Pine Afforestation Research Articles

Different-aged Pinus afforestation does not support typical Atlantic Forest fruit-feeding butterfly assemblages

The Atlantic Forest of the southern Brazilian highlands is a biocultural mosaic of Araucaria Forest and grasslands. Despite adverse impacts on biodiversity, extensive areas are being afforested with non-native pine (Pinus spp.), triggering forest succession on areas that were previously native grasslands. The long-term effects of afforestation with these non-native trees for biodiversity conservation are still unknown. Here, we assess this issue by comparing the fruit-feeding butterfly assemblages in young (20 year) and old (70 year) pine plots with nearby native Araucaria Forest. Abundance and richness of butterflies were positively correlated with temperature and mean humidity only in the native forest. Abiotic conditions differed between vegetation types: there was more sunlight, and was warmer and drier in the pine afforestation plots than in the Araucaria Forest. Butterfly species composition was similar between young and old pine plots, but distinct from the native Araucaria Forest. Butterfly species abundances in native forests were more evenly distributed than in afforestation sites. In these pine sites, assemblages were dominated by small, grass-feeding satyrines, whereas old pine sites had more liana-feeding biblidines, and the Araucaria Forest had more large-sized bamboo-feeding species. Our results indicate that even after 70 years of succession a non-native pine afforestation cannot support a butterfly assemblage as that found in the neighboring preserved forest. Moreover, threatened grassland specialist species have been locally extinct after only 20 years of pine afforestation. The evidence gathered here points against the use of silviculture with non-native trees in these biocultural mosaic landscapes.

Impact of Duration of Land Abandonment on Infiltration and Surface Runoff in Acidic Sandy Soil

Sandy soils are less fertile and, therefore, often abandoned in the Central European region. Land abandonment can cause the recovery of ecosystems by the replacement of crop species by vegetation that disperses from surrounding habitats and will be subsequently established (secondary succession). The objective of this study was to find the impact of secondary succession during more than 30 years of lasting abandonment of agricultural fields with acidic sandy soil on infiltration and surface runoff. The method of space-for-time substitution was used so that the fields abandoned at different times were treated as a homogeneous chronosequence. The impact of abandonment on infiltration and surface runoff was characterized by the changes in soil organic carbon content, pH, water and ethanol sorptivity, hydraulic conductivity, water drop penetration time, repellency index, time to runoff, and surface runoff coefficient. It was found that the abandoned soils previously subjected to agriculture showed a decrease in pH, a significant increase in soil water repellency, and a decrease in infiltration, which can lead to serious problems in terms of surface runoff and soil erosion. The pH(H2O) and pH(KCl) decreased monotonously and ethanol sorptivity did not change significantly during abandonment. The time to runoff did not change significantly between 10 and 30 years of abandonment, and it was not measured after 1 year of abandonment because no runoff occurred. The dependence of the other characteristics on the duration of field abandonment was not unambiguous. Water sorptivity and hydraulic conductivity showed a decrease between 1 and 10 years followed by a slight increase between 10 and 30 years of abandonment. On the other hand, soil organic carbon content, water drop penetration time, repellency index, and surface runoff coefficient showed an increase between 1 and 10 years followed by a slight decrease between 10 and 30 years of abandonment. To prevent soil water repellency and its consequences in sandy soils, an adequately high soil water content should be maintained, and mixed forest afforestation should be preferred to pine afforestation. This is extremely important in the context of climate change and the increasing frequency of prolonged dry periods.

Pine afforestation improves the biological soil attributes linked to methane oxidation in a temperate zone of Argentina

Background: Atmospheric methane (CH 4) is responsible for approximately 20% of global warming since the preindustrial era. Forests are land ecosystems whose role is crucial for mitigating the greenhouse effect due to their capacity to capture and store C and preserve other processes such as CH 4 oxidation in the soil. On the other hand, in the particular case of afforestation, there are contradictory results about the magnitude of CH 4 uptake variation due to changes in methanotrophic bacteria activity and its relationship with micro-environmental conditions. Results: The average potential CH 4 oxidation rate in the laboratory (MOL) of afforested soil was 186% greater than that of the grassland, which could be marginally attributed to differences in soil physicochemical parameters like bulk density, pH and organic matter. A seasonal pattern in MOL was observed in both land uses, with the highest values at the warm and rainy season. MOL magnitude increased with soil depth up to 10-15 cm, which corresponds with the mineral layer. Conclusion: Pine afforestation would improve the biological soil attributes linked to methane oxidising bacteria compared to the grassland systems.

Comparison of alternative harvesting systems for selective thinning in a Mediterranean pine afforestation (Pinus halepensis Mill.) for bioenergy use

Due to a continuous abandonment of marginal agricultural land, Mediterranean pine forests are growing both in biomass stock and area but remain mainly unmanaged. Pinus halepensis is one of the main pioneer species with strong expansion throughout the Mediterranean basin. In mature forests and pole stands, selective thinnings aimed to eliminate dominated and dead trees are necessary to improve the resilience and persistence of these forest ecosystems. Bioenergy market provides an opportunity to mobilise this woody material, helping to prevent and reduce wildfires in a context of climate change and energy transition. Despite the existing expertise on wood harvesting, there is a lack of practical knowledge about cost-effective methods for bioenergy use of selective thinnings in such forests. The objective of this study was to compare thinning harvesting methods in representative 63-year-old Pinus halepensis afforestation in pole stage for bioenergy uses, following the silvicultural treatments defined in the Spanish forest management plan. Time studies were performed over six representative plots in Navalón (Spain). Treatments included three plots with the traditional stem wood method combined with the logging of forest residues (integrated system), and three plots with the whole tree chipping (whole tree system). Time, productivity and fuel consumption were recorded for both systems. A woodchip quality assessment of each assortment was performed in the laboratory according to European standards. The results obtained demonstrated that time consumption and productivity were similar between the integrated harvesting system and the whole tree system. Regarding the total energy balance, it should be noted that both systems produce woodchips that contain over ten times more energy than that required to mobilise and process the obtained biomass. Fuel consumption, costs and degree of damage were slightly higher in the whole tree system due to the more intensive forwarding operation. The two assortments of woodchips in the integrated system had a higher (chipped log material) and lower quality (chipped crown material) than whole tree woodchips. In conclusion, integrated harvesting is a better option to diminish fuel consumption, cost and environmental impact, and also to obtain better quality woodchips for the production of added value biofuels (pellets).

Increased Post-Drought Growth after Thinning in Pinus nigra Plantations

In Mediterranean seasonally dry regions, the rise in dieback and mortality episodes observed in pine afforestations has been related to higher drought intensity and lack of appropriate management, which enhance competition between trees for water and light. However, there is little understanding of the benefits of silviculture for plantations under seasonal drought stress. A combination of dendrochronology and wood C and O isotope analyses was used in three Black pine (Pinus nigra) plantations to work out the responses of radial growth (BAI, basal area increment) and water-use efficiency (WUEi) to thinning treatments (removal of 40% of the stand basal area). Thinning had a positive effect on BAI and WUEi, reduced drought sensitivity, and reduced the temporal dependence on the previous year’s growth. These results were significant even 13–14 years after thinning and coherent for the three study sites. Differences were found between the sites regarding the physiological mechanisms of adaptation. In two sites, we inferred the enhanced WUEi was due to increased photosynthetic rates (A) at constant stomatal conductance (gs). In the third site, which had higher tree density and therefore competition, we inferred increases in both A and gs, with the former being proportionally larger than the latter.

Heavy metal accumulation of urban Scots pine (Pinus sylvestris L.) plantation.

In soil and plant tissues, the concentrations and reserves of manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), and lead (Pb) were calculated to measure the heavy metal quantities of the Scots pine afforestation. In the soil and plant tissues, heavy metal concentrations varied. The highest concentration of heavy metal was found in Mn and the lowest concentration in Pb in the soil. Heavy metal stocks followed the order of Mn > Zn > Ni > Cu > Pb in soil, and the order of Zn > Cu > Mn > Ni > Pb in the plant. In the Scots pine parts, Pb and Zn concentrations and BCFs follow Needle > Branch > Bark > Root > Trunk order, while Cu concentrations follow Root > Needle > Branch > Bark > Trunk order, Mn concentrations follow Needle > Branch > Bark > Trunk > Root order and Ni concentrations follow Needle > Branch > Root > Bark > Trunk order. In particular, Scots pine needles are considered to be ideal to be used as biomonitoring plants, especially in monitoring increases in heavy metal concentrations in urban areas. Besides, in order to be more effective in the retaining of heavy metals, it is proposed that mixtures of hyperaccumulator plants be added which are appropriate for climatic conditions.

Scots pine (Pinus sylvestris L.), the suitable pioneer species for afforestation of reclamation sites?

As a result of human population growth and human need for resources, the landscape has been increasingly transformed and devastated by mining activities. Subsequent reactivations are thus extremely important in the process of restoring the disturbed biosphere. The objective of this study was to determine differences between original forest sites and reclamation sites afforested with Scots pine (Pinus sylvestris L.) in terms of stand structure, diversity, biomass, productivity and climatic resistance. Three different types of reclamation were compared in the Czech Republic – (1) a post-mining coal site, (2) a former sand quarry and (3) a reclaimed sand dune that had been used for pasture. At the comparable stand age of 40–46 years, the stand volume and biomass were higher by 22% and 19%, respectively, on original forest sites (370–500 m3 ha−1, 332–422 t ha−1) compared to reclamation sites (318–371 m3 ha−1, 287–325 t ha−1). On the contrary, structure and diversity were more complex and richer in reclaimed areas. Climatic factors had a higher effect on radial growth on reclamation sites compared to original forest sites, but no significant differences were observed between the variants in terms of the occurrence of negative pointer years (extreme deflection in growth). A lack of precipitation and long-term droughts in vegetation periods were the main limiting factors of growth. Comparing all reclamation variants, the highest productivity was found on the reclaimed coal-mine, and the lowest differences between forest and reclamation sites were documented in the reclaimed sand quarry case. In relation to climate change, Scots pine proved a very adaptive and suitable tree species whose wood production on reclaimed post-mining sites is comparable to the original forest sites. Pine afforestation of reclamation sites brings invaluable environmental and production benefits.

Ağaçlandırma Çalışmaları Üzerinden Geçen Zamanın Toprak Özellikleri ve Azot Mineralizasyonu Üzerindeki Etkilerinin Belirlenmesi (Giresun-Şebinkarahisar Örneği)

Aim of study: In this study, it is aimed to reveal the effects of time on some soil properties and nitrogen mineralization potential in scotch pine afforestation areas.
 Material and methods: The study was carried out in the afforestation areas in Şebinkarahisar Forest Management Directorate. Soil samples were taken from two depth levels (0-15 cm and 15-30 cm Soil samples were taken from afforestation areas (afforested 1, 5 and 20 years ago) and adjacent unforested(control) areas. Some physical and chemical analyzes as well as nitrogen mineralization measurements were done in the soil samples.
 Main results: It was determined that the period after afforestation has a statistically significant effect on the change of soil properties. Thus, while the sand and C / N ratio decreased with afforestation, clay, bulk density and pH increased. The difference in the effect of the time passed over planting times in terms of net mineralization data in nitrogen mineralization was found to be statistically insignificant. Equal incubation conditions prevented the difference in planting time.
 Highlights: With the study, changes in soil properties have been revealed through afforestation studies in areas that are sensitive to erosion and the necessity of improving potantial erosion sites has emerged.

Fragmentation and grassland plants: individual and transgenerational effects

Understanding how individuals respond to habitat discontinuities could provide a first step in the large-scale evaluation of their responses to habitat fragmentation. Our objective was to evaluate habitat fragmentation effects on individual and population parameters of two native species of the Pampas grassland (Senecio pampeanus and Margyricarpus pinnatus). Both species grow in vegetation remnants surrounded by pine afforestation in the coastal dunes of the southern Pampas (Argentina). Plants reproductive aspects and offspring fitness were examined, and the influence of environmental maternal effects was analyzed through a common garden experiment. Individuals of S. pampeanus growing in smaller fragments produced fewer heads and fewer fruits per head than those associated with the continuous grassland and with larger fragments. However, M. pinnatus did not exhibit any difference in flower and fruit production with respect to fragment size. The seeds that came from the smallest fragments took longer to germinate for the two species, and in the case of M. pinnatus they also showed reductions in percent germination. We found evidence for influence of the maternal environment on percent germination and in seedling establishment time of M. pinnatus. Our results provide clues about the effects of fragmentation on plant reproduction, with consequences for the offspring, and also show that species respond differently according to their biological characteristics. Furthermore, the results obtained contribute to the understanding of mechanisms by which the subdivision of natural environments affects the persistence of populations and alters the structure of plant communities.

Overstory Effects on the Understory of Aleppo Pine Plantations—Implications for Ecosystem Restoration

At the end of the 19th century and along the first half of the 20th century, public policies in Mediterranean countries and elsewhere in Europe strongly promoted pine afforestation for land reclamation and wood production. In many cases, the transition to native forests, more resilient and more diverse, was also foreseen. This study aims to find the overstory characteristics that are best related to the understory of Aleppo pine (Pinus halepensis) plantations, to assist ecosystem restoration goals. We installed 33 circular plots in mature Aleppo pine plantations located in the southeastern Salento peninsula, Apulia, Italy. We measured overstory characteristics and the corresponding understory on these plots. We assessed the effects of overstory variables on understory development (plant density, plant height, and the Magini regeneration index) and diversity (species richness and the Shannon–Wiener index) using linear mixed models (LMM). Understory development and diversity were positively correlated with the Hart–Becking spacing index and negatively correlated with basal area and canopy cover, the three overstory variables that best explained variance. We used polynomial fitting and the subsequent derivation of these functions to determine the values of the Hart–Becking index and of the canopy cover that corresponded to the maximum development (33.7% and 84.6%, respectively) and diversity (32.6% and 86.5%, respectively) of the understory. Redundancy analysis (RDA) showed that late-successional species, including Quercus coccifera, were associated with higher levels of understory development and stand spacing. These results may assist in the restoration of native ecosystems in Aleppo pine plantations installed in similar ecological conditions.

THE RELATIONSHIPS BETWEEN THE SITE INDEX OF MARITIME PINE PLANTING AREAS AND SOME ECOLOGICAL FACTORS (CASE OF SINOP-BEKTAŞA REGION)

Türkiye’de odun hammaddesine olan talep artışını karşılamak için ağaçlandırma çalışmalarına ağırlık verilmesi zorunluluk haline gelmiştir. Ağaçlandırma çalışmalarında genellikle kanaatkâr ve hızlı gelişen türlerin kullanılması tavsiye edilmektedir. Bu itibarla, ülkemizde Sahilçamı (Pinus pinaster Ait.) endüstriyel ağaçlandırmalarda kullanılacak iyi bir tür olarak gözükmektedir. Bu nedenle, Sahilçamı’ nın gelişimini ve büyümesini etkileyen en önemli yetişme ortamı faktörlerini ve etki derecelerini saptayarak dönem sonunda en yüksek geliri elde etmek için verimliliğin en yüksek olduğu yerlerden çalışmaya başlamak önem arz etmektedir. Dolayısıyla, bu türün en iyi gelişme gösterdiği Batı Karadeniz Bölgesi’nde yetişme ortamı özelliklerini araştıran çalışmaların yetersiz olduğu görülmektedir. Bu çalışmada, Sinop-Bektaşa Orman İşletme Şefliği sınırları içerisinde yayılış gösteren Sahilçamı ağaçlandırma alanındaki toprakların mutlak derinlik, mekanik bileşim (tekstür), toprak tepkimesi, organik madde miktarı, dış toprak durumu ve humus formu gibi bazı özellikleri ile verimlilik (bonitet endeksi) arasındaki ilişkiler belirlenmeye çalışılmıştır. Bu amaçla, Sinop-Bektaşa Orman İşletme Şefliği sınırları içerisindeki Sahilçamı meşcerelerinden, 35 adet örnek alandan toplam 145 adet toprak örneği alınmıştır. Alınan toprak örnekleri üzerinde toprak türü, toprak reaksiyonu, organik madde, faydalanabilir su kapasitesi (FSK) vb. gibi özellikler belirlenmiştir. Ayrıca her bir örnek alan için 20 yaşındaki üst boy değerleri hesaplanmıştır. Hesaplanan verimlilik endeksi iyi, orta, düşük olmak üzere 3 gruba ayrılmıştır. Her bir örnek alandaki verimlilik endeksi ile bazı toprak özellikleri arasındaki ilişkiler istatistiksel olarak ortaya konulmuştur. Sonuç olarak; verimlilik endeksi ile % kil miktarı, % toz miktarı, ortalama % organik madde ve ortalama % FSK arasında pozitif, % kum miktarı arasında negatif ilişkiler bulunmuştur.

High Methane Uptake from Soils of Low and High Density Radiata Pine Afforestations Compared to Herbaceous Systems

ABSTRACT During a one-year period, methane (CH4) fluxes from soil were studied in a southern temperate region system using a static chamber technique. Four treatments on neighboring areas with similar environmental characteristics but different vegetation cover were considered: a natural grassland (NG), an agricultural land (AL), a low tree density radiata pine afforestation (P1 – suitable for silvopastoral use), and a dense radiata pine afforestation (P2). CH4 uptake increased in the following order: AL < NG < P1 and P2 (statistically significant differences), without differences between P1 and P2. CH4 fluxes were mainly influenced by soil water content (R = 0.78; p = .0001) and bulk density (R = 0.75; p = .0004) indicating that CH4 uptake by soils is primarily connected to methane soil diffusivity. The statistical differences of these parameters could partially justify CH4 flux differences found among treatments. However, a multiple linear regression analysis indicated that other factors such as soil temperature also control CH4 fluxes (R2 = 0.86, p≪4x10−6), and could explain temporal patterns. Results suggest that the low tree density afforestations, suitable for silvopastoral use, have a functional role (CH4 uptake) similar to that of dense forests, and could be a good option to mitigate CH4 emissions by livestock and agricultural sector.

Response of soil properties and microbial indicators to land use change in an acid soil under Mediterranean conditions

Land use change (LUC) can alter the soil quality and lead to soil degradation or soil conservation depending on the management practices. In the Mediterranean region, the impact of LUC on soil quality has been well described on neutral or alkaline soils, which are the most common in the area. However, some areas in the west of the Iberian Peninsula are covered by Raña surfaces, a continental detritic formation associated with quartzitic ranges and characterized by very acid and weathered soil. Seven following land uses were selected for this study: cork oak climax vegetation (Cork Oak), pine afforestation (Pine), natural revegetated shrubland (Shrub) and grassland (Grassland) after land abandonment, tilled olive grove (Olive), tilled annual cropland for animal forage (Tillage) and the same annual cropland managed by no-tillage (No-Tillage). The two tree-based uses, Pine and Cork oak, accumulated the highest contents of carbon (C) and nitrogen (N) fractions. However, the further acidification and the C accumulation in labile forms of Pine could hinder the feasibility of Pine plantations to restore acid and degraded soils. Instead, the natural revegetation succession after land abandonment (first Grassland and then Shrub) were found as a suitable alternative able to increase the C content and restore the microbial activity in comparison with Tillage and Olive, the two land uses which showed the lowest C and N content and reduced microbial activity. Furthermore, the improved aggregate stability in Shrub, probably caused by root exudates of dominant plant species, could play a key role in soil restoration. Microbial biomass C and N, C decomposability and enzymatic activities were the most sensible microbial indicators to discriminate among the studied land uses. A clear pattern of lower microbial biomass and enzymatic activity was found with increasing human intervention and soil disturbance. In this respect, soil managed by no-tillage contained higher soil C and N contents when compared to Tillage and the microbial indicators were comparable with those obtained under Cork Oak. Our results demonstrate that soil tillage reduction is an essential step to mitigate soil degradation in Raña soils and highlighted the suitability of No-tillage as an alternative to traditional tillage, which can increase crop productivity while building soil organic matter content. In addition, the natural soil revegetation, including natural grasslands, shrublands and climax cork oak vegetation are more preferable for degraded soil improvement when compared to pine plantations.

Pine afforestation, herriza and wildfire: a tale of soil erosion and biodiversity loss in the Mediterranean region

From a western society’s perspective, wildfires are catastrophic events that jeopardise biodiversity and cause soil erosion, not to mention risk to human lives and properties. However, many Mediterranean-type ecosystems are not only resilient to wildfires but sensitive to the lack of wildfires. This communication focuses on the Mediterranean heathland or herriza as a paradigmatic fire-prone ecosystem to illustrate how most negative impacts allegedly attributed to wildfires actually occur in commercial forestry plantations. They are caused by aggressive forestry practices prior to the wildfire. In natural Mediterranean habitats, such as the herriza, complete wildfire suppression may actually pose a serious threat to biodiversity. The large existing body of scientific knowledge on the relationships of Mediterranean ecosystems with fire should be incorporated into plans and policies dealing with wildfire and conservation to make them more appropriate and efficient. Finally, burned natural areas should not be regarded, or treated, as dead pieces of nature and destroyed ecosystems, but as a transitional stage within the dynamics of Mediterranean-type ecosystems.

Stand density effects on carbon and water fluxes in a semi-arid forest, from leaf to stand-scale

Drought-induced productivity reductions and tree mortality have been increasing in recent decades in forests around the globe. Prescribed reduction in stand density, i.e. thinning, has been proposed as a management tool to improve forest sustainability in face of a warmer, drier future. Thinning should potentially reduce net stand water use and improve water-availability for remaining trees, thus reducing their subsequent drought vulnerability. However, few studies have directly measured these effects.In 2009 we established a large-scale thinning experiment in a semi-arid, 40-years-old pine afforestation. Study plots (70 × 70 m) were thinned to 100, 200, and 300 trees ha−1, and compared with unthinned control plots (210–400 trees ha−1), each at five replications. Stem and needle growth, and needle gas exchange were measured along 3–9 consecutive years at seasonal to annual temporal resolution. Measurements at the tree-scale were further up-scaled using both simple upscaling relationships and using an ecosystem model of coupled carbon, energy and hydrology (Regional Hydro Ecologic Simulation System, RHESSys).At the needle scale, photosynthesis was 70% higher at the 100 trees ha−1 than at 300 trees ha−1, whereas transpiration was merely 10% higher. Consequently, stem and needle growth increased by 100% and 20%, respectively. For most parameters, there was little change between 200 and 100 trees ha−1. Applying RHESSys at the stand-scale, these effects on tree physiology translated into 35% reduction in CO2 uptake and a 47% reduction in tree water-use, which was compensated for by increased evaporation from exposed soil.Our long-term measurements at the dry timberline highlight the role of thinning in enhancing the activity and growth of remaining trees, with increased water-use efficiency. Unexpectedly, this density reduction was associated with a relatively small decrease in forest carbon uptake. Light availability was a limiting factor in the higher density plots, even in our light-abundant forest.

Changes in soil organic matter composition after Scots pine afforestation in a native European beech forest revealed by analytical pyrolysis (Py-GC/MS).

The introduction of coniferous species in former deciduous forests may exert changes in soil organic matter, particularly in its molecular composition. In this work, pyrolysis-gas chromatography-mass spectrometry was used to study changes in SOM quality related to the centennial afforestation of Scots pine in an area formerly covered by European beech forest in the NE-flank of the Moncayo Natural Park (NE-Spain). For each soil profile three organic layers (fresh litter, fragmented litter and humified litter) and mineral soil horizons (Ah, E, Bhs and C) were studied. A total of 128 compounds were identified in the pyrograms, and composition differences were detected among the organic and mineral soil layers as well as between soils under beech and pine, for the main compound classes: nitrogen compounds, aromatics, lignin methoxyphenols, polycyclic aromatic hydrocarbons, lipids and polysaccharide-derived moieties. Such chemical differences were found to be derived from the biomass composition of the predominant vegetation type that was incorporated into the soil and from its progression into the soil profile. The analysis of the distribution of alkanes indicated higher SOM stabilization in the native beech forest soil. The signal of beech biomarkers (long chain n-alkanes C31-C33) found in the pine E horizon indicates the permanence of SOM derived from the natural forest ca. 100 years after the afforestation.

Fingerprinting changes of source apportionments from mixed land uses in stream sediments before and after an exceptional rainstorm event

The loss of fertile topsoil is one of the principal soil degradation problems in mountain agroecosystems worldwide. Soil erosion rates reach their maximum during exceptional storm events that remove soil particles, especially from unprotected topsoil. In Mediterranean mountainous environments, several centuries of non-irrigated agriculture and the subsequent removal of natural vegetation for developing agriculture has increased the surface area prone to erosion. In addition, the irregularity in exceptional precipitation events results in a great loss of fertile soil, the subsequent siltation of reservoirs and a decrease in water quality. To analyse the soil response to exceptional events, 161 source samples were collected in a 23 km2 catchment that was mostly cultivated at the beginning of the last century. Source samples were distributed over the five main land use/land covers such as agricultural land, pine afforestation, open forest, bare soil and channel bank areas. Furthermore, 20 channel bed sediment samples were collected along the main streams before and after the exceptional storm event to document changes in the sediments. In addition, floodplain sediments were collected to provide a close replication of sediments deposited during regular storm events. Source apportionments were calculated using the FingerPro unmixing model in the pre-event, regular events and post-event scenarios.The unmixing outputs displayed a large variation of source apportionments from the upper part to the lower part of the catchment and from pre- to post-event sediments. After the event, a decrease of >70% of the clay fraction and its associated elements such as Fe, Al, K, Ba, Sr, Rb, Pb, Zn, V, 137Cs, 40K, 232Th and SOC along with a rise in contents of elements associated with the coarse fraction (Si, Nb, Zr, Ti, P and 226Ra) was recorded in the channel bed sediments. At the catchment outlet, the pre-event sediment showed substantial contributions from bare soil (29%) and from agriculture and channel banks, which both reached 35%, while the channel bank was the main source along the catchment ranging between 44 and 71%. The low contribution from soil under natural covers with a mean value <4% underlines the benefits of vegetation to prevent soil loss. In the post-event sediment, the channel bank contribution increased up to 63% at the catchment outlet. Our findings highlight the hazards of exceptional storm events on modifying sediment source contribution and exporting fine sediment.

Impact of land use change on organic carbon sequestration in Arenosol

Conversion of arable soils into other land uses can stabilize and increase accumulation of soil organic carbon (SOC) and in addition prevent deterioration in its properties. The data has shown changes in SOC sequestration in Ap horizon after arable land conversion (1995–2015) into managed grassland, abandoned and pine afforested. SOC in Arenosol topsoil was positively affected by long term fallow and conversion into grassland. Abandoned land and fertilised managed grassland accumulated significantly more SOC, 48% and 38% respectively compared with arable land. In unfertilised managed grassland SOC stocks decreased 2.3% during 21 years, but losses were lower than in fertilised arable land. Pine afforestation of loamy sand helped to reduce the intensity of SOM mineralization compared to arable land. The Ap horizon thickness in pine forest soil increased from 28 to 31 cm during 21 years period. However, SOC stock decreased by 1% due to reduction in carbon concentration.

Changes in Soil Hydro-Physical Properties and SOM Due to Pine Afforestation and Grazing in Andean Environments Cannot Be Generalized

Andean ecosystems provide important ecosystem services including streamflow regulation and carbon sequestration, services that are controlled by the water retention properties of the soils. Even though these soils have been historically altered by pine afforestation and grazing, little research has been dedicated to the assessment of such impacts at local or regional scales. To partially fill this knowledge gap, we present an evaluation of the impacts of pine plantations and grazing on the soil hydro-physical properties and soil organic matter (SOM) of high montane forests and páramo in southern Ecuador, at elevations varying between 2705 and 3766 m a.s.l. In total, seven study sites were selected and each one was parceled into undisturbed and altered plots with pine plantation and grazing. Soil properties were characterized at two depths, 0–10 and 10–25 cm, and differences in soil parameters between undisturbed and disturbed plots were analyzed versus factors such as ecosystem type, sampling depth, soil type, elevation, and past/present land management. The main soil properties affected by land use change are the saturated hydraulic conductivity (Ksat), the water retention capacity (pF 0 to 2.52), and SOM. The impacts of pine afforestation are dependent on sampling depth, ecosystem type, plantation characteristics, and previous land use, while the impacts of grazing are primarily dependent on sampling depth and land use management (grazing intensity and tilling activities). The site-specific nature of the found relations suggests that extension of findings in response to changes in land use in montane Andean ecosystems is risky; therefore, future evaluations of the impact of land use change on soil parameters should take into consideration that responses are or can be site specific.

When dynamism is the baseline: long-term ecology of a Mediterranean seasonal wetland in the Doñana National Park (Southwestern Europe)

Mediterranean seasonal wetlands are amongst the world’s most endangered ecosystems. Although seasonal wetlands’ conservation is a European continental-scale priority, their long-term ecological dynamics are not well known, hampering the detection of baseline conditions. However, a long-term ecological viewpoint could aid in the detection of spatiotemporal factors controlling wetland development. We have applied a multi-proxy palaeoecological approach (palynological, microcharcoal, magnetic susceptibility, loss on ignition and diversity estimates analyses) on a 360-cm core retrieved from the El Sopeton (ElSo), a temporary wetland nested between dunes in the paradigmatic Donana coastal area. The palaeoecological analyses reveal ~ 300–500-year-long wetland phases linked to dune immobilisation during humid periods. During the first wetland phase (AD ~ 40–315), upland and wetland vegetation diversity dynamics follow opposite trends owing to the different effect that dune proliferation had on them. Fixed dune landscapes provided upland spatial diversification, while they promoted a longer hydro-period in ElSo, simplifying wetland vegetation. During the second wetland phase (AD ~ 1550–2012), land-use change drove environmental dynamics. The mid-eighteenth-century pine afforestation to fix moving dunes marked an environmental tipping point, with the ElSo wetland transitioning from seasonal to permanent. This translated into a rising trend in upland diversity and a decreasing trend in the wetland one. Despite the recent pine afforestation, the palaeoecological findings evidence the autochthonous character of Pinus pinea, as well as the naturalness of the wetland species Hydrocharis morsus-ranae and Ricciocarpos natans. The geomorphological dynamism of the diverse Donana coastal setting is the baseline for the area, modulating wetland-upland water connectivity and, ultimately, controlling biodiversity trends. The preservation of Donana natural dynamism and landscape heterogeneity should be considered for the management, conservation and restoration of its seasonal wetlands.