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Berlin Brandenburg

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  • JSTOR Archival Journals  (7)
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  • 1
    Language: English
    In: Plant and Soil, 2010, Vol.333(1), pp.93-103
    Description: Assessment of belowground interactions in mixed forests has been largely constrained by the ability to distinguish fine roots of different species. Here, we explored near infrared reflectance spectroscopy (NIRS) to predict the proportion of woody fine roots in mixed samples and analyzed whether the prediction quality of NIRS models is related to the complexity of the fine-root mixture. For model calibration and validation purposes, 11 series of artificial mixed species samples containing known amounts of fine roots of up to four temperate tree species and non-woody plants were prepared. Three types of models with different calibration/validation approaches were developed and tested against external independent data for additional validation. With these models the proportion of each species in root mixtures was predicted accurately with low standard error of prediction (RMSECV/RMSEP 〈6.5%) and high coefficient of determination (r 2  〉 0.93) for all fine-root mixtures. In addition, NIRS models also provided satisfactory estimates for samples with low (〈15%) or no content of particular components. The predictive power of the NIRS models did not decrease substantially with increasing complexity of the root samples. The approach presented here is a promising alternative to hand sorting of fine roots, which may be influenced substantially by operator variation, and it will facilitate investigating belowground interactions between woody species.
    Keywords: Fine roots ; Belowground diversity ; Near-infrared reflectance spectroscopy (NIRS) ; NIRS model ; Species proportions
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 2
    Language: English
    In: Oecologia, 2012, Vol.169(4), pp.1105-1115
    Description: The phenomenon of overyielding in species-diverse plant communities is mainly attributed to complementary resource use. Vertical niche differentiation belowground might be one potential mechanism for such complementarity. However, most studies that have analysed the diversity/productivity relationship and belowground niche differentiation have done so for fully occupied sites, not very young tree communities that are in the process of occupying belowground space. Here we used a 5–6 year old forest diversity experiment to analyse how fine-root (〈2 mm) production in ingrowth cores (0–30 cm) was influenced by tree species identity, as well as the species diversity and richness of tree neighbourhoods. Fine-root production during the first growing season after the installation of ingrowth cores increased slightly with tree species diversity, and four-species combinations produced on average 94.8% more fine-root biomass than monocultures. During the second growing season, fine-root mortality increased with tree species diversity, indicating an increased fine-root turnover in species-rich communities. The initial overyielding was attributable to the response to mixing by the dominant species, Pseudotsuga menziesii and Picea abies , which produced more fine roots in mixtures than could be expected from monocultures. In species-rich neighbourhoods, P. abies allocated more fine roots to the upper soil layer (0–15 cm), whereas P. menziesii produced more fine roots in the deeper layer (15–30 cm) than in species-poor neighbourhoods. Our results indicate that, although there may be no lasting overyielding in the fine-root production of species-diverse tree communities, increasing species diversity can lead to substantial changes in the production, vertical distribution, and turnover of fine roots of individual species.
    Keywords: Species diversity ; Species richness ; Fine roots ; Overyielding ; Vertical niche differentiation ; BIOTREE
    ISSN: 0029-8549
    E-ISSN: 1432-1939
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  • 3
    Language: English
    In: BioScience July 2012, Vol.62(7), pp.633-645
    Description: The majority of the world’s forests are used for multiple purposes, which often include the potentially conflicting goals of timber production and biodiversity conservation. A scientifically validated management approach that can reduce such conflicts is retention forestry, an approach modeled on natural processes, which emerged in the last 25 years as an alternative to clearcutting. A portion of the original stand is left unlogged to maintain the continuity of structural and compositional diversity. We detail retention forestry’s ecological role, review its current practices, and summarize the large research base on the subject. Retention forestry is applicable to all forest biomes, complements conservation in reserves, and represents bottom-up conservation through forest manager involvement. A research challenge is to identify thresholds for retention amounts to achieve desired outcomes. We define key issues for future development and link retention forestry with land-zoning allocation at various scales, expanding its uses to forest restoration and the management of uneven-age forests.
    Keywords: Biology;
    ISSN: 00063568
    E-ISSN: 15253244
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  • 4
    Language: English
    In: Ecosystems, 2012, Vol.15(7), pp.1158-1172
    Description: In spite of the extensive area of bogs in the southern cone of South America, there have been very few studies on structure and dynamics of conifer bog forests in this region. Previously, it has been assumed that in the absence of intensive disturbance, the dominant conifer Pilgerodendron uviferum (D. Don) Florin would be replaced through other angiosperm species. Here we hypothesized (a) that this conifer can persist without intensive disturbances and develop into old-growth forests with continuing regeneration and (b) that high-severity disturbances through fire threaten its local persistence. To test this hypotheses, we analyzed diameter and age structure, foliar and soil nutrient levels and the light environment of old-growth and fire-disturbed P. uviferum stands on Chiloé Island (43ºS) in North Patagonia. Longevity (〉880 years), extremely slow growth (〈1 mm diameter per year) and tolerance to shade and stress are the main mechanisms of P. uviferum persistence in nutrient-poor and waterlogged conditions. Hence, old-growth P. uviferum forests are not a transitional phase in forest succession and may be maintained in the landscape for many centuries or millennia. However, in fire-disturbed stands, live trees of the species were rare and regeneration negligible, showing that high-severity fires can eliminate the species from parts of the landscape, where neither propagules nor seed trees survive. This underpins the importance of biological legacies such as seed trees for the recovery of disturbed sites, and points to the need for active restoration approaches to restore fire-degraded P. uviferum forests.
    Keywords: Chiloé Island ; Forest dynamics ; Light availability ; N/P ratio ; Persistence mechanisms ; Sphagnum
    ISSN: 1432-9840
    E-ISSN: 1435-0629
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  • 5
    Language: English
    In: Plant and Soil, 2006, Vol.280(1), pp.267-277
    Description: Significant increases in aboveground biomass production have been observed in mixed plantations of Eucalyptus globulus and Acacia mearnsii when compared to monocultures. However, this positive growth response may be enhanced or lost with changes in resource availability. Therefore this study examined the effect of the commonly limiting resources soil N, P and moisture on the growth of E. globulus and A. mearnsii mixtures in a pot trial. Pots containing two E. globulus plants, two A. mearnsii plants or one of each species were treated with high and low levels of N and P fertiliser. After 50 weeks, E. globulus plants grew more aboveground biomass in mixtures than monocultures. A. mearnsii were larger in mixtures only at low N, where both species were similar in size and the combined aboveground biomass of both species in mixture was greater than that of monocultures. At high N and both high and low levels of P fertiliser E. globulus appeared to dominate and suppress A. mearnsii. In these treatments, the faster growth of E. globulus in mixture did not compensate the reduced growth of A. mearnsii , so mixtures were less productive than (or not significantly different from) E. globulus monocultures. The greater competitiveness of E. globulus in these situations may have resulted from its higher N and P use efficiency and greater growth response to N and P fertilisers compared to A. mearnsii. This trial indicates that the complex interactions between species in mixtures, and thus the success of mixed plantations, can be strongly influenced by site factors such as the availability of N and P.
    Keywords: Acacia mearnsii ; competition ; Eucalyptus globulus ; facilitation ; mixed-species
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 6
    Language: English
    In: Plant and Soil, 2004, Vol.265(1), pp.31-46
    Description: Information of fine-root biomass and production is critical for quantifying the productivity and carbon cycle of forest ecosystems, and yet our ability to obtain this information especially at a large spatial scale (e.g., regional to global) is extremely limited. Several studies attempted to relate fine-root biomass and production with various aboveground variables that can be measured more easily so that fine-root biomass and production could be estimated at a large spatial scale, but found the correlations were generally weak or non-existed at the stand level. In this study, we tested a new approach: instead of using the conventional way of analysing fine-root biomass at the stand level, we analysed fine-root data at the tree level. Fine-root biomass of overstory trees in stand was first separated from that of understory and standardized to a common fine-root definition of 〈 2 mm or 〈 5 mm diameter. Afterwards, we calculated fine-root biomass per tree for a ‘representative’ tree size of mean basal area for each stand. Statistically significant correlations between the fine-root biomass per tree and the diameter at the ground surface were found for all four boreal and cool temperate spruce, pine, fir and broadleaf forest types, and so allometric equations were developed for each group using a total of n = 212 measurements. The stand-level fine-root biomass of trees estimated using the allometric equations agrees well with the measurements, with r 2 values of 0.64 and 0.57 ( n = 171), respectively, for fine-roots 〈 2 mmand 〈 5 mm diameter. This study further estimated fine-root production as the product of fine-root turnover rate and fine-root biomass, and determined the turnover rate as a function of fine-root biomass, stand age, and mean annual temperature. The estimates of tree fine-root production agree well with reported values, with r 2 value of 0.53 for 〈 2 mm and 0.54 for 〈 5 mm diameter ( n = 162) at the stand level.
    Keywords: boreal ; cool temperature ; fine-root biomass ; fine-root production ; forest ; new approach ; regional estimation ; turnover rate
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 7
    In: Ecological Monographs, February 2011, Vol.81(1), pp.25-41
    Description: Subtropical broad‐leaved forests in southeastern China support a high diversity of woody plants. Using a comparative study design with 30 × 30 m plots ( = 27) from five successional stages (1 m in height in each plot and counted all woody recruits (bank of all seedlings ≤1 m in height) in each central 10 × 10 m quadrant of each plot. In addition, we measured a number of environmental variables (elevation, slope, aspect, soil moisture, pH, C, N, and C/N ratio) and biotic structural variables (height and cover of layers). Adult species richness varied from 25 to 69 species per plot, and in total 148 woody species from 46 families were recorded. There was a clear successional gradient in species composition as revealed by nonmetric multidimensional scaling (NMDS), but only a poor differentiation of different successional stages with respect to particular species. Adult richness per 100 individuals (rarefaction method) increased with successional stage. None of the measured abiotic variables were significantly correlated with adult species richness. We found no evidence that rare species were responsible for the increasing adult species richness, as richness of rare species among both adults and recruits was independent of the successional stage. Furthermore, the similarity between established adults and recruits did not increase with successional stage. There was a constant number of recruit species and also of exclusive recruit species, i.e., those that had not been present as adult individuals, across all successional stages, suggesting a continuous random immigration over time.
    Keywords: Bef-China ; Chronosequence ; Detrended Correspondence Analysis Dca ; Gutianshan National Nature Reserve ; Immigration ; Negative Density Dependence ; Nonmetric Multidimensional Scaling Nmds ; Permanent Forest Dynamic Plots ; Random Assembly ; Secondary Forest Succession ; Zhejiang Province ; China
    ISSN: 0012-9615
    E-ISSN: 1557-7015
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