Betula pendula Ssp. distribution and growth in the sub-Carpathian curvature

Birch ssp. in the sub-Carpathians curvature can be found in composition with beech and other resinous species, unevenly distributed from the mountain peaks at around 1200 m down to 500-600, mainly from high hills to depressions at 600m, rarely seen on plain sites, crossing different geomorphological structures and overall accounting for 3857.1 ha. The main objective of the paper was to analyze the site and stand characteristics of Betula pendula ssp. Roth. in the subCarpathians curvature as followed: stand structure, stand types and stand site types, soils and different metrics, from growth to yields and its connectivity.The ecological adaptability to climate and soil and early fast growth, makes silver birch fulfill the overall requirements as a pioneer species, mostly naturally regenerated. Birch distribution is highly influenced by stand structure having low proportion in compositions, mean height of 15 m at age 50, and a diameter of 20m. Regarding the site, characteristics are more commonly found on fertile soils, corrugated or fragmented site type with a slope of 20-50° and it is distributed as secondary species in stands, averaging 750m in attitude, ranging from 500 to 1200m, 90% being in mixtures with other species with a mean annual increment of approximately 7 m³/year/ha regardless of stand site type. As an early successional species, it serves as a first colonizer but secondary species and quite often as an ecological instrument to improve the soil characteristics, biodiversity and prevent landslides in certain sites, lacking economic value other than fuel wood or other non-wood products.

Investigations of plant subfossil cuticles at a Holocene raised bog complex, northern New Zealand

<p>Subfossil plant cuticles, the very resistant waxy layer covering vascular land plants, are a neglected source of information in peat studies, despite their high preservation and identification potential. A lack of standardised methods and reference material are major contributing factors. In this thesis, a new method is introduced to test if subfossil plant cuticles from Moanatuatua Bog in the northern North Island of New Zealand can give a robust reconstruction of local bog surface vegetation changes during the Holocene. The method was successfully established and applied at coarse sampling resolution to show vegetation changes across the full length of the core and at fine sampling resolution around charcoal layers to reconstruct the post-fire response pattern of the main plant species on the bog. Additionally, bulk density and organic matter analyses were carried out to provide further insight into these changes. At the core site, towards the southern margins of Moanatuatua Bog, swamp forest had developed by 15000 cal yr BP. Until ca. 10500 cal yr BP, the vegetation assemblage was sedge-dominated, indicating swamp and/or fen conditions. A significant increase in macroscopic charcoal particles coincided with the transition to a more diversified vegetation composition. At around 4500 cal yr BP, the vegetation became restiad-dominated, indicating full raised bog conditions. The coarse resolution cuticle results were further compared to a pollen record from the same sequence, which was established independently. This comparison showed that plant subfossil cuticles can provide additional information to pollen analysis in cases where pollen is hard to identify or poorly preserved. Specifically, restiad pollen is hard to differentiate, yet cuticles of Empodisma and Sporadanthus have very distinct features. Also, Cyperaceae pollen is very poorly preserved at Moanatuatua Bog and the Cyperaceae pollen curve shows a poor match with the Cyperaceae cuticle record. It is suggested therefore that Cyperaceae pollen at this site – and potentially other peat sites – is a less reliable indicator of local sedge communities than a Cyperaceae cuticle record. At fine resolution, results were blurred across a time interval that was marginal for reconstructing response patterns due to the constraints imposed by sampling resolution and peat accumulation rate of Moanatuatua Bog. Nevertheless, two out of three charcoal layers recorded a local fire on the bog surface, with one layer displaying the expected vegetation response. After the fire, Empodisma, as a mid-successional species, re-established on the bog surface before Sporadanthus, a late-successional species. The other layer was dominated by sedges and showed no response pattern, as is to be expected due to the very fast recovery of sedges. In general, sample preparation for cuticle analysis proved to be fast with relatively little equipment or chemicals needed. With detailed reference material, identification to species level is possible due to distinctive and pronounced cuticle features. Plant cuticle analysis is therefore proposed to be a reliable tool to reconstruct long-term and short-term vegetation changes from peat sequences.</p>

Investigations of plant subfossil cuticles at a Holocene raised bog complex, northern New Zealand

<p>Subfossil plant cuticles, the very resistant waxy layer covering vascular land plants, are a neglected source of information in peat studies, despite their high preservation and identification potential. A lack of standardised methods and reference material are major contributing factors. In this thesis, a new method is introduced to test if subfossil plant cuticles from Moanatuatua Bog in the northern North Island of New Zealand can give a robust reconstruction of local bog surface vegetation changes during the Holocene. The method was successfully established and applied at coarse sampling resolution to show vegetation changes across the full length of the core and at fine sampling resolution around charcoal layers to reconstruct the post-fire response pattern of the main plant species on the bog. Additionally, bulk density and organic matter analyses were carried out to provide further insight into these changes. At the core site, towards the southern margins of Moanatuatua Bog, swamp forest had developed by 15000 cal yr BP. Until ca. 10500 cal yr BP, the vegetation assemblage was sedge-dominated, indicating swamp and/or fen conditions. A significant increase in macroscopic charcoal particles coincided with the transition to a more diversified vegetation composition. At around 4500 cal yr BP, the vegetation became restiad-dominated, indicating full raised bog conditions. The coarse resolution cuticle results were further compared to a pollen record from the same sequence, which was established independently. This comparison showed that plant subfossil cuticles can provide additional information to pollen analysis in cases where pollen is hard to identify or poorly preserved. Specifically, restiad pollen is hard to differentiate, yet cuticles of Empodisma and Sporadanthus have very distinct features. Also, Cyperaceae pollen is very poorly preserved at Moanatuatua Bog and the Cyperaceae pollen curve shows a poor match with the Cyperaceae cuticle record. It is suggested therefore that Cyperaceae pollen at this site – and potentially other peat sites – is a less reliable indicator of local sedge communities than a Cyperaceae cuticle record. At fine resolution, results were blurred across a time interval that was marginal for reconstructing response patterns due to the constraints imposed by sampling resolution and peat accumulation rate of Moanatuatua Bog. Nevertheless, two out of three charcoal layers recorded a local fire on the bog surface, with one layer displaying the expected vegetation response. After the fire, Empodisma, as a mid-successional species, re-established on the bog surface before Sporadanthus, a late-successional species. The other layer was dominated by sedges and showed no response pattern, as is to be expected due to the very fast recovery of sedges. In general, sample preparation for cuticle analysis proved to be fast with relatively little equipment or chemicals needed. With detailed reference material, identification to species level is possible due to distinctive and pronounced cuticle features. Plant cuticle analysis is therefore proposed to be a reliable tool to reconstruct long-term and short-term vegetation changes from peat sequences.</p>

Understanding the Long-Term Impact of Bamboos on Secondary Forests: A Case for Bamboo Management in Southern Brazil

As secondary forests become more common around the world, it is essential to understand successional pathways to ensure their proper forest management. Despite optimism about secondary forests in terms of landscape restoration, the influence of invasive species on their development has been poorly explored. Here, forest plots in the Araucaria Forest, Southern Brazil, are used to compare forest dynamics over a 14-year period between unmanaged bamboo forest development (control) and the removal of bamboo. Six control plots (15 × 15 m) were monitored for all adult trees since 2007 alongside six adjacent removal plots; after the initial measurement of the control in 2007, all plots were measured bi-annually from 2010 to 2020. Comparisons were based on tree species diversity, composition, and structure parameters. Removal plots show a trend towards developing a forest composition with more secondary and late successional species while the control plots demonstrate succession restricted to the pioneer trees that regenerated immediately after bamboo die-off (2005–2006). Without the presence of bamboos, removal plots are mirroring the well-known successional pathway typical of the Araucaria Forest. Conversely, bamboos are effectively arresting successional development in the control, resulting in lower levels of diversity and less complex forest structure. For the first time, this study presents a direct analysis of the influence of bamboos on forest succession, providing evidence on which practices to manage bamboo forests can be developed so these secondary forests can fulfill their ecological and economic potential.

Effects of Elevated CO2 and Nitrogen Loading on the Defensive Traits of Three Successional Deciduous Broad-Leaved Tree Seedlings

To elucidate changes in the defensive traits of tree seedlings under global environmental changes, we evaluated foliar defensive traits of the seedlings of successional trees, such as beech, oak, and magnolia grown in a natural-light phytotron. Potted seedlings were grown under the combination of two CO2 concentrations (360 vs. 720 ppm) and two nitrogen (N) treatments (4 vs. 15 kg N ha−1 yr−1) for two growing seasons using quantitative chemical analyses and anatomical method. We hypothesized that the effects of CO2 and N depend on the successional type, with late successional species providing greater defense of their leaves against herbivores, as this species exhibits determinate growth. Beech, a late successional species, responded the most to both elevated CO2 concentration (eCO2) and high N treatment. eCO2 and low N supply enhanced the defensive traits, such as the high leaf mass per area (LMA), high carbon to N ratio (C/N ratio), and increase in the concentrations of total phenolic and condensed tannin in agreement with the carbon–nutrient balance (CNB) hypothesis. High N supply decreased the C/N ratio due to the high N uptake in beech leaves. Oak, a mid–late successional species, exhibited different responses from beech: eCO2 enhanced the LMA, C/N ratio, and concentration of total phenolics of oak leaves, but only condensed tannin increased under high N supply. Magnolia did not respond to all treatments. No interactive effects were observed between CO2 and N supply in all species, except for the concentration of total phenolics in oak. Although the amounts of phenolic compounds in beech and oak varied under eCO2 and high N treatments, the distribution of these compounds did not change. Our results indicate that the changes in the defensive traits of forest tree species under eCO2 with N loading are related to the successional type.

Dynamics of natural regeneration after disturbance in a remnant of Mixed Ombrophilous Forest in southern Brazil

This study evaluated changes in the structure for remnant Mixed Ombrophilous Forest recovering from logging, which ceased over 40 years ago. Regarding the dynamics of the floristic composition of natural regeneration, 18 species remained (23.38% of the total) and 27 new species entered (35.06% of the total). The greatest increases were observed for Allophylus edulis, Myrsine umbellata, and Miconia cinerascens. When analyzing the dynamics of regeneration in ecological groups, it was observed that pioneer species had a similar value in both surveys (29.4% and 29.6%); secondary species decreased from 56.6% to 52.8%, and late-successional species increased from 0.2% to 6.0%. Therefore, the forest fragment studied is in a healing phase after disturbance, characterized by the increased regeneration of pioneer species as a result of sufficient light entering the interior of the forest.

Melinis repens (natal redtop).

Melinis repens, commonly known as Natal grass, is a short-lived perennial grass native to South Africa, the Arabian peninsula, India, the Seychelles island and Canary Islands. It is already widely distributed in tropical and subtropical regions due to its long use as a pasture grass and ornamental plant. Although considered a weed in many countries, it is not currently regulated. Wind disperses the seeds locally and long distance dispersal happens through the plant and seed trade. It mainly occurs in disturbed areas such as along roadsides and railway lines, but it can spread into natural areas interfering with early successional processes. It is mainly considered invasive in natural grasslands and shrublands. Holm et al. (1979) list it as a 'serious' weed in Australia, Brazil and Ghana, and 'principal' in Malaysia and Zambia. The dry biomass of the plant leads to an increase in fire frequencies and its dense growth crowds out native early successional species. Currently the main uses promoted for the plant are for reclaiming mined sites and planting as an ornamental plant.

Geodiversity of proglacial areas and implications on abiotic ecosystem services

&lt;p&gt;Proglacial areas, defined as the areas left free from glaciers since the Little Ice Age, are open-air laboratories to study the effects of climate change on high mountain environments. Their different abiotic features (i.e. geodiversity) depend mainly on the bedrock characteristics, the type of glaciers acting in the areas and the morphometry of their hydrographic basins, which influence the geomorphic dynamics (i.e., geomorphodiversity). From this, it could derive a different response of glacier forefields to deglaciation and particular evolutionary trends. Hydrological elements and dynamics are particularly variable (i.e. hydrogeodiversity), especially in terms of proglacial lakes diversification, having effects down-valley, even far from the strict proglacial area, and also in term of potential natural hazards. Moreover, geodiversity of proglacial areas may have implications on other types of &amp;#8220;diversity&amp;#8221;. After the glacier retreat, glacier forefields are, in fact, characterized by soils development and vegetation settlement. In particular, soils characterized by different ages and by different degree of development coexist over short distances (i.e. pedodiversity), functioning also as a support for living organisms. Biotic components gradually colonize such areas, from the pioneer to the late-successional species, bringing varied species along the proglacial plains (i.e. biodiversity). All these aspects can be discussed in the perspective of the abiotic ecosystem services (i.e. regulating, supporting, provisioning, and cultural) provided by glacier forefields. Regulating services are related to both atmospheric and terrestrial processes, including natural hazard regulation. Supporting services deal mainly with habitat provision and soils development. Provisioning services include both material (freshwater, building materials) and immaterial (i.e. tourism) resources. Finally, cultural services, that are the most numerous, take into account, among the others, the spiritual and historical meaning, the geohistorical importance for the Earth Sciences development, the educational and geotourism-related opportunities, and the landscape benefit effects. Considering all these aspects, and the intense dynamics proglacial areas are affected by, which will be illustrated through examples mainly from the European Alps, it emerges the importance of a careful monitoring and management of such areas, hopefully through an even more holistic approach.&lt;/p&gt;

CO2 refixation is higher in leaves of woody species with high mesophyll and stomatal resistances to CO2 diffusion

The percentage of respiratory and photorespiratory CO2 refixed in leaves (Pr) represents part of the CO2 used in photosynthesis. The importance of Pr as well as differences between species and functional types are still not well investigated. In this study, we examine how Pr differs between six temperate and boreal woody species: Betula pendula, Quercus robur, Larix decidua, Pinus sylvestris, Picea abies, and Vaccinium vitis-idaea. The study covers early and late successional species, deciduous broadleaves, deciduous conifers, evergreen conifers, and evergreen broadleaves. We investigated whether some species or functional types had higher refixation percentages than others, whether leaf traits could predict higher Pr, and whether these traits and their impact on Pr changed during growing seasons. A/Ci-curves, measured early, mid and late season, were used to estimate and compare Pr, mesophyll resistance (rm), and stomatal resistance (rs) to CO2 diffusion. Additionally, light images and transmission electron microscope images were used to approximate the fraction of intercellular airspace and cell wall thickness. We found that evergreens, especially late successional species, refixed a significantly higher amount of CO2 than the other species throughout the entire growing season. In addition, rm, rs and leaf mass per area, traits that typically are higher in evergreen species, were also significantly, positively correlated with Pr. We suggest that this is due to higher rm decreasing diffusion of (photo) respiratory CO2 out of the leaf. Cell wall thickness had a positive effect on Pr and rm, while the fraction of intercellular airspace had no effect. Both were significantly different between evergreen conifers and other types. Our findings suggest that species with a higher rm use a greater fraction of mitochondria-derived CO2, especially when stomatal conductance is low. This should be taken into account when modeling the overall CO2 fertilization effect for terrestrial ecosystems dominated by high-rm species.

Invasibility and Recoverability of a Native Plant Community Following Invasion Depend on its Successional Stages

Background: Exotic species invasions represent important causes of biodiversity loss in ecosystems. Yet, knowledge remains limited on the invasion advantage of exotic species (invasibility of native plants) and the ability of native species to recover following invasions at different stages of succession.Results: We selected three grasses (Setaria viridis, Artemisia gmelinii, and Bothriochloa ischaemum) representing early, middle, and late successional species, respectively, and an exotic species (Panicum virgatum) from a stable grassland community. Four types of field soil were collected to treat the three early, middle, and later successional species, plus the exotic species. We examined the invasion ability of the exotic species on native communities and the recoverability of these communities following invasion across succession. We compared the performance of the four plant species grown in their “own” and “other” soils in a 2-year glasshouse experiment. Here we show that exotic species performed better in soils of early and mid-successional species, owing to higher soil nutrients and microbial residues, than in the soil of later successional species. In the soil of exotic species, early and mid-successional species exhibited poor growth, while that of later successional species was unchanged.Conclusions: Our study demonstrated that soil nutrients and microbial residues create a soil legacy regulating the invasibility and recoverability (or resilience) of native plant communities and how it changed with vegetation succession.