Do multipurpose companion trees affect high value timber trees in a silvopastoral plantation system?

Establishment of native timber trees on deforested land may contribute to the livelihood of farmers, to improved ecosystem services and to increased greenhouse gas uptake. Here, we present a new silvopastoral planting design to assess species performance and interspecific competition or facilitation effects among native timber and multipurpose trees in Central America. Two timber species, Tabebuia rosea and Cedrela odorata, were established in three low-density planting regimes allowing combined tree and future livestock production: (1) solitary planting, (2) companion planting with Guazuma ulmifolia, and (3) companion planting with the nitrogen-fixing Gliricidia sepium. We quantified survival, growth and reforestation potential of the two timber species subjected to the different planting regimes for the first 2 years after establishment. Nitrogen concentration as well as stable nitrogen and carbon isotope composition (δ¹⁵N, δ¹³C) of leaves of the timber saplings were determined. T. rosea showed higher survival and better growth than C. odorata under varying environmental conditions (soil, concomitant vegetation). Performance of the timber saplings was unaffected by either companion species. Planting regimes had no effect on foliar nitrogen concentration and δ¹⁵N of the two timber species, although δ¹⁵N values indicated nitrogen fixation activity in G. sepium trees. Planting regimes affected foliar δ¹³C values in T. rosea. δ¹³C values were significantly higher in solitarily growing individuals, suggesting lower exposition to water stress conditions in saplings surrounded by companion species. As we found positively correlated growth traits among timber and multipurpose trees, a combined planting may benefit farmers by providing additional goods and services.     

Are neighboring trees in tune? Wood formation in Pinus pinaster

Neighboring trees growing under identical environmental conditions can exhibit different dynamics and periods of growth. Despite the recent advances in cambial biology, the exogenous and endogenous factors generating asynchronous xylem growths still remain undetermined. This study investigated timings and duration of xylem formation in maritime pine (Pinus pinaster Ait.) from an even-aged plantation in Portugal growing under Mediterranean climate. Cambial phenology and stem diameter were monitored weekly, from March to December 2010, on two classes of trees divided according to the tree ring widths of the last 15 years, but similar age and size: fast- and slow-growing trees. We tested the hypothesis that differences in tree ring widths result from cell production which in turn affects timings of xylogenesis and that the bimodal growth pattern, typical of the Mediterranean, originates from a double reactivation of the cambium: in spring and autumn. Cambial activity started earlier and ended later in fast-growing trees, confirming that cell production is a key factor determining the duration of xylogenesis. Intra-annual variations in stem diameter recorded by band dendrometers revealed two peaks of increment occurring in spring and late summer. However, the number of cambial cells did not increase in late summer, which suggested that the second peak of increment was caused by stem rehydration, rather than by a reactivation of cell division. These results demonstrated that the variability in the timings of xylem phenology observed among trees of the same age and size and growing under similar environmental conditions was closely related to cell production and not to age or size per se.     

Carbon dynamics in trees: feast or famine?

Research on the degree to which carbon (C) availability limits growth in trees, as well as recent trends in climate change and concurrent increases in drought-related tree mortality, have led to a renewed focus on the physiological mechanisms associated with tree growth responses to current and future climate. This has led to some dispute over the role of stored non-structural C compounds as indicators of a tree's current demands for photosynthate. Much of the uncertainty surrounding this issue could be resolved by developing a better understanding of the potential functions of non-structural C stored within trees. In addition to functioning as a buffer to reconcile temporal asynchrony between C demand and supply, the storage of non-structural C compounds may be under greater regulation than commonly recognized. We propose that in the face of environmental stochasticity, large, long-lived trees may require larger C investments in storage pools as safety margins than previously recognized, and that an important function of these pools may be to maintain hydraulic transport, particularly during episodes of severe stress. If so, survival and long-term growth in trees remain a function of C availability. Given that drought, freeze-thaw events and increasing tree height all impose additional constraints on vascular transport, the common trend of an increase in non-structural carbohydrate concentrations with tree size, drought or cold is consistent with our hypothesis. If the regulated maintenance of relatively large constitutive stored C pools in trees serves to maintain hydraulic integrity, then the minimum thresholds are expected to vary depending on the specific tissues, species, environment, growth form and habit. Much research is needed to elucidate the extent to which allocation of C to storage in trees is a passive vs. an active process, the specific functions of stored C pools, and the factors that drive active C allocation to storage.     

Multipurpose shade trees in coffee and cocoa plantations in Côte d'Ivoire

Coffee and cocoa are the main cash crops of Côte d'Ivoire. They are mainly produced by small farmers in a rather extensive way. The shade trees used are mostly wild forest species yielding many different products. In the Baoulé region, an inventory of those trees and their, often multiple, uses was established. Of the 41 tree species, 22 are used as firewood and 16 as timber for local constructions. Nineteen furnish pharmaceutical products for traditional medicine and 15 have edible parts (fruits, leaves, flowers, palm wine). Those products are essential in daily life and play an important role in the local economy. The plantations can therefore be considered as agroforestry systems. Part of the world-wide research on coffee and cocoa should be reoriented to such systems, adapted to small farmer holdings, where few inputs are available and conditions of production are less favourable.Translated with modifications from: Les arbres d'ombrage et leurs utilisations dans les plantations de café et de cacao dans le sud du V-Baoulé, Côte d'Ivoire, J. For. Suisse 143(2): 149–165, 1992.     

Intercropping trees’ effect on soil oribatid diversity in agro-ecosystems

The benefits of tree-based intercropping (TBI) compared to conventional agro-ecosystems in North America could include climate change mitigation and adaptation, although enhancing resilience to climate change through increasing soil diversity remains poorly explored. Diversity of soil microarthropods supports a series of ecological services that may be altered by soil desiccation due to climate change. Here we study the effect of red oak and hybrid poplar TBI on soil oribatid mite species assemblages associated to forage crops (mix of Timothy-grass and red clover). Abundance and species density of oribatids were affected by treatment, depth and the interaction of both variables. Abundance of oribatid mites was significantly lower in the oak TBI, showing a homogeneous vertical distribution in opposition to a decreasing with depth distribution under poplar TBI and conventional crops. Species density was significantly higher in the conventional crop, showing again significant differences in depth that were not present in both TBI treatments. Distance to tree did not affect mite abundance nor species density. TBI increased oribatid richness (obtained by sample-based rarefaction and extrapolation) only in the presence of oaks. The distribution of oribatids was strongly associated to tree fine root biomass and stress the importance of underground organic resources for the oribatid fauna and their ecological functions. If increasing drought associated with climate change desiccates superficial levels of agro-ecosystem soils, deeper sources of organic resources, such as tree roots, should become crucial in the maintenance of diverse microarthropod communities.     

Can distribution of trees explain variation in nitrous oxide fluxes?

Abstract

The impact of distance to tree stems on nitrous oxide (N₂O) fluxes was examined to determine whether it is possible to improve the accuracy of flux estimates from boreal forest soils. Dark static chambers were placed along transects between pairs of trees within a Norway spruce stand and fluxes of N₂O and carbon dioxide (CO₂) were measured during the period 1999–2003. The groundwater table was measured on every sampling occasion along the transects. In addition, radiation transmission, potential diffusion rate and biomass of forest floor vegetation were measured once at each chamber site along one of the transects and soil samples were collected at three depths, from which pH, denitrification enzyme activity, soil moisture, organic matter, and carbon and nitrogen content were determined. There was a high level of variation in the N₂O fluxes, both spatially and temporally. However, the spatial variation in the N₂O fluxes within the transect could not be explained by differences in any of the measured variables. Sometimes, mainly when no major peaks occurred, N₂O fluxes were significantly correlated with CO₂ release. It is concluded that distance to stems cannot be used to improve the design of sampling schemes or for extrapolating flux levels to larger scales.     

Functional composition of tall-statured trees underpins aboveground biomass in tropical forests

The influences of trait diversity(i.e.,the niche complementarity effect) and functional composition(i.e.,the mass ratio effect) on aboveground biomass(AGB) is a highly debated topic in forest ecology.Therefore,further studies are needed to explore these mechanisms in unstudied forest ecosystems to enhance our understanding,and to provide guidelines for specific forest management.Here,we hypothesized that functional composition would drive AGB better than trait diversity and stem size inequality ...     

Interannual dynamics of stemwood nonstructural carbohydrates in temperate forest trees surrounding drought

Interactions between water and carbon dynamics underlie drought-related tree mortality.While whole-tree water relations have been shown to play a key role in the response to and recovery from drought,the role of nonstructural carbohydrates(NSC) and how their storage and allocation changes surrounding drought events deserves further attention and is critical for understanding tree survival.Here,we quantified in situ NSC responses of temperate forest trees to the 2016 drought in the northeastern U...     

Stress-wave velocity of trees and dynamic Young’s modulus of logs of 4-year-old Eucalyptus camaldulensis trees selected for pulpwood production in Thailand

Eucalyptus camaldulensis Dehnh. is extensively planted in Thailand to produce wood chips used as raw material for pulp and paper. To promote the utilization of the wood from plantation-grown E. camaldulensis for solid lumber, stress-wave velocity of trees and dynamic Young’s modulus of logs were investigated for 4-year-old trees of eight half-sib families selected for pulpwood production on the basis of the growth characteristics in the previous tree breeding program. For the eight families, the mean stem diameter at 1.3 m above ground level and mean tree height were 7.6 cm and 11.9 m, respectively. The mean stress-wave velocity of eight families was 3.45 km/s. Dynamic Young’s modulus of logs ranged from 7.88 to 17.64 GPa, and the mean value for the eight families was 11.72 GPa. Stress-wave velocity of trees was significantly correlated with dynamic Young’s modulus of logs, suggesting that dynamic Young’s modulus of wood can be evaluated nondestructively by stress-wave velocity of trees. Significant differences in stress-wave velocity and dynamic Young’s modulus of logs were obtained among families. Thus, to promote the utilization of E. camaldulensis wood for solid lumber production, selection of trees with high Young’s modulus should be applied to trees already selected for the growth characteristics in the previous tree breeding program.     

Biodiversity of arbuscular mycorrhizal fungi in different trees of madhupur forest, Bangladesh

Roots and rhizosphere soils of Acacia auriculiformis A. Cunn. ex Benth., A. mangium Wild., Artocarpus heterophyUus Lamk. C., Dalbergia sissoo Roxb. ex A. P. D., Eucalyptus camaldulensis Dehnn., Hevea brasiliensis （Wild. ex Juss） Muell. Arg., Swietenia macrophylla King. and Tectona grandis L. were collected from different locations of Madhupur forest area to study the biodiversity of Arbuscular Mycorrhizal （AM） fungal colonization and spore population. All the plants showed AM colonization. Out of eight selected plants, mycelial colonization was lowest in the roots of A. heterophyllus （22%） and the highest was in the roots of H. brasiliensis （78%）. Mycelial intensity was observed poor （25%-77%） and moderate （23%-57%） in all plants species and abundant （11%-40%） was in most of the plant species. Vesicular colonization was observed in five plant species. The lowest was recorded in E. camaldulensis （4%） and the highest was in H. brasiliensis （21%）. Poor （24%-56%）, moderate （16%-100%） and abundant （11%-40%） type of vesicular intensity were observed. Arbuscular colonization was observed in three plants. The highest was in A. mangium （72%） and the lowest was in S. macrophylla （17%）. Arbuscular intensity was recorded as poor （12%-44%）, moderate （22%-100%） and abundant （4%-47%）. The highest AM fungal spore population was in A. auriculiformis （714） and the lowest was in D. sissoo （102）. Five AM fungal genera were recorded. Glomus was found to be dominant. A few spores remained unidentified. Significant correlation was observed between percent coloniza- tion and spore population. The results of the present study indicate the occurrence of AM fungi and the mycotrophism of the plants of Madhupur forest area and the applicability of AM technology in the forest management of Madhupur forest.     

Height growth recovery and crown development in top‐damaged Pinus sylvestris trees

Leader shoot damage was imposed on young Scots pines (3 m high) in four ways: by caging the uppermost whorl including the leader shoot with 10 pine shoot beetles; by caging the two uppermost whorls with 20 beetles; by topping the tree below the 1984 whorl; by topping the trees as above and removing all current shoots in whorl 1983. Six years later, top‐damaged trees were still significantly shorter than undamaged controls, although the annual height growth rate had recovered to the pre‐damage level within 3 years. Recovery occurred in two ways: lateral branches from the nearest intact whorl took dominance over the damaged leader or secondary branches developed from interfascicular buds on the damaged leader shoot. Approximately one and two years of height growth were lost in the former and latter case, respectively. Only 5 of the 34 top‐damaged trees escaped technical defects (crooks and/or vertical branches). Stem diameter and crown development were slightly affected.     

Selection of mixed-effects parameters in a variable–exponent taper equation for birch trees in northwestern Spain

Context

Taper equations predict the variation in diameter along the stem, therefore characterizing stem form. Several recent studies have tested mixed models for developing taper equations. Mixed-effects modeling allow the interindividual variation to be explained by considering both fixed-effects parameters (common to the population) and random-effects parameters (specific to each individual).

Aims

The objective of this study is to develop a mixed-effect variable exponent taper equation for birch trees in northwestern Spain by determining which fixed-effects parameters should be expanded with random-effects parameters.

Methods

All possible combinations of linear expansions with random effects in one and in two of the fixed-effects model parameters were tested. Upper stem diameter measurements were used to estimate random-effects parameters by the use of an approximate Bayesian estimator, which calibrated stem profile curves for individual trees.

Results

Parameter estimates for more than half of the mixed models investigated were nonsignificant. A first order autoregressive error structure was used to completely remove the autocorrelation between residuals, as mixed-effects modeling were not sufficient for this purpose.

Conclusion

The mixed model with the best fitting statistics did not provide the best calibration statistics for all upper stem diameter measurements. From a practical point of view, model calibration should be considered an essential criterion in mixed model selection.     

Discrimination method of forked larch trees

For the demands of automatic pruning, an effective discrimination rule of the forked and non-forked larch trees is established. First, information of trunk and branch diameters of a larch plantations was collected from the west mountain of Beijing. The growth characteristics of the forked and non-forked trees were studied. Given the statistical characteristics of the trunk and branch diameters, a discriminant function of the forked branch and non-forked larch trees was established statistically. Excellent discrimination results were obtained by the function and the rule. The study presents an effective discrimination rule to separate forked trees from straight trees for automatic pruning.     

How do trees affect spatio-temporal heterogeneity of nutrient cycling in mediterranean annual grasslands?

? In this study we analyzed heterogeneity in nutrient cycling induced by trees in Mediterranean annual grasslands, comparing years of higher and lower than average precipitation and analyzing the effects of two different solar radiation scenarios.

? Organic matter and consequently upper soil N, K, Ca and Mg were significantly greater in those locations receiving the highest levels of solar radiation, and as expected from many other studies in the literature, there was an increase in all macronutrients (except P) as well as pH below the canopy.

? Contrary to what was expected, plant nutrient concentrations did not directly reflect those found in the soil, with the exception of K. The studied grassland responded to increased nutrient availability by enhancing growth and changing botanical composition rather than by increasing plant nutrient concentrations. Hence, the total amount of accumulated nutrients in the ecosystem was larger below the tree than outside it, although this is mainly a consequence of plant growth enhancement. The levels of Ca, Mg, and Na in plants decreased during the driest year, and the N content was mostly determined by the composition of the grass.

? Temporal nutrient variability, particularly within-years, explained most of the variability in plant nutrient concentration, while spatial variability induced by trees was determined to be of secondary importance. These results are significant for ecosystem nutrient modelling.

     

Does litterfall from native trees support rainfed agriculture? Analysis of Ficus trees in agroforestry systems of southern dry agroclimatic zone of Karnataka, southern India

Trees of the genus Ficus, integral components of indigenous rainfed agro-ecosystems of the southern dry agro-climatic zone of Karnataka, southern India, have traditionally been associated with the ecological service of soil quality enhancement in addition to various direct use benefits. We assessed the soil enrichment service of Ficus benghalensis L. a common Ficus species in these agroforestry systems, by quantifying nutrient return via litter fall. Litterfall estimation and chemical analysis of litter showed that F. benghalensis trees produce 3,512 kg ha-1 of litter annually which, on decomposition, can satisfy up to 76.70 % of N, 20.24% of P and 67.76% of K requirements of dryland crops annually per hectare. This can lead to an avoided cost of compost of US $ 36.46 ha-1·a-1 in dryland farming systems. The slow rate of decay of Ficus litter, as revealed in litter decomposition studies indicates its potential as ideal mulch for dryland soils. We discuss the complementarity between Ficus litterfall and cropping patterns in Mandya, and its implications for rainfed agricultural systems.     

Patchy stomatal behavior during midday depression of leaf CO₂ exchange in tropical trees

We investigated effects of heterogeneous stomatal behavior on diurnal patterns of leaf gas exchange in 10 tree species. Observations were made in middle and upper canopy layers of potted tropical rainforest trees in a nursery at the Forest Research Institute Malaysia. Measurements were taken from 29 January to 3 February 2010. We measured in situ diurnal changes in net photosynthetic rate and stomatal conductance in three leaves of each species under natural light. In both top-canopy and sub-canopy species, midday depression of net assimilation rate occurred in late morning. Numerical analysis showed that patchy bimodal stomatal behavior occurred only during midday depression, suggesting that the distribution pattern of stomatal apertures (either uniform or non-uniform stomatal behavior) varies flexibly within single days. Direct observation of stomatal aperture using Suzuki's Universal Micro-Printing (SUMP) method demonstrated midday patchy stomatal closure that fits a bimodal pattern in Shorea leprosula Miq., Shorea macrantha Brandis. and Dipterocarpus tempehes V.Sl. Inhibition of net assimilation rate and stomatal conductance appears to be a response to changes in vapor pressure deficit (VPD). Variable stomatal closure with increasing VPD is a mechanism used by a range of species to prevent excess water loss from leaves through evapotranspiration (viz., inhibition of midday leaf gas exchange). Bimodal stomatal closure may occur among adjacent stomata within a single patch, rather than among patches on a single leaf. Our results suggest the?occurrence of patches at several scales within single leaves. Further analysis should consider variable spatial scales in heterogeneous stomatal behavior between and within patches and within single leaves.     

Do tannins in leaves of trees and shrubs from African and Himalayan regions differ in level and activity?

Mature leaves of trees and shrubs from sub-humid tropical regions of Benin (Acioa barteri, Cassia sieberiana, Dialium guineense, Dichrostachys cinerea, Guiera senegalensis, Milletia thonningii, Piliostigma reticulatum) and arid and semiarid regions of Zimbabwe and Niger (Acacia holosericea, A. nilotica, Dichrostachys cinerea, Securidaca longepedunculata, Parinari cuvetelio, Ziziphus mucronata) in Africa, and from sub-tropical region in foot-hills of North-West Humid Himalayan range (Albizia stipulata, Bauhenia variegata, Cedrela toona, Celtis australis, Dendrocalamus hamiltonii, Grewia optiva, Leucocephala leucocephala, Morus alba, Papulus ciliata, Quercus incana, Q. semecarpifolia, Q. glauca, Q. serrata, Q. ilex, Robinia pseudoacacia, Salix tetrasperma) were analysed for crude protein, total phenols (TP), protein precipitation capacity (PPC) and operational activity of tannins (values are as mean ± SE). There was no significant difference in the crude protein values of forages obtained from the Himalayan and African region (15.2 ± 1.16 and 14.1 ± 1.19%, respectively), however the levels of TP and biological value of tannins as PPC were significantly higher for the African forages (TP 15.7 ± 4.27 vs 6.0 ± 1.0%; PPC 327.2 ± 113.6 vs 56 ± 15.9 mg bovine serum albumin precipitated/g). The operational activity of tannins expressed as mg protein precipitated per unit of phenols was also significantly higher in forages from the African regions (1.97 ± 0.47 vs 0.66 ± 0.17). For a small set of leaves from arid and semiarid zones of Middle East (Syria, A. cyanophylla; Israel, A. saligna) and India (Eugenia jambolana, Eucalyptus punctata, Prosopis cineraria and Shorea robusta) TP, PPC and tannin activity were closer to those for the African forages.This revised version was published online in November 2005 with corrections to the Cover Date.     

Effects of intercropping systems of trees with soybean on soil physicochemical properties in juvenile plantations

The intercropping system of tree with soybean in juvenile plantations, as a short-term practice, was applied at Lao Shan Experimental Station in Mao’er Shan Forest of Northeast Forestry University, Harbin, China. The larch (Larix gmelinii)/soybean (Glycine max.) and ash (Fraxinus mandshurica) intercropping systems were studied in the field to assess the effects of the intercropping on soil physicochemical properties. The results showed that soil physical properties were improved after soybean intercropping with larch and ash in one growing season. The soil bulk density in larch/soybean and ash/soybean systems was 1.112 g·cm⁻³ and 1.058 g·cm⁻³, respectively, which was lower than that in the pure larch or ash plantation without intercropping. The total soil porosity also increased after intercropping. The organic matter amount in larch/soybean system was 1.77 times higher than that in the pure larch plantation, and it was 1.09 times higher in ash/soybean system than that in the pure ash plantation. Contents of total nitrogen and hydrolyzable nitrogen in larch/soybean system were 4.2% and 53.0% higher than those in the pure larch stand. Total nitrogen and hydrolyzable nitrogen contents in ash/soybean system were 75.5% and 3.3% higher than those in the pure ash plantation. Total phosphorus content decreased after intercropping, while change of available phosphorus showed an increasing trend. Total potassium and available potassium contents in the larch/soybean system were 0.6% and 17.5% higher than those in the pure larch stand. Total potassium and available potassium contents in the ash/soybean system were 56.4% and 21.8% higher than those in the pure ash plantation. Biography: FAN A-nan (1972–), female, Ph. Doctor in Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P. R. China.     

Detecting large-scale diversity patterns in tropical trees: Can we trust commercial forest inventories?

In this paper we seek to identify the floristic determination biases contained in large-scale commercial inventories conducted by logging companies and to determine whether this impacts on the observed patterns of alpha and beta diversity. The study focused on floristic data recently collected by industrial timber companies in the tropical forests of the Central African Republic (28,229 0.5-ha plots spread over 14,000 km²). A subset of these plots (n = 1107) was later re-sampled for controlling purposes by experienced botanists. The proportion of agreement between the two samplings was assessed for each species and independently for small and large trees, and at genus and family resolutions. Unsurprisingly, large trees and common species were more accurately identified than small trees and rare species. We found that the quality of the floristic determination increased slightly from species to families. We also detected a significant variation between concessions in the quality of the floristic determination that was more dependent on working conditions during forest inventories than on field workers. Contrary to a widespread belief, we did not find a strong bias toward commercial species, showing that commercial inventory data could also be valid for non-commercial species in ecological studies. Finally, we found that both alpha and beta diversity patterns in commercial inventories were highly consistent with those of the re-sampled inventory. This latter result shows that commercial inventories are well suited to detect large-scale patterns of floristic variation. Large-scale commercial inventories could thus play an important role in the identification of large-scale patterns in tropical tree diversity. This could enhance our ability to manage tropical forests by designing representative reserve networks and developing management plans that integrate diversity patterns at the landscape scale.     

Geographical variation in age–height relationships for dominant trees in Japanese cedar (Cryptomeria japonica D. Don) forests in Japan

In this study, we analyzed Japanese National Forest Inventory data to investigate the geographical variation in the relationship between tree height and age for dominant trees, and the effects of climatic conditions on these relationships. Our analysis focused on Cryptomeria japonica forests in 13 regions of Japan. The age–height relationships were classified into two regional groups that were distinguished by their climatic conditions. Several categories of climatic variables (warmth, solar radiation, precipitation, and snow depth) were significantly correlated with the parameters of a model for the age–height relationships. Our results also suggest the existence of a latitudinal cline for the maximum tree height of C. japonica in Japan. In regions with cold temperatures, deep snow, low solar radiation, and low summer precipitation, C. japonica shows a late-maturity pattern for height increase, with slow initial growth and a large maximum size. In regions with the opposite climatic conditions, it shows an early-maturity pattern with fast initial growth and small maximum size.