Ricardo Ruiz-Peinado

How does biomass distribution change with size and differ among species? An analysis for 1200 plant species from five continents

Summary We compiled a global database for leaf, stem and root biomass representing c. 11 000 records for c. 1200 herbaceous and woody species grown under either controlled or field conditions. We used this data set to analyse allometric relationships and fractional biomass distribution to leaves, stems and roots. We tested whether allometric scaling exponents are generally constant across plant sizes as predicted by metabolic scaling theory, or whether instead they change dynamically with plant size. We also quantified interspecific variation in biomass distribution among plant families and functional groups. Across all species combined, leaf vs stem and leaf vs root scaling exponents decreased from c. 1.00 for small plants to c. 0.60 for the largest trees considered. Evergreens had substantially higher leaf mass fractions (LMFs) than deciduous species, whereas graminoids maintained higher root mass fractions (RMFs) than eudicotyledonous herbs. These patterns do not support the hypothesis of fixed allometric exponents. Rather, continuous shifts in allometric exponents with plant size during ontogeny and evolution are the norm. Across seed plants, variation in biomass distribution among species is related more to function than phylogeny. We propose that the higher LMF of evergreens at least partly compensates for their relatively low leaf area : leaf mass ratio.

Growth and Yield Models for Pinus halepensis Mill

A partir de los datos obtenidos de 72 parcelas instaladas en 1965, en masas repobladas de Pinus halepensis, inventariadas en 1965, 1970, 1975, 1980, 1988 y 1999, se han elaborado modelos de crecimiento y produccion de selvicultura encontrada para cuatro calidades de estacion. Las curvas de calidad se han definido por la altura dominante alcanzada a los 80 anos de edad y se han ajustado por el modelo de Richards, resultando las siguientes curvas: calidad 20, calidad 17, calidad 14 y calidad 11. Posteriormente se han elaborado modelos de produccion de selvicultura variable incluyendo dos regimenes de claras, simulados a traves de la variacion del indice de Hart-Becking, para las calidades 20 y 17, que son las que presenta un mayor interes productivo. Para las calidades 14 y 11 se representan tablas con un unico regimen moderado de claras, como corresponde a su mayor interes protector y su menor interes productivo.

Species proportions by area in mixtures of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.)

Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) dominate many of the European forest stands. Also, mixtures of European beech and Scots pine more or less occur over all European countries, but have been scarcely investigated. The area occupied by each species is of high relevance, especially for growth evaluation and comparison of different species in mixed and monospecific stands. Thus, we studied different methods to describe species proportions and their definition as proportion by area. 25 triplets consisting of mixed and monospecific stands were established across Europe ranging from Lithuania to Spain in northern to southern direction and from Bulgaria to Belgium in eastern to western direction. On stand level, the conclusive method for estimating the species proportion as a fraction of the stand area relates the observed density (tree number or basal area) to its potential. This stand-level estimation makes use of the potential from comparable neighboring monospecific stands or from maximum density lines derived from other data, e.g. forest inventories or permanent observations plots. At tree level, the fraction of the stand area occupied by a species can be derived from the proportions of their crown projection area or of their leaf area. The estimates of the potentials obtained from neighboring monospecific stands, especially in older stands, were poorer than those from the maximum density line depending on the Martonne aridity index. Therefore, the stand-level method in combination with the Martonne aridity index for potential densities can be highly recommended. The species’ proportions estimated with this method are best approximated by the proportions of the species’ leaf areas. In forest practice, the most commonly applied method is an ocular estimation of the proportions by crown projection area. Even though the proportions of pine were calculated here by measuring crown projection areas in the field, we found this method to underestimate the proportion by 25% compared to the stand-level approach.

Aboveground biomass equations for sustainable production of fuelwood in a native dry tropical afro-montane forest of Ethiopia

Key messageBiomass equations are presented for five tree species growing in a natural forest in Ethiopia. Fitted models showed more accurate estimations than published generalized models for this dry tropical forest.ContextBiomass equations are needed to correctly quantify harvestable stock and biomass for sustainability efforts in forest management, but this kind of information is scarce in Ethiopia.AimsThis study sought to develop biomass models for five of the most common native tree species in the Chilimo dry afro-montane mixed forest in the central highlands of Ethiopia: Allophyllus abyssinicus, Olea europaea ssp. cuspidata, Olinia rochetiana, Rhus glutinosa, and Scolopia theifolia. Comparison with generalized models was intended to show the greater accuracy of the specific models.MethodsA total of 90 trees from different diameter classes were selected, felled, and divided into different biomass compartments. Biomass equation models were fitted using joint-generalized least squares regression to ensure the additivity property between the biomass compartments and total biomass.ResultsThese were the first models developed for these species in African tropical forests. Models were including diameter at breast height and total height as independent variables, obtaining more accurate biomass estimations using these models than from generalized models.ConclusionFitted models are reliable for estimating aboveground biomass in the Chilimo forest and for more general application in similar forest types. Model applicability for biomass or carbon estimation is high within forest inventory data contexts.

EuMIXFOR empirical forest mensuration and ring width data from pure and mixed stands of Scots pine (Pinus sylvestris L.) and European beech (Fagus sylvatica L.) through Europe

Key messageThis data set provides unique empirical data from triplets of Scots pine (Pinus sylvestrisL.) and European beech (Fagus sylvaticaL.) across Europe. Dendrometric variables are provided for 32 triplets, 96 plots, 7555 treesand 4695 core samples. These data contribute to our understanding of mixed stand dynamics.Dataset access athttp://dx.doi.org/10.5061/dryad.8v04m. Associated metadata available athttps://metadata-afs.nancy.inra.fr/geonetwork/apps/georchestra/?uuid=b3e098ca-e681-4910-9099-0e25d3b4cd52&hl=eng.

Aleppo pine vulnerability to climate stress is independent of site productivity of forest stands in southeastern Spain

Key messageClimate is the main driver of Aleppo pine radial growth variability irrespective of site productivity, with the climate effects on tree growth more limiting from 1970 onwards.AbstractForest management adaptation to climate change requires identifying the previously most vulnerable stands and the possible climate impacts on forests. This study evaluates whether site index, as an indicator of forest productivity, is related to climate–growth responses and assesses the way in which local site factors modulate climate–tree growth relationships. Tree-ring width series and soil characteristics were obtained from six Pinus halepensis stands with different site indices and similar climate. Dendrochronological methods were used to compare tree climate–growth responses among sites and to study temporal trends in inter-annual growth variability and climate–growth relationships (before and after 1970). The influence of topographic and soil features on tree growth was assessed by means of partial least squares. Stands with low site indices tended to present higher mean sensitivities and greater percentages of missing rings, this relation being modulated mainly by clay percentage and nutrient status in soil. Climate is the major Aleppo pine radial growth driver in the study area with similar growth–climate relationship among sites. Radial growth was mainly influenced by spring temperature and precipitation and previous autumn–winter precipitation. This relationship was stronger after 1970 than before this year, showing also a 2-month advancement of the most influential climate variables after 1970, from May to March. These results and the increasing temporal trend found in mean sensitivity after 1970 highlight the vulnerability of these stands to climate change. Site index was not found to be directly related to stand vulnerability, although local site factors modulate in part the tree-growth response.

Resin-tapped pine forests in Spain: Ecological diversity and economic valuation

Abstract Since ancient times, Mediterranean pine forests have been habitat for human activity, providing a wide range of goods such as timber, seeds, resin and derived products. Among them, tar and resin have played an historical role on the interaction between human activity and forests. In Spain, the resin played an important role in the economic and social development in rural areas during 20th century. But after 1980, resin production plummeted and the virtual disappearance of resin tapping caused the abandonment of traditional forest activities and the subsequently losses of ecosystem forest services (provision, regulation and cultural). This paper deals with some of the ecosystem services provided by resin tapped pine forests and shows how the abandonment of this traditional forestry activity would lead to a loss of social welfare beyond the economic activity. Among these ecosystem services, special attention is paid to the biodiversity of the pine forests. For that purpose, a stratified vegetation sampling was conducted in the leading resin-tapping Spanish region. Ecological analysis was therefore compared with the social preferences for several attributes associated to resin-tapped pine forests in Spain, including the biodiversity of flora.

Mediterranean Pine Forests: Management Effects on Carbon Stocks

In the Mediterranean area, the role of forest as carbon sinks is particularly significant since usually ecosystem services provided by forests are frequently of greater value than their direct productions. In this chapter, how carbon sequestration changes over time and with different management regimes in Mediterranean pine forests are presented. The information come from a number of sources including: (i) carbon stock estimates under different management plans using a chronosequence trial in Pinus sylvestris forests; (ii) simulations based on the process model 3-PG of the effect of different thinning regimes on Pinus pinaster biomass under a climate change scenario; (iii) a comparison of the effect of different age structures in Pinus pinea forest using the PINEA growth model which includes the biomass allocated in cones and considers the different wood uses; and finally, (iv) a model for estimating coarse woody debris.

Forest Carbon Sequestration: The Impact of Forest Management

Regardless of their geographical location , forests play an important role in CO2 fixation. Carbon stored in terrestrial ecosystems is distributed among three compartments: living plant biomass (stem, branches, foliage, roots), plant detritus (fallen branches and cones, forest litter, tree stumps, tree tops, logs) and soil (organic mineral humus, surface and deep mineral soil). Trees acquire energy for their living structures through photosynthesis, which requires CO2 captured by stomata in the leaves. Part of the captured CO2 is used to create living biomass, while the remainder is released back into the atmosphere through autotrophic respiration. When leaves or branches die and decompose, they increase soil carbon and also release a small amount into the atmosphere through heterotrophic respiration.

Tree allometry variation in response to intra- and inter-specific competitions

Key messageCrown, height and stem allometry vary with stand density and species composition, the plasticity in response to inter- and intra-specific competitions being related to species shade tolerances.AbstractDetermining the way in which variability in tree allometry is modulated by intra- and inter-specific competitions in different species and stand compositions is of particular interest for forest modelling and practice. In this study, we explore this variability by developing models for tree crown diameter, total height and diameter at a height of 4 m, which include intra- and inter-specific competition terms. More than 19,000 Scots pine, silver fir, sessile oak and European beech trees from 4711 sample plots belonging to the Spanish National Forest Inventory were included in the study, covering both monospecific and two species mixed stands in Northern Spain. Trees growing under conditions of high competition displayed narrower crowns, greater heights and less taper for a given tree diameter, the plasticity in crown and height in response to intra-specific competition being related to species shade tolerance. The inter-specific competition effect on crown diameter and height was related to the difference in shade tolerance between the two species of the mixture, while stem taper did not exhibit this pattern. These results suggest that trees in mixed stands indeed show a modified allometry, which might be related to complementary resource acquisition strategies. The large variability observed in tree allometry indicates the need to consider both intra- and inter-specific competitions in allometric models.