Forest diversity promotes individual tree growth in central European forest stands

Most experimental evidence on the relationship between biodiversity and ecosystem functioning comes from ecosystems with fast-growing plants, such as grasslands. Although forests provide essential ecological services, they have been less well investigated.  We used dendrochronology to compare the tree radial growth rates of four important timber species in replicated, spatially mapped stands that differed in tree composition and diversity within a central European managed forest.  Growth rates differed among species but were largely unaffected by the density of neighbouring trees.  Increasing stand diversity enhanced individual growth rates, after accounting for the effects of tree density and size. These increases were statistically indistinguishable among the four species. In contrast, the effects of stand and neighbourhood species composition on growth rates were non-significant.  Policy implications. Our study of long-established central European forest stands revealed levels of tree diversity can be increased in managed forests, with the potential for modest increases in tree growth rates. These results suggest that in addition to the biodiversity and risk mitigation benefits associated with shifting practices away from monoculture management, increased carbon sequestration and yields in mature forests are likely to be realized. Our results suggest that it is possible to increase forest diversity with little or no costs to production and even with the potential for modest increases in tree growth rates

Firsthand Experience and The Subsequent Role of Reflected Knowledge in Cultivating Trust in Global Collaboration

While scholars contend that firsthand experience - time spent onsite observing the people, places, and norms of a distant locale - is crucial in globally distributed collaboration, how such experience actually affects interpersonal dynamics is poorly understood. Based on 47 semistructured interviews and 140 survey responses in a global chemical company, this paper explores the effects of firsthand experience on intersite trust. We find firsthand experience leads not just to direct knowledge of the other, but also knowledge of the self as seen through the eyes of the other - what we call “reflected knowledge”. Reflected and direct knowledge, in turn, affect trust through identification, adaptation, and reduced misunderstandings

Patterns of Ancestry, Signatures of Natural Selection, and Genetic Association with Stature in Western African Pygmies

African Pygmy groups show a distinctive pattern of phenotypic variation, including short stature, which is thought to reflect past adaptation to a tropical environment. Here, we analyze Illumina 1M SNP array data in three Western Pygmy populations from Cameroon and three neighboring Bantu-speaking agricultural populations with whom they have admixed. We infer genome-wide ancestry, scan for signals of positive selection, and perform targeted genetic association with measured height variation. We identify multiple regions throughout the genome that may have played a role in adaptive evolution, many of which contain loci with roles in growth hormone, insulin, and insulin-like growth factor signaling pathways, as well as immunity and neuroendocrine signaling involved in reproduction and metabolism. The most striking results are found on chromosome 3, which harbors a cluster of selection and association signals between approximately 45 and 60 Mb. This region also includes the positional candidate genes DOCK3, which is known to be associated with height variation in Europeans, and CISH, a negative regulator of cytokine signaling known to inhibit growth hormone-stimulated STAT5 signaling. Finally, pathway analysis for genes near the strongest signals of association with height indicates enrichment for loci involved in insulin and insulin-like growth factor signaling

Positive effects of liana cutting on seedlings are reduced during El Niño‐induced drought

1.Liana cutting is a management practice currently applied to encourage seedling regeneration and tree growth in some logged tropical forests. However, there is limited empirical evidence of its effects on forest demographic rates in Southeast Asia.2.We used 22 four‐hectare plots in the Sabah Biodiversity Experiment (a reduced impact logging site) enrichment line planted with 16 dipterocarp species to assess the effects of complete liana cutting on tree growth and survival. We compared plots where lianas were only cut along planting lines (standard enrichment line planting) with those with one (2014) or two rounds (2011 and 2014) of complete liana cutting. 3.We found increased seedling growth following the first complete liana cut in 2011 relative to the enrichment line planting, consistent with previous studies. The response after three years to the cutting in 2014 depended on whether lianas had been previously cut or not: in twice‐cut plots, seedling growth was not significantly different from the standard enrichment planting controls, whereas growth in plots with only one complete cut in 2014 was significantly slower. Seedling survival decreased through time for both once‐ and twice‐cut liana treatments but remained stable in controls. 4.Sapling growth after the 2014 liana cutting showed a similar pattern to seedling growth, while tree growth following the 2014 liana cutting was significantly lower than controls regardless of whether lianas were cut twice (2011 and 2014) or once (2014). 5.Differences in response between the two rounds of liana cutting were likely due to changes in precipitation ‐ 2011 was followed by consistent rainfall while 2014 was followed by two severe droughts within two years. 6.Synthesis and applications. Our results generally support the widely‐reported positive effects of liana cutting on tree growth and survival. However, reduced growth and survival after the 2015/16 El Niño suggests that drought may temporarily undermine the benefits of liana cutting in logged tropical forests. Managers of similar areas in SE Asia should consider halting liana cutting during El Niño events. In other tropical areas, seedling survival should be monitored to assess to what extent results from SE Asia are transferable.</p

Positive effects of liana cutting on seedlings are reduced during El Niño‐induced drought

1.Liana cutting is a management practice currently applied to encourage seedling regeneration and tree growth in some logged tropical forests. However, there is limited empirical evidence of its effects on forest demographic rates in Southeast Asia.2.We used 22 four‐hectare plots in the Sabah Biodiversity Experiment (a reduced impact logging site) enrichment line planted with 16 dipterocarp species to assess the effects of complete liana cutting on tree growth and survival. We compared plots where lianas were only cut along planting lines (standard enrichment line planting) with those with one (2014) or two rounds (2011 and 2014) of complete liana cutting. 3.We found increased seedling growth following the first complete liana cut in 2011 relative to the enrichment line planting, consistent with previous studies. The response after three years to the cutting in 2014 depended on whether lianas had been previously cut or not: in twice‐cut plots, seedling growth was not significantly different from the standard enrichment planting controls, whereas growth in plots with only one complete cut in 2014 was significantly slower. Seedling survival decreased through time for both once‐ and twice‐cut liana treatments but remained stable in controls. 4.Sapling growth after the 2014 liana cutting showed a similar pattern to seedling growth, while tree growth following the 2014 liana cutting was significantly lower than controls regardless of whether lianas were cut twice (2011 and 2014) or once (2014). 5.Differences in response between the two rounds of liana cutting were likely due to changes in precipitation ‐ 2011 was followed by consistent rainfall while 2014 was followed by two severe droughts within two years. 6.Synthesis and applications. Our results generally support the widely‐reported positive effects of liana cutting on tree growth and survival. However, reduced growth and survival after the 2015/16 El Niño suggests that drought may temporarily undermine the benefits of liana cutting in logged tropical forests. Managers of similar areas in SE Asia should consider halting liana cutting during El Niño events. In other tropical areas, seedling survival should be monitored to assess to what extent results from SE Asia are transferable.</p

Growth rates and relative change in non-structural carbohydrates of dipterocarp seedlings in response to light acclimation

Background Light is a driver of tropical forest dynamics and key to understanding the coexistence of dipterocarps, and how their key demographic rates and traits trade-off with acclimation to light. Aims Light is a driver of tropical forest dynamics and key to understanding the coexistence of dipterocarps, and how their key demographic rates and traits trade-off with acclimation to light. Methods We examined the relationship between size-specific growth rates (SGR), wood density and total non-structural carbohydrate (NSC) concentration under experimental shade house conditions. Results Based on their functional response to light acclimation we grouped dipterocarps into light demanders, shade-tolerants and a generalist species. Light demanders respond to a simulated gap opening with increased growth, whereas shade-tolerants and the generalist show a higher relative change in wood density and NSC concentration, including starch and water soluble carbohydrates. Iditol–a hitherto unknown alditol in dipterocarps–was identified across all six species, and the generalist responded to a gap opening with a significantly reduced relative change in alditol concentration compared to light demanders and shade-tolerants. Conclusions Selected dipterocarps can be grouped into light demanders and shade-tolerants based on their acclimation to light, however, the generalist species did not follow the proposed growth-storage trade-off.</p

Forest diversity promotes individual tree growth in central European forest stands

Most experimental evidence on the relationship between biodiversity and ecosystem functioning comes from ecosystems with fast-growing plants, such as grasslands. Although forests provide essential ecological services, they have been less well investigated. We used dendrochronology to compare the tree radial growth rates of four important timber species in replicated, spatially mapped stands that differed in tree composition and diversity within a central European managed forest. Growth rates differed among species but were largely unaffected by the density of neighbouring trees. Increasing stand diversity enhanced individual growth rates, after accounting for the effects of tree density and size. These increases were statistically indistinguishable among the four species. In contrast, the effects of stand and neighbourhood species composition on growth rates were non-significant. Policy implications. Our study of long-established central European forest stands revealed levels of tree diversity can be increased in managed forests, with the potential for modest increases in tree growth rates. These results suggest that in addition to the biodiversity and risk mitigation benefits associated with shifting practices away from monoculture management, increased carbon sequestration and yields in mature forests are likely to be realized. Our results suggest that it is possible to increase forest diversity with little or no costs to production and even with the potential for modest increases in tree growth rates

Forest diversity promotes individual tree growth in central European forest stands

Most experimental evidence on the relationship between biodiversity and ecosystem functioning comes from ecosystems with fast-growing plants, such as grasslands. Although forests provide essential ecological services, they have been less well investigated. We used dendrochronology to compare the tree radial growth rates of four important timber species in replicated, spatially mapped stands that differed in tree composition and diversity within a central European managed forest. Growth rates differed among species but were largely unaffected by the density of neighbouring trees. Increasing stand diversity enhanced individual growth rates, after accounting for the effects of tree density and size. These increases were statistically indistinguishable among the four species. In contrast, the effects of stand and neighbourhood species composition on growth rates were non-significant. Policy implications. Our study of long-established central European forest stands revealed levels of tree diversity can be increased in managed forests, with the potential for modest increases in tree growth rates. These results suggest that in addition to the biodiversity and risk mitigation benefits associated with shifting practices away from monoculture management, increased carbon sequestration and yields in mature forests are likely to be realized. Our results suggest that it is possible to increase forest diversity with little or no costs to production and even with the potential for modest increases in tree growth rates