Litterfall, litter decomposition and associated nutrient fluxes in Pinus halepensis: influence of tree removal intensity in a Mediterranean forest

The online version of this article (doi:10.1007/s10342-015-0893-z) contains supplementary material, which is available to authorized users[EN] 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.This work has been supported by a fellowship from the Generalitat Valenciana, Conselleria de Educacion, Formacion y Empleo awarded to L. Lado-Monserrat (BFPI/2008/041). Silvicultural treatments were carried out by the Mediterranean Centre for Environmental Studies (CEAM) through programme "I + D en relacion con la restauracion de la cubierta vegetal y otros aspectos de investigacion forestal". Dataloggers and probes were provided by the Generalitat Valenciana through Project "Efecto de diferentes sistemas de aclareo de masa forestal sobre la disponibilidad de agua, nutrientes y la regeneracion de la masa arborea y arbustiva en parcelas de pinar" (GV06/126). We acknowledge Joana Oliver, Ruth M. Tavera and Daniel Fortanet for their help in the laboratory and in the field. The authors wish to thank Francisco Galiana for his assistance, including help in fieldwork and providing information about the experimental design of the silvicultural treatments. Thanks also go to Rafael Herrera from the Centro de Ecologia, Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela and two anonymous reviewers for critically reviewing the manuscript.Lado Monserrat, L.; Lidón, A.; Bautista, I. (2015). Litterfall, litter decomposition and associated nutrient fluxes in Pinus halepensis: influence of tree removal intensity in a Mediterranean forest. European Journal of Forest Research. 134(5):833-844. https://doi.org/10.1007/s10342-015-0893-zS8338441345Almagro M, Martínez-Mena M (2012) Exploring short-term leaf-litter decomposition dynamics in a Mediterranean ecosystem: dependence on litter type and site conditions. Plant Soil 358:323–335Alvarez A, Gracia M, Vayreda J, Retana J (2012) Patterns of fuel types and crown fire potential in Pinus halepensis forests in the Western Mediterranean Basin. For Ecol Manage 270:282–290Austin AT, Vivanco L (2006) Plant litter decomposition in a semi-arid ecosystem controlled by photodegradation. Nature 442:555–558Bates JD, Svejcar TS, Miller RF (2007) Litter decomposition in cut and uncut western juniper woodlands. J Arid Environ 70:222–236Binkley D (2008) Three key points in the design of forest experiments. For Ecol Manage 255:2022–2023Blair JM, Crossley DA Jr (1988) Litter decomposition, nitrogen dynamics and litter microarthropods in a southern Appalachian hardwood forest 8 years following clearcutting. J Appl Ecol 25:683–698Blanco JA, Zavala MA, Imbert JB, Castillo FJ (2005) Sustainability of forest management practices: evaluation through a simulation model of nutrient cycling. For Ecol Manage 213:209–228Blanco JA, Imbert JB, Castillo FJ (2006) Influence of site characteristics and thinning intensity on litterfall production in two Pinus sylvestris L. forests in the western Pyrenees. For Ecol Manage 237:342–352Blanco JA, Imbert JB, Castillo FJ (2008) Nutrient return via litterfall in two contrasting Pinus sylvestris forests in the Pyrenees under different thinning intensities. For Ecol Manage 256:1840–1852Blanco JA, Imbert JB, Castillo FJ (2011) Thinning affects Pinus sylvestris needle decomposition rates and chemistry differently depending on site conditions. Biogeochemistry 106:397–414Caldentey J, Ibarra M, Hernández J (2001) Litter fluxes and decomposition in Nothofagus pumilio stands in the region of Magallanes, Chile. For Ecol Manage 148:145–157Christensen JH, Krishna Kumar K, et al. (2013) Climate phenomena and their relevance for future regional climate change. In: Stocker TF, Qin D, Plattner G-K et al (Eds.) Climate change 2013: the physical science basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USACortina J, Vallejo VR (1994) Effects of clearfelling on forest floor accumulation and litter decomposition in a radiata pine plantation. For Ecol Manage 70:299–310Entry JA, Rose CL, Cromack K Jr (1991) Litter decomposition and nutrient release in ectomycorrhizal mat soils of a Douglas fir ecosystem. Soil Biol Biochem 23:285–290Fabbio G, Merlo M, Tosi V (2003) Silvicultural management in maintaining biodiversity and resistance of forests in Europe—the Mediterranean region. J Environ Manage 67:67–76Galiana F, Pérez-Badía R, Camarero E, Estruch V, Currás R (2001) Estimación de la Radiación solar incidente en pinares de Pinus halepensis sometidos a tratamientos selvícolas de cortas finales. In: Junta de Andalucía. Consejería de Medio Ambiente (Ed.) Actas del III Congreso Forestal Español. Junta de Andalucía. Granada (Original in Spanish)García-Plé C, Vanrell P, Morey M (1995) Litter fall and decomposition in a Pinus halepensis forest on Mallorca. J Veg Sci 6:17–22González Utrillas N, González Pérez E, Galiana F (2005) Variación del crecimiento diametral de la masa de pinar de carrasco en cortas finales experimentales, en los montes de Tuejar y Chelva (Valencia). IV Congreso Forestal Español. Zaragoza. Soc. Esp. Cien. For. (Original in Spanish)Guo LB, Sims REH (1999) Litter decomposition and nutrient release via litter decomposition in New Zealand eucalypt short rotation forests. Agric Ecosyst Environ 75:133–140GVA (1995) Mapa de Suelos de la Comunidad Valenciana. Chelva (666). Proyecto LUCDEME (Icona), Centro de Investigaciones sobre Desertificación y Conselleria d’Agricultura i Mig Ambient. Generalitat Valenciana. Valencia, Spain. (Original in Spanish)Hennessey TC, Dougherty PM, Cregg BM, Wittwer RF (1992) Annual variation in needle fall of a loblolly pine stand in relation to climate and stand density. For Ecol Manage 51:329–338Inagaki Y, Kuramoto S, Torii A, Shinomiya Y, Fukata H (2008) Effects of thinning on leaf-fall and leaf-litter nitrogen concentration in hinoki cypress (Chamaecyparis obtusa Endlicher) plantation stands in Japan. For Ecol Manage 255:1859–1867Jonard M, Misson L, Ponette Q (2006) Long-term thinning effects on the forest floor and the foliar nutrient status of Norway spruce stands in the Belgian Ardennes. Can J For Res 36:2684–2695Kim C, Sharik TL, Jurgensen MF (1996a) Canopy cover effects on mass loss, and nitrogen and phosphorus dynamics from decomposing litter in oak and pine stands in northern Lower Michigan. For Ecol Manage 80:13–20Kim C, Sharik TL, Jurgensen MF (1996b) Litterfall, nitrogen and phosphorus inputs at various levels of canopy removal in oak and pine stands in northern lower Michigan. Am Midl Nat 135:195–204Kim C, Son Y, Lee WK, Jeong J, Noh NJ, Kim SR, Yang AR, Ju NG (2012) Influence of forest tending (Soopkakkugi) works on litterfall and nutrient inputs in a Pinus densiflora stand. For Sci Technol 8:83–88Kimmins JP (2004) Forest ecology, a foundation for sustainable management and environmental ethics in forestry. Prentice-Hall, New JerseyKimmins JP, Mailly D, Seely B (1999) Modelling forest ecosystem net primary production: the hybrid simulation approach used in FORECAST. Ecol Modell 122:195–224Klemmedson JO, Meier CE, Campbell RE (1990) Litter fall transfers of dry matter and nutrients in ponderosa pine stands. Can J For Res 20:1105–1115Kunhamu TK, Kumar BM, Viswanath S (2009) Does thinning affect litterfall, litter decomposition, and associated nutrient release in Acacia mangium stands of Kerala in peninsular India? Can J For Res 39:792–801Lytle DE, Cronan CS (1998) Comparative soil CO2 evolution, litter decay, and root dynamics in clearcut and uncut spruce–fir forest. For Ecol Manage 103:121–128Molina AJ, Del Campo AD (2012) The effects of experimental thinning on throughfall and stemflow: a contribution towards hydrology-oriented silviculture in Aleppo pine plantations. For Ecol Manage 269:206–213Navarro FB, Romero-Freire A, Del Castillo T, Foronda A, Jiménez MN, Ripoll MA, Sánchez-Miranda A, Hutsinger L, Fernández-Ondoño E (2013) Effects of thinning on litterfall were found after years in a Pinus halepensis afforestation area at tree and stand levels. For Ecol Manage 289:354–362Olson JS (1963) Energy storage and the balance of producers and decomposers in ecological systems. Ecology 44:322–331Pérez Cueva AJ (1994) Atlas Climático de la Comunidad Valenciana. Colección Territori nº 4. Generalitat Valenciana. Conselleria d’Obres Publiques, Urbanisme i Transport, ValenciaPetritsch R, Hasenauer H, Pietsch SA (2007) Incorporating forest growth response to thinning within biome-BGC. For Ecol Manage 242:324–336Prescott CE (1997) Effects of clearcutting and alternative silvicultural systems on rates of decomposition and nitrogen mineralization in a coastal montane coniferous forest. For Ecol Manage 95:253–260Prescott CE (2002) The influence of the forest canopy on nutrient cycling. Tree Physiol 22:1193–1200Prescott CE, Blevins LL, Staley CL (2000) Effects of clear-cutting on decomposition rates of litter and forest floor in forests of British Columbia. Can J For Res 30:1751–1757Roig S, Del Río M, Cañellas I, Montero G (2005) Litter fall in Mediterranean Pinus pinaster Ait. stands under different thinning regimes. For Ecol Manage 206:179–190Sardans J, Peñuelas J, Rodà F (2005) Changes in nutrient use efficiency, status and retranslocation in young post-fire regeneration Pinus halepensis in response to sudden N and P input, irrigation and removal of competing vegetation. Trees 19:233–250Scarascia-Mugnozza G, Oswald H, Piussi P, Radoglou K (2000) Forests of the Mediterranean region: gaps in knowledge and research needs. For Ecol Manage 132:97–109Slovik S (1997) Tree physiology. In: Hüttl RF, Schaaf W (eds) Magnesium deficiency in forest ecosystems. Kluwer Academic Publishers, London, pp 101–214Taylor BR, Parkinson D (1988) Does repeated freezing and thawing accelerate decay of leaf litter? Soil Biol Biochem 20:657–665Torras O, Saura S (2008) Effects of silvicultural treatments on forest biodiversity indicators in the Mediterranean. For Ecol Manage 255:3322–3330Trofymow JA, Barclay HJ, McCullough KM (1991) Annual rates and elemental concentrations of litter fall in thinned and fertilized Douglas-fir. Can J For Res 21:1601–1615Wallace ES, Freedman B (1986) Forest floor dynamics in a chronosequence of hardwood stands in central Nova Scotia. Can J For Res 16:293–302Whitford WG, Meentemeyer V, Seastedt TR, Cromack Jr K, Crossley Jr DA, Santos P, Todd RL, Waide JB (1981) Exceptions to the AET model: deserts and clear-cut forest. Ecology 62:275–277Yin X, Perry JA, Dixon RK (1989) Influence of canopy removal on oak forest floor decomposition. Can J For Res 19:204–21

The C:N:P:S stoichiometry of soil organic matter

The formation and turnover of soil organic matter (SOM) includes the biogeochemical processing of the macronutrient elements nitrogen (N), phosphorus (P) and sulphur (S), which alters their stoichiometric relationships to carbon (C) and to each other. We sought patterns among soil organic C, N, P and S in data for c. 2000 globally distributed soil samples, covering all soil horizons. For non-peat soils, strong negative correlations (p < 0.001) were found between N:C, P:C and S:C ratios and % organic carbon (OC), showing that SOM of soils with low OC concentrations (high in mineral matter) is rich in N, P and S. The results can be described approximately with a simple mixing model in which nutrient-poor SOM (NPSOM) has N:C, P:C and S:C ratios of 0.039, 0.0011 and 0.0054, while nutrient-rich SOM (NRSOM) has corresponding ratios of 0.12, 0.016 and 0.016, so that P is especially enriched in NRSOM compared to NPSOM. The trends hold across a range of ecosystems, for topsoils, including O horizons, and subsoils, and across different soil classes. The major exception is that tropical soils tend to have low P:C ratios especially at low N:C. We suggest that NRSOM comprises compounds selected by their strong adsorption to mineral matter. The stoichiometric patterns established here offer a new quantitative framework for SOM classification and characterisation, and provide important constraints to dynamic soil and ecosystem models of carbon turnover and nutrient dynamics

Nutrient-cycling microbes in Coastal Douglas-fir forests: Regional-scale correlation between communities, in situ climate, and other factors

Microbes such as fungi and bacteria play fundamental roles in litter-decay and nutrient-cycling; however their communities may respond differently than plants to climate change. The structure (diversity, richness and evenness) and composition of microbial communities in climate transects of mature Douglas-fir stands of coastal British Columbia rainshadow forests was analysed, in order to assess in situ variability due to different temperature and moisture regimes. We compared DGGE profiles of fungi (18S-FF390/FR1), nitrogen-fixing bacteria (NifH-universal) and ammonia-oxidizing bacteria (AmoA) PCR amplicons in forest floor and mineral soil samples from three transects located at different latitudes, each transect spanning the Coastal Western Hemlock and Douglas-fir biogeoclimatic zones. Composition of microbial communities in both soil layers was related to degree days above 0°C (2725 - 3489), while pH (3.8 - 5.5) best explained shifts in community structure. At this spatial scale, climatic conditions were likely to directly or indirectly select for different microbial species while local site heterogeneity influenced community structure. Significant changes in microbial community composition and structure were related to differences as small as 2.47% and 2.55°C in mean annual moisture and temperature variables, respectively. The climatic variables best describing microbial composition changed from one functional group to the next; in general they did not alter community structure. Spatial distance, especially associated with latitude, was also important in accounting for community variability (4 - 23%); but to a lesser extent than the combined influence of climate and soil characteristics (14 - 25%). Results suggest that in-situ climate can independently account for some patterns of microbial biogeography in coastal Douglas-fir forests. The distribution of up to 43% of nutrient-cycling microorganisms detected in forest soils responded to smaller abiotic gradients than host trees

Combining Area-Based and Individual Tree Metrics for Improving Merchantable and Non-Merchantable Wood Volume Estimates in Coastal Douglas-Fir Forests

Forest management practices can increase climate change mitigation potential through applications focused on carbon budgets. One such application involves utilizing non-merchantable material (i.e., logging residues typically piled and burned) for bio-energy. However, limited remote sensing data is available for estimating wood residues until after timber has been harvested, at which point recovery of residual wood is of little financial interest. This research utilizes a hybrid method to develop models that provide pre-harvest estimates of the amount of merchantable and non-merchantable material that would result from harvesting and investigates the scalability and transferability of such measures to the harvest block level. Models were trained using 38 plots across two sites dominated by Douglas-fir, then expanded to ten harvest blocks, and transferred to eight blocks from two sites without training data before being compared against multiple independent block-level estimates. Model results showed root mean square errors of 35% and 38% for merchantable and non-merchantable volumes, respectively. Merchantable volume estimates in blocks with training had average absolute differences from the harvest scale (9&ndash;34%) similar to transferred blocks without training (15&ndash;20%). Non-merchantable model results were also similar in both trained and transferred harvest blocks, with the pre-harvest model results having lower differences from the post-harvest geospatial versus field surveys. The results from this study show promise for hybrid methods to improve estimates of merchantable wood volume compared to conventional forest cover data approaches, and provide the ability to predict non-merchantable volumes within the range of accuracy of post-harvest residue survey methods

Combining Area-Based and Individual Tree Metrics for Improving Merchantable and Non-Merchantable Wood Volume Estimates in Coastal Douglas-Fir Forests

Forest management practices can increase climate change mitigation potential through applications focused on carbon budgets. One such application involves utilizing non-merchantable material (i.e., logging residues typically piled and burned) for bio-energy. However, limited remote sensing data is available for estimating wood residues until after timber has been harvested, at which point recovery of residual wood is of little financial interest. This research utilizes a hybrid method to develop models that provide pre-harvest estimates of the amount of merchantable and non-merchantable material that would result from harvesting and investigates the scalability and transferability of such measures to the harvest block level. Models were trained using 38 plots across two sites dominated by Douglas-fir, then expanded to ten harvest blocks, and transferred to eight blocks from two sites without training data before being compared against multiple independent block-level estimates. Model results showed root mean square errors of 35% and 38% for merchantable and non-merchantable volumes, respectively. Merchantable volume estimates in blocks with training had average absolute differences from the harvest scale (9–34%) similar to transferred blocks without training (15–20%). Non-merchantable model results were also similar in both trained and transferred harvest blocks, with the pre-harvest model results having lower differences from the post-harvest geospatial versus field surveys. The results from this study show promise for hybrid methods to improve estimates of merchantable wood volume compared to conventional forest cover data approaches, and provide the ability to predict non-merchantable volumes within the range of accuracy of post-harvest residue survey methods

An improved butanol-HCl assay for quantification of water-soluble, acetone:methanol-soluble, and insoluble proanthocyanidins (condensed tannins)

Abstract Background Condensed tannins (CT) are the most abundant secondary metabolite of land plants and can vary in abundance and structure according to tissue type, species, genotype, age, and environmental conditions. Recent improvements to the butanol-HCl assay have separately helped quantification of soluble and insoluble CTs, but have not yet been applied jointly. Our objectives were to combine previous assay improvements to allow for quantitative comparisons of different condensed tannin forms and to test protocols for analyses of condensed tannins in vegetative plant tissues. We also tested if the improved butanol-HCl assay can be used to quantify water-soluble forms of condensed tannins. Results Including ~50% acetone in both extraction solvents and final assay reagents greatly improved the extraction and quantification of soluble, insoluble and total condensed tannins. The acetone-based method also extended the linear portion of standard integration curves allowing for more accurate quantification of samples with a broader range of condensed tannin concentrations. Estimates of tannin concentrations determined using the protocol without acetone were lower, but correlated with values from acetone-based methods. With the improved assay, quantification of condensed tannins in water-soluble forms was highly replicable. The relative abundance of condensed tannins in soluble and insoluble forms differed substantially between tissue types. Conclusions The quantification of condensed tannins using the butanol-HCl assay was improved by adding acetone to both extraction and reagent solutions. These improvements will facilitate the quantification of total condensed tannin in tissues containing a range of concentrations, as well as to determine the amount in water-soluble, acetone:MeOH-soluble and insoluble forms. Accurate determination of these three condensed tannin forms is essential for careful investigations of their potentially different physiological and ecological functions

Canopy openness and leaf area in chronosequences of coastal temperate rainforests

Abstract: We examined spatial and temporal differences in canopy openness and effective leaf area (L e ) in a series of eight forest chronosequences located on southern Vancouver Island, British Columbia. Structural attributes were measured on the west and east side of the island in immature, mature, and old-growth stands using hemispherical photography and the LAI-2000 plant canopy analyzer (PCA). Old-growth forest canopies were distinct from those of younger stands: they were more open, more heterogeneous in their openness, and maintained a lower stand L e . Although the overall developmental trajectories of forests were similar across the study sites, site-to-site differences in the rate and magnitude of these temporal changes indicated that site-specific factors also play a significant role in determining the character of forest canopies and their development. The most significant changes in canopy structure did not emerge until the later stages of stand development (150-200 years). Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) dominated east-side forests were, on average, more open, more heterogeneous, and had a lower stand L e than the stands dominated by western hemlock (Tsuga heterophylla (Raf.) Sarg.) and western redcedar (Thuja plicata Donn.) forming the west-side chronosequences. Shoot clumping, along with other evidence, suggested that species-related differences in leaf display and the geometry of branching structure might have contributed significantly to these regional patterns. Résumé : Les auteurs ont examiné les différences spatiales et temporelles dans l&apos;ouverture de la canopée, ainsi que la surface foliaire effective (L e ) dans une série de huit chronoséquences forestières situées dans le sud de l&apos;île de Vancouver, en Colombie-Britannique. Les attributs structuraux ont été mesurés sur les côtés ouest et est de l&apos;île dans des peuplements immatures, matures et vieux, en utilisant la photographie hémisphérique et le LAI-2000 PCA (plant canopy analyzer). Les canopées des vieilles forêts sont différentes de celles des jeunes peuplements. Elles sont plus ouvertes, plus hétérogènes quant à leur ouverture et ont conservé une valeur de L e plus faible. Bien que le sens général du déve-loppement des forêts soit similaire à travers les sites étudiés, les différences entre les sites situés côte-à-côte, dans le taux et l&apos;amplitude de ces changements temporels, indiquent que des facteurs spécifiques au site jouent également un rôle important dans la détermination du caractère des canopées forestières et de leur développement. Les changements les plus importants dans la structure de la canopée ne sont pas apparus avant les derniers stades de développement du peuplement (150-200 ans). Les forêts dominées par le Douglas vert (Pseudotsuga menziesii (Mirb.) Franco) sur la côte est de l&apos;île sont, en moyenne, plus ouvertes, plus hétérogènes et ont un L e du peuplement plus faible que les peuplements dominés par la pruche de l&apos;Ouest (Tsuga heterophylla (Raf.) Sarg.) et le thuya géant (Thuja plicata Donn.) qui forment les chronoséquences sur la côte ouest de l&apos;île. Les bouquets de rejets, ensemble avec d&apos;autres indices, suggè-rent que les différences liées aux espèces dans la disposition des feuilles et la géométrie de la structure de la ramification contribuent, de façon importante, à la formation de ces patrons régionaux. [Traduit par la Rédaction] Frazer et al. 25