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Carbon Accumulation Potential from Natural Forest Regrowth of Godech Municipality, Western Bulgaria

Grigorov Borislav

Civil and Environmental Engineering Reports

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2021

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Vol. 31, no. 1

192--199

EN

The present research deals with carbon sequestration, as an important process for mitigating the effects of climate change. The investigation focuses on a 30-year period and it covers only aboveground biomass that builds up from natural forest regrowth, excluding any plantation techniques. Potential carbon sequestration rate from natural forest regrowth in Godech Municipality was measured in Mg C ha⁻¹ yr⁻¹ and the resolution of the map was 1x1 km. The results of the study display that carbon accumulation values in the researched area were consistent with those that were expected in the largest parts of Bulgaria. The biggest share of Godech Municipality falls within the range of 0.82 – 0.96 Mg C ha⁻¹ yr⁻¹ with restricted areas around the villages of Barlya, Smolcha, Gubesh, Murgash and Varbnitsa that may accumulate between 0.96 – 1.11 Mg C ha⁻¹ yr⁻¹. In conclusion, carbon accumulation only from natural forest regrowth provides representative information, however it would have been better if different plantation techniques were regarded as well. The successful results of the investigation should encourage other studies of this type in the neighbouring municipalities.

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The relationships between aboveground biomass and Voronoi area of coexisting species in an old-field community

Du F., Xu X., Zhang X., Sui Y., Shao M., Hu L., Shan L.

Polish Journal of Ecology

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2012

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Vol. 60, nr 3

479-489

EN

Voronoi area of coexisting species in a community has an important role in determining their performances as it is related with the available resources around individuals. Biomass formed within certain Voronoi area probably can be a mark of species that characterised resource competition ability of coexisting species in natural community. In this article, we tried to probe the subject in the following three aspects: 1) what is the apparent relationship between individuals' aboveground biomass and their available Voronoi area for species in natural community? 2) what is the possible theoretic relationship between them? 3) additionally, whether there are any possible indices that can be elicited from species' occupied Voronoi area to reflect species' competitive ability. Using individual-based investigation of aboveground biomass and their corresponding positions, Voronoi area of all individuals of coexisting species in an old field community were computed. The growth of an individual could be regard as a process to compete for resources that is limited by the available area or volume encompassed by the neighborhood individuals. We extended logistic growth model to describe the relationship between Voronoi area and aboveground biomass of coexisting species by relating limiting rhizospheral resource with the Voronoi area around an individual. Theoretically, the individuals aboveground biomass is also controlled by factor-ceiling effects of Voronoi area. So the extended model was fitted with boundary analysis method. And also, their linear relationship was fitted. Under the prediction that competive ability is one of the main driving factors of community succession, two parameters as the Voronoi area of coexisting species and the Voronoi area per unit of aboveground biomass were used to check whether they can designate species' competitive abilities and competitive hierarchies. This was presented by fitting the two parameters with the successional niche positions that was represented by the ordination values along abandonment ages of old field communities in the local area. The results showed that: 1) For most species, the linear regression demonstrated that Voronoi area of an individual that occupied larger Voronoi area tended to have greater aboveground biomass. The nonlinear regression of showed that the relationship might depend upon species' growth characteristics, like shade tolerance and root proliferation. Generally, the relationship could be better fitted by the extended logistic growth model using boundary analysis method than by the linear regression, except for some shade-preferring or clone species. If factor-ceiling effects were considered, at the highest, about 48% of the variation of aboveground biomass could be interpreted by Voronoi area. For some other species with light preference or clone proliferation, the determination coefficient was around zero. 2) Species. averaged Voronoi area had significant and positive Kendall's tau-b and Spearman correlations with successional niches, and species' per-unit aboveground biomass positions of Voronoi area has significantly negative rank correlation with successional niche positions. These indicate that both of them can reflect species' competitive ability and hierarchy to some extent.

3

Relationship between seed size and plant abundance in an alpine meadow of the Qinghai-Tibetan Plateau

Liu B., Luo Y.

Polish Journal of Ecology

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2009

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Vol. 57, nr 3

573-579

EN

Theoretical and field studies on seed size and plant abundance relationship have been conducted in various communities. However, inconsistent patterns have emerged from these studies, and still little is known about alpine meadows. Here we identified four models and their predictions: the seed size/number trade-off model (SSNTM), the succession model (SM), the spatial competition model (SCM), and the triangle model (TM), in order to assess the relationship between seed size and abundance in alpine meadows, and to elucidate underlying mechanisms. The study site was situated on the eastern Qinghai-Tibetan Plateau at 3500 m above sea level. From 1999 through 2001, two indices of plant abundance (aboveground biomass and density) were simultaneously measured in 45 quadrates (0.25 m[^2]). Data for 101 plant species (mostly Cyperaceae, Poaceae, Asteraceae, Ranunculaceae and forbs) showed that seed size is like log normal distributed, and it slightly skewed in smaller-sized seeds. The SSNTM, the TM, the SM and the SCM models were not supported in this alpine meadow, and the relationship between seed size and abundance was always positive (although in some samples, the relationship was not significant). The positive correlation between seed size and abundance observed for some grassland communities was also demonstrated in the alpine meadow. It suggests that seed size depends on the plant growth form, but the biomass-density relationship is inconsistent with previous studies. This suggests that the measure of abundance used in these studies is not the only reason for inconsistency of seed size.

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Invariant allometric relationship between aboveand below-ground biomass along a moisture gradient in North-West China

Cheng D., Wang G., Tang Q., Li T., Zhong Q.

Polish Journal of Ecology

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2009

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Vol. 57, nr 4

669-675

EN

Biomass allocation pattern is an important plant characteristic which influences how plants respond to abiotic and biotic heterogeneity. Prior studies indicate that above-ground biomass scales nearly isometrically with respect to below-ground biomass regardless of environment or phyletic affinity. However, such rule has been mostly tested with data on trees and usually without drought stress. Given the importance of this predicted relationship, it should be evaluated for a wider range of species and environmental conditions. Variations of the above- and belowground biomass (M[A] and M[R], respectively) were determined from five sites in north-west China, which compose a natural moisture gradient (aridity index ranging from 0.95 to 1.98). Model Type II regression protocols were used to compare the numerical values of M[A] vs M[R] scaling exponents (i.e. slopes of log-log linear relationships). The resulting five scaling exponents were indistinguishable and had a similar, nearly isometric slope (i.e. M[A] [is proportional to] M[R] [is approximately equal to] 1.0). Significant variation was observed in the Y-intercepts of the five regression curves, because of the absolute differences in M[A] or M[R]. These results support prior allometric theory, which reveals an isometric relationship between above- and below-ground biomass, and may provide a suitable method to estimate the regional below-ground biomass based on the direct aboveground measurements.