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Producción de biomasa y fijación de carbono por los matorrales españoles y por el horizontes orgánico superficial de los suelos forestales
Abstract and Figures
Los montes constituyen un gran almacén de carbono orgánico, formado por las partes aérea y radical de los árboles, matorrales y de otras cubiertas no arboladas –como las herbáceas-, así como por el carbono acumulado en el horizonte orgánico superficial y a lo largo del perfil del suelo mineral.
En este trabajo se realiza una estimación de biomasa de las formaciones de matorral y arbustedos de mayor significación en la vegetación española y así, por extensión, evaluar la producción de biomasa de los diferentes tipos de cubiertas leñosas no arboladas en las que entran como componentes.
En la segunda parte de este manual se presentan datos y ecuaciones para la estimación de la necromasa depositada sobre la superficie del suelo (capa orgánica del suelo), completando así esta trilogía, a falta de un estudio, ya en curso, sobre el carbono almacenado en los suelos forestales, lo que permitiría una primera aproximación general a la cuantificación del carbono acumulable en los montes españoles (árboles, matorrales, horizonte orgánico y suelo mineral), a los que habría que agregar los pastos herbáceos y otras comunidades de esta categoría fisonómico-estructural, que ahora se difieren para posteriores estudios.
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... La gran mayoría de ecuaciones existentes para estimar la carga de matorral tienen en cuenta solamente variables biométricas. Para el desarrollo de estos modelos alométricos a nivel comunidad, la mayoría de los autores utilizaron como variables predictoras la altura y la cobertura (Montero et al., 2020;Vega et al., 2022). Estos dos últimos autores incluyen en sus estudios un modelo de estimación de biomasa de jarales de C. ladanifer entre otras muchas comunidades de matorral. ...
... A partir de estas mediciones se obtuvieron el valor de cobertura del matorral, FCCmat (%), y el valor promedio de las alturas máximas de matorral, h mat (m), en cada parcela de muestreo. Por último, a partir de estas dos variables se calculó la carga total del matorral o biomasa, W mat (t/ha), mediante la ecuación alométrica propuesta por Montero et al. (2020) para jarales de C. ladanifer. Los estadísticos descriptivos (media, rango y desviación típica) para estas tres variables del combustible se muestran en la Tabla 1. ...
... Además, se exploró la opción de estimar la carga de combustible de forma indirecta. Es decir, se ajustaron las variables de entrada (h mat y FCC mat ) de la ecuación de estimación biomasa en jarales de Montero et al. (2020) a partir de métricas LIDAR, y, a continuación, con estas variables predichas se estimaron las cargas de combustible utilizando esta misma ecuación. Los ajustes independientes de h mat y FCC mat fueron peores que el ajuste directo de la W mat . ...
Las comunidades de matorral de Cistus ladanifer L. (jara pringosa) son uno de los ecosistemas más característicos, abundantes y propensos a sufrir incendios del monte mediterráneo. Además, estos jarales tienen un potencial considerable para la extracción de productos derivados de gran valor en la industria farmacéutica, alimentaria y cosmética. Por lo tanto, estimar su biomasa es esencial para gestionar y priorizar su aprovechamiento, calcular su contenido de carbono y fijación de CO 2 , así como predecir su comportamiento ante el fuego y posibles emisiones. En este estudio se pretende estimar la carga de combustible de los jarales de C. ladanifer del sur de España a partir de los datos LIDAR aéreos del PNOA. Para ello, se llevaron a cabo inventarios de campo no destructivos con mediciones de la altura media y cobertura de matorral en 143 parcelas circulares en Andalucía. Estas dos variables del combustible se utilizaron como entrada en una ecuación específica existente para estimar la carga de combustible de C. ladanifer. Mediante análisis de regresión lineal, se obtuvo un modelo que permite la estimación de la carga de combustible de estos jarales a partir del porcentaje de primeros retornos LIDAR en el tramo de altura 0.2-4 m, explicando el 72% de la variabilidad observada. Estos resultados pueden resultar de gran utilidad para desarrollar cartografías de biomasa de los jarales con fines preventivos y de extinción de incendios, y para la planificación de su aprovechamiento.
... Para determinar las emisiones de GEI se sigue lo establecido en las Directrices del IPCC (2006, 2013, que utiliza también Sistema Español de Inventario (2014). La fijación de carbono en la vegetación y sustrato de los humedales, se determinará según metodología de Montero et al. (2020). Se considerará como vegetación sembrada en los humedales, Phragmites australis, con una producción de biomasa seca de 3.7 kgBS/m 2 año (Kadlec y Wallace, 2009) y 0.2048 kgC/ m 2 año fijados en el sustrato (Hernández, comunicación personal). ...
... Posteriormente en el laboratorio se caracterizarán los suelos según metodología propuesta por (Sparks et al., 2020). También se determinará la acumulación de carbono en diferentes tipos de vegetación del barranco (cespitosa, herbácea, arbustiva etc.), tanto a partir de referencias (Hernández et al., 2015;Montero et al., 2020;Moore et al., 2012;Roncucci et al., 2012;Windham, 2001;), como de muestreos propios. ...
... This pyrophyte plant usually forms a dense and continuous stands on acidic and siliceous soils (Guzmán and Vargas, 2009) and covers great areas of burnt degraded forests, abandoned pastures and poor uncultivated lands mainly in Spain, Portugal, south of France and north of Morocco (Frazao et al., 2018). The biggest extensions can be found in Spain, where it is distributed in more than 2 million hectares and is dominant in a little more than 460,000 ha (Montero et al., 2020). C. ladanifer exhibits strong climate adaptability and resilience, thriving in conditions of low water, high solar exposure and poor contaminated soils (Núñez-Olivera et al., 1996;Santos et al., 2016;Rossini-Oliva et al., 2016;Frazao et al., 2018). ...
... At present, the industrial-scale commercial exploitation of C. ladanifer is almost exclusively limited to the region of Andalusia in Southern Spain (Alves-Ferreira et al., 2019). Despite its presence in substantial areas across Spain (Montero et al., 2020), regions like Extremadura, Castilla La Mancha, and Castilla y León in Central Spain hold untapped potential (Mediavilla et al., 2021a). The harvesting of C. ladanifer is typically carried out manually during a short period of time, from June to November . ...
The fluctuation in yield, composition, antibacterial and antioxidant activity of the essential oil (EO) of rockrose (Cistus ladanifer L.) obtained from two locations in central Spain was analysed and compared over the course of one year. Fifteen kilograms of C. ladanifer, collected monthly or fortnightly from two sites with different plant age (7 and 12 years), underwent steam-distillation. GC (FID)-MS analyses were done to determine the volatile profile of EOs. Obtained EO yields varied significantly (P<0.001) throughout the year, ranging between 0.03 to 0.19% w/d.w. (±0.05) with the highest yields (>0.1%) observed from September to February. The younger population exhibited higher EO yields that the older one. Both rockrose populations displayed a high content of α-pinene (40.4–62.0%); the other predominant constituents included allo-aromadendrene + trans-pinocarveol, limonene, bornyl acetate and viridiflorol. The higher EO yields coincided with a higher content of α-pinene and a lower content of the other components. Furthermore, EOs’ antibacterial potential was tested against Bacillus cereus. Only a weak antibacterial potency (512–1024 μg/mL) was revealed, with stronger potency in case of older rockrose population. In vitro antioxidant capacity, evaluated by ORAC method, showed similar results for both populations, with its stronger potential between February and May.
... Efforts to model shrubland fuel load dynamics at the stand level have been limited, in terms of the types of shrublands examined, and have focused primarily on total fuel or some specific fraction [39,[47][48][49][50][51], including in some cases live or dead fuel [35,52,53]. Dynamic models that consider total fuel load and various fuel fractions, differentiating by size and physiological state, at the stand level are even scarcer [54][55][56]. ...
... The guide curve for the high heath-dominated communities in our study shows a lower MAI at juvenile stage (5 years of age) than that reported by Fernandes et al. [47] and similar to those found by Fernandez-Abascal et al. [162] for the same species and by Montero et al. [51] in E. arborea in sites under Mediterranean climate; although, they surpass the value of these other Mediterranean communities from 10 years of age onwards. ...
Compatible model systems were developed for estimating fuel load dynamics in Ulex europaeus (gorse) and in Erica australis (Spanish heath) dominated shrub communities at stand level. The models were based on intensive, detailed destructive field sampling and were fitted simultaneously to fulfill the additivity principle. The models enable, for the first time, estimation of the biomass dynamics of the total shrub layer, size fractions and vegetative stage, with reasonably good accuracy. The approach used addresses the high variability in shrub biomass estimates by using a site index (SI) based on biomass levels at a reference age of 10 years. Analysis of the effect of climatic variables on site index confirmed the preference of gorse for mild temperatures and the ability of high heath communities to tolerate a wider range of temperatures. In the gorse communities, SI tended to increase as summer rainfall and the mean temperature of the coldest month increased. However, in the heath communities, no relationships were observed between SI and any of the climatic variables analyzed. The study findings may be useful for assessing and monitoring fuel hazards, updating fuel mapping, planning and implementing fuel reduction treatments and predicting fire behavior, among other important ecological and biomass use-related applications.
... The percentage of C in the tree biomass is 47.2% for Q. suber (Montero et al., 2005), 46.7% for Q. ilex and 50.8% for Olea europaea var. sylvestris (Montero et al., 2020). For cade (Juniperus oxycedrus), we used the allometric equation from Montero et al. (2005) which was developed in Málaga and only relies on DBH, and a C content of 51.5% (Montero et al., 2020). ...
... sylvestris (Montero et al., 2020). For cade (Juniperus oxycedrus), we used the allometric equation from Montero et al. (2005) which was developed in Málaga and only relies on DBH, and a C content of 51.5% (Montero et al., 2020). For olive trees, we used the power-law equation proposed by Brunori et al. (2017), developed for Olea europaea 'Leccino' in Italy, as a more local equation was not found. ...
Afforestation of degraded areas was suggested as CO2 sink, contributing to climate change mitigation. Yet, few studies have assessed this sink by combining measurements on carbon (C) in the biomass and the soil, despite it being crucial to properly estimate the mitigation potential. Here, we assessed the combined C stocks of afforestation plots of different ages on former cropland in a Cambisol landscape in Extremadura, Spain. The plots were afforested with two native tree species (Quercus ilex L. and Quercus suber L. in a density ratio of 3:1), planted at several occasions between 1998 and 2011. Stocks of afforested areas in 2022 were compared to non-afforested negative controls on arable land, to a closeby olive grove and a forest with signs of degradation. Tree biomass was estimated from allometric equations, soil organic carbon (SOC) stocks were measured to 30 cm depth, based on equivalent soil mass. The biomass C accumulation rate in afforested plots increased with tree density and elevation (p < 0.05; range: 25 to 75 g C m−2 yr−1). SOC stocks, in contrast, were not significantly different in afforested and non-afforested plots at any depth and in tendency even lower in afforested plots younger than 20 years. Consequently, total (biomass plus soil) C stocks in afforested plots were not significantly higher than in non-afforested ones. Nevertheless, SOC stocks and contents between the tree rows were significantly lower compared to soil next to the trees in the olive grove (about 1200 vs. 2200 g C m−2 in the top 30 cm) and in tendency in the afforested plots (about 1200 vs. 1500 g C m−2 in the top 30 cm; p < 0.1). The fact that the degraded forest (about 6800 g C m−2) and the olive grove (about 5300 g C m−2) did have significantly higher total C stocks than the afforested and non-afforested sites (about 2300 and 1800 g C m−2) could indicate that afforestation could soon become a C sink. However, our study clearly shows that afforestation is not automatically a C sink. Timing of different C pools` losses and gains affect net ecosystem carbon sequestration. While improved soil management in afforestation may reduce SOC losses, afforestation with Mediterranean Quercus trees under current management practices may require decades before being a C sink. This finding should temper expectations that afforestation with such tree species is a rapid solution to combat climate change.
... We analysed the performance of empirical models derived from Sentinel-2 data for LFMC monitoring in fire-prone shrubland dominated by Cistus ladanifer, a representative shrub that is widely distributed in the Western Mediterranean region, including the Iberian Peninsula, Southern France and north of Morocco and Algeria [30]. This shrub species is commonly used as a wildfire risk indicator species by fire management services in Spain because of its extensive distribution (nearly 3 million hectares, including monospecific shrubland and understorey in forest stands [31]) and also because the moisture content varies widely throughout the year [16,21,25]. The specific objectives of this study were as follows: (i) to extrapolate previous empirical models for the region of Madrid (central Spain) and the same shrubland species to a different geographical area in the region of Andalusia (southern Spain) and thus assess the potential transferability of the models accounting for site variability (spatial validation); (ii) to calibrate new empirical models with field data collected in the study area (region of Andalusia, southern Spain), comparing ...
Estimating live fuel moisture content (LFMC) is critical for assessing vegetation flammability and predicting potential fire behaviour, thus providing relevant information for wildfire prevention and management. Previous research has demonstrated that empirical modelling based on spectral data derived from remote sensing is useful for retrieving LFMC. However, these types of models are often very site-specific and generally considered difficult to extrapolate. In the present study, we analysed the performance of empirical models based on Sentinel-2 spectral data for estimating LFMC in fire-prone shrubland dominated by Cistus ladanifer. We used LFMC data collected in the field between June 2021 and September 2022 in 27 plots in the region of Andalusia (southern Spain). The specific objectives of the study included (i) to test previous existing models fitted for the same shrubland species in a different study area in the region of Madrid (central Spain); (ii) to calibrate empirical models with the field data from the region of Andalusia, comparing the model performance with that of existing models; and (iii) to test the capacity of the best empirical models to predict decreases in LFMC to critical threshold values in historical wildfire events. The results showed that the empirical models derived from Sentinel-2 data provided accurate LFMC monitoring, with a mean absolute error (MAE) of 15% in the estimation of LFMC variability throughout the year and with the MAE decreasing to 10% for the critical lower LFMC values (<100%). They also showed that previous models could be easily recalibrated for extrapolation to different geographical areas, yielding similar errors to the specific empirical models fitted in the study area in an independent validation. Finally, the results showed that decreases in LFMC in historical wildfire events were accurately predicted by the empirical models, with LFMC <80% in this fire-prone shrubland species.
... Les diferències a la part arbustiva i a la fusta morta poden respondre a les diferències pròpies dels sistemes estudiats, quant a l'estructura forestal (més abundància de matollars en sistemes mediterranis, més abundància de fusta morta en boscos de muntanya més desenvolupats) i a l'ecologia (clima, fisiografia). Montero et al. (2020), Alberdi et al. (2020) i López-Senespleda et al. (2021). ...
El segundo informe del INF1-AND se dedica a la estimación del carbono almacenado en los bosques de Andorra. Este informe es crucial para comprender el papel de los bosques andorranos en la mitigación del cambio climático, ya que cuantifica el carbono presente en diferentes componentes del ecosistema forestal. A continuación, se presentan los puntos clave del informe:
Carbono en la biomasa aérea: Se estima la cantidad de carbono almacenado en la parte aérea de los árboles, que incluye el tronco, las ramas y el follaje.
Carbono en la biomasa subterránea: Se calcula el carbono contenido en las raíces de los árboles, lo que es importante para entender el ciclo completo del carbono en el ecosistema forestal.
Carbono en la materia orgánica del suelo: Se evalúa el carbono almacenado en la materia orgánica del suelo, que incluye la hojarasca, los restos de plantas y otros materiales orgánicos en descomposición.
Capacidad de sumidero de carbono: Se analiza la capacidad de los bosques para absorber carbono de la atmósfera y almacenarlo en forma de biomasa y materia orgánica del suelo.
El informe utiliza datos de campo obtenidos de la red de parcelas permanentes establecidas en el marco del INF1-AND, así como modelos alométricos y factores de conversión para estimar el carbono en los diferentes compartimentos del bosque. Los resultados muestran que los bosques de Andorra actúan como un sumidero significativo de carbono, contribuyendo a la reducción de CO2 en la atmósfera.
Los humedales artificiales han demostrado su utilidad en el tratamiento de aguas residuales siendo herramientas claves en las acciones para mitigar el cambio climático al actuar como sumideros de carbono. No obstante, esta capacidad de captura se ve contrarrestada por las emisiones de gases de efecto invernadero (GEI) generadas durante los procesos bacterianos de descontaminación que ocurren en el sustrato de los humedales. Por lo tanto, es crucial establecer un balance de carbono que considere el carbono capturado por la vegetación a través de fitodepuración y el sustrato, frente a los GEI emitidos, los cuales son expresados en términos de CO2 equivalente (CO2e), considerando el potencial de calentamiento global a 100 años. En este estudio, el balance incluye las emisiones directas de CH4 y N2O, así como las emisiones indirectas de N2O, calculadas utilizando la metodología del Panel Intergubernamental de Expertos sobre el Cambio Climático (IPCC). Las emisiones de CO2 no biogénico fueron despreciadas, y el CO2 biogénico no fue considerado como GEI. Se evaluaron dos alternativas de tratamiento de aguas residuales utilizando humedales artificiales de flujo subsuperficial horizontal (HAFSsH) y de flujo vertical (HAFSsV) como tratamiento biológico secundario: i) Pretratamiento + Tanque Imhoff + HAFSsH; y ii) Pretratamiento + Tanque Imhoff + HAFSsV. Ambas alternativas incluyen un HAFSsV para el tratamiento de fangos primarios. El balance de carbono se calculó para evaluar la capacidad de los humedales artificiales tanto de forma independiente como dentro de un sistema integral de tratamiento de aguas residuales. Los resultados demostraron que, en ambas tipologías de humedales, la fijación de carbono supera a las emisiones de GEI, permitiéndoles funcionar como sumideros de carbono. Notablemente, el HAFSsV fue más eficiente en la captura de carbono por unidad de área de implantación en comparación con el HAFSsH, considerando estándares similares de calidad del agua efluente. Por otro lado, el sistema integral de tratamiento de aguas residuales resultó ser una fuente neta de carbono, siendo los tanques Imhoff los principales responsables de las emisiones de CO2e en ambas alternativas evaluadas. Se recomienda investigar alternativas de tratamiento de aguas residuales que permitan prescindir de las unidades de tratamiento primario, con el objetivo de que el sistema integral funcione como un sumidero de carbono, logrando una mayor eficiencia tanto en la depuración del agua como en la mitigación del cambio climático. Constructed wetlands have demonstrated their usefulness in wastewater treatment as key tools in climate change mitigation actions by acting as carbon sinks. However, this capture capacity is offset by greenhouse gas (GHG) emissions generated during the bacterial decontamination processes that occur in the wetland substrate. Therefore, it is crucial to establish a carbon balance that considers the carbon sequestered by the vegetation through phytodegradation and the substrate versus the GHG emitted, which are expressed in terms of CO2 equivalent (CO2e), considering the 100-year global warming potential. In this study, the balance includes direct CH4 and N2O emissions, as well as indirect N2O emissions, calculated using the methodology of the Intergovernmental Panel on Climate Change (IPCC). Non-biogenic CO2 emissions were disregarded, and biogenic CO2 was not considered as a GHG. Two wastewater treatment alternatives were evaluated using horizontal subsurface flow (HAFSsH) and vertical flow (HAFSsV) constructed wetlands as a secondary biological treatment: i) Pretreatment + Imhoff Tank + HAFSsH; and ii) Pretreatment + Imhoff Tank + HAFSsV. Both alternatives include a HAFSsV for primary sludge treatment. The carbon balance was calculated to evaluate the capacity of constructed wetlands both independently and within an integrated wastewater treatment system. The results showed that in both wetland typologies, carbon sequestration exceeds GHG emissions, allowing them to function as carbon sinks. Notably, HAFSsV was more efficient in carbon sequestration per unit area of implantation compared to HAFSsH, considering similar effluent water quality standards. On the other hand, the integrated wastewater treatment system turned out to be a net source of carbon, with the Imhoff tanks being the main responsible for CO2e emissions in both alternatives evaluated. It is recommended to investigate wastewater treatment alternatives that make it possible to dispense with the primary treatment units, so that the integrated system can function as a carbon sink, achieving greater efficiency in both water purification and climate change mitigation.
Labdanum resin or “gum” can be obtained from Cistus ladanifer L. by two different extraction methods: the Zamorean and the Andalusian processes. Although its main use is in the fragrance and perfumery sectors, ethnobotanical reports describe its use for medicinal purposes in managing hyperglycemia and mental illnesses. However, data concerning the bioactivities and pharmacological applications are scarce. In this work, it was found that the yield of labdanum resin extracted by the Andalusian process was 25-fold higher than the Zamorean one. Both resins were purified as absolutes, and the Andalusian absolute was purified into diterpenoid and flavonoid fractions. GC-EI-MS analysis confirmed the presence of phenylpropanoids, labdane-type diterpenoids, and methylated flavonoids, which are already described in the literature, but revealed other compounds, and showed that the different extracts presented distinct chemical profile. The potential antidiabetic activity, by inhibition of α-amylase and α-glucosidase, and the potential neuroprotective activity, by inhibition of acetylcholinesterase, were investigated. Diterpenoid fraction produced the higher α-amylase inhibitory effect (~30% and ~40% at 0.5 and 1 mg/mL, respectively). Zamorean absolute showed the highest α-glucosidase inhibitory effect (~14% and ~24%, at 0.5 and 1 mg/mL, respectively). Andalusian absolute showed the highest acetylcholinesterase inhibitory effect (~70% and ~75%, at 0.5 and 1 mg/mL, respectively). Using Caco-2 and HepG2 cell lines, Andalusian absolute and its purified fractions showed moderate cytotoxic/anti-proliferative activity at 24 h exposure (IC50 = 45–70 µg/mL, for Caco-2; IC50 = 60–80 µg/mL, for HepG2), whereas Zamorean absolute did not produce cytotoxicity (IC50 ≥ 200.00 µg/mL). Here we show, for the first time, that labdanum resin obtained by the Andalusian process, and its fractions, are composed of phytochemicals with anti-diabetic, neuroprotective and anti-proliferative potential, which are worth investigating for the pharmaceutical industry. However, toxic side-effects must also be addressed when using these products by ingestion, as done traditionally.
Litterfall plays a key role in the dynamic of forest ecosystems, ultimately determining forest productivity and carbon and nutrient cycling. Increasing our understanding on the role of structural and environmental factors controlling litterfall amount and seasonality is of paramount importance for modelling and estimating soil carbon sequestration and nutrient cycling under climate change scenarios. However, the effect of climatic conditions on litterfall has been scarcely studied, especially in Mediterranean ecosystems. Here, we used nine years of seasonally collected litterfall data in two contrasting Mediterranean cork oak forests to evaluate the effect of climatic variables on leaf fall and lit-terfall. First, we isolated the litterfall seasonal trend and the between-sites differences in production by using linear mixed models. Then, we evaluated the effect of climatic variables and whether this effect was site-specific. We found a consistent litterfall seasonal pattern, mainly determined by leaf shedding (70% of litterfall). Leaf fall mainly occurs in spring with a second but much smaller peak in autumn some years. Mean temperature, precipitation and mean wind speed strongly influenced litterfall, but this effect was site-specific. In the forest site located at higher latitude and altitude, leaf fall increased linearly with temperature and showed a positive quadratic response to precipitation. In the water-limited site, leaf fall was reduced as temperature increased and did not respond to precipitation. These results have implications for modelling and predicting soil carbon sequestration, nutrient cycling, and the forest ecosystem productivity. Specifically, carbon and nutrient cycling models can be improved by incorporating idiosyncratic forest sites responses to climatic variability.
The main objective of this work was to study the dynamics of litterfall and litter decomposition in Pinus sylvestris and Pinus halepensis plantations in Castilla y León Region (Spain) as well as the effect of local density on these parameters. Four stands of each species were selected and eight plots were established on each stand. A littertrap and 15 litterbags were set on each plot. Litterfall was collected monthly and a litterbag was removed every three months. The dry weight of litterfall was determined separately for each fraction. The loss of weight over time of needles in the litterbags was also determined. Finally, the relationship between local basal area in the plots and the studied parameters was assessed. The obtained results show significant and positive effects of basal area on litterfall and significant and negative effects on decay rate of needles in the litterbags.
Our knowledge about the influence of silvicultural treatments on nutrient cycling processes in Mediterranean forests is still limited. Four levels of tree removal were compared in an Aleppo pine forest in eastern Spain to determine the effects on litterfall, litter decomposition and the associated nutrient fluxes after 12 years. Removal treatments included clearfelling, two shelterwood intensities (60 and 75 % of basal area removed) and untreated controls. Twelve years later, the basal area removed still explained 60 % of litterfall mass variance and 60 % of C, 52 % of N, 45 % of P, 17 % of K, 47 % of Ca and 60 % of Mg return variances. Litter decomposed somewhat more slowly in clearfellings compared to controls (p = 0.049), accumulated more Ca and released less K compared to the other three treatments. This was explained by contamination with mineral particles due to the poorly developed O horizon in clearfellings. We conclude that the management practices reduced the nutrient return via litterfall, but the nutrient release through decomposition seems poorly sensitive to canopy disturbance. In order to accurately quantify the harvesting impacts on nutrient cycling in this Mediterranean forest system, it is necessary to measure the litterfall of the understory layer.
Two equations were generated to determine biomass and carbon in Abies religiosa (H.B.K.) Schl. et Cham. These equations were of the form Y = b Xk, where Y is the content of biomass or carbon, and X the diameter at the breast height (DBH). In order to estimate the values b and k, date from 26 trees of an area under forest management were used, with basal a diameter between 6.5 and 79 cm at the stand called "El Innominado" at San Felipe Hidalgo, in Nanacamilpa County, Tlaxcala, México. The biomass of each component of every tree was determined (logs, branches and foliage). Ten random subsamples of log, ten of branches and six of foliage were analyzed to determine carbon content. The carbon concentration in log was 46.6 %, in branches was 46 % and 46.1 % in the foliage. The carbon concentration average by tree was 46.5 %. The greater percentage of biomass (84.5 %) was found in the log including the stump, whereas in the branches in and the foliage it was 6.9 and 8.6 %, respectively. The adjustment of parameters b and k of the proposed model were obtained with the biomass and the basal diameter of the 26 trees (B=0.0713 DN 2.5104 ). The variables of the predictive model of accumulated carbon by tree (CAA) based on the Dbh were determined by an identical procedure, and the result was CAA = 0.0332 DN2.5104. The parameters for both equations had a coefficient of determination (R²) of 0.99.
Aim of study: The aim of the study was to determine the baseline carbon stock in forest floor and mineral soils in pine and oak stands in acid soils in Northern Spain.
Area of study: The study area is situated in northern Spain (42° N, 4° W) on “Paramos y Valles” region of Palencia
Material and methods: An extensive monitoring composed of 48 plots (31 in pine and 17 in oak stands) was carried out. Litter layers and mineral soil samples, at depths of 0-30 cm and 30-60 cm, were taken in each plot. An intensive monitoring was also performed by sampling 12 of these 48 plots selected taken in account species forest composition and their stand development stage. Microbial biomass C (CMB), C mineralization (CRB), and soil organic C balance at stand level were determined in surface soil samples of intensive monitoring.
Main results: No differences in soil C content were detected in the two forest ecosystems up to 60 cm depth (53.0±25.8 Mg C ha-1 in Pinus spp. plantations and 60.3±43.8 Mg C ha-1 in oak stands). However, differences in total C (CT), CMB and CRB were found in the upper 10 cm of the soils depending on the stand development stage in each species forest composition (Pinus nigra, Pinus pinaster, Pinus sylvestris and Quercus pyrenaica). Plots with high development stage exhibited significant lower metabolic quotient (qCO2), so, meant more efficient utilization of C by the microbial community. The C content in the forest floor was higher in pine stands (13.7±0.9 Mg C ha-1) than in oak stands (5.4±0.7 Mg C ha-1). A greater turnover time was found in pine ecosystems vs. oak stands. In contrast, forest floor H layer was nonexistent in oak stands.
Research highlights: Results about litterfall, forest floor and mineral soil dynamics in this paper can be used strategically to reach environmental goals in new afforestation programs and sustainable forest management approaches.
Keywords: C stocks; pine; Quercus pyrenaica; litter; metabolic quotient (qCO2).
Standardized methods and measurements are crucial for ecological research, particularly in long-term ecological studies where the projects are by nature collaborative and where it can be difficult to distinguish signs of environmental change from the effects of differing methodologies. This second volume in the Long-Term Ecological Research Network Series addresses these issues directly by providing a comprehensive standardized set of protocols for measuring soil properties. The goal of the volume is to facilitate cross-site synthesis and evaluation of ecosystem processes. Chapters cover methods for studying physical and chemical properties of soils, soil biological properties, and soil organisms, and they include work from many leaders in the field. The book is the first broadly based compendium of standardized soil measurement methods and will be an invaluable resource for ecologists, agronomists, and soil scientists.
Fire severity, defined as the magnitude of fire effects in an ecosystem, is a key factor to consider in planning management strategies for protecting forests against fire. Although prescribed burning has been used as a fuel reduction tool in forest ecosystems, it is quite limited in the Mediterranean region. Furthermore, little is known about how tree crowns are affected by prescribed underburning aimed at reducing fire severity in conifer stands. As part of an ongoing study to assess the effects of prescribed burning on the tree canopy, litterfall is currently being monitored in a network of experimental plots located in mixed (Pinus nigra and Pinus pinaster) and pure (P. nigra) conifer stands in the Cuenca Mountains (Castilla La Mancha, Spain). A total of 12 study plots (30m×30m) were established in a completely randomized experimental design to determine the effect of burning, with 2 treatments: no burning (control) and burning (i.e. with three replicate plots for each treatment and site). Burning was conducted in May 2016. In each plot, 8 litterfall collectors were installed at regular intervals, according to international protocols (ICP Forests), and all biomass falling into the collectors is being monitored monthly. The specific objective of this study is to assess how prescribed burning affects the rate of generation of foliar and non-foliar litterfall biomass due to the fire. In addition, the Leaf Area Index was estimated before burning and one year later to verify possible changes in the structure of the stands. This information could be used to help minimize the negative impacts of prescribed underburning on litterfall. To our knowledge, this study represents the first attempt to evaluate the effect of prescribed burning on litterfall biomass in Europe.
The goal of this study is to evaluate the decomposition of poplar leaves in the field, cultivated on short rotation conditions under two different edafoclimatic conditions. The experiment was scheduled to have a duration of three years and was conducted in a plantation of poplars (Populus spp) in high density (33300 tree/ha) with drip irrigation in two different Spanish regions: Soria and Madrid. This work presents the preliminary results, which are corresponded with the initial 20 months of the study. The decomposition leaves were collected using the method of the litter-bag, which allows the evaluation of leaves decomposition, estimating the weight losses as a function of time, as well as the chemical characteristics of the remaining ones. Carbon and nitrogen contents were determined every four months, while phosphorous and potassium were evaluated every eight months. Although the initial material depends on the same genetics, the vegetal development in different soils causes differences in the composition of leaves, which influences the decomposition processes and the supply of nutrients into soils.