Aboveground biomass and nitrogen nutrition in a chronosequence of pristine Dahurian Larix stands in eastern Siberia

1995 ◽  
Vol 25 (6) ◽  
pp. 943-960 ◽  
Author(s):  
E.-D. Schulze ◽  
W. Schulze ◽  
H. Koch ◽  
A. Arneth ◽  
G. Bauer ◽  
...  
Keyword(s):  
Aboveground Biomass ◽  
Forest Type ◽  
Nitrogen Nutrition ◽  
Carbon Accumulation ◽  
Eastern Siberia ◽  
Available N ◽  
N Nutrition ◽  
N Cycle ◽  
Fire Cycle ◽  
N Pool

Measurements of aboveground biomass and nitrogen (N) nutrition were made during July 1993 in 50-, 130-, and 380-year-old stands of Larixgmelinii (Rupr.) Rupr. in eastern Siberia. Constituting six forest types based on understorey plants, the stands were representative of vegetation throughout the Yakutsk region. Average tree height, diameter, and density ranged from 2 m, 23 mm, and 50 800 stems/ha in the 50-year-old stand to 11 m, 160 mm, and 600 stems/ha in the oldest stand. Aboveground biomass in the 50-year-old stand was 4.4 kg•m−2, and the aboveground N pool was 1.1 mol•m−2. This was slightly higher than the N pool in a 125-year-old stand with a Ledum understorey (1.0 mol•m−2), despite its higher biomass (7.2 kg•m−2). The highest observed aboveground biomass in a 125-year-old stand (characterized by the N2-fixing understorey plant Alnasterfruticosa) reached 12.0 kg•m−2, but the corresponding N pool was only 1.6 mol•m−2. In the oldest stand, aboveground biomass was 8.9 kg•m−2 and the N pool was 1.1 mol•m−2. There was thus a relatively constant quantity of N in the aboveground biomass of stands differing in age by almost 400 years. We postulate that N sets a limit on carbon accumulation in this boreal forest type. Trees were extremely slow growing, and there was essentially no aboveground biomass accumulation between the ages of 130 and 380 years because of a lack of available N. This conclusion was supported by graphical analysis indicating that the self-thinning process in our stands was not governed by the availability of radiation according to allometric theory. Much of the available N was used in the production of tree stems where 86% of the aboveground N (and 96% of aboveground biomass) was immobilized in the oldest stand. N in wood of the old stand exceeded the N pool in the litter layer and was 20% of the N pool in the Ah horizon. The processes of carbon and N partitioning were further explored by the estimation of carbon and N fluxes during three periods of forest development. We calculated a loss of ecosystem N during the period of self-thinning, while in the mature stands the N cycle appeared to be very tight. The immobilized N is returned from the wood into a plant-available form only by a recurrent fire cycle, which regenerates the N cycle. Thus fire is an essential component for the persistence of the L. gmelinii forest.

Nitrogen nutrition during ontogeny of hemiepiphytic Clusia species

2002 ◽  
Vol 29 (6) ◽  
pp. 733 ◽  
Author(s):  
Wolfgang Wanek ◽  
Stefan K. Arndt ◽  
Werner Huber ◽  
Marianne Popp
Keyword(s):  
Nitrogen Nutrition ◽  
Life Stage ◽  
Growth Stages ◽  
N Availability ◽  
Available N ◽  
Lowland Tropical Forest ◽  
N Nutrition ◽  
Canopy Soil ◽  
Plant Growth Stages ◽  
N Pool

This paper originates from a presentation at the IIIrd International Congress on Crassulacean Acid Metabolism, Cape Tribulation, Queensland, Australia, August 2001. We investigated the nitrogen (N) nutrition of Clusia osaensis, C. peninsulae and C. valerii during the seedling, epiphytic and hemiepiphytic phase in a lowland tropical forest in Costa Rica in order to elucidate nutritional adaptations of different plant growth stages to their habitat. Although all Clusia individuals were non-mycorrhizal, excised roots of seedlings, but also of epiphytic and hemiepiphytic stages, showed a distinct preference for glycine uptake. The shift in main rooting site from canopy soil to terrestrial soil was not reflected by changes in uptake rate or preference, although N availability and the composition of the available N pool changed significantly. High foliar N concentrations indicated that epiphytic seedlings seemed to be sufficiently supplied with N by maternal seed resources and canopy soils. With development, the epiphytic plants of Clusia may face N limitation due to higher N demands with increasing growth and restricted resources in the tree crowns. 15N natural abundance data indicate that epiphytes mainly accessed atmospheric and, to a lesser extent, canopy soil N sources and, after becoming terrestrially anchored, in the hemiepiphytic life stage exploited the larger nutrient reservoir of the ground soil. In consequence, Clusia species did not show an adaptation to the different N availability situations that they experienced whether canopy or ground-rooted.

scholarly journals Monitoring the nitrogen nutrition status of rice plants using spectral and image technologies

2020 ◽  
Author(s):  
Ye Chun ◽  
Liu Ji Zhong ◽  
Liu Ying ◽  
Li Yan Da ◽  
Cao Zhong Sheng ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Aboveground Biomass ◽  
Nitrogen Nutrition ◽  
Nutrition Status ◽  
Nitrogen Accumulation ◽  
Area Index ◽  
Plant Nitrogen ◽  
N Nutrition ◽  
Rice Plants

Abstract Background: We aimed to investigate methods to estimate the nitrogen (N) nutrition status of rice plants using data obtained using a digital camera and a spectroradiometer. The overall aim was to compare the advantages and potential of image technology and spectral technology to monitor rice N indexes accurately, inexpensively, and in real time to optimize fertilization strategies. Realizing the technical selection of definite spectrum or image diagnosis aiming at different rice nitrogen nutrition indexes. We conducted field trials of rice plants grown with different levels of N fertilizer in 2018 to 2019. Spectral information and images of the rice canopy were obtained, various image and spectral characteristic parameters were selected to construct models to estimate rice N status.Results: The determination coefficients of the models constructed using the ratio vegetation index (RVI[800,550]) and cover canopy (CC) as dependent variables were most significant. Among the models using spectral parameters, those constructed using RVI[800,550] to estimate rice N indexes had the obviously coefficient of determination (R2) values, which were 0.69, 0.58, and 0.65 for the models to estimate leaf area index(LAI), aboveground biomass(AGB), and plant N accumulation(PNA). As for image parameter, those using CC to predict rice N indexes showed the highest R2 values (0.76, 0.65, and 0.71 for the models to estimate LAI, AGB, and PNA, respectively) (P < 0.01). The model using the spectral parameter RVI[800,550] had a good fit and stability in estimating plant nitrogen accumulation (R2 = 0.65, root mean square error (RMSE) = 1.35 g·m-2, relative RMSE (RRMSE) = 14.05%), and the model using the image parameter CC had a good fit in predicting leaf area index (R2 = 0.76, RMSE = 0.28, RRMSE = 7.26%) and aboveground biomass (R2 = 0.65, RMSE = 22.03 g·m-2, RRMSE = 7.52%). Different detection technology should be adopted for different rice varieties and rice N nutrition indexes. Conclusions: Spectral and image parameters can be used as technical parameters to estimate rice N status. The spectral parameter RVI[800,550] can be used to accurately estimate plant nitrogen accumulation, and the image parameter CC can be used to accurately estimate leaf area index and aboveground biomass.

scholarly journals Root-Derived Proteases as a Plant Tool to Access Soil Organic Nitrogen; Current Stage of Knowledge and Controversies

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 731
Author(s):  
Bartosz Adamczyk
Keyword(s):  
Cropping Systems ◽  
N Uptake ◽  
Organic N ◽  
Inorganic N ◽  
Available N ◽  
Plant Nitrogen ◽  
N Cycle ◽  
Soil Organic Nitrogen ◽  
Use Efficiency ◽  
N Pool

Anthropogenic deterioration of the global nitrogen (N) cycle emerges mainly from overuse of inorganic N fertilizers in nutrient-limited cropping systems. To counteract a further dysregulation of the N cycle, we need to improve plant nitrogen use efficiency. This aim may be reached via unravelling all plant mechanisms to access soil N, with special attention to the dominating high-molecular-mass N pool. Traditionally, we believe that inorganic N is the only plant-available N pool, however, more recent studies point to acquisition of organic N compounds, i.e., amino acids, short peptides, and proteins. The least known mechanism of plants to increase the N uptake is a direct increase of soil proteolysis via root-derived proteases. This paper provides a review of the knowledge about root-derived proteases and also controversies behind this phenomenon.

Empirical relationships between temperature and nitrogen availability across North American forests

1992 ◽  
Vol 22 (5) ◽  
pp. 707-712 ◽  
Author(s):  
Xiwei Yin
Keyword(s):  
N Mineralization ◽  
Regional Scale ◽  
Mineral Soil ◽  
Published Data ◽  
N Availability ◽  
Net N Mineralization ◽  
Soil N ◽  
Litter Fall ◽  
Available N ◽  
N Pool

Published data were analyzed to examine whether nitrogen (N) availability varies along macroclimatic gradients in North America. Extractable N produced during 8-week aerobic laboratory incubation was used as an index of potential net N mineralization. Mean extractable N during the growing season in the forest floor plus top mineral soil was used as an index of the available N pool. Using multiple regression, potential net N mineralization was shown to increase with available N and with litter-fall N (R2 = 0.722). Available N increased with increasing total soil N and with decreasing mean January and July air temperatures (R2 = 0.770). These relationships appeared to hold also for deciduous and coniferous forests separately across regions. Results suggest that net N mineralization output under uniform temperature and moisture conditions can be generally expressed by variations of N input (litter fall) and the available soil N pool, and that the available soil N pool is predictable along a temperature gradient at a regional scale.

scholarly journals Influence of Variable Selection and Forest Type on Forest Aboveground Biomass Estimation Using Machine Learning Algorithms

Forests ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 1073 ◽  
Author(s):  
Li ◽  
Li ◽  
Li ◽  
Liu
Keyword(s):  
Machine Learning ◽  
Remote Sensing ◽  
Variable Selection ◽  
Aboveground Biomass ◽  
Forest Type ◽  
Learning Algorithms ◽  
Forest Biomass ◽  
Machine Learning Algorithms ◽  
Biomass Estimation ◽  
Landsat 8

Forest biomass is a major store of carbon and plays a crucial role in the regional and global carbon cycle. Accurate forest biomass assessment is important for monitoring and mapping the status of and changes in forests. However, while remote sensing-based forest biomass estimation in general is well developed and extensively used, improving the accuracy of biomass estimation remains challenging. In this paper, we used China’s National Forest Continuous Inventory data and Landsat 8 Operational Land Imager data in combination with three algorithms, either the linear regression (LR), random forest (RF), or extreme gradient boosting (XGBoost), to establish biomass estimation models based on forest type. In the modeling process, two methods of variable selection, e.g., stepwise regression and variable importance-base method, were used to select optimal variable subsets for LR and machine learning algorithms (e.g., RF and XGBoost), respectively. Comfortingly, the accuracy of models was significantly improved, and thus the following conclusions were drawn: (1) Variable selection is very important for improving the performance of models, especially for machine learning algorithms, and the influence of variable selection on XGBoost is significantly greater than that of RF. (2) Machine learning algorithms have advantages in aboveground biomass (AGB) estimation, and the XGBoost and RF models significantly improved the estimation accuracy compared with the LR models. Despite that the problems of overestimation and underestimation were not fully eliminated, the XGBoost algorithm worked well and reduced these problems to a certain extent. (3) The approach of AGB modeling based on forest type is a very advantageous method for improving the performance at the lower and higher values of AGB. Some conclusions in this paper were probably different as the study area changed. The methods used in this paper provide an optional and useful approach for improving the accuracy of AGB estimation based on remote sensing data, and the estimation of AGB was a reference basis for monitoring the forest ecosystem of the study area.

The use of the 15N isotope dilution technique to estimate the contribution of associated biological nitrogen fixation to the nitrogen nutrition of Paspalum notatum cv. batatais

1983 ◽  
Vol 29 (8) ◽  
pp. 1036-1045 ◽  
Author(s):  
Robert M. Boddey ◽  
Phillip M. Chalk ◽  
Reynaldo L. Victoria ◽  
Eiichi Matsui ◽  
Johanna Döbereiner
Keyword(s):  
Isotope Dilution ◽  
Nitrogen Nutrition ◽  
Control Plant ◽  
Paspalum Notatum ◽  
Dilution Technique ◽  
N Nutrition ◽  
Advantages And Disadvantages ◽  
Reduction Activity ◽  
Dilution Experiments ◽  
Biological Nitrogen

This paper reports the results of a field experiment to investigate the use of the 15N-dilution technique to measure the contribution of biological N2 fixation to the N nutrition of the batatais cultivar of Paspalum notatum. The pensacola cultivar of this grass supports little associated N2 fixation as evidenced by the low associated C2H2 reduction activity and was thus used as a nonfixing control plant. The grasses were grown in 60-cm diameter concrete cylinders sunk into the soil, and the effects of four different addition rates of labelled nitrogen (NH4)2SO4, were investigated. The data from seven harvests clearly demonstrated that there was a significant input of plant associated N2 fixation to the nutrition of the batatais cultivar amounting to approximately 20 kg N∙ha−1∙year−1. Problems associated with the conduct of such isotope dilution experiments are discussed including the importance of using nonfixing control plants of similar growth habit, the advantages and disadvantages of growing the plants in cylinders as opposed to field plots, and the various methods of application of labelled N fertilizer.

Amending aeolian sandy soil in the Mu Us Sandy Land of China with Pisha sandstone and increasing phosphorus supply were more effective than increasing water supply for improving plant growth and phosphorus and nitrogen nutrition of lucerne (Medicago sativa)

2020 ◽  
Vol 71 (8) ◽  
pp. 785
Author(s):  
Honghua He ◽  
Zekun Zhang ◽  
Rui Su ◽  
Zhigang Dong ◽  
Qing Zhen ◽  
...  
Keyword(s):  
Plant Growth ◽  
Water Supply ◽  
Medicago Sativa ◽  
Sandy Soil ◽  
Nitrogen Nutrition ◽  
Sandy Land ◽  
Retention Capacity ◽  
Mu Us Sandy Land ◽  
N Nutrition ◽  
P Supply

Plant growth is often constrained by low availability of water and phosphorus (P) in soils in arid and semi-arid areas. Aeolian sandy soils cover &gt;90% of the sandy area of the Mu Us Sandy Land (MUSL) in Northwest China. These soils have low water- and nutrient-retention capacity, limiting their ability to support plant growth. Pisha sandstone, a type of loose rock widely distributed in the MUSL, is regarded as an environmental hazard because it easily weathers, resulting in severe soil erosion and water loss. However, the retention capacity of the aeolian sandy soil can be significantly improved through blending with Pisha sandstone. We investigated the impacts of water supply (35% and 70% of soil water-holding capacity) and P supply (0, 5 and 20 mg P kg–1 soil) on plant growth and P and nitrogen (N) nutrition by growing lucerne (Medicago sativa L.) in MUSL aeolian sandy soil amended or not with Pisha sandstone. Soil type and P supply had greater effects than water supply on lucerne growth and on P and N nutrition. Biomass accumulation and shoot P and N concentrations were increased by amending the aeolian sandy soil with Pisha sandstone and increasing P supply. The N:P ratios in shoots indicated that plant growth was limited by P but not by N. Aeolian sandy soil amended with Pisha sandstone and supplied with P at 5 mg kg–1 enhanced lucerne growth; this practice is feasible for pasture development in the MUSL.

Interactive effect of nitrogen nutrition, nitrate reduction and seasonal variation on oxalate synthesis in leaves of Napier-bajra hybrid (Pennisetum purpureum × P. glaucum)

2019 ◽  
Vol 70 (8) ◽  
pp. 669
Author(s):  
Meenakshi Goyal ◽  
Rupinder Kaur
Keyword(s):  
Seasonal Variation ◽  
Nitrogen Nutrition ◽  
Monsoon Season ◽  
Block Design ◽  
Interactive Effect ◽  
Urinary Calculi ◽  
Positive Association ◽  
Pennisetum Purpureum ◽  
N Nutrition ◽  
Oxalate Synthesis

Oxalate may cause hypocalcaemia or formation of urinary calculi in animals with prolonged grazing of Napier grass (Pennisetum purpureum) × pearl millet (bajra, P. glaucum) hybrid (NBH). We investigated the influence of nitrate metabolism, nitrogen (N) nutrition, N forms and seasonal variation on oxalate accumulation in leaves of NBH in a field experiment in Ludhiana, India. The experiment was a randomised block design with three N sources (nitrate, amide and ammonium), three application rates (50, 75 and 100 kg N/ha), four seasons (summer, monsoon, autumn, pre-winter) and three replicates. Applied N nutrition induced oxalate synthesis and activities of nitrate reductase (NR) and nitrite reductase (NiR) enzymes. A positive association of N nutrition with both oxalate accumulation and nitrate-reducing enzymes was found. Nitrate-N increased oxalate accumulation and NiR activity more than ammonium and amide. A differential effect of seasons on NR and NiR activities, as well as on oxalate accumulation, was observed. Among different harvest seasons, NR and NiR activities were positively associated with oxalate accumulation in summer and the monsoon season. These results suggest that N fertilisation, particularly in nitrate form, is associated with upregulation of nitrate-reducing enzymes, leading to oxalate accumulation in NBH leaves.

scholarly journals The accuracy of species-specific allometric equations for estimating aboveground biomass in tropical moist montane forests: case study of Albizia grandibracteata and Trichilia dregeana

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Damena Edae Daba ◽  
Teshome Soromessa
Keyword(s):  
Forest Ecosystem ◽  
Aboveground Biomass ◽  
Forest Type ◽  
Model Performance ◽  
Allometric Equation ◽  
Allometric Equations ◽  
Coefficient Of Determination ◽  
Biomass Estimation ◽  
Moist Forest ◽  
Species Specific

Abstract Background Application of allometric equations for quantifying forests aboveground biomass is a crucial step related to efforts of climate change mitigation. Generalized allometric equations have been applied for estimating biomass and carbon storage of forests. However, adopting a generalized allometric equation to estimate the biomass of different forests generates uncertainty due to environmental variation. Therefore, formulating species-specific allometric equations is important to accurately quantify the biomass. Montane moist forest ecosystem comprises high forest type which is mainly found in the southwestern part of Ethiopia. Yayu Coffee Forest Biosphere Reserve is categorized into Afromontane Rainforest vegetation types in this ecosystem. This study was aimed to formulate species-specific allometric equations for Albizia grandibracteata Tuab. and Trichilia dregeana Sond. using the semi-destructive method. Results Allometric equations in form of power models were developed for each tree species by evaluating the statistical relationships of total aboveground biomass (TAGB) and dendrometric variables. TAGB was regressed against diameter at breast height (D), total height (H), and wood density (ρ) individually and in a combination. The allometric equations were selected based on model performance statistics. Equations with the higher coefficient of determination (adj.R2), lower residual standard error (RSE), and low Akaike information criterion (AIC) values were found best fitted. Relationships between TAGB and predictive variables were found statistically significant (p ≤ 0.001) for all selected equations. Higher bias was reported related to the application of pan-tropical or generalized allometric equations. Conclusions Formulating species-specific allometric equations is found important for accurate tree biomass estimation and quantifying the carbon stock. The developed biomass regression models can be applied as a species-specific equation to the montane moist forest ecosystem of southwestern Ethiopia.

The contribution of nitrogen fertiliser to the nitrogen nutrition of rainfed wheat crops in Australia: a review

1989 ◽  
Vol 29 (3) ◽  
pp. 455 ◽  
Author(s):  
GK McDonald
Keyword(s):  
Nitrogen Nutrition ◽  
Average Rate ◽  
Grain Protein Content ◽  
Grain Legumes ◽  
Grain Legume ◽  
Wheat Crop ◽  
Total Consumption ◽  
N Nutrition ◽  
Australian Wheat ◽  
Legume Production

Very little nitrogen (N) fertiliser is applied to wheat crops in Australia. Currently, about 105 t of N fertiliser (less than 20% of Australia's total consumption) are used annually at an average rate of 2-3 kg Nha. This scant use of N fertiliser over much of the Australian wheat belt N is because the N derived from a legume-dominant pasture ley is thought to provide a wheat crop's N requirement. However, trends in the grain protein content of Australian wheat and some other indices of soil fertility suggest that legume-based pastures have not always been able to supply all the N required for adequate nutrition of the wheat crop and that there has been some occasional need for extra N from applications of fertiliser. Recent declines in the productivity and quality of pastures has further increased the need for supplementary applications of N fertiliser. The increase in grain legume production also has been partly based on the presumption that grain legumes contribute to the N economy of the following wheat crop. Many experiments throughout the wheat belt show a yield advantage of wheat grown after a grain legume, but these rotation trials also show that the level of productivity of the grain legume has little effect on the yield of the following wheat crop. A review of these experiments suggests that grain legumes, directly, contribute little to the N nutrition of a following wheat crop and their benefit may be from the legume acting as a disease break or providing the opportunity to control grassy weeds.

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