Mineral nutrition, soil factors and growth rates of Gmelina arborea plantations in the humid lowlands of northern Costa Rica

The purpose of this study was to determine the factors which are responsible for clearly visible growth irregularities in Gmelina arborea stands by relating growth rates to soil and site properties. All Gmelina plantations under study, established on degraded pasture soils in the Atlantic lowlands of Costa Rica, showed the same growth pattern: very poor growth and chlorotic foliage of trees in mid-slope positions, and fast growth and healthy leaves of trees on hilltops and hillbases. The variation in site and soil properties and tree growth rates was analysed, investigating 24 plots in eight different plantations. Leaf samples were taken from 120 trees (five trees per site). Foliar analysis revealed that the tree growth is highly dependent on the supply of N, P, K and S, indicating that poorly growing trees suffer from a multiple nutrient disorder. To identify the most restricting soil factor, simple correlations between growth rates and soil chemical and physical properties were applied to the entire data set. The best correlation was obtained with exchangeable soil K (r=0.78, P<0.001). Subdivision of the data set into plots on brown soils (eight) and plots on red soils (16) and subsequent correlation analysis resulted in much stronger relationships. Growth depressions in mid-slope positions had other causes on brown soils than on red soils. On the acid brown soils the combination of the variables Al saturation and bulk density could explain 82% of the variation of tree growth. Al saturation of up to 80% in brown soils inhibits nutrient uptake, particularly of N and P. The red soils dominate on Ca---Mg-enriched, alluvial terraces and were among the first soils to be cultivated in the region. During the agricultural use and at the establishment of the tree plantations, they received dolomitic lime to reduce Al toxicity. Here, very low K/Mg ratios (less than 0.03) may induce K deficiency. Therefore, the best multiple regression model for tree growth rates on red soils is obtained with K/Mg ratio and thickness of the humic A-layer (r²=0.75, P<0.001). Inclusion of the variable bulk density resulted in a clear improvement of the model, explaining 91% of the growth variability.     

Influence of plantation site and wastewater sludge fertilization on the performance and foliar nutrient status of two willow species grown under SRIC in southern Quebec (Canada)

Salix discolor Mühl. (Sd) and Salix viminalis L. (Sv) were planted under short-rotation intensive culture (SRIC) on three unirrigated abandoned farmland sites with different drainage conditions, one well-drained (S₁) and the other two poorly-drained (S₂, S₃). One dose of dried and granulated sludge equivalent to 150 (T₁) kg of “available” N ha⁻¹ was applied to some plots in the spring of the second season while others were left unfertilized (T₀). The aims of the experiment were (i) to investigate plant response (growth and productivity) to plantation site conditions and sludge application; (ii) study nutrient status by foliar analysis. Over three seasons, growth in height and aboveground biomass were greater for S. viminalis than for S. discolor on all sites. S. viminalis planted on poorly-drained site 2 had the highest biomass yield (45.28 t ha⁻¹). Both species showed best height and diameter growth on poorly-drained sites. For both species, best performances were obtained on wastewater sludge fertilized plots. Comparative foliar analysis suggested that unfertilized sandy soil (S₁) and low foliar nitrogen concentration and content were limiting factors in the performance of the two species. Soil nitrate concentration increased as a result of sludge application. Heavy metal accumulation from sludge does not represent a risk to the environment. It was concluded that S. viminalis had the best productivity on clay sites, and that a moderate dose of dried and pelleted sludge (150 kg of “available” N ha⁻¹) may be a good fertilizer during the establishment of willows in SRIC, and may reduce nitrate leaching.     

Growth and mineral nutrient analysis of teak (<Emphasis Type="Italic">Tectona grandis</Emphasis>) grown on acidic soils in south China

Teak (Tectona grandis L.f.) is widely planted in the world due to its high market demand, economic, ecological and social value. Its plantations have mostly been established and expanded into sites that are acidic to severely acidic in southern China. But, there are no available and specific evidence-based nutrient management techniques. To better recognize and understand the relationship between teak tree growth and nutrient content in the foliage and soil and establish nutrient norms are critical to optimally manage these young plantations. We studied the foliar nutrient and soil chemistry in 19 representative teak plantations aged 5–8 years. Regression analysis indicated that the mean annual increment of teak volume was linearly and positively correlated with foliar N, Ca, Fe and B concentrations, with soil base saturation percentage, available P and Zn concentrations, and negatively correlated with soil Al concentration. Only if the Ca and Mg contents in soil were enhanced, could the increase in soil base saturation percentage benefit teak growth. A revised classification of low-and high-yielding stands was established by using a sorting method of principal components over 6 foliar macro and 8 micro elements in a Diagnosis and Recommendation Integrated System (DRIS). Specific DRIS norms for teak plantations in acid soils were derived. The nutrient balance of N, P, K Ca, Mg, Zn, B with Fe or Al, Ca with Mg, and Fe with Al provided a key to promote the growth of teak in acid soils. Meanwhile, soil Zn was also found as a primary trace element that affected teak growth in this study.     

Floristic regeneration in five types of teak plantations in Thailand

Teak is the most important timber species in northern Thailand, and as such, large areas of teak forest have been disturbed or become highly degraded. Teak plantations have been established on this highly degraded land, where the rate of natural recovery is relatively slow. At the study site, five mixed or pure teak plantation types have been established to ameliorate limiting soil properties in order that long-term productivity is maintained. Observations within these plantations in northern Thailand have suggested that native species become established naturally under the shade of a “nurse” plantation, one that shades out early successional species. The objective of this study was to investigate the influence of the number of species in nurse plantations on the diversity and number of seedlings representative of mature native forests that become established within the plantations. Five types of plantations were investigated: (1) Tectona grandis L.f. (T); (2) T.grandis and Tamarindus indica L. (TT); (3) T.grandis and Gmelina arborea Roxb. (TG); (4) T.grandis, T. indica and G. arborea (TTG); (5) T.grandis, T.indica and Anacardium occidentale L. (TTA). These plantations were established primarily for the production of T.grandis (teak), with the other species introduced as economic trees. The plantations were surrounded by native stands of species representative of late successional and mature teak forests. In each of the plantations studies measurements were made on species density, species diversity, and evenness of plants regenerating in the understorey. Results showed that plantations consisting of several species in the overstorey had a higher diversity of native forest species in the understorey than the single-species plantation. Mixed plantation types were also found to reduce the density of the grass Imperata cylindrica (L.) P. Beauv. Consideration of the establishment of woody species found that TG and TTA had high densities of trees and shrubs. This suggested that if the goal of management was to regenerate forest with a high diversity of tree species similar to that found in native mature forests, multiple-species plantations, especially TG and TTA, would be more effective nurse communities than the single-species plantation in providing an environment into which seeds of native species could disperse and germinate. In addition, several climax species, such as Xylia xylocarpa (Roxb.) Taub. var. kerrii (Craib & Hutch) I.C. Nielsen, Pterocarpus macrocarpus Kurz, Largerstroemia sp., Afzelia xylocarpa (Kurz) Craib, Lannea coromandelica (Houtt) Merr., Spondias pinnata (L.f.) Kurz, Garuya pinnata Roxb., Terminalia mucronata Craib & Hutchison, Diospyoros mollis Griff., Irvingia malayana Oliv. ex Benn., Milletia leucantha Kurz, Dalbergia oliviri Gamble ex Prain, Chukrasia tabularis A. Juss and Schleichera oleosa (Lour.) Oken, were found in the early stages of succession, thus indicating that some may be suitable for planting in future restoration processes in order to accelerate natural succession and provide economic returns to managers.     

Relationships between soil and foliar nutrients in young densely planted mini-plots of Pinus radiata and Cupressus lusitanica

The long-term nature of forest crop rotations makes it difficult to determine impacts of forestry on soil nutrients that might be depleted by forest growth. We used small scale, highly stocked plots to compress the length of the rotation and rapidly induce nutrient depletion. In the study, two species (Pinus radiata D. Don and Cupressus lusitanica Miller) are compared under two disturbance regimes (soil undisturbed and compacted), and two fertiliser treatments (nil and plus fertiliser), applied in factorial combination at 33 sites, covering the range of climatic and edaphic variation found in plantation forests across New Zealand. To assess our ability to rapidly highlight important soil properties, foliar nutrient concentrations were determined 20 months after planting. It was hypothesised that the densely planted plots, even at a young age, would create sufficient pressure on nutrient resources to allow development of relationships between properties used as indicies of soil nutrient availability and foliar nutrient concentrations. For both species significant relationships between foliar nutrients and 0–10 cm layer soil properties from unfertilised plots were evident for N (total and mineralisable N) and P (total, acid extractable, organic, Bray-2 and Olsen P). With the exception of Ca in C. lusitanica, foliar K, Ca and Mg were correlated with their respective soil exchangeable cation measures. The results thus confirm the utility of the experimental approach and the relevance of the measured soil properties for forest productivity.

In unfertilised plots foliar N and P concentrations in P. radiata exceeded those in C. lusitanica, the differences being eliminated by fertiliser application. Foliar N/P ratios in P. radiata also exceeded those in C. lusitanica. In contrast to N and P, foliar K, Ca and Mg concentrations were all higher in C. lusitanica, the difference being particularly marked for Ca and Mg. P. radiata contained substantially higher concentrations of the metals Zn, Mn and Al than C. lusitanica, whereas the latter contained higher B concentrations. Possible reasons for differences between species in foliar nutrient concentrations are discussed.     

不同立地条件对淡竹出笋及生长的影响

淡竹(Phyllostachys glauca)是山东地区的主要栽培竹种。文章以日照海滨国家森林公园、泰安大津口和泰安罗汉崖3种不同立地条件的淡竹林为研究对象，对影响其生长的主要因子进行调查分析。结果表明：3种立地条件的淡竹林中，以日照国家森林公园的淡竹生长表现最优，其次为泰安大津口的淡竹林，泰安罗汉崖的淡竹林生长表现最差。对不同水分条件下的淡竹林研究发现，土壤含水率小于7%时，淡竹叶绿素含量大幅下降，土壤含水率在13%左右时，最适宜淡竹发笋。土壤水分是影响淡竹出笋、退笋以及成竹生长的主要影响因子，也是影响淡竹产量的重要立地因子。     

Water/nutrient interactions affecting the productivity of stands of Pinus radiata

The accumulation of above-ground biomass and the seasonal patterns of leaf-area development, foliar nutrient concentrations and tree and soil water-status have been measured for fertilised, irrigated, and control stands of Pinus radiata D. Don growing on a low-productivity site, average annual precipitation of 790 mm, near Canberra in southeastern Australia. In the second growing-season after treatments commenced, projected leaf-area index reached peak values of 7 on the irrigated/fertilised stands compared with approximately 5 on the other stands. Average canopy nitrogen concentration (dry-weight basis) varied across the treatments from 9 to 17 mg g⁻¹. Measurements of soil and tree water-status over a 2-year period indicated that stands which were not irrigated experienced summer droughts of up to 4 months duration.

Annual volume production measured over the 2-year period ranged from 17 to 45 m³ ha⁻¹. The extent to which this variation could be attributed to differences in leaf area, rats of photosynthesis, duration of the period of positive net photosynthesis, and hence growth, was analysed in terms of a process-based model of stand growth dependent on climate and soil water-balance.

Annual canopy net photosynthesis simulated by the model ranged from 18 t carbon ha⁻¹ for the control stand to 38 t ha⁻¹ for the irrigated/fertilised stands. Simulations indicated that 67% of this difference could be attributed to the role of irrigation in extending the period of active growth. The additional leaf area carried by the irrigated/fertilised stands contributed a further 23%, while differences in rates of photosynthesis, related to nitrogen nutrition, explained the remaining 10%.     

A basal area increment model for individual trees growing in even- and uneven-aged forest stands in Austria

Because of the gradual shift from pure even-aged forest management in central Europe, existing yield tables are becoming increasingly unreliable for forest management decisions. Individual tree-based stand growth modeling can make accurate stand growth predictions for the full range of conditions between pure even-aged and mixed-species uneven-aged stands. The central model in such a simulator is basal area increment for individual trees. Spatial information is not needed, and age and site index are intentionally not used to gain generality for all possible stand conditions. A basal area increment model is developed for all the main forest species in Austria: spruce (Picea abies), fir (Abies alba), larch (Larix decidua), Scots pine (Pinus sylvestris), black pine (Pinus nigra), stone pine (Pinus cembra), beech (Fagus silvatica), oak (Quercus robur, Quercus petraea and Quercus cerris), and for all other broadleaf species combined. The Austrian National Forest Inventory provided 5-year basal area increment from 44 761 remeasured trees growing on 5416 forested plots in the 1980s. This large sample is representative of forest conditions and forest management practices throughout Austria and therefore provides an excellent data base for the development of an increment model. The resulting increment model explained from 20 to 63% of the variation for all nine species and from 33 to 63% of the variation if the minor species Pinus cembra is excluded. These results compared quite closely with those of Wykoff for mixed conifer stands in the Northern Rocky Mountains. In the Austrian model, size variables (breast height diameter and crown length) accounted for 14–47% of the variation in basal area increment, depending on tree species. The best competition measure was the basal area of larger trees, which provides a tree-specific measure of competition without requiring spatial information; crown competition factor provided only minor improvement. Competition variables accounted for 9% of the variation on average, and up to 15% for some species. Topographic factors (elevation, slope, aspect) explained up to 3% of the variation, as did soil factors. Remaining site factors; such as vegetation type and growth district accounted for a maximum of 3% of the variation in increment. In total, site factors explained from 2 to 6% of the variation. Even though site factors account for a small percentage of the variation, they are not only significant, but serve to localize a particular prediction. These species-specific interrelationships between basal area increment and the various size, competition, and site varibles correspond quite well with ecological expectations and silvicultural understanding of these species in Austria. Because the sample base is so strong, the resulting growth models can be recommended not only for all of Austria but for surrounding regions with similar growth conditions.     

Effect of burning and brush treatments on nutrient and soil physical properties in young longleaf pine stands

Over a period of 16 years, unburned longleaf pine (Pinus palustris Mill.) pole stands grew an average of 27% more volume than similar stands regularly burned. Treatments included biennial burns in winter, spring, and summer plus an unburned check, each of which was combined with three supplemental treatments, namely, initial herbicide injection of all hardwoods, repeated handclearing of all woody stems, and no treatment. All unburned and winter-burned plots were paired to study this growth reduction relative to treatments. The status of nitrogen, phosphorus, available moisture holding capacity, bulk density, and macropore space was determined in both surface and subsurface soils. Foliage from pines on sampled plots was analyzed for N, P, K, Ca, Mg, Mn, Cu, Fe, and Zn. Burning did not significantly affect either soil N and P or foliar nutrients. However, burning reduced available moisture holding capacity and macropore space and increased the bulk density of surface soils, and also reduced the moisture-holding capacity of subsurface soils. The results from this and other studies suggest that growth losses are due, at least in part, to increased moisture stress associated with changes in soil physical properties.     

White spruce foliar nutrient concentrations in relation to tree growth and soil nutrient amounts

Concentrations of foliar N, P, S, K, Ca, and Mg were studied in relation to stand age, tree growth, site index, and soil nutrient amounts for natural white spruce stands on a wide range of site conditions in the sub-boreal spruce zone of British Columbia, Canada. While Ca was sufficient in every sampled stand, relatively widespread deficiency in N was diagnosed. Deficiencies of other nutrients were diagnosed only on wet to very wet sites. Foliar N, P and K were negatively correlated with stand age and positively correlated with height and diameter growth. White spruce site index was positively correlated with foliar nutrients, and their relationships were quantified using a quadratic function. Foliar nutrients, except Ca, are positively correlated with soil nutrients measured in routine chemical analysis, and their relationships were quantified using Mitscherlich's function. It is recommended that the existing standards need to be modified should they be applied to nutrient diagnosis in natural white spruce stands. These standards appear too high for N and too low for P, K, and Ca.     

章古台沙地不同树种年龄和树种的生态系统叶片和土壤养分研究

对辽宁省章古台地区的几种主要针叶树种的针叶养分及其林分表层(0-15cm)土壤养分进行研究。结果表明,不同年龄樟子松(45、29和20年)(Pinussylvestrisvar.mongolica)林地表层土壤养分并无显著差别,而29年樟子松林分表层土壤全N、全P和N:P比显著高于相近年龄的赤松(P.densiflora)(29年)和油松林(P.tabulaeformis)(31年)。随着樟子松年龄的增加,叶片P含量逐渐减少,而叶片N和K含量则未表现出随年龄而变化的趋势;对于年龄相近的三个树种,叶片N和P含量表现为:樟子松>赤松>油松,而叶片K含量在三个树种中并无显著差别。表层土壤的全N和全P,有机质和全P以及叶片N和P含量之间表现出了显著的相关性,但是,林分表层土壤养分和树木针叶养分之间并无显著相关关系,这可能与当地对凋落物的过度收集,过度放牧以及土壤水分含量低有关。最后,根据国外研究结果引入N:P比阈值来分析研究区域的N,P养分状况,基于章古台地区这几种针叶树种针叶N:P比,我们认为研究区域的樟子松随着年龄的增加受N限制的可能性降低,29年的赤松林整体表现出不受N和P养分限制,而31年的油松林则表现为系统N和P都供应不足。图3表3参45。     

Relationship between height growth of Scots pine (Pinus sylvestris L.) and site factors in Great Britain

The rate of height growth in Scots pine stands throughout Great Britain was examined in relation to site factors. The site factors included measures of geographical variation, topography, soil chemical and physical variables at two levels, several measures of soil phosphorus status, foliar monoterpenes and estimates of mean values of climatic variables. Principal component analysis was used to make an initial selection of regressor variables from 88 site factors for use in multiple regression equations. A dependent variable was obtained by removing the effect of age on height. The dependence of this expression on site variables was then examined using step-up multiple regression, starting with the selection of regressor variables made by the principal component analysis (P.C.A.), then adding transformations and interaction terms until 69% of variation was significantly accounted for over Great Britain, and up to 99% for parts of the country. Simpler equations using only those regressor variables which could be read from maps were also calculated.Variations in growth over Great Britain are associated mainly with solar radiation, soil texture and soil moisture content. For separate parts of the country the solar radiation term disappears from regression equations.     

Growth and nutrition of young European ash (<Emphasis Type="Italic">Fraxinus excelsior</Emphasis> L.) and sycamore maple (<Emphasis Type="Italic">Acer pseudoplatanus</Emphasis> L.) on sites with different nutrient and water statuses

This study aimed to improve knowledge about the nutritional status, site requirements and site classification for European ash (Fraxinus excelsior L.) and sycamore maple (Acer pseudoplatanus L.) by reinvestigating young plantations from 1991/1992 on windfall-affected areas in Bavaria/Germany after another decade. Compared to the first survey in 1995, most stands improved their nutritional status until 2006. With the data set of element concentrations in leaves of ash and sycamore available, the range of adequate nutrition could be determined for these species in the pole stage phase. Both species show considerable height growth on a wide range of sites. Mean annual height growth of dominant sycamore trees increased with rising foliar N or P concentrations but not for Ca, Mg, K, Mn, Fe and Al. For ash, there was no relationship between the foliar nutrient level of any element and mean annual height growth. However, total height around age 20 was favourably influenced by high base saturation and a good water supply at well-drained sites. On acid soils, where nutrients are delivered by subsurface water flow, well-growing stands are found as well. Soil water status according to the state forest soil classification had no significant impact on mean annual height growth. Ash and sycamore show reduced productivity on some (moderately) dry soils and fail on poorly drained moist sites. Based on these results, the classification of forest sites suitable for ash and sycamore within the Bavarian study sites was revised. Dedicated to Professor Dr. Karl-Eugen Rehfuess on his 75th birthday.     

Replacement of wildfire by whole-tree harvesting in jack pine forests: Effects on soil fertility and tree nutrition

Large areas of northern coniferous forests once naturally maintained by stand-replacing wildfires have shifted to an anthropogenic disturbance regime of clearcut harvesting followed by natural or artificial regeneration, with unknown consequences for soil biogeochemical processes. We used a comparative approach to investigate the effects of whole-tree harvesting (WTH) vs. stand-replacing wildfire (WF) on soil C and nutrient availability, and nutrition and growth of the succeeding stand, in jack pine (Pinus banksiana) forests of northern Lower Michigan. We compared total carbon (C), total nitrogen (N), potential N mineralization, and extractable phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) among stands regenerated via WTH or WF in two age classes (4–7 years and 12–18 years). We also measured jack pine foliar nutrition and height growth in these same stands, as well as estimating the contribution of legacy dead wood to ecosystem nutrient capital in young stands. We found some evidence in support of our hypothesis that WTH would leave behind greater pools of soil C and N, but lower pools of P and base cations. However, the differences we observed were confined entirely to surface organic horizons, with the two disturbance regimes indistinguishable when viewed cumulatively to our maximum sampling depth of 30 cm. Estimates of nutrient pools in legacy wood inherited by young jack pine stands were also small in comparison to total soil pools (ranging from 1 to 9% depending on the element), suggesting that decomposition and nutrient release from this material is not likely to result in noticeable differences in soil fertility later in stand development. Similar levels of soil nutrients between WTH- and WF-origin stands were reflected in our measures of jack pine foliar nutrition and height growth, which were both unaffected by mode of stand origin. Results from this study suggest that soil nutrient levels following WTH fall within the natural range of variation produced by WF in these jack pine forests; however, comparison with a similar study on boreal jack pine suggests that latitudinal effects on O-horizon nutrient capital may influence the degree to which WTH matches the effects of WF on soil nutrient availability.     

Effects of silvicultural treatments and seasonal patterns on foliar nutrients in young post-fire Pinus halepensis forest stands

Tree growth and health status appear to be related to foliar nutrient contents. Foliar nutrient concentration might be the result of a complex interaction between soil nutrients and effective availability caused by climate, water and other site and treatment effects. This study examines foliar macronutrient (N, P, K, Ca, Mg) and organic C concentrations in Aleppo pine (Pinus halepensis) needles (between 5 and 18 months old), as well as time course variability (nine dates, from July 1999 to November 2001). Variability was assessed depending on quality site (two sites, Yeste and Calasparra; SE Spain) and seven silvicultural treatments including thinning, scrubbing, pruning and particular combinations of them. Foliar macronutrient concentrations for Aleppo pine in South-eastern Spain were slightly lower (N, P, K,) or higher (Mg, Ca) than the considered as adequate ranges for Aleppo pine and Pinus genera. However, our results agree well with other normal ranges reported for Aleppo pine in Spain and for other North American Pinus species such as P. elliottii, P. taeda and P. palustris. Site, treatment and date (season) affected significantly the foliar macronutrient and C concentration, although the most important was the date, likely due to the two growth periods per year that Aleppo pine has in Mediterranean sites. Silvicultural treatments affected foliar nutrient concentration, so that the concentrations of N, P and K were higher when treatments included thinning than those that did not. The contrary was true for Mg and Ca. However, treatments did not affect the time course of the concentration, i.e., seasonality was not broken due to treatments. Moreover, the effect of the treatments was markedly high along the first year after they were applied but the differences were attenuate 2 years later. Site affected the time course of N, K, Mg and C in a different way: while for N, K and C, at the end of study period, they were higher in Calasparra than in Yeste, for Mg the contrary was true. Nutrient ratios had a different behaviour regarding to single nutrient: although date was significant, we did not appreciate seasonality. In addition, some nutrient ratios were not affected by treatments (N/P, N/K, Ca/Mg,) or by site (N/Ca, K/Ca). Average foliar N concentration and Ca/Mg ratio explained significantly the mean diameter and height growth, so that higher is the foliar N concentration and lower is Ca/Mg, higher is the growth.     

Genetic variation in foliar nutrient concentration in relation to foliar carbon isotope composition and tree growth with clones of the F1 hybrid between slash pine and Caribbean pine

The objectives of this study were: (1) to quantify the genetic variation in foliar nutrient concentration in relation to foliar carbon isotope composition (δ¹³C) and tree growth of 122 clones of ca. 4-year-old F₁ hybrids between slash pine (Pinus elliottii Engelm var. elliottii) and Caribbean pine (P. caribaea var. hondurensis Barr. et Golf.) grown at two experimental sites with different water and nutrient availability in southeast Queensland, Australia and (2) to examine the potential of using foliar nutrient concentration of the 4-year-old tree canopies for selecting elite F₁ hybrid pine clones with improved nutrient-use efficiency (NUE) and water-use efficiency (WUE), and ultimately enhanced tree growth under ambient growing conditions. There were significant differences in foliar nutrient concentrations between two canopy positions (upper outer and lower outer canopy) sampled, between summer and winter, and between the two sites. This highlights that foliar nutrient concentrations are influenced by sampling and environment. Significant genetic variations in foliar nutrient concentrations were detected between the clones, between the female parents, and between the male parents of the clones in both sampling seasons at both sites. Depending on the nutrient concerned, canopy position, season, and site sampled, the clones accounted for 4.7–33.9% of the total variation in foliar nutrient concentrations, the clone female parents for 0–25.1% and the clone male parents for 0–28.6%. The site-by-clone interactions were statistically significant for foliar N, P, Mg, Cu, Zn, Mn, Fe and mineral concentrations at the upper outer canopy in summer, and for foliar N concentration in winter. There were significant, positive correlations between clone means of foliar δ¹³C and N concentration at the upper outer canopy in summer for the wet site, while clone foliar δ¹³C was also positively related to clone foliar N concentration at both canopy positions in summer for the dry site. This suggests that clone WUE as reflected in foliar δ¹³C may be improved by selecting elite clones with higher foliar N concentration and increased photosynthesis, leading to enhanced tree growth when both water and N are the major growth-limiting factors. This is supported by the positive correlation detected between clone tree height and foliar N concentration at the upper outer canopy for both sites. Thus, foliar nutrient (particularly N) concentration, together with foliar δ¹³C, may be useful for assisting in selection of exotic pine clones with improved NUE and WUE, and enhanced tree growth under the nutrient- and water-limiting environments.     

Boron nutrition of Pinus radiata in relation to soil development and management

Nutritional surveys in New South Wales Pinus radiata plantations have shown differences in both foliage and soil boron status, particularly as a result of variations in soil parent materials. Plantations on acid igneous parent materials are particularly susceptible to the development of B deficiency, which appears to be further exacerbated bu soil/landscape relationships, water stress and certain management practices.

Boron deficiency in P. radiata on acid igneous soils at Sunny Corner State Forest, N.S.W., was particularly noticeable on lower slopes which usually have relatively high available moisture. These lower-slope soils had severely leached surface horizons, less extractable B, and fewer B-sorption characteristics than the upper sections of the soil catena. These soil properties also adversely affect the capacity of these soils to retain either Na-borate or Ca-borate fertilizers (borax and colemanite, respectively). For equal amounts of B, up to 95% of the borax applied to in-situ soil columns rapidly moved beyond the top 0.3 m of the soil profiles within 21 months, while less than 16% of the colemanite had moved beyond the columns. Leached surface soils of the lower-slope site retained lesser amounts of either B-fertilizer.

Colemanite offers the most cost-effective means of maintaining adequate levels of soil-B in these soil types due to its lower solubility. Management of B deficiency in P. radiata involves appropriate site selection, forest management practices and fertilizers usage.     

Relating growth and nutrition to site factors in young chestnut plantations established on agricultural and forest land in northern Spain

The growth and nutritional status of 97 hybrid chestnut plantations on former agricultural land and forest land were studied in relation to site conditions (climatic variables and soil properties). A single family of curves was obtained for classifying the early height growth of hybrid and sweet chestnut. Soil limitations and nutrient deficiencies were evident in the former forest land, whereas the agricultural soils were found to be generally suitable for growing chestnut. The stands with highest growth rates were characterized by high foliar concentrations of K, P and Ca. Successful growth of the plantations was always related to high summer precipitation, low elevation and absence of long periods of risk of frost. The results confirm the adaptability of chestnut to most sites where it has been planted for timber production.     

Sugar maple (Acer saccharum Marsh.) decline during 1979–1989 in northern Pennsylvania

Sugar maple decline has been observed in northern Pennsylvania since the early 1980s. We investigated the interactions between soil moisture stresses in sugar maple and other factors, such as soil chemistry, insect defoliation, geology, aspect, slope, topography, and atmospheric deposition. In the summer of 1998, we sampled 28 sugar maple (Acer saccharum Marsh.) plots drawn from the USFS Forest Inventory and Analysis (FIA) plots, containing declining and non-declining sugar maple trees across northern Pennsylvania for a variety of soil physical and chemical parameters, site characteristics, and tree health. Foliage from declining plots was found to have significantly lower base cations and higher Mn as compared to that from non-declining plots. Soils in declining plots had lower base cations and pH, a Ca:Al⁻≤1, lower percent clay and higher percent sand and rock fragments than soils on non-declining plots, suggesting that trees on declining plots are at risk of nutritional and drought stress. Regression relationships between foliar and soil chemistry indicated that foliar nutrition was highly correlated with soil chemistry in the upper 50 cm of the soil. Declining sugar maple plots in this study occurred at higher elevations on sandstone dominated geologies. Soils were found to be base poor-sandy soils that contained high percentages of rock fragments. Soils below 50 cm on declining plots had lower soil pH and foliar chemistry indicated lower foliar base cations. A trend, while not significant was found with declining plots experiencing a greater number of and more severe insect defoliations.     

Sphaeropsis shoot blight and altered nutrition in red pine plantations treated with paper mill waste sludge

During 1993 progressive, severe shoot blight and canker disease in crowns of mature, merchantable red pines (Pinus resinosa) in central Wisconsin was noted in plantations in which paper mill waste sludge previously had been applied. For eight treated plantations and six non‐treated plantations, incidence of shoot blight attributed to the pathogenic fungus Sphaeropsis sapinea (syn. Diplodia pinea) was quantified during 1993 or 1994. Foliage and soil samples also were collected for analyses. Sphaeropsis shoot blight was more frequent in treated plantations than in the non‐treated stands (means of 81% of trees and 10.2% of shoots compared with 7% of trees and 0.1% of shoots, respectively). Consistent with other reports of damage caused by some diseases of conifers in situations of altered host nutrition, mean foliar N concentrations were higher in treated plantations (1.61%) than non‐treated plantations (1.31%) (p < 0.001). Mean foliar Zn, Mn, Cu, and Al concentrations were lower in treated plantations than non‐treated plantations, and mean soil P, Ca, and Mg concentrations were higher in treated plantations than non‐treated plantations.