope) were shifted away from Quercus spp. abundance toward greater importance of Acer saccharum (sugar maple) in ordination space. Plots in glade-like environments shifted toward greater Juniperus virginiana (eastern redcedar) importance. Environmental analysis indicated that soil properties (pH, organic matter, Ca, Mg, and K) and slope position were highly correlated with ordination axes. Saplings of Quercus spp. exhibited greatly reduced abundance in the most recent sample and the reduction in Quercus spp. density was highest in plots with greatest canopy cover. While Acer saccharum saplings were still quite abundant in BREA forests, smaller sapling size classes were becoming notably depleted, reflecting growth of a cohort of plants established before the 1968 sample toward and into tree-sized individuals. Seedlings surveys emphasized that A. saccharum seedlings have become very rare in BREA forests, while Quercus spp. seedling densities are higher, but likely below those needed for eventual adequate recruitment to the canopy. Although a number of mechanisms to explain apparent A. saccharum regeneration failure can be developed, herbivory, recent climate trends (warming late-winter conditions) and increased litter layer depth are the most plausible explanations for the observed scarcity of A. saccharum seedlings. Although increasing importance of A. saccharum in the canopy of BREA forests appears inevitable in coming decades, longer-term trends are unclear given the shortage of seedling regeneration.     

Nitrogen-tillage-residue management

Summary NCSWAP (nitrogen and carbon cycling in soil, water and plant) is a simulation model of the soil-crop-water system which integrates water flow dynamics, crop growth, N transformations, tillage and residue effects, soil temperature, and solute transport. A small plot field study was initiated in May of 1980 to determine the effects of N rate (2 or 20 g N/m²), tillage (rototill or no-till), and residue management system (residue return or noresidue) on soil parameters, and maize (Zea mays L.) production.Significant differences due to treatments (N rate, tillage, and residue) were not detected in 1981 for the measured soil-plant parameters including soil moisture, yield, and N uptake. Therefore, two representative treatment combinations (N rates of 2 or 20 g N/m²-tilled-no residue) characterized the field research data. Calculated and observed data sets were compared for several parameters including: (1) soluble NO₃–N, (2) N leaching losses (3) plant total-N and¹⁵N, (4) root growth, (5) soil moisture, and (6) fertilizer efficiency.The objectives of this study were to initiate the validation process of the model NCSWAP, and to illustrate how NCSWAP can be used as a research tool to infer operational characteristics of the N cycle.Contribution of the Soil and Water Management Research Unit, USDA-ARS, and the Department of Soil Science, University of Minnesota, St. Paul, MN 55108. Minn Agric. Exp. Sta., Sci. J., Ser. Paper 13907.Senior Laboratory Technician; Research Chemist, USDA-ARS and Professor; Professor of Soil Microbiology; and Soil Scientist, USDA-ARS and Assistant Professor; all Department of Soil Science, University of Minnesota, respectively. Inquiries about NCSWAP should be sent to J. A. E. Molina.     

Knop's Solution What It Seems

Biology and World Health (Revised Edition) by Madeleine P. Grant. Abelard-Schuman, 257 Park Avenue South, New York, N.Y. 10010. 1970. 241 pp. Indexed and Bibliography. $5.95. Reviewed by Robert C. Hayden.

The Scientific American Book of Projects for The Amateur Scientist by C. L. Strong. Simon and Schuster, Rockefeller Center, 630 Fifth Ave., New York, N. Y. 10020. 1970. 584 pp., Indexed. $3.95 paperback. Reviewed by Robert C. Hayden.

From One Drop of Water by Clifford R. Nelson. Julian Messner, 1 West 39 Street, New York, N.Y. 10018. 1970. 30 pp. $3.50. Reviewed by Robert C. Hayden.

Animal Feet by George F. Mason. William Morrow and Co., Inc., 105 Madison Ave., New York, N.Y. 10016. 1970. 95 pp., Indexed. $3.95. Reviewed by Robert C. Hayden.

What We Find When We Look at Maps by John Oliver. McGraw-Hill Book Co., 330 West 42nd St., New York, N.Y. 10036. 1970. 39 pp., $4.72 lib. edn. Reviewed by Robert C. Hayden.

The Secret Life of the Forest by Richard Ketchum. American Heritage Press, New York, N.Y. 1970. 111 pp., $7.95. Reviewed by Robert C. Hayden.     

Shade adaptation and shade tolerance in saplings of three Acer species from eastern North America

Summary Saplings of three, co-occurring maple species in a mature maple-beech forest differed in a suite of structural and physiological characters that separated the canopy species, Acer, saccharum, from the two subcanopy species, A. pensylvanicum and A. spicatum. Acer saccharum had both more dense wood and tougher and heavier but thinner leaves than the subcanopy species. Acer pensylvanicum had the largest, lightest leaves with high stomatal density and its canopy architecture was the most effective in terms of leaf display for light interception. Acer spicatum had weaker wood similar to that of A. pensylvanicum but also small, soft and relatively poorly displayed leaves. Both subcanopy species maintained marginally higher average rates of photosynthesis over the growing season in the understory environment. We consider juvenile A. saccharum only shade-tolerant, capable of persisting through long periods in the closed canopy until a gap occurs but not specifically adapted to the understory environment. Juvenile A. sacchrum appears to be constrained functionally by the requirements set by the canopy environment that adults will occupy. Characters such as high wood density are already expressed in the understory sapling; this investment in denser wood slows the growth of saplings, but is necessary for structural reasons in the adult. Juvenile A. saccaharum have morphological and photosynthetic characters better suited to gas exchange and extension growth under the increased photon flux densities in large forest gaps, characteristics that will also be advantageous in the sunlit canopy environment of adults.Both subcanopy maples appear to be more truly shade-adapted, although in somewhat different ways. Acer pensylvanicum has characteristics that enhance the potential for capture and utilization of sunflecks and is able to sustain higher growth rates than A. saccharum in the shaded subcanopy environment. Acer spicatum shares some shade-adapted features with A. pensylvanicum, and its habit of lateral spread through stem layering may confer an additional advantage in foraging for small light gaps.     

Effect of inulin on yeast inulinase production in sauerkraut brine

Kluyveromyces marxianus NRRL Y-1196 produced the highest inulinase activity (38 U/mg protein) of six yeasts examined after 24 h growth in sauerkraut brine in shaking flasks at 30°C with 0.3% inulin as an enzyme inducer. The enzyme was recovered by acetone fractionation, with a yield of 81%. It had maximum activity at pH 4.4 and 55°C with K _m values for inulin and sucrose of 3.92 mm and 11.9 mm, respectively. The yeast raised the pH from 3.4 to above 7.0, using all the lactic acid in the brine. Growth of K. marxianus in sauerkraut brine with a small amount of inulin may usefully decrease the BOD and concomitantly produce inulinase.The authors are with the Department of Food Science and Technology, Cornell University, Geneva, New York 14456, USA     

生态恢复对马尾松叶片化学计量及氮磷转移的影响

为了解生态恢复对侵蚀红壤恢复的马尾松林叶片碳氮磷化学计量及氮磷养分转移的影响,在福建省长汀县河田镇典型侵蚀红壤区选取恢复13、30、33a的马尾松林为研究对象,并以未治理侵蚀地(CK1)和次生林(CK2)分别作为恢复前和恢复后的对照,通过测定马尾松叶片的碳、氮、磷含量,计算其计量比,内稳性指数和氮磷转移率,分析了侵蚀红壤生长的马尾松养分限制与养分转移的关系。结果表明:在侵蚀红壤恢复过程中,马尾松1年龄叶片C、N、P含量及1年龄叶片C∶N、C∶P、N∶P变化较小,这与马尾松较高的内稳性有关(N和P内稳性指数分别为7.57和3.89)。所有实验地马尾松1年龄叶片N∶P处于11.0—13.4之间,表明马尾松的生长受N、P共同限制,其中马尾松叶片N转移率显著低于P转移率,这与生态恢复过程中马尾松养分利用效率、生长需求以及土壤养分供应状况有关。1年龄叶片C∶N、C∶P分别与马尾松N、P转移率成负相关关系,当马尾松叶片C∶N、C∶P较低时,表明N、P利用效率较低,叶片衰老时更多的N和P被转移利用;反之,则N、P利用效率较高,转移率低。同时,C∶N、C∶P分别与树高、胸径成显著负相关关系,即马尾松生长对N、P的需求同样会影响化学计量比的变化,从而影响养分转移。虽然侵蚀地生态恢复过程中土壤N、P含量增加,但仍较贫瘠,不足以满足马尾松的生长,马尾松养分转移率较高,因此,为了提高侵蚀地恢复的马尾松林的生产力,建议下一步恢复措施中适当施加N肥和P肥。该研究将侵蚀红壤不同生态恢复年限的马尾松叶片C、N、P化学计量及养分转移结合,有助于全面、系统地揭示生态恢复过程马尾松林的养分循环,对指导侵蚀红壤恢复和提高马尾松生产力具有重要意义。     

The World of Darkness

Bowden, Charles Killing the Hidden Waters Austin: University of Texas Press, 1977 174 pp., $9.96 Reviewed by Malcolm F. Farmer

Cogswell, Howard L. Water Birds of California Berkeley: University of California Press, 1977 416 pp., $5.75 paper Reviewed by Karl L. Trever

Grant, Edward Physical Science in the Middle Ages New York: Cambridge University Press, 1977 128 pp., $4.95 Reviewed by Emanuel D. Rudolph

Piltz, Albert, and Robert Sund Creative Teaching of Science in the Elementary School, 2d ed. Boston: Allyn and Bacon, Inc., 1977 310 pp., $7.95 Reviewed by Herbert H. Grossman

Lucas, David J., Harold I. James, John Simpson A First Science Dictionary: College Edition New York: Crane, Russak &; Company, Inc., 1977 206 pp., $8.50 Reviewed by Lawrence P. Eblin

Gribben, John, ed. Climatic Change New York: Cambridge University Press, 1978 280 pp., $37.50 cloth, $11.95 paper Reviewed by Waring B. Hill

Caroe, G.M. William Henry Bragg 1862–1942: Man and Scientist New York: Cambridge University Press, 1978 212 pp., $16.95 Reviewed by Gilbert Wright

Rowe, Mary Budd Teaching Science as Continuous Inquiry: A Basic New York: McGraw-Hill Book Co., 1978 509 pp., $16.00 Reviewed by Elmer F. Kohlmiller

Branley, Franklyn M. Color: From Rainbows to Lasers New York: Thomas Y. Crowell Co., 1978 87 pp., $8.95 Reviewed by Van E. Neie

McNutt, Kristen W., and David R. McNutt Nutrition and Food Choices Chicago: Science Research Associates, Inc., 1978 506 pp., $10.36 Reviewed by Manfred Kroger

Allen, Arthur James A Whaler and Trader in the Arctic: 1895–1944 Anchorage: Alaska Northwest Publishing Company, 1978 213 pp., $5.95 paper Reviewed by Vagn Flyger

Coleman, William Biology in the Nineteenth Century: Problems of Form, Function, and Transformation, rev. ed. New York: Cambridge University Press, 1978 187 pp., $13.95 cloth, $5.95 paper Reviewed by Donald J. Zinn