Forest Nutrition Research Articles

Pengaruh Aplikasi Solid Decanter dan Biochar terhadap Kadar Hara dalam Air Lindi Tanah Pascatambang Batu Bara

Open pit coal mining activities affect the decline in soil quality characterized by damage of soil structure, loss of nutrients and decreased biodiversity. Organic matter is one of the soil reformers that has been felt its benefits in improving soil properties both physical, chemical, and bi ological properties. This study aims to determine the effect of solid and biochar administration on post coal mining soil on water storage capacity and giraffe power on nutrients in percolation water administration. This research was carried out at the Laboratory of Soil Science and Forest Nutrition, Mulawarman Samarinda University, East Kalimantan following the rules of Factorial Complete Random Design with two factors, namely solid percentage and biochar with percolation water treatment during the one month incubation period. The results showed the application of S2B2 (solid 20% + biochar 25%) was able to have an influence on water giraffe power with a three day incubation period end value of 92.2 ml, fifteen days of 89.3 ml and thirty days of 85.6 ml. The application of biochar 5% and 25% in post coal mine soils of fifteen days and thirty days incubation period shows the ability to absorb calcium nutrient levels in leachate water. The combined application of S2B2 (solid 20% + biochar 25%) showed a good ability to absorb calcium and magnesium nutrient levels in leachate water that decreased during the incubation period.

Soil phosphorus status and P nutrition strategies of European beech forests on carbonate compared to silicate parent material

Sustainable forest management requires understanding of ecosystem phosphorus (P) cycling. Lang et al. (2017) [Biogeochemistry,https://doi.org/10.1007/s10533-017-0375-0] introduced the concept of P-acquiring vs. P-recycling nutrition strategies for European beech (Fagus sylvatica L.) forests on silicate parent material, and demonstrated a change from P-acquiring to P-recycling nutrition from P-rich to P-poor sites. The present study extends this silicate rock-based assessment to forest sites with soils formed from carbonate bedrock. For all sites, it presents a large set of general soil and bedrock chemistry data. It thoroughly describes the soil P status and generates a comprehensive concept on forest ecosystem P nutrition covering the majority of Central European forest soils. For this purpose, an Ecosystem P Nutrition Index (ENIP) was developed, which enabled the comparison of forest P nutrition strategies at the carbonate sites in our study among each other and also with those of the silicate sites investigated by Lang et al. (2017). The P status of forest soils on carbonate substrates was characterized by low soil P stocks and a large fraction of organic Ca-bound P (probably largely Ca phytate) during early stages of pedogenesis. Soil P stocks, particularly those in the mineral soil and of inorganic P forms, including Al- and Fe-bound P, became more abundant with progressing pedogenesis and accumulation of carbonate rock dissolution residue. Phosphorus-rich impure, silicate-enriched carbonate bedrock promoted the accumulation of dissolution residue and supported larger soil P stocks, mainly bound to Fe and Al minerals. In carbonate-derived soils, only low P amounts were bioavailable during early stages of pedogenesis, and, similar to P-poor silicate sites, P nutrition of beech forests depended on tight (re)cycling of P bound in forest floor soil organic matter (SOM). In contrast to P-poor silicate sites, where the ecosystem P nutrition strategy is direct biotic recycling of SOM-bound organic P, recycling during early stages of pedogenesis on carbonate substrates also involves the dissolution of stable Ca-Porg precipitates formed from phosphate released during SOM decomposition. In contrast to silicate sites, progressing pedogenesis and accumulation of P-enriched carbonate bedrock dissolution residue at the carbonate sites promote again P-acquiring mechanisms for ecosystem P nutrition.

Effects of fertilization on the growth dominance of Inland Northwest forests of the United States

Large trees have disproportionally large competitive advantage in access to light, which has been proposed to increase growth dominance of large trees (e.g., a larger proportion of volume growth than standing volume is in large trees in a stand). Tree growth may also be limited by the availability of other resources besides light. Nutrient deficiency, especially of nitrogen, is considered common among temperate forests including mixed-conifer forests of the Inland Northwest of the United States. Data from a long-term forest nutrition study across four Inland Northwest states were analyzed to evaluate nitrogen ​× ​potassium fertilization's effects on growth dominance over an eight-year period following treatment. Our results show that growth dominance varied substantially across plots in each vegetation series and fertilization treatment, and its mean values generally were at minuscule magnitudes, negative, and not significantly different from 0. We propose that this lack of a clear pattern in growth dominance was the result of the mixed-species composition where shade-tolerant species remained in lower crown positions, yet their relative growth kept pace with large trees. Limited moisture availability at dry sites may have hampered the development of growth dominance. Growth dominance also was lowered by mortality observed among relatively large trees. The largely negative growth dominance across fertilization treatments indicated that small trees seem to have maintained higher relative growth rates than large trees, even if absolute growth was higher among large trees. In the case fertilization does improve stand growth, a significant part of this improved growth will be lost in density-dependent mortality over time if not captured through thinning/harvesting.

Using regional forest nutrition data to inform urban tree management in the northeastern United States

Managing tree health in urban environments is complicated due to the disconnect that exists between novel environmental conditions created by urbanization and those under which tree species evolved. Soils influence tree health and growth, but optimal nutrient and pH recommendations are often informed by agricultural and horticultural norms which do not typically include norms for forest tree species. At the Arnold Arboretum in Boston, Massachusetts, USA, we investigated the relationships between tree health, foliar chemistry, and soil chemistry for three native forest tree species (Acer saccharum, Quercus alba, and Tsuga canadensis) located throughout the arboretum. We compared these ranges and relationships to data collected from trees of the same species growing in forested areas throughout the northeastern United States. For all species, the distributions of most foliar nutrient concentrations were similar in the arboretum and across the region. However, foliar potassium (K) concentrations were lower at the arboretum than in reference datasets. Soil pH was higher at the arboretum than most forest soils in the region, potentially a result of liming and irrigation with city water. Concentrations of soil and foliar magnesium were also high at the arboretum. Potassium deficiency could result from the blocking of K uptake by magnesium or limited K availability due to forest floor loss. In addition, there is some evidence that manganese is at low to deficient levels. These results show the value of comparing chemical conditions between urban tree populations with trees in natural forests in nearby rural settings to identify potential areas of concern and inform soil management strategies.

Impact of Climate Change on Soil Hydro-Climatic Conditions and Base Cations Weathering Rates in Forested Watersheds in Eastern Canada

Increases in mean annual air temperature (MAAT) and mean annual precipitation (MAP) are projected for north eastern North America, which will alter soil hydro-climatic conditions and hence the rate of many soil processes. Among them, chemical weathering of soil minerals is an essential source of base cations (BC) which control the acid-base status of surface waters and are crucial for forest nutrition. In this modeling study, MAAT and MAP projections from a regional and a global climate models were first used to project changes in soil temperature (MAST) and soil water content (SWC) with the ForStem and ForHym models for 21 eastern Canadian forested catchments. The models predicted an increase in MAST by 2.03-2.05°C and 2.87-3.42°C for the 2041-2070 and 2071-2100 periods, respectively, and small decreases (<5%) in SWC. In a second step, these projected changes in MAST and SWC were used to estimate changes in BC weathering rates (WR) and soil pH with the geochemical model PROFILE. The simulations indicated that BC WR would increase by 13-15% and 20-22% for the 2041-2070 and 2071-2100 periods, respectively. The increase in BC WR was accompanied by an increase not only in base cation concentrations, but also in soil pH at most sites, suggesting that future temperature increase has the potential to ameliorate the acid-base status and the fertility of soils in eastern Canada through its impact on WR.

Natural Recovery and Liming Effects in Acidified Forest Soils in SW-Germany

In the state of Baden-Wuerttemberg, Southwest-Germany, a large-scale forest liming trial was government-funded in 1983 and a lime treatment was carried out in autumn 1983 until early winter 1984. Repeated liming was applied in 2003. The limed sites and adjacent control plots were surveyed repeatedly: in 2003 before the second lime application and again in 2010 and 2015. Research of this scope presents a rare opportunity to evaluate firstly the long-term development of acidified soils with their potential for natural recovery on established control plots, and secondly the long-term effects of repeated lime application—at a collective of study sites of various growth regions and soil properties. A natural recovery in soil pH was observed since 2003, on average limited to an increase of 0.2–0.4 pH units in the forest floor and 0.1–0.3 pH units in the mineral soil until 2015. The majority of the organic layers still show very strong or extreme acidity with a pH value 3.9 on average and in the mineral soil with pH values between 3.8 and 4.6 on average. The exchangeable cations calcium and magnesium slightly increased also, although the base saturation remained &lt;20% by 2015. The exchangeable acid cation concentrations indicated no significant changes and thus no recovery. The lime treatment greatly accelerated the rise in pH by 1.2–1.3 units and base saturation by 40–70% in the organic layer, as well as 0.3–1.2 pH units and base saturation by 7–50% in mineral soil. These effects were decreasing (yet still significant) with depth in the measured soil profile as well as with time since last treatment. Changes in soil cation exchange capacity after liming were significant in 0–5 cm mineral soil, below that they were negligible as the significant increase in base cations were accompanied by decreasing acid cations aluminum and iron (III) especially in the upper soil profile. Additionally, a decrease of forest floor and an enrichment of organic carbon and nitrogen in the mineral topsoil tended to follow liming at some sites. Overall the liming effects had a high variability among the study sites, and were more pronounced in the more acidic and coarser textured sites. Liming of acidified forest soils significantly adds to natural recovery and therefore helps to establish greater buffering capacities and stabilize forest nutrition for the future.

Divergent Patterns of Carbon, Nitrogen, and Phosphorus Mobilization in Forest Soils

Carbon (C), nitrogen (N), and phosphorus (P) become released in inorganic or organic forms during decomposition of soil organic matter (SOM), often at varying rates. Our study aimed at identifying the individual patterns and controls of C, N, and P mobilization in soils under beech forests. We exposed organic and mineral horizons sampled along a nutrient availability gradient in Germany to either permanent moist conditions or to dry spells in microcosms and quantified the release of inorganic and organic C, N, and P. In the moist control treatment, releases of DOC, DON and DOP were interrelated and depended on the C:N:P ratio of SOM, whilst net mineralization rates of C, N and P were poorly correlated. Mineralization of C decreased with soil depth from Oi to A horizons, reflecting the increasing SOM stability. Net mineralization of N and P showed divergent depth patterns. In the Oi horizon, microbial immobilization was more pronounced for N than for P. In A horizons, net mineralization of P was less than of N, very likely because of strong sorption of released phosphate by mineral phases. Counterintuitively, net P mineralization in A horizons increased towards P-poor sites, probably due to decreasing contents of clay and pedogenic oxides, and thus, declining P sorption. Drying and rewetting caused stronger mobilization of inorganic and organic P, and organic N than of inorganic C and inorganic N, most likely by lysis of microbial biomass with tight C:N:P ratios. Due to the divergent patterns in N and P cycling, the organic layer is more important for the mineralization of P than the mineral soil; for N the mineral soil is most relevant. Consequently, the loss of the organic layer would deteriorate P nutrition, in particular at nutrient-poor sites. Overall, our results indicate that the cycling of C, N, and P is not directly coupled due to the different microbial processing and, in the mineral soil, differential sorption of N and P. This may ultimately cause imbalances in the N and P nutrition of forests.

Citric acid extraction—An underestimated method in forest nutrition?

AbstractSince recent studies reveal citric acid to be favorable for estimating plant‐available P in soils, we investigated if it can also be used for assessing other nutrients. According to our results, it provides stronger correlations with the tree nutrition for Mg (beech, spruce), Ca+K (beech) and Fe (spruce) than the standard methods for determining exchangeable cations. Thus, when estimating plant‐available P by citric acid‐extraction, these cations should be additionally measured in ICP analysis.

The changes of soil nutrient status after a 10y period in the Natural Forest Region Český les

The periodical survey of forest nutrition was done in the in the Natural Forest Region (NFR) of Český les – the mountain range on a state border between the Czech Republic and the Federal Republic of Germany. The results of chemical analysis done in 2015 were compared with those provided in 2004. The trend of mineral nutrition deteriorating of forest trees has been going on, except for magnesium. The content of magnesium in spruce needles was found to be higher by 56.6 mg·kg&lt;sup&gt;–1&lt;/sup&gt; in the current year’s needles and by 24.8 mg·kg&lt;sup&gt;–1&lt;/sup&gt; in the previous year´s ones. The contents of magnesium in soil determined in the extract of HNO&lt;sub&gt;3&lt;/sub&gt; were significantly higher. The increase is 389 mg·kg&lt;sup&gt;–1&lt;/sup&gt;, 373 mg·kg&lt;sup&gt;–1&lt;/sup&gt; and 312 mg·kg&lt;sup&gt;–1&lt;/sup&gt; in the forest floor, respectively in organomineral and mineral horizons. However, it is not valid for the available values determined by the Mehlich method. The determination of nutrient values in the extract of HNO&lt;sub&gt;3&lt;/sub&gt; seems to be suitable for the evaluation of changes occurred in soil and probably for the simulation of nutrition strategy of trees.

The effects of fertilization on the health status, nutrition and growth of Norway spruce forests with yellowing symptoms

ABSTRACTWe studied the effects of magnesium (Mg) NPK fertilizer applied in 2000 to maturing Norway spruce (Picea abies /L./ Karst.) stands with yellowing symptoms and situated on poor acidified soils in the Šumava mountains (the Czech Republic). Long-term defoliation, nutrient content in the foliage and diameter increment were evaluated in three specific variants: yellowing trees, trees without yellowing symptoms and fertilized trees. The results indicate differences in soil characteristics, nutrient content and radial growth with response to climate. Fertilization increased Mg content and base saturation in the soil and decreased the amount of exchangeable aluminum and hydrolytic acidity. Differences were significant especially in magnesium, calcium and phosphorus contents in the foliage of yellowing trees. There was also a significant difference in manganese content; yellowing trees showed deficiency in comparison with both fertilized and unfertilized healthy trees. Two years after the initial fertilization (to present), defoliation and yellowing symptoms in the unfertilized yellowing trees were more pronounced compared to other variants. These symptoms were more influenced by fertilization than foliation. The duration of significant positive effects of fertilization on diameter increment lasted for a shorter time than the effect on foliage. Simultaneously, higher sensitivity to climatic factors was observed in the fertilized trees.

English

The purpose of this work was to assess biometric parameters of cedar seedlings (Acrocarpus fraxinifolius) associated with visual symptomatology of macronutrients deficiency, growth rate, and content and accumulation of nutrients in aerial parts of seedlings grown in nutritive solution. The trial was established in completely randomized design with seven treatments, four replications, and one plant per pot. Treatments consisted of complete nutrient solution, Hoagland and Arnon, and deprivation of the following selected single nutrients: N, P, K, Ca, Mg and S. Micronutrients were provided to all treatments. The following biometric parameters were assessed 90 days after the transplant: shoot height, root collar diameter, root and shoot dry weight. The Dickson index and the ratio given by roots dry weight and shoot dry weight were obtained, as well as the content and accumulation of nutrients in aerial parts of seedlings. The Sisvar statistical analysis system was run for analysis of variance, and averages were compared by means of Scott-Knott test at 5% significance. Treatments consisting of omissions of macronutrients were found to be limiting factors of plants growth and obtaining of seedlings shoot dry weight in the following order: N &gt; P &gt; K &gt; Ca &gt; Mg &gt; S. Deficiencies of these macronutrients caused visible morphological abnormalities, where common symptoms of deficiency of N, P, K and Ca appeared before symptoms of deficiency of Mg and S. The content of nutrients found in aerial parts of seedlings of A. fraxinifolius grown in nutritive solution was greater for treatments consisting of deprivation of N, P and K. The content of nutrients found for treatments consisting of deprivation of Mg and S was not significantly different from that found for the complete nutrients solution. &nbsp; Key words: Nutritional requirements, forest nutrition, Indian cedar.

Nitrogen nutrition of beech forests in a changing climate: importance of plant-soil-microbe water, carbon, and nitrogen interactions

For 15+ years, a beech (Fagus sylvatica L.) dominated forest on calcareous soil was studied on two opposing slopes with contrasting microclimate in Tuttlingen, Swabian Alb, Germany. The cool-humid NE aspect of these slopes represents the majority of beech forests under current climate, the warmer and drier SW aspect represents beech forests under future climate conditions. The field studies were supplemented by investigations under controlled conditions. The research program aimed to provide a comprehensive understanding of plant-soil-microbe water, carbon and nitrogen feedbacks in a changing climate and a holistic view of the sensitivity of beech to climate change. The results of comparative and experimental studies underpin the high vulnerability of adult beech and its natural regeneration on calcareous soil to both direct climate change effects on plant physiology and indirect effects mediated by soil biogeochemical cycles. Mechanisms contributing to this vulnerability at the ecosystem and organismic level indicate a high significance of competitive interactions of beech with other vegetation components and soil microbial communities. Obvious forest management practices such as selective felling did not necessarily counteract negative effects of climate change.

MICRONUTRIENTS AND BIOMASS IN Eucalyptus dunnii Maiden STAND

ABSTRACT The expansion of silviculture in Brazil, and the consequent intensive practices for soil preparation with high demand for fertilizers require sustainable nutrient management of forest sites. The objective of this study was to quantify the biomass and the micronutrient stocks of a 60-month-old Eucalyptus dunnii stand established in Alegrete, Rio Grande do Sul. The stand was established in a Rhodic Paleudult soil with low fertility and texture varying between sandy loam and sandy-clay loam. For the sampling of stand biomass, twelve trees were harvested, sectioned at ground level, and subsequently fractionated into the components roots, leaves, branches, stembark and stemwood to determine the dry mass and micronutrient content. The total biomass of the stand was 67.49 Mg ha-1, with mass allocation in descending order from: stem wood &gt; root &gt; bark &gt; branches &gt; leaves. Total micronutrient stocks for boron (B), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) were 562.57, 401.46, 9913.28, 31877.82, and 766.96 g ha-1, respectively. In addition, we found greater accumulation of Zn in the wood, high Mn accumulation especially in the bark, and high Fe content in the roots. Therefore, based on these micronutrient levels and their allocation between biomass fractions, we emphasize that the practice of retaining forest residues on-site after harvest is essential for forest nutrition through nutrient cycling and for soil conservation and fertility.

On the combined effect of soil fertility and topography on tree growth in subtropical forest ecosystems—a study from SE China

Aims The aim of our research was to understand small-scale effects of topography and soil fertility on tree growth in a forest biodiversity and ecosystem functioning (BEF) experiment in subtropical SE China. Methods Geomorphometric terrain analyses were carried out at a spatial resolution of 5×5 m. Soil samples of different depth increments and data on tree height were collected from a total of 566 plots (667 m2 each). The soils were analyzed for carbon (soil organic carbon [SOC]), nitrogen, acidity, cation exchange capacity (CEC), exchangeable cations and base saturation as soil fertility attributes. All plots were classified into geomorphological units. Analyses of variance and linear regressions were applied to all terrain, soil fertility and tree growth attributes. Important Findings In general, young and shallow soils and relatively small differences in stable soil properties suggest that soil erosion has truncated the soils to a large extent over the whole area of the experiment. This explains the concurrently increasing CEC and SOC stocks downslope, in hollows and in valleys. However, colluvial, carbon-rich sediments are missing widely due to the convexity of the footslopes caused by uplift and removal of eroded sediments by adjacent waterways. The results showed that soil fertility is mainly influenced by topography. Monte–Carlo flow accumulation (MCCA), curvature, slope and aspect significantly affected soil fertility. Furthermore, soil fertility was affected by the different geomorphological positions on the experimental sites with ridge and spur positions showing lower exchangeable base cation contents, especially potassium (K), due to leaching. This geomorphological effect of soil fertility is most pronounced in the topsoil and decreases when considering the subsoil down to 50cm depth. Few soil fertility attributes affect tree height after 1–2 years of growth, among which C stocks proved to be most important while pHKCl and CEC only played minor roles. Nevertheless, soil acidity and a high proportion of Al on the exchange complex affected tree height even after only 1–2 years growth. Hence, our study showed that forest nutrition is coupled to a recycling of litter nutrients, and does not only depend on subsequent supply of nutrients from the mineral soil. Besides soil fertility, topography affected tree height. We found that especially MCCA as indicator of water availability affected tree growth at small-scale, as well as aspect. Overall, our synthesis on the interrelation between fertility, topography and tree growth in a subtropical forest ecosystem in SE China showed that topographic heterogeneity lead to ecological gradients across geomorphological positions. In this respect, small-scale soil–plant interactions in a young forest can serve as a driver for the future development of vegetation and biodiversity control on soil fertility. In addition, it shows that terrain attributes should be accounted for in ecological research.

The role of nutrients in drought-induced tree mortality and recovery.

Contents 513 I. 513 II. 514 III. 517 518 References 518 SUMMARY: Global forests are experiencing rising temperatures and more severe droughts, with consistently dire forecasts for negative future impacts. Current research on the physiological mechanisms underlying drought impacts is focused on the water- and carbon-associated mechanisms. The role of nutrients is notably missing from this research agenda. Here, we investigate what role, if any, forest nutrition plays for survival and recovery of forests during and after drought. High nutrient availability may play a detrimental role in drought survival due to preferential biomass allocation aboveground that (1) predispose plants to hydraulic constraints limiting photosynthesis and promoting hydraulic failure, (2) increases carbon costs during periods of carbon starvation, and (3) promote biotic attack due to low tissue carbon: nitrogen (C:N). When nutrient uptake occurs during drought, high nutrient availability can increase water use efficiency thus minimizing negative feedbacks between carbon and nutrient balance. Nutrients are released after drought ceases, which might promote faster recovery but the temporal dynamics of microbial immobilization and nutrient leaching have a significant impact on nutrient availability. We provide a framework for understanding nutrient impacts on drought survival that allows a more complete analysis of forest ecosystem responses.

Elemental Ratios in Foliage and Soil of a Jeffrey Pine Stand Subjected to Thinning and Burning Restoration Practices

Forest thinnings accomplished through cut-to-length and whole-tree harvesting followed by a prescribed underburn were assessed for their influences on mineral nutrition in eastern Sierran Jeffrey pine (Pinus jeffreyi Grev. & Balf.). As derived from foliar elemental concentrations determined at six samplings distributed over three growing seasons, molar Ca/Al, Mg/Al, K/Al, Ca/Mn, Mg/Mn, and K/Mn were generally higher in the unthinned treatment and lower in burned stand portions. Conducted under drought conditions, the driest phase of the study resulted in lower Ca/Al, Mg/Al, and K/Al and higher Ca/Mn and Ca/Zn when averaged across treatments. Foliar K/Mn, K/Zn, and K/Cu were generally lower in the early portion of the growing season compared to the late portion. At mid growing season, Mg/Al, K/Al, Mg/Mn, K/Mn, K/Fe, K/Zn, and K/Cu were higher in young needles while Ca/Al, Ca/Fe, Mg/Fe, Ca/Zn, Ca/Cu, and Mg/Cu were so in older ones. At mid study, soil Ca/Fe was higher in the unthinned treatment generally and especially in its unburned portion while K/Cu was higher overall in burned stand portions, most especially in the unthinned treatment. These findings provide insight into the interrelationships of base cations and metallic elements in forest nutrition as influenced by restoration practices.

Phosphorus in accumulated harvest residues on skid trails

Phosphorus is an essential yet scarce macronutrient, and as such forest nutrition often relies on cycling of P between biomass and soils through litterfall and roots. For technical and soil protection reasons, modern harvesting systems create thick brash mats on skid trails by depositing residues, thus concentrating P there. What portion of this redistributed P is immobilized, lost, or recycled could be significant to forest nutrition and management. However, open questions exist regarding the quantity and fate of P deposited on skid trials. The aim of this study was to determine how much P is redistributed to skid trails and what happens to that P. We modeled the amount of P deposited on a skid trail during a whole-tree thinning of an Abies alba Mill. stand, and quantified P stocks in the forest floor and mineral soil five years after the operation. An estimated 60% of harvested P from the encatchment was deposited on the skid trail. Five years after the harvest, forest floor P stocks in the skid trail dropped from an extrapolated 8.9 to 4.4 gm−2. The difference of 4.5gm−2 of P was not evident in mineral soil stocks, and loss through runoff or leaching would be minimal. With the greatest concentration of roots in the forest floor on the middle of the skid trail, mineralization and uptake of the missing P was the most likely explanation. This suggests that accumulated P on skid trails can be recycled through uptake by trees. Further testing in other stands and on which vegetation takes up accumulated P is still needed.

Ectomycorrhizal Communities on the Roots of Two Beech (Fagus sylvatica) Populations from Contrasting Climates Differ in Nitrogen Acquisition in a Common Environment.

Beech (Fagus sylvatica), a dominant forest species in Central Europe, competes for nitrogen with soil microbes and suffers from N limitation under dry conditions. We hypothesized that ectomycorrhizal communities and the free-living rhizosphere microbes from beech trees from sites with two contrasting climatic conditions exhibit differences in N acquisition that contribute to differences in host N uptake and are related to differences in host belowground carbon allocation. To test these hypotheses, young trees from the natural regeneration of two genetically similar populations, one from dryer conditions (located in an area with a southwest exposure [SW trees]) and the other from a cooler, moist climate (located in an area with a northeast exposure [NE trees]), were transplanted into a homogeneous substrate in the same environment and labeled with (13)CO2 and (15)NH4 (+). Free-living rhizosphere microbes were characterized by marker genes for the N cycle, but no differences between the rhizospheres of SW or NE trees were found. Lower (15)N enrichment was found in the ectomycorrhizal communities of the NE tree communities than the SW tree communities, whereas no significant differences in (15)N enrichment were observed for nonmycorrhizal root tips of SW and NE trees. Neither the ectomycorrhizal communities nor the nonmycorrhizal root tips originating from NE and SW trees showed differences in (13)C signatures. Because the level of (15)N accumulation in fine roots and the amount transferred to leaves were lower in NE trees than SW trees, our data support the suggestion that the ectomycorrhizal community influences N transfer to its host and demonstrate that the fungal community from the dry condition was more efficient in N acquisition when environmental constraints were relieved. These findings highlight the importance of adapted ectomycorrhizal communities for forest nutrition in a changing climate.

Short- and long-term nutritional effects and retention of potassium derived from fertilizer in a sugar maple stand in southern Quebec

The short-term (1–3 years) and long-term (23 years) effects of liming combined with potassium (K) fertilization on forest nutrition and K cycling were examined in a sugar maple (Acer saccharum Marsh.) stand in southern Quebec. Sugar maple leaves were sampled annually from 1988 (prefertilization year) to 1991 and in 2011–2012. Ten understory plant species, sugar maple sapwood, and soils were also sampled in 2012 and analyzed for K, calcium (Ca), magnesium (Mg), and rubidium (Rb). The recovery of fertilizer K was determined using the Rb/K reverse tracer method. Fertilization neither increased growth nor maintained higher sugar maple leaf K levels over the long term; however, leaf K to Ca and K to Mg ratios were still higher in fertilized plots than in control plots in 2012. The percentage of leaf K derived from fertilizer peaked 3 years after fertilization (36% ± 5%) and was down to 1989 levels by 2012 (15% ± 6%). Understory vegetation generally showed no differences in leaf K concentration between treatments, but percent K from fertilizers was greater than 25% in several species. There was no significant effect of fertilization on soil K, Ca, and Mg availability by 2012. Our results suggest that significant amounts of fertilizer K are still present on the site after 23 years but that base cation levels in leaves and upper soil horizons have returned to near prefertilization levels except for a slight enrichment in K. Although small, the effects of fertilization with liming on soil fertility and plant nutrient status in a maple stand can be long lasting.

ESTOQUES DE BIOMASSA E NUTRIENTES EM TRÊS ESPÉCIES DE Parkia EM PLANTIOS JOVENS SOBRE ÁREA DEGRADADA NA AMAZÔNIA CENTRAL

As estratégias de distribuição de biomassa e nutrientes utilizadas pelas espécies florestais podem refletir sua capacidade de sobrevivência em plantios sobre áreas degradadas. O objetivo deste estudo foi quantificar os estoques de biomassa e nutrientes nos compartimentos arbóreos de Parkia multijuga, Parkia nitida e Parkia pendula em plantios sobre área degradada em Manaus, AM. A biomassa foi determinada pelo método destrutivo em seis árvores de cada espécie, que foram compartimentadas em: folhas, galhos finos (Ø &lt;10 cm), galhos grossos (Ø ≥10 cm), fuste, raízes médias (2 mm ≤ Ø &lt;5 cm) e raízes grossas (Ø ≥5 cm). Aos quatro anos, Parkia multijuga exibiu 60% do total de biomassa nos compartimentos aéreos e 40% nos subterrâneos. Parkia nitida exibiu 84% nos compartimentos aéreos e apenas 16% nos subterrâneos. Parkia pendula exibiu 67% nos compartimentos aéreos e 33% nos subterrâneos. A ordem de acúmulo de macronutrientes nos compartimentos foi: N &gt; Ca &gt; K &gt; Mg &gt; P. O fato de Parkia multijuga adotar estratégias de alocação de biomassa e nutrientes que favorecerão seu desempenho sobre sítios com baixa disponibilidade de recursos sustenta sua indicação para a composição de programas de reflorestamento em áreas degradadas na Amazônia.Palavras-chave: Espécies florestais nativas; nutrição florestal; reflorestamento; restauração. AbstractBiomass and nutrients in three species of Parkia plantings on degraded area in Central Amazon. Biomass and nutrients partitioning strategies in tree species may reflect their ability to survive in plantations on degraded areas. The objective of this study was to investigate the content of biomass and nutrients in tree components of Parkia multijuga, Parkia nitida and Parkia pendula on plantings in degraded area in Manaus, AM. The biomass was determined by the harvest method in six trees of each species, which were subdivided into leaves, fine branches (Ø &lt; 10 cm), coarse branches (Ø ≥10 cm), stem wood, medium roots (≤ 2 mm Ø &lt; 5 cm ) and coarse roots (Ø ≥ 5 cm). At 4 years, Parkia multijuga allocated 60% of the total biomass to above-ground components and 40% to below-ground. Parkia nitida allocated 84% to above-ground and 16% to below-ground. Parkia pendula allocated 67% to above-ground components and 33% to below-ground. The order of the nutrient accumulation in tree compartments was: N &gt; Ca &gt; K &gt; Mg &gt; P. Parkia multijuga, by adopting better strategies of distribution of biomass and nutrients, it is a recommended species for reforestation programs on degraded sites in the Amazon.Keywords: Native forest species; forest nutrition; reforestation; restoration.