Do forest decision-makers in Southeastern Norway adapt forest management to climate change?

To study whether, why, and how forestry decision-makers in Southeastern Norway adapt to climate change, we conducted a series of semi-structured interviews in focus groups consisting of non-industrial private forest owners, forest managers, and forest advisors. Our results show that a majority of the participants believed in climate change as a phenomenon, and had experienced events or observed changes that they attributed to climate change. However, we found little evidence of concern regarding climate change impacts on forest ecosystems and forestry among the participants. Instead, the majority regarded climate change more as an opportunity for the Norwegian forest-based sector than a threat. A minority had implemented proactive practices motivated by climate change but in all but one case, the adjustments were adaptation of forest infrastructure. In general, the participants agreed that the uncertainty associated with the effects of climate change and the (economical) uncertainty associated with adaptation of forest ecosystems were too large to change forest management practices at present. However, many participants, in particular the managers, are already adapting in response to experienced problems, such as increased frequency and duration of periods with low carrying capacity of the ground implying reduced or no accessibility within and to stands.     

Mixing oak and pine trees does not improve the functional response to severe drought in central French forests

Key message

Mixing sessile oak and Scots pine in central France to reduce intraspecific competition for water resources did not improve the ability of these two species to withstand severe drought during the summer.

Context

In order to reduce the impact of increasingly extreme droughts on forests, managers must adapt their practices to future climate conditions. Maintaining a greater diversity of tree species in temperate forest ecosystems is one of the recommended options.

Aims

We addressed how interactions between sessile oak and Scots pine in mixed forests in central France affect their functional response to drought.

Methods

We characterized the carbon isotope composition (δ¹³C) in the tree growth rings formed during wet (2001, 2007) or dry (2003, 2004) summers for each of the two species growing both in pure and in mixed stands in order to compare the effect of stand composition on variations in carbon isotope discrimination (Δ¹³C) among contrasted years.

Results

The severe drought in 2003 induced a strong decrease in Δ¹³C for all trees and in all stands as compared to 2001. This decrease was greater in pine than in oak. There was no significant difference between pure and mixed stands in the response of either species to drought.

Conclusion

Mixing sessile oak and Scots pine in stands in central France does not improve the ability of either species to withstand severe drought during the summer.

     

Anatomical and biochemical trait network underlying genetic variations in tomato fruit texture

Firmness is an indicator of fruit freshness and a main component of tomato (Solanum lycopersicum) fruit texture. In this work, the genetic variability in fruit firmness and stiffness was analyzed in pre- and postharvest periods and underlying anatomical and biochemical traits were identified. Three tomato contrasted parental lines and six derived quantitative trait loci (QTL)-NILs harboring texture QTL on chromosome 4 (QTL4) and 9 (QTL9) were analyzed; the seasonal variability was assessed on two distant trusses. Firmness and stiffness were measured by compression and puncture tests at harvest and after 7-day storage at 20 °C. QTL4 poorly influenced the textural variables, on the contrary to QTL9 which increased firmness measured by puncture test and had similar effects in the two genetic backgrounds. According to this test, firmness increased along the season, but ranks among genotypes and QTL effects were hardly affected. Only some of the QTL effects were still significant after storage and firmness losses were not predicted by firmness at harvest. Fruit firmness and stiffness measured by puncture tests correlated with both morphological (locular number, R = −0.89), histological (cell size, R < −0.80) and biochemical (dry matter (R > 0.82) and soluble sugar content (R < −0.74)) fruit traits. In contrast, compression test values hardly correlated with any of the measured traits. This work provided an original comprehensive approach to analyse fleshy fruit firmness and paves the way for a future predictive model.     

Einfluss der biologischen Bewirtschaftung auf die Phytodiversität in der Diasporenbank und oberirdischen Vegetation biologisch bewirtschafteter Ackerflächen

The project deals with the evaluation whether the conversion to organic farming leads to an increase of weed diversity. Additionally to the analysis of the above ground vegetation and the soil seedbank on the small permanent plots a mapping of the surrounding vegetation was conducted in 2012. The number of weed species varies highly over the years, but the inventory of species differs only slightly from the one found on the surrounding fields. The number of seeds per m² is highly correlated with the number of above ground weeds species. The crop has shown the highest influence on both.     

Flooding responses of three earthworm species,Allolobophora chlorotica,Aporrectodea caliginosa and Lumbricus rubellus,in a laboratory-controlled environment

To get a better understanding of earthworm’ responses towards flooding, three laboratory experiments were performed with the species Allolobophora chlorotica, Aporrectodea caliginosa and Lumbricus rubellus.Flooding response was determined in a pot experiment, in which the earthworms were incubated for 42 days in flooded or non-flooded soil, with or without heavy metal pollution. To determine moisture preference, earthworms were incubated for 9 days in aquaria with five compartments, containing soil with a moisture gradient (%, w/w), ranging from 35%, 45% (field capacity), 55%, 65% (saturated) to 65%+ (saturated and an extra water layer). Effects on earthworm health were studied by incubating earthworms of each species for 42 days in soil with the same range of moisture contents and determining the dry/wet weight ratio and dry weight gain as an indication of earthworm health.A. chlorotica was tolerant to water, although the worms tended to escape from flooded soil. Their health was significantly lower in the flooded soils (P<0.05). A. caliginosa showed little response to flooding. This species, however, was affected by the heavy metal pollution in the pot experiment. L. rubellus was sensitive towards flooding, with escape and avoidance behaviour being the main mechanism of survival. This species was able to survive when forced to stay in flooded soil for at least 42 days, but this significantly reduced its health (P<0.05).These results suggest that earthworms are able to survive in inundated soils, but there are large differences between species in response to flooding conditions.     

The Impact of Bioturbation by Small Mammals on Heavy Metal Redistribution in an Embanked Floodplain of the River Rhine

Floodplains along large European rivers are diffusely polluted with heavy metals due to emissions in the past. Because of low mobility of heavy metals in floodplain soils and improvements of water quality, these pollutants will remain in place, and can gradually become covered with less contaminated sediments. Bioturbators, especially earthworms, can play an important role in the mixing and surfacing of contaminated substrate. Surfaced substrate can be redistributed by recurrent flooding events, even to areas outside the floodplain. The question remained to what extent bioturbation by small mammals contributes to the redistribution of heavy metals from river sediments in floodplains. Extensive fieldwork on bioturbators such as voles, moles and earthworms and their distribution patterns, as well as on sediment deposition and bioturbation, was conducted at the ‘Afferdensche en Deestsche Waarden’ floodplain over the years 2001–2003. Field data were combined with data of experiments in field enclosures and substrate columns to calculate the amounts of sediment and heavy metals (Zn, Cu, Pb and Cd) redistributed during the floods as well as on an annual basis. Moles and voles surfaced considerable amounts of substrate and heavy metals, but not as much as earthworms which contribute a substantial proportion of the total deposition and redistribution during floods. Although the impact of moles and voles on the redistribution during floods was only locally important, on an annual basis the bioturbation activity of especially moles in floodplains cannot be neglected. The annual amounts of substrate and heavy metals surfaced by all investigated bioturbators were even larger than the total amounts of substrate and heavy metals deposited during floods.     

Soil properties, grassland management, and landscape diversity drive the assembly of earthworm communities in temperate grasslands

Earthworms are widespread soil organisms that contribute to a wide range of ecosystem services. As such, it is important to improve our knowledge, still scanty, of the factors that drive the assembly of earthworm communities. The aim of the present study was to conjointly evaluate the effects on the assembly of earthworm communities of i) soil properties (texture, organic matter content, and pH), ii) grassland management (grassland age, livestock unit, and type of fertilization), iii) landscape diversity (richness, diversity of surrounding habitats, and grassland plant diversity), and iv) presence of hedgerows. The study was conducted in temperate grasslands of Brittany, France. Earthworms were sampled in 24 grasslands and, in three of these grasslands, they were sampled near a hedgerow or near a ditch (control without a hedgerow). Soil properties explained the larger portion of the variation in the earthworm community parameters compared to grassland management or landscape diversity. The increase in soil organic matter content and pH were the most favorable factors for earthworm abundance and biomass, in particular for endogeic species. Regarding grassland management, the increase in the livestock unit was the most damaging factor for earthworm communities, in particular for the anecic earthworm biomass and endogeic species richness. Surprisingly, landscape diversity negatively affected the total earthworm abundance and epigeic earthworm biomass, but it was related to an increase in the epi-anecic species. At a finer scale, we also demonstrated that the presence of hedgerows surrounding grasslands enhanced earthworm species richness, especially within the epigeic and anecic ecological categories. This study highlights that the earthworm ecological categories respond specifically to environmental filters; further studies need to be conducted to elucidate the factors that drive the assembly of earthworm communities at this ecological category level. We recommend that policymakers should act on landscape management to favor earthworm diversity in order to improve the ecosystem services they drive.