Biomass Production Research Articles

Effect of nitrogen fertilizer on growth, yield and quality parameters of three sugarcane (<em>Saccharum Officinarum</em> L.) varieties

This study examines the effects of nitrogen on the growth, yield and quality of three sugarcane varieties under irrigated conditions in the low country dry zone of Sri Lanka. Three sugarcane varieties (SL96-128, SL04-624 and SL8306) were tested at four nitrogen fertilizer levels (0, 100, 200, 300 kg/ha) in a split plot design with four replicates. Selected growth, yield and quality parameters were studied in this field experiment. The results of the study demonstrated that application of 100kg/ha or 300kg/ha N fertilizer has shown highest girth of stem (cm), partitioning biomass to millable stalk (PBMS), brix and pol percentage in all three varieties, SL04-624, SL8306 and SL96-128. In addition, variety SL04-624 have shown highest total above ground biomass production (dry matter) (41987.8kg/ha), partitioning biomass to millable stalk (PBMS) (74.5%), brix (19.4%), pol (17.1%) and pure obtainable cane sugar (POCS) (12.3%). Therefore 100k/ha (N2) could be concluded as the best rate of N fertilizer application for the varieties tested in this study considering the cost of production, environmental and groundwater pollution. SL04-624 could be recommended as the most suitable variety for low country wet zone of Sri Lanka responding to 100kg/ha N fertilizer.

Comparative assessment of Brassica cultivars for genotypic variability in phytoremediation of soil exposed to lead (Pb) contamination.

The soil pollution caused with accretion of pollutant elements like lead (Pb) is the major environmental concern nowadays. Phytoremediation of contaminated soils using Brassica cultivars that act as hyperaccumulator plants for Pb emerges as an important technique for decontamination of Pb spiked soils. Therefore, pot study was carried out to compare the efficiency of three Brassica cultivars and select the most efficient cultivar for phytoremediation of Pb spiked soils. The experimental soil was contaminated with Pb applied @ 0, 125, 250, 500, 750, and 1,000 mg kg-1 soil. Our outcomes reflected that increased rates of Pb pollution in soil from 125 to 1,000 mg kg-1 soil resulted in decline of yield but enhanced the Pb acquisition of all Brassica cultivars. Comparison of cultivars indicated the highest biomass production (16.7 g pot-1), Pb acquisition (4,011.7 μg pot-1), contamination indices i.e., tolerance index (70.6), and bioaccumulation coefficient (17.03) by Brassica juncea produced thereby proving it as the most efficient cultivar for phytoremediation of Pb spiked soil.

Removal of Nitrogen, Phosphates, and Chemical Oxygen Demand from Community Wastewater by Using Treatment Wetlands Planted with Ornamental Plants in Different Mineral Filter Media

This study aimed to explore the impact of various ornamental plants (Heliconia psittacorum, Etlingera elatior, Spatyphilum walisii) grown in different filter media (porous river rock (PR) and tepezyl (TZ)) on the removal of pollutants in vertical-subsurface-microcosm treatment wetlands (TWs). This study also sought to assess the adaptability of these plant species to TW conditions. Twenty-four microcosm systems were utilized, with twelve containing PR and twelve containing TZ as the filter media. Each porous media type had three units planted with each species, and three were left unplanted. Rural community wastewater was treated in the TWs. The results showed no significant differences in the effects of the porous media on pollutant removal performance (p > 0.05). However, it was noted that while both porous media were efficient, TZ, a residue of construction materials, is recommended for sites facing economic constraints. Additionally, the removal efficiency was found to be independent of the type of ornamental plant used (p > 0.05); however, the measured parameters varied with plant spp. The adaptation of the plants varied depending on the species. H. psittacorum grew faster and produced a larger number of flowers compared to the other species (20–22 cm). S. wallisii typically produced 7–8 flowers. E. elatior did not produce flowers, and some plants showed signs of slight disease and pests, with the leaves turning yellow. In terms of plant biomass, the type of porous media used did not have a significant effect on the production of above (p = 0.111) or below-ground biomass (p = 0.092). The removal percentages for COD in the presence and absence of plants were in the ranges of 64–77% and 27–27.7%, respectively. For TN, the numbers were 52–65% and 30–31.8%, and for N-NO3, they were 54–60% and 12–18%. N-NH4 saw removal rates of 67–71% and 28–33%, while P-PO4 saw removal rates of 60–72% and 22–25%. The difference in removal percentages between microcosms with and without plants ranged from 30 to 50%, underscoring the importance of plants in the bio-removal processes (phytoremediation). These results reveal that incorporating ornamental plants in TWs with TZ for wastewater in rural areas holds great promise for enhancing the visual appeal of these systems and ultimately gaining public approval. Our findings also enable us to offer recommendations for selecting suitable plants and substrates, as well as designing combinations for TWs.

Semi-continuous cultivation of microalgae to treat coal mine effluent in pilot scale: Nutrient removal, biodesalination and fatty acid composition analysis

Coal excavation is associated with discharge of an enormous amount of mine water rich in salt and trace metal ions, which require efficient treatment before use. Considering the potentiality of microalgae for high salt tolerance, salt removal and metallic pollutant removal from aqueous system, present study focuses semi-continuous cultivation of candidate microalgae Chlorella pyrenoidosa (NCIM 2738) in bubble column reactor (BCR) and open raceway pond (ORP) for nutrient supplemented coal mine effluent (NSCME) treatment. In between different hydraulic retention times (HRTs), HRT 6 d provide maximum average biomass productivity of 950 mg L−1 d−1 in BCR and 728.4 mg L−1 d−1 in ORP. HRT 9 d facilitates a maximum lipid content of 1.8 g L ̶ 1 in BCR and 1.4 g L ̶ 1 in ORP. Further, HRT 9 d had the maximum COD removal efficiency (96.5 % in BCR and 94.2 % in ORP) and maximum salinity removal efficiency (93 % in BCR and 92 % in ORP). Fatty acid methyl esters (FAME) characterization highlighted potential biodiesel applicability with cetane number (CN) of 53.94. Energy dispersive X-ray spectroscopy (EDS) revealed an excess amount of salt and metal ions deposition on the surface of harvested microalgae samples. Outdoor large-scale C. pyrenoidosa cultivation can be integrated with coal mine closure plans to meet sustainable development goals (SDGs) 6, 7 and 13.

N:P ratio and salinity as keys: A study on optimizing biomass and lipid production in marine Chlorella sp. NITT 02 and Picochlorum sp. NITT 04 for biodiesel production

A first study on nitrogen to phosphorus (N:P) supply ratio with different N sources (NaNO3, urea, and L-Asparagine) and salinity within the cultivation medium of microalgal species towards biomass and lipid enhancement is demonstrated. Among the three nitrogen sources, L-Asparagine at N:P supply ratio of 75:1 and 100:1 gave the highest biomass concentration for the tested microalgal species. For chlorella sp. NITT 02, the DCW of 1.257 ± 0.003 g L−1 at N:P = 100:1 and 1.256 ± 0.005 g L−1 at N:P = 75:1 was obtained for L-Asaparagine, followed by urea (N:P = 100:1 → 0.842 ± 0.002 g L−1; N:P = 75:1 → 0.843 ± 0.004 g L−1). The DCW of Picochlorum sp. NITT 04 with L-Asparagine (N:P = 100:1 → 0.964 ± 0.026 g L−1; N:P = 75:1 → 0.965 ± 0.034 g L−1) and urea (N:P = 100:1 → 0.911 ± 0.012 g L−1; N:P = 75:1 → 0.908 ± 0.01 g L−1) was attained maximum than NaNO3. The systematic exploration of the interaction between N:P ratio and salinity towards lipid content enhancement were performed by RSM-CCD approach. The optimal N:P ratio of 1.4:0.6 and salinity of 7.5 ppt resulted in maximum lipid content of 49.252 ± 0.187 % for Chlorella sp. NITT 02 with the total FAME content of 93.49 %. For Picochlorum sp. NITT 04, the optimal N:P ratio of 1.4:0.6 and salinity of 24 ppt resulted in maximum lipid content of 49.717 ± 0.073 % with the total FAME content of 91.71 %. The FAME analysis confirms the use of tested microalgal species towards biodiesel production and concurrent use of residual biomass for biorefinery applications.

Avoiding overflow metabolite formation in Komagataella phaffii fermentations to enhance recombinant protein production

BackgroundKomagataella phaffii (K. phaffii), formerly known as Pichia pastoris, is a widely utilized yeast for recombinant protein production. However, due to the formation of overflow metabolites, carbon yields may be reduced and product recovery becomes challenging. This study investigates the impact of oxygen availability, different glucose concentrations and feeding strategies on overflow metabolite formation and recombinant protein production in K. phaffii.ResultsHigh glucose concentrations in batch fermentation, as applied in literature, lead to substantial ethanol accumulation, adversely affecting biomass yield and product formation. Increasing dissolved oxygen setpoints does not significantly reduce ethanol formation, indicating that glucose surplus, rather than oxygen availability, drives overflow metabolism. Decreasing the initial glucose concentration to 5 g/L and adapting the feeding strategy of the fed-batch phase, effectively mitigates overflow metabolite formation, improving biomass yield by up to 9% and product concentration by 40% without increasing process time.ConclusionsThese findings underscore the importance of a suitable glucose-feeding strategy in K. phaffii fermentation processes and highlight the detrimental effects of overflow metabolites on productivity. By optimizing carbon source utilization, it is possible to enhance fermentation efficiency and recombinant protein production with K. phaffii.

Microclimate and the spatio-temporal dynamics of natural production of two ectomycorrhizal fungi from the Guineo-Sudanian ecozone in Benin

The study aims to determine the relation between the micro-climate and the natural production of Amanita subviscosa, and Lactifluus gymnocarpoides, in the Guinea-Sudanian ecozone. Nine permanent plots of 50 ×50 m were installed in three different vegetations of the “Ouémé Supérieur” forest reserve in central Benin. The mycological surveys were carried out during three (3) mycological seasons, each from June to October at a frequency of two visits per week and per plot. The number of fruiting bodies and the fresh biomass were recorded. Microclimatic parameters (soil water content, air temperature, soil temperature, relative humidity and precipitation) were measured using a rain gauge and a HOBO micro station data logger installed at the middle of each plot. We tested several Generalized Linear Mixed Effects Models (GLMM) using the lme4 package to obtain the effect of recorded microclimate factor on the number of fruit bodies of each species and the Linear Mixed Effects Model (LMM) using the package nlme for fresh biomass. The study showed that soil water content is the main driver of fungal fruiting phenology and increased biomass production. The fruiting of A. subviscosa is positively affected by air temperature and soil water content (p = 0.0004) but negatively affected by relative air humidity. The fructification of L. gymnocarpoides is only positively affected by the air temperature and negatively affected by relative air humidity and soil water content. Soil water content significantly affects the fresh biomass of A. subviscosa (p≈0) while the fresh biomass of L. gymnocarpoides is significantly affected by soil water content and relative air humidity (p≈0). All species for their natural production have specific response at microclimate parameters variation.

Potential of a novel brine-struvite-based growth medium for sustainable biomass and phycocyanin production by Arthrospira platensis.

Nutrient recovery is crucial for sustainability as it helps to recycle valuable resources, reduce environmental pollution, and promote the efficient use of natural materials in various agricultural and industrial processes. The present study investigated the impact of using brine and struvite as sustainable nutrient sources on the growth and c-phycocyanin (C-PC) production by the cyanobacterium Arthrospira platensis. Three modified growth media were compared to the standard SAG-spirul medium under yellow-white light [YLT], and blue-white light [BLT]. In the modified medium BSI, a struvite solution was utilized to replace dipotassium phosphate, while diluted brine was used to replace NaCl and de-ionized H2O. For BSII, struvite and brine were used as in BSI, with elimination of the micronutrient from the solution. In BSIII, no other nutrient sources than bicarbonate-buffer were used in addition to struvite and brine. For each medium, A. platensis was cultivated and incubated under YLT or BLT till the stationary phase. The results showed that the combinations of brine and struvite did not have any significant negative impact on the growth rates in BSIII. However, adding struvite as a phosphorus source boosted C-PC production just as effectively as YLT, with boosting biomass yield, unlike when only BLT was used. In conclusion, the brine/struvite-based media resulted in high biomass productivity with higher C-PC yields, making it an ideal growth medium for commercial sustainable C-PC production.

Interactions between arbuscular mycorrhizal fungi and phosphate-soluble bacteria affect ginsenoside compositions by modulating the C:N:P stoichiometry in Panax ginseng.

The biomass production as well as the accumulation of secondary metabolites of plant is highly determined by the absorption of nutritional elements, in particular nitrogen (N) and phosphorus (P). Arbuscular mycorrhizal fungi (AMF) can absorb soluble P and transport it to plants, while phosphate solubilizing bacteria (PSB) can increase the content of solubilizing P in soil. Previous studies have identified the effects of either AMF or PSB inoculation on altering plant C:N:P stoichiometry, whether AMF interact with PSB in promoting plant growth and changing elemental concentration and composition of secondary metabolites by altering plant C:N:P stoichiometry remains ambiguous. In this study, we investigated the effects of inoculation of AMF, PSB, and their co-inoculation AMP (AMF and PSB) on the biomass growth, the C:N:P stoichiometry, the core microorganisms of rhizosphere soil, and the ginsenoside compositions of ginseng (Panax ginseng). The results showed that compared to control or single inoculation of AMF or PSB, co-inoculation of AMF and PSB significantly increased the AMF colonization rate on ginseng roots, increased the biomass of both above and under-ground parts of ginseng. Similarly, co-inoculation of AMF and PSB substantially increased the concentrations of N and P, reduced the ratios of C:P and N:P in the above-ground part of ginseng. The co-inoculation of AMF and PSB also increased concentrations of total ginsenosides and altered the compositions of ginsenosides in both the above and under-ground parts of ginseng. Analysis the rhizosphere microorganism showed that the co-inoculation of AMF and PSB recruited distinct core microorganisms that differ from the control and treatments with single inoculation of AMF or PSB. Our results suggested that PSB inoculation enhanced the positive effect of AMF in improving the absorption of nutrimental elements, altered the C:N:P stoichiometry and, ginsenosides concentration and composition of ginseng, influenced the plant rhizosphere microbial community. These findings offer valuable insights into enhancing plant biomass production and promoting secondary metabolites by improving the plant-fungi-bacterial relationships.

Integrated processes for olive mill wastewater treatment and its revalorization for microalgae culture.

The olive oil industry generates 30 million cubic meters of olive mill wastewaters (OMWWs) annually. OMWWs are a major environmental concern in the Mediterranean region due to their high organic matter content, suspended solids, unpleasant odor, and dark color. The application of primary treatments such as coagulation-flocculation, adsorption, and hybrid systems combining coagulation-flocculation with adsorption has enabled to remove part of the organic matter, color, turbidity, and growth-inhibiting compounds from OMWWs. Among these methods, the hybrid system combining activated carbon and chitosan has proven to be the best removal efficiency. Subsequently, secondary treatment involving the cultivation of Chlorella sp. on OMWWs pretreated with chitosan achieved the highest maximal specific growth rate (0.513 ± 0.022day⁻1) and biomass productivity (0.621 ± 0.021g/L/day). Notably, the fatty acids (FA) profile produced by Chlorella sp. cells grown under these conditions differed, underscoring the potential of OMWWs as a microalgal growth medium. This innovative approach not only addresses environmental issues but also opens new avenues for sustainable bioproducts.

Cover crop systems impact on biomass production, carbon-to-nitrogen ratio, forage quality, and soil health in a semi-arid environment

Cover cropping is a soil restorative strategy that can save degraded soils and offer additional benefits relative to the traditional fallow-based practice in semi-arid cropping systems. This study aimed to (i) quantify the above (shoot)- and belowground (root) biomass production, nutritive value, and tissue carbon and nitrogen concentrations from different annual cool-season cover crop systems, and (ii) determine their effects on soil organic carbon, total nitrogen, soil respiration, and soil microbial population biomass in a semi-arid environment. Treatments used were monocultures of annual ryegrass (Lolium multiflorum Lam.), oat (Avena sativa L.), faba bean (Vicia faba L.), yellow sweetclover [Melilotus officinalis (L.) Lam], winter pea (Pisum sativum L.), two three-species mixtures (Mix 1: annual ryegrass + faba bean + yellow sweetclover and Mix 2: Oat + faba bean + winter pea), and a fallow laid out in a randomized complete block design with three replications. Averaged across years, Mix 2 produced greater shoot biomass (9714 kg DM ha−1; SE = 699) than all other cover crop systems except, the monoculture of oat (7970 kg DM ha−1; SE = 699). The plant tissue C/N ratio of the mixtures and monoculture legumes was mostly similar (range = 19.4–29.1). Overall, legumes produced superior relative feed value (RFV; 112–161) compared to grass monocultures and mixtures (RFV; 80–95). Soil gram-negative bacteria biomass was greatest under the yellow sweetclover monoculture. Based on the results of this study, the mixed cover crop systems (Mix 1 and Mix 2) offered a better chance of fulfilling the dual role of soil health improvement and feed quality for livestock in this semi-arid environment.

Rehabilitation of a degraded acid Mediterranean soil after 11 years of by‐product calcium amendments and pasture improvement

AbstractThe clearing of natural vegetation and tillage for agricultural purposes makes acid soils highly vulnerable to degradation, resulting in significant losses of soil fertility and crop productivity. This work focused on nature‐based agricultural solutions to rehabilitate degraded acid soils in low‐resource systems. We studied after 6 and 11 years how the introduction of a legume‐rich pasture replacing a natural pasture or a tilled forage crop, with and without Ca‐amendment, contributed to recover the soil health, the fertility and the productivity of degraded Ultisols in Western Spain. Industrial by‐products, mainly sugar foam, were used as Ca‐amendment to promote circular economy. The Ca‐amendment factor influenced soil chemistry to 30 cm depth, while the type of soil use affected soil organic matter (SOM) to 15 cm; and both factors had positive effects on biomass productivity. Except for pH and Ca, no interaction between factors was found. Ca‐amendment increased nutrient availability and soil pH, and Al ion precipitated at 0–15 cm depth. As a result, biomass production increased by 35% relative to no Ca‐amendment. Forage cop produced 66% more biomass than pastures, but this increase did not translate into an increase in SOM. In fact, the legume‐rich pasture was the best option to recover soil organic C and N levels, earlier and deeper. Over the 11 years, the use of pastures and Ca‐amendment enhanced biomass production stability. Relative to natural, the improved pasture did not increase plant biomass but provided higher biomass stability and quality in terms of legume abundance, which was promoted when sugar foam was applied. Pastures also favoured key biological variable as earthworm's population, increasing it by four times with respect to forage crops. Compared to the non‐amended and unfertilized natural pasture out of the experiment, the use of improved pasture, followed by natural pasture, combined with sugar foam and fertilization enhanced soil health, soil fertility and biomass production stability. Thus, this solution has proven effective for restoring degraded acid soils, promoting diversity and mitigating climate change, while offering a more economically beneficial alternative.

Pilot plant cultivation of microalga Dictyosphaerium chlorelloides with night illumination from LEDs sources

Illumination during the night with white LEDs increased the growth of the microalga Dictyosphaerium chlorelloides strain CCALA 330 on a thin-film platform unit (150 L volume, 12 m2 area) approximately 2.5× in comparison to the platform illuminated only by the Sun. The mean PAR intensity on the Sun-illuminated unit was 71 μmol m−2 s−1, on the Sun + LEDs unit 549 μmol m−2 s−1, the mean temperatures were 15 °C and 20.1 °C. On the Sun unit the algae grew to a maximum of 15 g L−1 dry weight in 42 days, with Sun + LEDs into 17.8 g L−1 during 24 days when the both units reached the stationary phase of the growth curve. Biomass production was 3.3 in the Sun and 8.54 g m−2 d−1 in the Sun + LED, i.e. 0.27 and 0.68 g L−1 d−1. In total, the mean of 37.5 and 58.2 kWh per night were consumed, so the total electricity consumptions for biomass production was 0.20 and 0.40 kWh g−1 DW during LED + Sun cycles 1 and 2, respectively. The production of the extracellular polysaccharides was practically the same for both platforms, and constant during time. A more substantial double increase was only after 30 days of cultivation in both platforms and reached 4 g L−1. The fluorescence measurements proved good physiological state of the cultures. The PAR was found as a main driver of the photosynthetic activity. The correlation of the growth and fluorescence parameters to the environmental conditions was much more profound in the Sun pilot plant, therefore the reliable set of monitored parameters should be defined according to the cultivation type, for both of them we propose OD680/OD720 ratio as a proxy of nutrient deficiency.

Salinity as an Abiotic Stressor for Eliciting Bioactive Compounds in Marine Microalgae.

This study investigated the impact of culture medium salinity (5-50 PSU) on the growth and maximum photochemical yield of photosystem II (Fv/Fm) and the composition of carotenoids, fatty acids, and bioactive substances in three marine microalgae (Chrysochromulina rotalis, Amphidinium carterae, and Heterosigma akashiwo). The microalgae were photoautotrophically cultured in discontinuous mode in a single stage (S1) and a two-stage culture with salt shock (S2). A growth model was developed to link biomass productivity with salinity for each species. C. rotalis achieved a maximum biomass productivity (Pmax) of 15.85 ± 0.32 mg·L-1·day-1 in S1 and 16.12 ± 0.13 mg·L-1·day-1 in S2. The salt shock in S2 notably enhanced carotenoid production, particularly in C. rotalis and H. akashiwo, where fucoxanthin was the main carotenoid, while peridinin dominated in A. carterae. H. akashiwo also exhibited increased fatty acid productivity in S2. Salinity changes affected the proportions of saturated, monounsaturated, and polyunsaturated fatty acids in all three species. Additionally, hyposaline conditions boosted the production of haemolytic substances in A. carterae and C. rotalis.

Nuclear DNA Markers to Distinguish between Salix caprea, Salix gracilistyla, and Their Interspecific Hybrids

The Salix genus of the Salicaceae family has advantages such as rapid initial growth, a high germination rate, and asexual reproduction; therefore, it is used as a short-rotation energy crop for biomass production. The National Institute of Forest Science created new interspecific hybrid cultivars with superior biomass production by artificially interbreeding Salix caprea L. and Salix gracilistyla Miq. Identifying these hybrids during the seedling stage is challenging because their separate reproductive and vegetative growth stages necessitate prolonged observation of their morphological characteristics. Consequently, a reliable identification method is required to overcome these limitations. This study aimed to develop nuclear DNA markers to distinguish between S. caprea, S. gracilistyla, and their interspecific hybrids. An evaluation of 35 nuclear simple-sequence repeat (nSSR) markers in the Salix genus revealed two markers that distinguish these parent species and their hybrids. A sequence analysis confirmed the presence of insertion-deletion (InDel) regions within the nSSR markers that differed between S. caprea and S. gracilistyla. To effectively identify hybrids, a primer set comprising the InDel region, which exhibited only interspecies differences and no intraspecies differences, was developed. The results of this study will facilitate the genetic resource management of interspecific hybrids between S. caprea and S. gracilistyla, thus allowing for early identification and improved management of hybrids.

Municipal wastewater treatment using an innovative two-stage sequential microalgal co-cultivation system with different hydraulic retention time: A sustainable approach to circular economy

The present study proposes a sustainable circular bioeconomy approach for municipal wastewater (MWW) treatment, employing a sub-pilot two-stage sequential microalgal co-cultivation system (TSSCS), and evaluates the impact of hydraulic retention time (HRT) on MWW treatment efficiency, as well as biomass and biomolecule productivity. In the first stage of TSSCS, 2 ratios of Tetraselmis indica and one ratio of Picochlorum sp. (2TS:1PC) were used for the treatment of 75% raw MWW + 25% ASN-III, while in the second stage, 2PC:1TS was employed for the treatment of 50% 2TS:1PC effluent+ 50% ASN-III. At the end of the first and second stages of TSSCS, nutrient removal efficiencies were as follows: total nitrate (TN) was <80% and 90% on HRT-10 and HRT-12; total phosphate (TP) was <85% and 95% on HRT-16, and chemical oxygen demand (COD) was <75% and <85% on HRT-14 and HRT-10, respectively. In the TSSCS, 2TS:1PC (S1) and 2PC:1TS (S2) showed maximum biomass productivity of 2.65 and 2.78g/L on /L on HRT-14 and HRT-12, respectively. Additionally, biomass of 2TS:1PC (S1) and 2PC:1TS (S2) contains lipid content (38.67 and 40.67%), β-carotene (4.09 and 3.00mg/g), and astaxanthin (0.69 and 0.31mg/g), respectively.

Influence of bio-stimulants on biomass production, soil properties and nutrient uptake by chilli (Capsicum annuum L.)

Influence of bio-stimulants on biomass production, soil properties and nutrient uptake by chilli (Capsicum annuum L.)

MADS-box transcription factors as green-revolution regulators for plant longevity and biomass production

MADS-box transcription factors as green-revolution regulators for plant longevity and biomass production

Carbon stock assessment of a reforestation site within Mt. Arayat protected landscape, Pampanga, Philippines

The Philippines has very few studies in terms of biomass production and carbon stocks in reforestation sites and the level of emission that has been avoided due to forest protection activities. Most of carbon stock estimates being used in the country are based on secondary data or studies in other countries using the same species. The study aimed to provide a reliable assessment on the contribution of reforestation sites in biomass production and carbon stocks and the potential of these plantation to contribute to the climate change mitigation efforts in the Philippines. The guideline prepared by the Philippines’ Department of Environment and Natural Resources – Forest Management Bureau (DENR-FMB) in 2021 on Forest Resources Assessment (FRA) which follows the manual of Food and Agriculture Organization of the United Nations (FAO) Forestry Department in conducting FRA was used during data collection. A tract was established in the southern portion of the reforestation site wherein the species planted in 2012 are already very prominent and their diameter at breast height (DBH) and total height were measured and their corresponding wood specific gravity were taken into account. Carbon stocks were estimated using Chave et al.’s and Brown’s allometric equations. The estimated carbon stocks using Chave et al.’s formula is 542.3 tC/ha while the estimated carbon stock using Brown’s formula is 2001.6 tC/ha. The results of computation using Brown’s equation are considerably higher than the results using Chave et al.’s equation considering that Brown’s equation only took into consideration the DBH of trees while Chave et al.’s equation included the height and wood specific gravity of each species. The study demonstrated how important our forests in terms of their roles as carbon sinks and therefore contribute to our country’s efforts in climate change mitigation.

The spatiotemporal stability of plant diversity is disconnected from biomass stability in response to human activities in a South American temperate grassland

Human activities alter biomass, nutrient availability, and species dominance in grasslands, impacting their richness, composition, and biomass production. Stability (invariability in time or space) can inform the predictability of plant communities in response to human activities. However, this measure has been simplistically analyzed for temporal (interannual) changes in live biomass, disregarding their spatial stability and the temporal stability of other plant community attributes. Moreover, the simultaneous analysis of temporal and spatial stabilities of plant communities has been scarcely assessed. Here, we test how biomass removal and nutrient addition simultaneously modify the temporal and spatial stabilities of plant richness (α diversity), composition dissimilarity (β diversity), aboveground live biomass, and the role of plant species dominance in the stability responses. We conducted a factorial experiment of biomass removal (grazing, mowing, or intact -no removal-) and nutrient addition (unfertilized or fertilized with nitrogen, phosphorus, and potassium) in a temperate grassland of Argentina, South America. We replicated the experiment in 6 blocks over 10 years to estimate the temporal and spatial stabilities of the plant community. The spatiotemporal stability of plant richness and composition dissimilarity decreased in the intact grassland, while the temporal stability of live biomass increased, compared to the grazed and mowed grasslands. Nutrient addition reduced the spatiotemporal stability of live biomass and the spatial stability of plant richness. The stability of species richness as well as that of composition dissimilarity was negatively associated with plant dominance, while the live biomass stability was not. Our results suggest that simplifying the effect of biomass removal and nutrient addition on grassland stability is not feasible, as plant diversity stability responses are not surrogates for biomass stability. The contrasting spatiotemporal stability responses of plant diversity and biomass represent a step forward in predicting human activities' impact over time and across space in temperate grasslands.