Considering the Effect of Land-Based Biomass on Dune Erosion Volumes in Large-Scale Numerical Modeling

This paper presents and validates a novel root model which accounts for the effect of belowground biomass on dune erosion volumes in XBeach, based on a small-scale wave flume experiment that was translated to a larger scale. A 1D-XBeach model was calibrated by using control runs considering a dune without vegetation. Despite calibration, a general model–data mismatch was observed in terms of overestimated erosion volumes around the waterline. Furthermore, the prediction of overwash had to be induced by increasing the maximum nearshore wave height within the XBeach simulation. Subsequently, applying the root model resulted in a good agreement with the belowground biomass cases, and the consideration of spatially varying rooting depths further improved the results. Predictions of the root model while using locally increased friction coefficients were in line with the aboveground and belowground biomass cases. However, the effect of the root model on the erosion predictions varied among the hydrodynamic conditions, so further improvements are required. Therefore, future research should focus on quantifying the effects of land-based biomass and individual plant characteristics, such as root density, on dune erodibility at large scales, along with their influences on the temporal evolution of dune scarping and avalanching.

Partition of biomass and nitrogen in a potato crop under three nitrogen fertilization treatments

Nitrogen nutrition considerably influences the process of growing and producing potato crops. The aim of this study was to determine the effects of nitrogen nutrition on the pattern of biomass and nitrogen partitioning during the growth of potato crop in Mérida, Mérida, Venezuela. Experimental land plots were set, with a randomized blocks design, and with three different fertilization treatment settings for the "Granola" cultivar. The first one without nitrogen (0-N), the next one with 133 Kg N Ha-1 (133-N), and the last one with 400 Kg N Ha-1 (400-N). In the main phenological stages of the crop, biomass and nitrogen levels were measured for each organ. The performance of the tubers and the total biomass are strongly influenced by the availability of nitrogen and assimilatory biomass. The total biomass production, as well as the biomass and nitrogen partitioning to each organ, showed the following sequence: 400-N > 133-N > 0-N. However, biomass and nitrogen partitioning to the roots and stolons was higher in the treatment with limited nitrogen levels. Proportional changes among aboveground and belowground biomass are adaptive responses to nitrogen deficit conditions, which, in their turn, are determining factors in crop production.

Effet de la terre des termitières sur la croissance de trois cultivars de la morelle noire (Solanum nigrum L. : Solanaceae) cultivée à Brazzaville (Congo)

La productivité de la morelle noire est faible sur les sols surexploités dans les zones périurbaines de Brazzaville. L’objectif était d’évaluer l’apport de la terre des termitières sur la croissance végétale de trois cultivars de la morelle noire. Les termitières collectées ont été broyées, tamisées et amendées les planches de 3 m x 1,2 m. Une planche ayant reçu 0 kg, 2 kg, 4 kg et 6 kg de terre des termitières, 60 plants d’un cultivar ont été repiqués aux écartements 20 x 20 cm selon un schéma bi factoriel complet 4 x 3 logé dans un dispositif en bloc complètement randomisé. Les traitements ont été répétés trois fois. Les résultats ont révélé une meilleure croissance en hauteur et en diamètre ainsi qu’un meilleur développement foliaire des plants amendés avec les doses de la terre des termitières en comparaison de ceux n’en ayant pas reçu. L’apport de 6 kg de terre des termitières montre une influence positive sur le développement racinaire de plants des trois cultivars. L’apport 2 kg, 4 kg et 6 kg de terre de termitières améliore la croissance végétative et le rendement en biomasses aérienne et souterraine de trois cultivars de morelle noire cultivés au Congo. © 2020 International Formulae Group. All rights reserved. Mots clés: Congo, fertilisation, termitières champignons, croissance végétative, Solanum nigrum L. English Title: Effect of the termite mounds on the vegetative production of three cultivars of black nightshade (Solanum nigrum L.: Solanaceae) grown in Brazzaville, Congo English Abstract The productivity of black nightshade is low on the overexploited soils in the suburban areas of Brazzaville. The objective was to evaluate the contribution of termite mound on the plant growth of three black nightshade cultivars. The termite mounds were collected, crushed, sieved and amended the planks of 3m x 1.2m. A board having received 0 kg, 2 kg, 4 kg and 6 kg of termite mounds, 60 plants of a cultivar were transplanted at 20 x 20 cm intervals according to a complete 4 x 3 bi-factorial diagram housed in a block plan completely randomized. The treatments were repeated three times. The results showed better growth in height and diameter, as well as better foliar development of seedlings amended with termite mounds compared to those that did not. The contribution of 6 kg of termite mound had a positive influence on the root development of the three cultivars. The contribution of 2 kg, 4 kg and 6 kg of termite mound improved vegetative growth and yield in aboveground and belowground biomass of three black nightshade cultivars grown in Congo. © 2020 International Formulae Group. All rights reserved. Keywords: Congo, cultivar, fertility, Termite fungi, vegetative production, Solanum nigrum L.

Relationships between aboveground and belowground biomass stock – a case study from mountain area temperate forests in the northern Carpathians

<p>The content of organic carbon in forest is partitioned between organic carbon accumulated in aboveground biomass (AGB) and belowground biomass (BGB) and is impacted by various natural and human factors. Growing interest in estimates of global biomass (and organic carbon) pools require research on a local scale in the context of potential environmental factors affecting their spatial distribution. Therefore, our aim of the research was to both derive and evaluate the relationship between aboveground biomass consisting mainly of European beech (Fagus sylvatica L.), spruce (Picea abies L. Karst) and fir (Abies alba Mill.) and BGB with particular emphasis on fine root biomass (FRB) as the most dynamic part of the root system and soil organic matter stock (SOM). Data were collected at 32 national forest inventory plots in mountainous temperate forests with different history of forest management located across the Carpathian range in Poland. All study plots were characterized with very similar soil properties (Cambisols). Moreover, numerous environmental factors affecting biomass distribution were taken under consideration. The largest aboveground biomass occurred in beech-dominated stands (~40 Mg ha<sup>-1</sup> to over ~ 440 Mg ha<sup>-1</sup>). In the sampled depth layer (0-40 cm) the highest SOM stock was identified in soils under beech-dominated stands (median ~158 Mg ha-1). FRB was the highest under fir-dominated stands (median ~3.7 Mg ha-1). The amount of SOM and FRB differed also in the analyzed soil depth layers (10 cm interval up to 40 cm) reaching mostly the highest values at soil depths of 0-10 cm. The highest amount of biomass (both aboveground and the belowground) has been identified in beech-dominated forests. We examined relationships between AGB, FRB, and SOM, but were not able to identify clear significant correlations based only on vegetation parameters. Derived results illustrate the complexity of identifying significant relationships between aboveground and belowground biomass stocks. Employing the same models may be an erroneous strategy for different study sites because of local environmental factors that strongly determine aboveground and belowground biomass stock. Accordingly, creating biomass and carbon models at larger scales in northern Carpathians based on forest aboveground data may cause an over- or underestimation due to the significant impact of both abiotic and biotic factors. </p><p> </p><p>This research study was funded by the Polish National Science Centre (RS4FOR Project: Forest change detection and monitoring using passive and active remote sensing data (No. 2015/19/B/ST10/02127) and via Project No. UJ/IGiGP/K/DSC/004779.</p>