Andrzej M. Jagodziński

Positive biodiversity-productivity relationship predominant in global forests.

Global biodiversity and productivity The relationship between biodiversity and ecosystem productivity has been explored in detail in herbaceous vegetation, but patterns in forests are far less well understood. Liang et al. have amassed a global forest data set from >770,000 sample plots in 44 countries. A positive and consistent relationship can be discerned between tree diversity and ecosystem productivity at landscape, country, and ecoregion scales. On average, a 10% loss in biodiversity leads to a 3% loss in productivity. This means that the economic value of maintaining biodiversity for the sake of global forest productivity is more than fivefold greater than global conservation costs. Science, this issue p. 196 Global forest inventory records suggest that biodiversity loss would result in a decline in forest productivity worldwide. INTRODUCTION The biodiversity-productivity relationship (BPR; the effect of biodiversity on ecosystem productivity) is foundational to our understanding of the global extinction crisis and its impacts on the functioning of natural ecosystems. The BPR has been a prominent research topic within ecology in recent decades, but it is only recently that we have begun to develop a global perspective. RATIONALE Forests are the most important global repositories of terrestrial biodiversity, but deforestation, forest degradation, climate change, and other factors are threatening approximately one half of tree species worldwide. Although there have been substantial efforts to strengthen the preservation and sustainable use of forest biodiversity throughout the globe, the consequences of this diversity loss pose a major uncertainty for ongoing international forest management and conservation efforts. The forest BPR represents a critical missing link for accurate valuation of global biodiversity and successful integration of biological conservation and socioeconomic development. Until now, there have been limited tree-based diversity experiments, and the forest BPR has only been explored within regional-scale observational studies. Thus, the strength and spatial variability of this relationship remains unexplored at a global scale. RESULTS We explored the effect of tree species richness on tree volume productivity at the global scale using repeated forest inventories from 777,126 permanent sample plots in 44 countries containing more than 30 million trees from 8737 species spanning most of the global terrestrial biomes. Our findings reveal a consistent positive concave-down effect of biodiversity on forest productivity across the world, showing that a continued biodiversity loss would result in an accelerating decline in forest productivity worldwide. The BPR shows considerable geospatial variation across the world. The same percentage of biodiversity loss would lead to a greater relative (that is, percentage) productivity decline in the boreal forests of North America, Northeastern Europe, Central Siberia, East Asia, and scattered regions of South-central Africa and South-central Asia. In the Amazon, West and Southeastern Africa, Southern China, Myanmar, Nepal, and the Malay Archipelago, however, the same percentage of biodiversity loss would lead to greater absolute productivity decline. CONCLUSION Our findings highlight the negative effect of biodiversity loss on forest productivity and the potential benefits from the transition of monocultures to mixed-species stands in forestry practices. The BPR we discover across forest ecosystems worldwide corresponds well with recent theoretical advances, as well as with experimental and observational studies on forest and nonforest ecosystems. On the basis of this relationship, the ongoing species loss in forest ecosystems worldwide could substantially reduce forest productivity and thereby forest carbon absorption rate to compromise the global forest carbon sink. We further estimate that the economic value of biodiversity in maintaining commercial forest productivity alone is

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

166 billion to

Responses of leaf structure and photosynthetic properties to intra-canopy light gradients: A common garden test with four broadleaf deciduous angiosperm and seven evergreen conifer tree species

490 billion per year. Although representing only a small percentage of the total value of biodiversity, this value is two to six times as much as it would cost to effectively implement conservation globally. These results highlight the necessity to reassess biodiversity valuation and the potential benefits of integrating and promoting biological conservation in forest resource management and forestry practices worldwide. Global effect of tree species diversity on forest productivity. Ground-sourced data from 777,126 global forest biodiversity permanent sample plots (dark blue dots, left), which cover a substantial portion of the global forest extent (white), reveal a consistent positive and concave-down biodiversity-productivity relationship across forests worldwide (red line with pink bands representing 95% confidence interval, right). The biodiversity-productivity relationship (BPR) is foundational to our understanding of the global extinction crisis and its impacts on ecosystem functioning. Understanding BPR is critical for the accurate valuation and effective conservation of biodiversity. Using ground-sourced data from 777,126 permanent plots, spanning 44 countries and most terrestrial biomes, we reveal a globally consistent positive concave-down BPR, showing that continued biodiversity loss would result in an accelerating decline in forest productivity worldwide. The value of biodiversity in maintaining commercial forest productivity alone—US

Soil modification by different tree species influences the extent of seedling ectomycorrhizal infection.

166 billion to 490 billion per year according to our estimation—is more than twice what it would cost to implement effective global conservation. This highlights the need for a worldwide reassessment of biodiversity values, forest management strategies, and conservation priorities.

Seasonal variation in chemistry, but not morphology, in roots of Quercus robur growing in different soil types

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.

Tree Age Effects on Fine Root Biomass and Morphology over Chronosequences of Fagus sylvatica, Quercus robur and Alnus glutinosa Stands

Spectra of leaf traits in northern temperate forest canopies reflect major differences in leaf longevity between evergreen conifers and deciduous broadleaf angiosperms, as well as plastic modifications caused by within-crown shading. We investigated (1) whether long-lived conifer leaves exhibit similar intra-canopy plasticity as short-lived broadleaves, and (2) whether global interspecific relationships between photosynthesis, nitrogen, and leaf structure identified for sun leaves adequately describe leaves differentiated in response to light gradients. We studied structural and photosynthetic properties of intra-tree sun and shade foliage in adult trees of seven conifer and four broadleaf angiosperm species in a common garden in Poland. Shade leaves exhibited lower leaf mass-per-area (LMA) than sun leaves; however, the relative difference was smaller in conifers than in broadleaves. In broadleaves, LMA was correlated with lamina thickness and tissue density, while in conifers, it was correlated with thickness but not density. In broadleaves, but not in conifers, reduction of lamina thickness was correlated with a thinner palisade layer. The more conservative adjustment of conifer leaves could result from a combination of phylogenetic constraints, contrasting leaf anatomies and shoot geometries, but also from functional requirements of long-lived foliage. Mass-based nitrogen concentration (Nmass) was similar between sun and shade leaves, and was lower in conifers than in deciduous broadleaved species. Given this, the smaller LMA in shade corresponded with a lower area-based N concentration (Narea). In evergreen conifers, LMA and Narea were less powerful predictors of area-based photosynthetic rate (Amax(area)) in comparison with deciduous broadleaved angiosperms. Multiple regression for sun and shade leaves showed that, in each group, Amax(mass) was related to Nmass but not to LMA, whereas LMA became a significant codeterminant of Amax(mass) in analysis combining both groups. Thus, a fundamental mass-based relationship between photosynthesis, nitrogen, and leaf structure reported previously also exists in a dataset combining within-crown and across-functional type variation.

The optimal sample size in pollen morphological studies using the example of Rosa canina L. (Rosaceae)

Established vegetation can facilitate the ectomycorrhizal infection of seedlings, but it is not known whether this interaction is limited by the phylogenetic relatedness of trees and seedlings. We use a series of bioassay experiments to test whether soil modification by different ectomycorrhizal tree species causes different levels of seedling infection, whether the extent of seedling infection is a function of the relatedness of tree and seedling, and whether the effect of trees on seedlings is mediated by biotic or abiotic soil factors. We found that soils from under different tree species do vary in their mycorrhizal infectiveness. However, this variation is not related to the genetic relatedness of trees and seedlings but instead, appears to be an attribute of the overstory species, irrespective of seedling species, mediated through a suite of humus- and base-cation-related abiotic effects on soils. Modification of abiotic soil properties by overstory trees should be considered as an important factor in the effect of different overstory trees on the extent of seedling mycorrhizal infection.

Variability of perigynium morphology of Central European members of Carex sect. Phaestoglochin (Cyperaceae) from variable plant communities

Patterns of root traits among different root orders and their variation across seasons are of considerable importance for soil resource acquisition and partitioning in forest ecosystems. We evaluated whether morphological, anatomical and biochemical traits varied among root orders of Quercus robur (L.) sampled across spring, summer and fall seasons and growing in two different soil types with contrasting site fertility. We found no consistent differences in root diameter and specific root length in relation to soil type or growing season. There was, however, a strong seasonal variation in patterns of nitrogen (N) concentration among root orders. During spring and summer, N concentration was highest in the most distal, absorptive portion of the root system. At the end of the growing season, we observed a sharp decline in the N concentration of these lower-order, absorptive roots and an increase in N concentration of the higher-order, transport roots. The specific mechanisms driving the seasonally changing N concentration remain unclear but are likely related to different functions of lower-order roots for absorption and higher-order roots for structure and storage. Future work should identify how common the observed seasonal changes in N concentration are across species and determine what specific environmental cues plants or roots use to trigger shifts in resource allocation within the root branching hierarchy.

Climate change, tourism and historical grazing influence the distribution of Carex lachenalii Schkuhr – A rare arctic-alpine species in the Tatra Mts

There are few data on fine root biomass and morphology change in relation to stand age. Based on chronosequences for beech (9–140 years old), oak (11–140 years) and alder (4–76 years old) we aimed to examine how stand age affects fine root biomass and morphology. Soil cores from depths of 0–15 cm and 16–30 cm were used for the study. In contrast to previously published studies that suggested that maximum fine root biomass is reached at the canopy closure stage of stand development, we found almost linear increases of fine root biomass over stand age within the chronosequences. We did not observe any fine root biomass peak in the canopy closure stage. However, we found statistically significant increases of mean fine root biomass for the average individual tree in each chronosequence. Mean fine root biomass (0–30 cm) differed significantly among tree species chronosequences studied and was 4.32 Mg ha-1, 3.71 Mg ha-1 and 1.53 Mg ha-1, for beech, oak and alder stands, respectively. The highest fine root length, surface area, volume and number of fine root tips (0–30 cm soil depth), expressed on a stand area basis, occurred in beech stands, with medium values for oak stands and the lowest for alder stands. In the alder chronosequence all these values increased with stand age, in the beech chronosequence they decreased and in the oak chronosequence they increased until ca. 50 year old stands and then reached steady-state. Our study has proved statistically significant negative relationships between stand age and specific root length (SRL) in 0–30 cm soil depth for beech and oak chronosequences. Mean SRLs for each chronosequence were not significantly different among species for either soil depth studied. The results of this study indicate high fine root plasticity. Although only limited datasets are currently available, these data have provided valuable insight into fine root biomass and morphology of beech, oak and alder stands.

Morphological studies of pollen grains of the Polish endemic species of the genus Rubus (Rosaceae)

This study undertook an investigation of an important problem, so far completely overlooked in the palynological literature — to determine the optimal sample size for pollen grain morphological studies. In other words, we investigated the number of pollen grains which should be measured in order to obtain a representative mean value of a given quantitative feature which, in consequence, would make it possible to more accurately describe the pollen of a given taxon. Investigations were conducted on a sample comprising 3850 Rosa canina L. pollen grains on the basis of the length of the polar axis (P), the equatorial diameter (E) and the P/E ratio, at the flower, specimen and population levels. The size of the pollen samples analysed reflected common sample numbers employed in previous pollen morphology studies, namely from five through 10, 20, 30, 50, 100 up to 200 pollen grains. The statistical analyses performed revealed a relatively low variability in pollen grain biometric features at the levels of flower, specimen and population. At the lowest level of variability analysed, it is sufficient to take measurements of several grains to obtain values satisfactorily representing the variability within the flower level. At the level of a specimen or population, the number of grains necessary to secure representative mean values should range from 15 to 20. However, when the research objective is not only information regarding mean values of pollen grain biometric features but also the analysis of their variability (min—max), then the sample size should include approximately 30 grains. The results obtained, apart from their significance in taxonomic studies, also possess important practical significance; measurements of pollen grain biometric features are very labour-intensive and costly and, sometimes, because of difficulties in obtaining satisfactory quantities of plant material (e.g. herbarium specimens, rare species, paleopalynological collections), also very sparse.