Modelling of forest carbon dynamics in different forest management scenarios: A case study on poplar and black locust plantations in Hungary

Comparison of litterfall production and leaf litter decomposition between an exotic black locust plantation and an indigenous oak forest near Yan’an on the Loess Plateau, China

Purpose: The aim of the study was to investigate the study of carbon sequestration in forest ecosystems in DRC. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: Research on carbon sequestration in DRC's forests underscores their crucial role as significant carbon sinks. These forests store substantial amounts of carbon in biomass and soils, contributing significantly to global climate regulation efforts. However, challenges like deforestation and illegal logging threaten this capacity, highlighting the importance of sustainable forest management and conservation. Enhancing carbon sequestration in DRC's forests is essential for mitigating climate change impacts and preserving biodiversity. Unique Contribution to Theory, Practice and Policy: Ecological succession theory, resource allocation theory & social-ecological systems theory may be used to anchor future studies on the study of carbon sequestration in forest ecosystems in DRC. Encourage the adoption of sustainable forestry practices that enhance carbon sequestration while supporting biodiversity conservation and local livelihoods. Align forest management policies with national and international climate change mitigation goals, emphasizing the role of forests as natural carbon sinks.

Groundwater uptake of vegetation in discharge regions is known to play an important role, e.g., in the Hungarian Great Plain. Nevertheless, only little detailed monitoring of water table fluctuations and groundwater uptake (ETgw) were reported under varying hydrologic conditions and vegetation cover. In this study, results of water table monitoring under forest plantations and adjacent corn plots in discharge and recharge regions were analyzed to gain better understanding of the relation of vegetation cover to groundwater uptake. A poplar (Populus tremula) plantation and adjacent corn field plot were surveyed in a local discharge area, while a black locust (Robinia pseudoacacia) plantation and adjacent corn field plot were analyzed in a recharge area. The water table under the poplar plantation displayed a night-time recovery in the discharge region, indicating significant groundwater supply. In this case an empirical version of the water table fluctuation method was used for calculating the ETgw that included the groundwater supply. The mean ETgw of the poplar plantation was 3.6 mm day-1, whereas no water table fluctuation was observed at the nearby corn plot. Naturally, the root system of the poplar was able to tap the groundwater in depths of 3.0-3.3 m while the shallower roots of the corn did not reach the groundwater reservoir in depths of 2.7-2.8 m. In the recharge zone the water table under the black locust plantation showed step-like changes referring to the lack of groundwater supply. The mean ETgw was 0.7 mm day-1 (groundwater depths of 3.0-3.2 m) and similarly no ETgw was detected at the adjacent corn plot with groundwater depths between 3.2 and 3.4 m. The low ETgw of the young black locust plantation was due to the lack of groundwater supply in recharge area, but also the shallow root system might have played a role. Our results suggest that considerations should be given to local estimations of ETgw from water table measurements that could assist to better understanding of groundwater use of varying vegetation types in recharge and discharge zones.

The restoration effects of black locust (Robinia pseudoacacia L) plantation on surface soil properties and carbon sequestration on lower hillslopes in the semi-humid region of Coruh Drainage Basin in Turkey

The black locust (Robinia pseudoacacia L.) is an important tree species not only for the vegetation rehabilitation but also for the photosynthetic carbon dynamics on the Loess Plateau. Slope aspect and stand age play important roles in the photosynthesis of the black locusts. To investigate the photosynthetic carbon fixation capacity (PCFC) of the juvenile and mature black locusts located on the sunny and shady slopes, we have analyzed the capacity and daily dynamics of photosynthesis of the whole canopy of juvenile (6-year-old) and mature (18-year-old) black locusts located on the sunny (southeast facing) and shady (northwest facing) slopes. Mature plantations on the sunny slopes have lower average daily E, VPD, CE, A n, LAI and PCFC than those on the shady slopes. Juvenile plantations have higher average daily g s, E, C i/C a, CE, A n and PCFC compared to the mature plantations. It is concluded that the lower average daily A n and PCFC of the mature black locust plantations on the sunny slopes may be due to variations in the microclimatic conditions between sunny and shady slope aspects. The higher average daily A n and PCFC of the juvenile black locust plantations are likely associated with stand age-related differences in tree sizes.

A disconnect between O horizon and mineral soil carbon – Implications for soil C sequestration

The many opportunities for mitigating atmospheric carbon emissions in developing countries include reforesting degraded lands, implementing sustainable agricultural practices on existing lands and slowing tropical deforestation. This analysis shows that over the next 10 years, 48 major tropical and subtropical developing countries have the potential to reduce the atmospheric carbon burden by about 2.3 billion tonnes of carbon. Given a central price of $10 per tonne of carbon and a discount rate of 3%, this mitigation would generate a net present value of about $16.8 billion collectively for these countries. Achieving these potentials would require a significant global effort, covering more than 50 million hectares of land, to implement carbon-friendly practices in agriculture, forest and previously forested lands. These estimates of host-country income potentials do not consider that outside financial investment may or may not be available. Our calculations take no account of the additional benefits of carbon sequestration in forest soils undergoing reforestation, increased use of biomass and reduced use of fossil-fuel inputs and reduced agricultural emissions. In all events, realizing these incomes would necessitate substantially greater policy support and investment in sustainable land uses than is currently the case.

Carbon sequestration occurs when cultivated soils are re-vegetated. In the hilly area of the Loess Plateau, China, black locust (Robinia pseudoacacia) plantation forest and grassland were the two main vegetation types used to mitigate soil and water loss after cultivation abandonment. The purpose of this study was to compare the soil carbon stock and flux of these two types of vegetation which restored for 25 years. The experiment was conducted in Yangjuangou catchment in Yan’an City, Shaanxi Province, China. Two adjacent slopes were chosen for this study. Six sample sites were spaced every 35–45 m from summit to toe slope along the hill slope, and each sample site contained three sampling plots. Soil organic carbon and related physicochemical properties in the surface soil layer (0–10 cm and 10–20 cm) were measured based on soil sampling and laboratory analysis, and the soil carbon dioxide (CO2) emissions and environmental factors were measured in the same sample sites simultaneously. Results indicated that in general, a higher soil carbon stock was found in the black locust plantation forest than that in grassland throughout the hill slope. Meanwhile, significant differences in the soil carbon stock were observed between these two vegetation types in the upper slope at soil depth 0–10 cm and lower slope at soil depth 10–20 cm. The average daily values of the soil CO2 emissions were 1.27 μmol/(m2·s) and 1.39 μmol/(m2·s) for forest and grassland, respectively. The soil carbon flux in forest covered areas was higher in spring and less variation was detected between different seasons, while the highest carbon flux was found in grassland in summer, which was about three times higher than that in autumn and spring. From the carbon sequestration point of view, black locust plantation forest on hill slopes might be better than grassland because of a higher soil carbon stock and lower carbon flux.

Plant nitrogen (N) and phosphorus (P) resorption is an important strategy to conserve N and P in the face of nutrient limitation. However, little is known about the variation of N and P resorption efficiency (NRE and PRE) and their correlation with leaves and soil C:N:P stoichiometry in black locust forests (Robinia pseudoacacia L.) of different ages. In this study, we measured C, N, and P concentrations in soil, green leaves, and senesced leaves from black locust forests of different ages (i.e, 10-, 20-, 30-, 36-, and 45-year-old), and calculated the NRE, PRE, and C:N:P stoichiometry ratios. The NRE and PRE tended to increase and then decrease with stand age, ranging from 46.8% to 57.4% and from 37.4% to 58.5%, with averages of 52.61 and 51.89, respectively. The PRE:NRE decreased with increased stand ages. The C:P and N:P of soil and green leaves increased with stand ages, indicating the increase of P limitation. In the senesced leaves, C:P and N:P were lower than in green leaves and first increased and then decreased with stand age. The PRE was significantly negatively correlated with the C:P and N:P of soil and green leaves. The NRE was significantly correlated with the C concentration of green leaves, P of the senesced leaves, and C:N. Results suggested that the NRE and PRE responded differently to soil and plant nutrients in black locust forests of different ages. In addition, the black locust plantations would alter the conservation and use strategy of nutrients in the ecosystem through a plant-mediated pathway. Future studies should elucidate the central nutrient utilization strategy of black locust in response to a nutrient-poor environment and determine how it is involved in regulating nutrient resorption.

The effects of restoration on soil properties in degraded land in the semi-arid region of Turkey

Changes in arbuscular mycorrhizal fungal attributes along a chronosequence of black locust (Robinia pseudoacacia) plantations can be attributed to the plantation-induced variation in soil properties

Soil moisture plays an important role in vegetation restoration and ecosystem rehabilitation in fragile regions. Therefore, understanding the soil water dynamics and water budget in soil is a key target for vegetation restoration and watershed management. In this study, to quantitatively estimate the water budget of the GFGP forests in a dry year and a wet year and to explore the recharge in deep profiles, the vertical and temporal soil moisture variations in a black locust (Robinia pseudoacacia) plantation were simulated under typical rainfall events and two-year cycles in a loess area between April 2014 and March 2016. We calibrated and tested the HYDRUS-1D (Salinity Laboratory of the USDA, California, USA) model using the data collected during in situ field observations. The model’s performance was satisfactory, the R2, Nash efficiency coefficient (NSE), root mean square error (RMSE), and mean absolute error (MAE) were 0.82, 0.80, 0.021, and 0.030, respectively. For the four rainfall events of 9.1 mm, 25 mm, 71.1 mm, and 123.6 mm, the infiltration amounts were 8.1 mm, 19.3 mm, 65.2 mm, and 95.3 mm, respectively. Moreover, the maximum infiltration depths were 30 cm, 100 cm, 160 cm, and >200 cm, respectively. Additionally, in the two-year model cycles, the upward average water flux was 1.4 mm/d and the downward water flux was 1.69 mm/d in the first-year cycle; the upward average annual water flux was 1.0 mm/d and the downward water flux was 1.1 mm/d in the second-year cycle. The annual water consumption amounts in the two-year cycles were 524.6 mm and 374.2 mm, and the annual replenishment amounts were 616.8 mm and 401 mm. The amounts of percolation that recharged the deep soil were only 28.1 mm and 2.04 mm. A lower annual rainfall would cause a water deficit in the deep soil, which was not conducive to the growth of Robinia pseudoacacia vegetation. To ensure the high-quality sustainable development of the forest land, it is suggested to adjust the stand density in a timely manner and to implement horizontal terraces to increase the infiltration and supply of precipitation. Our study provides an improved understanding of the soil water movement in Robinia pseudoacacia plantations and a simulated temporal moisture variation under different time scales. The results of our study provide a feasible approach for the sustainable management of Robinia pseudoacacia plantations during vegetation restoration.

This study presents a static model of mixed black locust (Robinia pseudoacacia L.) plantation stand structures for inventory stand structures between 10 and 40 years of age. Due to its local character, the model can be advantageous in planning tending operations, making structural factor predictions for the standing stock (main stand) after tending cuts, and preparing local wood production and silvicultural models. The model data presented in this paper show that poplars account for 55–62 % of the volume per hectare due to their faster growth rate in mixed black locust and poplar plantations. Maintaining the black locust part of the stand necessitates harvesting the poplars by the age of 10 at the latest.

Poplar and black locust plantations are widely used for production of raw materials for biofuel. In this study, the main characteristics affecting energy content were evaluated for 2-year-old plantations obtained from 3 different sites of various qualities were evaluated. The ‘I-214’ poplar and the black locust had smaller (16 to 21%) bark ratios, while the ‘Kopecky’ poplar had a higher (22 to 26%) bark gain yield. The black locust had a higher basic density than that of the poplars, which were wood (446 kg/m3) and bark (402 kg/m3). The higher heating value of the bark of the black locust (19.51 to 19.59 MJ/kg) and of the ‘Kopecky’ (19.58 to 19.86 MJ/kg) was greater than that of the wood; in the case of the ‘I-214’ (19.59 to 19.81 MJ/kg), the higher heating value of the wood was higher. The ash content of the bark (4.50 to 8.22%) was several times greater in the case of poplars and black locust than that of the wood (0.46 to 1.29%). In the case of the wood, the ash content increased by the degradation of the site's quality. There were remarkable differences between the black locust and the poplars, as well as the individual poplar clones among the main energetic characteristics.

At the beginning of the 1970’s, two fertilization experimental areas were established in Gödöllő. After different long-term fertilization treatments, sessile oak (Quercus petraea) and black locust (Robinia pseudoacacia) plantations were planted in the second half of the 1990’s. In the present research, the effects of former fertilization were studied in these two different forests, with the help of soil Collembola communities as indicators. Soil cores and litter samples were collected from the chosen 30 plots to determine the most important soil parameters and to extract Collembola specimens. According to the results, soil organic carbon (SOC), AL-P2O5 and AL-K2O contents were significantly higher in the two highest-dose treatments of the sessile oak plantation compared to the control. In the black locust plantation, only AL-P2O5 content differed significantly in the second highest-dose treatment when compared to the control. Among the two plantations significant differences can be observed in almost every parameter, except for AL-K2O and nitrogen content. The effects of former fertilizer application are reflected in occasional differences in total Collembola abundance, species richness and diversity, mostly related to the treatments with the highest doses. Due to the relatively young age of the plantations, very few typical forest Collembola species were observed, while species characteristic for open habitats are still predominant. The higher SOC content in the black locust plots is well reflected in the higher Collembola abundance compared to the sessile oak plots. Nevertheless, species richness, diversity and equitability were higher in the plantations of the native sessile oak.