Biomass partitioning and nitrogen retranslocation in black spruce seedlings on competitive mixedwood sites: a bioassay study

1998 ◽  
Vol 28 (2) ◽  
pp. 206-215 ◽  
Author(s):  
V Malik ◽  
V R Timmer

Black spruce (Picea mariana (Mill.) BSP) seedlings were exponentially nutrient loaded by applying 3 or 6 times more fertilizer than recommended for conventional seedling production in the nursery. Loaded seedlings were similar in height and biomass to nonloaded seedlings after nursery culture, but their tissue N, P, and K content was almost twice as much as that of nonloaded seedlings. The seedlings were transplanted on intact potted substrates (bioassays) retrieved with natural vegetation from two boreal mixedwood sites and grown for one season in a greenhouse to study early- and late-season growth and nutrient dynamics, and nutrient loading and herbicide effects on N retranslocation processes. After transplanting, height and biomass growth of loaded seedlings were, respectively, 9-14% and 24-49% more than nonloaded seedlings in herbicide-treated plots, and 14-32% and 42-85% more in untreated plots, resulting in 32-39% biomass reduction in natural vegetation. The effect of nutrient loading on growth was attributed to earlier and greater biomass and N partitioning to current needles and roots that promoted N uptake (up to 20.9 ± 1.7 mg) compared with nonloaded seedlings (up to 11.8 ± 1.2 mg). Although both loading and herbicide treatments stimulated seedling growth and N uptake, N retranslocation from older to actively growing tissues was promoted by loading but reduced by herbicide treatment. The results demonstrate the high dependence of seedlings on internal nutrient reserves when planted in competitive environments, and that nutrient retranslocation is mainly driven by current growth, nutrient uptake, and internal nutrient reserves.

2000 ◽  
Vol 30 (2) ◽  
pp. 191-201 ◽  
Author(s):  
M Quoreshi ◽  
V R Timmer

Containerized black spruce (Picea mariana (Mill.) BSP) seedlings fertilized conventionally (12.5 mg N/plant) or exponentially (12.5, 25, or 50 mg N/plant) and inoculated with Hebeloma crustuliniforme (Bull. Ex St-Amans) Quel. or Laccaria bicolor (R. Mre.) Orton were periodically monitored for a 20-week greenhouse rotation to assess growth dynamics, steady-state N and P nutrition, and ectomycorrhizal development. Growth and nutrient accumulation increased exponentially for the exponential regimes and more linearly for the conventional regime, although final biomass was similar except for the low-dose exponential addition. Shoot/root biomass ratios were relatively stable for most of the growing season, characterizing steady-state nutrient supply that benefits seedling outplanting performance and mycorrhizal colonization. Exponential fertilization also stimulated mycorrhiza formation even at high loading (25 or 50 mg N) rates that build up nutrient reserves in the seedlings without affecting seedling size. Plant nutrient uptake was more efficient under exponential fertilization and (or) fungal colonization, although efficiency dropped off at high loading levels. Vector nutrient diagnosis revealed marked nutrient dilution under conventional fertilization, but steady-state nutrition under exponential fertilization that coincided with satisfactory mycorrhiza development on seedlings. Dilution-free nutrient conditions for seedlings may provide stable carbohydrates for symbiosis and may develop enhanced tolerance to high fertilizer inputs.


2001 ◽  
Vol 31 (8) ◽  
pp. 1357-1366 ◽  
Author(s):  
Moses Imo ◽  
Victor R Timmer

Enhanced nutrient mobilization from old to current growth is a key mechanism that confers competitive ability to nutrient-loaded black spruce (Picea mariana (Mill.) BSP) seedlings planted on high-competition forest sites in northern Ontario. This study examines effects of nutrient loading and differing vegetation management (herbicide, fertilization, shading) on growth, partitioning, and net retranslocation of N between current and old shoots of newly planted black spruce seedlings on six contrasting boreal sites. Nutrient loading during nursery culture improved seedling growth and N uptake and retranslocation after transplanting. Herbicide application accelerated growth and N uptake only on the high-competition Alnus, hardwood, and mixedwood sites but had no effect on the less competitive feathermoss and Vaccinium sites. Weed removal on competitive sites reduced N retranslocation significantly. Field fertilization reduced N retranslocation in seedlings and promoting tree growth and N uptake on the less competitive feathermoss and Vaccinium sites. However, fertilization stimulated weeds on high-competition sites suppressing seedling biomass and N uptake. Factors that seem to affect net N retranslocation include the type and level of internal N reserves, biomass and N accumulation and partitioning, external N supply, and other stresses that limit plant growth such as competition.


1990 ◽  
Vol 20 (8) ◽  
pp. 1165-1171 ◽  
Author(s):  
Alison D. Munson ◽  
V. R. Timmer

First and second-season morphological responses of outplanted Piceamariana (Mill.) B.S.P. (black spruce) seedlings to site conditions of three cutover boreal ecosystems were analysed in terms of biomass and nutrient allocation to structural components (current shoots, previous year's shoots, stem, and roots). Improved N nutrition on an upland Feathermoss site had the greatest positive effect on biomass and nutrient allocation to current shoots, while allocation to other components was reduced. Seedlings on lowland Alnus – Herb poor and Ledum sites responded to site nutrient stress by allocating more biomass to the stem and roots. Multivariate procedures indicated that the overall pattern of biomass and nutrient allocation was significantly affected by site, and also differed depending on the individual element considered (N, P, K, Ca, Mg). Changes in nutrient-use efficiency with site were also investigated. With decreased seedling N uptake on the two lowland sites, biomass production per unit N increased, but specific absorption rate of roots decreased. Under N limitation, evidence for nutrient retranslocation was noted by decreases in nutrient content in the same component over 2 years and by lower concentrations in older shoots than in current growth. The alternative allocation of biomass and nutrients to seedling components with changes in site nutrition has implications for tree development on specific sites, and also for management of site nutrient regime to improve early seedling performance.


1991 ◽  
Vol 21 (7) ◽  
pp. 1058-1065 ◽  
Author(s):  
V. R. Timmer ◽  
A. D. Munson

Black spruce (Piceamariana (Mill.) B.S.P.) containerized seedlings were raised at high fertilizer regimes, i.e., "nutrient loaded," during greenhouse culture to assess whether increased preplant nutrient reserves improved site-specific outplanting performance. Growing media electrical conductivity levels during the greenhouse phase ranged between 0.9–1.2 and 0.3–0.6 dS/m for loaded and nonloaded seedlings, respectively. Although similar in total biomass and P and K content at rotation end, the loaded seedlings contained 78% more N than the nonloaded seedlings, demonstrating induced luxury consumption of N from loading. After overwintering, the seedlings were planted on intact potted surface soils from three ecological site types (upland Feathermoss, lowland Alnus, and lowland Ledum) of contrasting fertility. In the first growing season, N loading significantly increased height growth and dry matter production on all substrates; relative response was higher on the more N-deficient lowland sites. Plant nutrients were markedly diluted after establishment, except for N of nonloaded seedlings. The loading response was closely associated with the buildup of preplant N, which served as a critical nutrient source for internal retranslocation to new growth. Loading stimulated not only N uptake after outplanting, but also uptake of other nutrients presumably because of the expanded root system with this treatment. Balanced nutrient loading offers a cost-efficient alternative to field fertilization by promoting outplanting performance of container stock, and by avoiding competition response and operational constraints often associated with on-site fertilization.


1996 ◽  
Vol 26 (9) ◽  
pp. 1651-1659 ◽  
Author(s):  
V. Malik ◽  
V.R. Timmer

Nutrient-loaded and conventionally fertilized containerized black spruce (Piceamariana (Mill.) BSP) seedlings were planted on a boreal mixedwood site in the Greater Clay Belt of Ontario to study their growth and interaction with natural vegetation. At planting, nutrient-loaded seedlings were similar in height and biomass to conventionally fertilized seedlings, but contained 39, 69, and 22% more tissue N, P, and K content, respectively. After two field growing seasons, nutrient-loaded seedlings attained 15–18% more height and 16–39% more biomass, resulting in 15–27% reduction in the biomass of neighbouring vegetation. Aboveground biomasses of seedlings and neighbouring vegetation were inversely related. Interspecific competition was more intense in the second year than in the first year of outplanting. Nutrient loading prior to planting stimulated nutrient uptake and root growth after planting, and reduced soil N availability by 6–20% during the first season, suggesting greater preemption of belowground nutrient resources. The enhanced competitive ability of loaded seedlings over naturally occurring vegetation was probably due to the contrasting nutrient utilization traits induced by greenhouse fertilization. Nutrient-loaded seedlings translocated more nutrients to actively growing parts from reserves built up during the greenhouse preconditioning phase than did conventionally fertilized seedlings. First-season growth and nutrient responses in the field and in previous greenhouse trials were significantly correlated, demonstrating the effectiveness of using intact bioassays to simulate and predict short-term field responses to competition treatments.


2017 ◽  
Vol 14 (4) ◽  
pp. 755-766 ◽  
Author(s):  
Yingying Tang ◽  
Sarah F. Harpenslager ◽  
Monique M. L. van Kempen ◽  
Evi J. H. Verbaarschot ◽  
Laury M. J. M. Loeffen ◽  
...  

Abstract. The sequestration of nutrients from surface waters by aquatic macrophytes and sediments provides an important service to both natural and constructed wetlands. While emergent species take up nutrients from the sediment, submerged and floating macrophytes filter nutrients directly from the surface water, which may be more efficient in constructed wetlands. It remains unclear, however, whether their efficiency is sufficient for wastewater purification and how plant species and nutrient loading affects nutrient distribution over plants, water and sediment. We therefore determined nutrient removal efficiencies of different vegetation (Azolla filiculoides, Ceratophyllum demersum and Myriophyllum spicatum) and sediment types (clay, peaty clay and peat) at three nutrient input rates, in a full factorial, outdoor mesocosm experiment. At low loading (0.43 mg P m−2 d−1), plant uptake was the main pathway (100 %) for phosphorus (P) removal, while sediments showed a net P release. A. filiculoides and M. spicatum showed the highest biomass production and could be harvested regularly for nutrient recycling, whereas C. demersum was outcompeted by spontaneously developing macrophytes and algae. Higher nutrient loading only stimulated A. filiculoides growth. At higher rates ( ≥  21.4 mg P m−2 d−1), 50–90 % of added P ended up in sediments, with peat sediments becoming more easily saturated. For nitrogen (N), 45–90 % was either taken up by the sediment or lost to the atmosphere at loadings  ≥  62 mg N m−2 d−1. This shows that aquatic macrophytes can indeed function as an efficient nutrient filter but only for low loading rates (polishing) and not for high rates (purification). The outcome of this controlled study not only contributes to our understanding of nutrient dynamics in constructed wetlands but also shows the differential effects of wetland sediment types and plant species. Furthermore, the acquired knowledge may benefit the application of macrophyte harvesting to remove and recycle nutrients from both constructed wetlands and nutrient-loaded natural wetlands.


1986 ◽  
Vol 16 (6) ◽  
pp. 1320-1326 ◽  
Author(s):  
K. Van Cleve ◽  
O. W. Heal ◽  
D. Roberts

Using a bioassay approach, this paper considers the nitrogen-supplying power of forest floors from examples of the major forest types in interior Alaska. Yield and net N uptake by paper birch seedlings grown in standardized mixtures of quartz sand and forest floor organic matter, and separate incubation estimates of N mineralization and nitrification for the forest floors, were employed to evaluate potential N supply. Black spruce and floodplain white spruce forest floors supplied only one-fifth the amount of N taken up by seedlings growing in other forest floors. Incubation estimates showed these forest floors yielded 4 and 15 times less extractable N, respectively, than the more fertile birch forest floors. In comparison with earlier estimates of P supply from these same forest floors, the upland types showed greater deficiency of N whereas floodplain types showed greater deficiency of P in control of seedling yield. The latter condition is attributed to the highly calcareous nature of the floodplain mineral soil, the consequent potential for P fixation, and hence greater potential deficiency of the element compared with N in mineralizing forest floors. Nitrogen concentration of the forest floors was the best predictor of bioassay response.


1999 ◽  
Vol 29 (4) ◽  
pp. 474-486 ◽  
Author(s):  
Moses Imo ◽  
Victor R Timmer

Impacts of methods to overcome competing vegetation (fertilization, herbicide application, and shading) on conventional and nutrient-loaded black spruce (Picea mariana (Mill.) BSP) seedlings were examined on six forest site types in northeastern Ontario using vector competition analysis. Four sites (Alnus; hardwood; mixedwood, herb rich; and mixedwood, herb poor) were selected to represent high competition, and two sites (feathermoss and Vaccinium) to represent low-competition forest sites. Although similar in biomass before planting, loaded seedlings had greater N, P, and K content than nonloaded seedlings. After planting, loaded seedlings outperformed growth of nonloaded seedlings under all vegetation-control treatments on all sites. Herbicide application eliminated noncrop vegetation but resulted in significantly higher seedling biomass only on the high-competition Alnus site. Field fertilization stimulated weed growth resulting in seedling suppression on the high-competition sites, while nutrient loading countered weed competition on most sites. Interpretation of these results by vector competition analysis revealed that, without fertilization, competition for nutrients was the primary factor limiting seedling growth, while competition for light and (or) moisture was greater after fertilizer addition on weed-prone sites. Similar interpretation revealed no seedling-weed interactions in the less competitive sites.


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