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Drafts by Patrick Gross

Nachhaltigkeit verlangt eine breit angelegte sozial-ökologische Transformation. Diese kann weder ... more Nachhaltigkeit verlangt eine breit angelegte sozial-ökologische Transformation. Diese kann weder von Oben (Top-Down) verordnet werden, noch allein von Unten (Bottom-Up) heranwachsen. Es bedarf der politischen Flankierung zivilgesellschaftlichen Engagements (Side-by-Side). In der Tat bedingen sich Nachhaltigkeit und partizipative Politikmuster. Doch was in der Theorie wesensgleich ist, gestaltet sich in der Praxis sehr ambivalent. Nur wenn bestimmte Idealbedingungen erfüllt sind, kann Nachhaltigkeit durch Partizipation gelingen.

Papers by Patrick Gross

Atmospheric Measurement Techniques, 2016

Annals of Botany, 2015

ABSTRACT • Background and Aims. The carbon (C) and nitrogen (N) needed for plant growth can eithe... more ABSTRACT • Background and Aims. The carbon (C) and nitrogen (N) needed for plant growth can either come from soil N and current photosynthesis or through remobilization of stored resources. The contribution of remobilization to new organ growth on a whole plant basis is quite well known in deciduous woody plants and evergreen conifers but this information is very limited in broadleaf evergreen trees. We compared the contribution of remobilized C and N to the construction of new organs in spring, and the importance of different organs as C and N sources in one-year-old potted seedlings of four ecologically distinct evergreen Mediterranean trees: Quercus ilex, Q. coccifera, Olea europaea and Pinus hapelensis. • Methods We used a dual 13C and 15N isotope labeling, to disentangle the contribution of currently taken up and stored C and N to new growth. Stored C was labeled under simulated winter conditions. • Key results Oaks allocated most C assimilated under simulated winter conditions in coarse roots while O. europaea and P. halepensis allocated it in the leaves. Remobilization was the main N source (> 74%) for new fine root growth in early spring but by mid spring, soil supplied most of N required for new growth (> 64%). Current photosynthesis supplied > 60% of the C in new fine roots by mid spring in most species. Across species, the proportion of remobilized C and N in new shoots increased with relative growth rate. Quercus species, the slowest growing trees, primarily used currently acquired resources while P. halepensis, the fastest growing species, mainly used reserves. Increase in the amount of stored N increased N remobilization, which fostered absolute growth both within and across species. Old leaves were major sources of remobilized C and N but stems and roots also supplied considerable amounts of both compounds in all species except in P. halepensis, which mainly relied on foliage formed in the previous growing season to supply stored resources. • Conclusions Seedlings of Mediterranean evergreen trees have distinct C and N storage physiology with growth speed driving the contribution of remobilized resources to new growth.

Annals of botany, Jan 29, 2015

The carbon (C) and nitrogen (N) needed for plant growth can come either from soil N and current p... more The carbon (C) and nitrogen (N) needed for plant growth can come either from soil N and current photosynthesis or through remobilization of stored resources. The contribution of remobilization to new organ growth on a whole-plant basis is quite well known in deciduous woody plants and evergreen conifers, but this information is very limited in broadleaf evergreen trees. This study compares the contribution of remobilized C and N to the construction of new organs in spring, and assesses the importance of different organs as C and N sources in 1-year-old potted seedlings of four ecologically distinct evergreen Mediterranean trees, namely Quercus ilex, Q. coccifera, Olea europaea and Pinus hapelensis. Dual (13)C and (15)N isotope labelling was used to unravel the contribution of currently taken up and stored C and N to new growth. Stored C was labelled under simulated winter conditions. Soil N was labelled with the fertilization during the spring growth. Oaks allocated most C assimilat...

Tree Physiology, 2008

Soil nitrogen can alter storage and remobilization of carbon and nitrogen in forest trees and aff... more Soil nitrogen can alter storage and remobilization of carbon and nitrogen in forest trees and affect growth responses to elevated carbon dioxide concentration ([CO 2 ]). We investigated these effects in oak saplings (Quercus robur L.) exposed for two years to ambient or twice ambient [CO 2 ] in combination with low-(LN, 0.6 mmol N l -1 ) or high-nitrogen (HN, 6.1 mmol N l -1 ) fertilization. Autumn N retranslocation efficiency from senescing leaves was less in HN saplings than in LN saplings, but about 15% of sapling N was lost to the litter. During the dormant season, nonstructural carbohydrates made up 20 to 30% of the dry mass of perennial organs. Starch was stored mainly in large roots where it represented 35-46% of dry mass. Accumulation of starch increased in large roots in response to LN but was unaffected by elevated [CO 2 ]. The HN treatment resulted in high concentrations of N-soluble compounds, and this effect was reduced by elevated [CO 2 ], which decreased soluble protein N (-17%) and amino acid N (-37%) concentrations in the HN saplings. Carbon and N reserves were labeled with 13 C and 15 N, respectively, at the end of the first year. In the second year, about 20% of labeled C and 50% of labeled N was remobilized for spring growth in all treatments. At the end of leaf expansion, 50-60% of C in HN saplings originated from assimilation versus only 10-20% in LN saplings. In HN saplings only, N uptake occurred, and some newly assimilated N was allocated to new shoots. Through effects on the C and N content of perennial organs, elevated [CO 2 ] and HN increased remobilization capacity, thereby supporting multiple shoot flushes, which increased leaf area and subsequent C acquisition in a positive feedback loop.

Tree Physiology, 2001

Pedunculate oak (Quercus robur L.) seedlings were grown for 3 or 4 months (second-and third-flush... more Pedunculate oak (Quercus robur L.) seedlings were grown for 3 or 4 months (second-and third-flush stages) in greenhouses at two atmospheric CO 2 concentrations ([CO 2 ]) (350 or 700 µmol mol -1 ) and two nitrogen fertilization regimes (6.1 or 0.61 mmol N l -1 nutrient solution). Combined effects of [CO 2 ] and nitrogen fertilization on partitioning of newly acquired carbon (C) and nitrogen (N) were assessed by dual 13 C and 15 N short-term labeling of seedlings at the second-or third-flush stage of development. In the low-N treatment, root growth, but not shoot growth, was stimulated by elevated [CO 2 ], with the result that shoot/root biomass ratio declined. At the second-flush stage, overall seedling biomass growth was increased (13%) by elevated [CO 2 ] regardless of N fertilization. At the third-flush stage, elevated [CO 2 ] increased growth sharply (139%) in the high-N but not the low-N treatment. Root/shoot biomass ratios were threefold higher in the low-N treatment relative to the high-N treatment. At the second-flush stage, leaf area was 45-51% greater in the high-N treatment than in the low-N treatment. At the-third flush stage, there was a positive interaction between the effects of N fertilization and [CO 2 ] on leaf area, which was 93% greater in the high-N/elevated [CO 2 ] treatment than in the low-N/ambient [CO 2 ] treatment. Specific leaf area was reduced (17-25%) by elevated [CO 2 ], whereas C and N concentrations of seedlings increased significantly in response to either elevated [CO 2 ] or high-N fertilization. At the third-flush stage, acquisition of C and N per unit dry mass of leaf and fine root was 51 and 77% greater, respectively, in the elevated [CO 2 ]/high-N fertilization treatment than in the ambient [CO 2 ]/low-N fertilization treatment. However, there was dilution of leaf N in response to elevated [CO 2 ]. Partitioning of newly acquired C and N between shoot and roots was altered by N fertilization but not [CO 2 ]. More newly acquired C and N were partitioned to roots in the low-N treatment than in the high-N treatment.

Journal of Experimental Botany, 2011

The distribution of carbon (C) into whole grapevine fruiting cuttings was investigated during flo... more The distribution of carbon (C) into whole grapevine fruiting cuttings was investigated during flower development to determine the relative contribution of inflorescence and leaf photoassimilates in the total C balance and to investigate their partitioning towards other plant organs. A 13 C labelling procedure was used to label C photoassimilates by leaves and inflorescences in grapevine. Investigations were carried out at various stages of flower/berry development, from separated cluster to fruit set, using grapevine fruiting cuttings with four leaves (Vitis vinifera L. cv. Chardonnay). This is the first study reporting that, during its development, (i) the carbon needs of the inflorescence were met by both leaf and inflorescence photosynthesis, and (ii) the inflorescence amazingly participated significantly to the total C balance of grapevine cuttings by redistributing an important part of its own assimilates to other plant organs. With regard to flowering, 29% of C assimilated by the inflorescence remained in the inflorescence, while partitioning towards the stem reached 42% and, as a lower proportion, 15% in leaves, and 14% in roots.

Atmospheric Measurement Techniques, 2016

Annals of Botany, 2015

Annals of botany, Jan 29, 2015

Tree Physiology, 2008

Tree Physiology, 2001

Journal of Experimental Botany, 2011

Journal of Experimental Botany, 2012

Trees will have to cope with increasing levels of CO 2 and ozone in the atmosphere. The purpose o... more Trees will have to cope with increasing levels of CO 2 and ozone in the atmosphere. The purpose of this work was to assess whether the lignification process could be altered in the wood of poplars under elevated CO 2 and/or ozone. Young poplars were exposed either to charcoal-filtered air (control), to elevated CO 2 (800 ml l 21 ), to ozone (200 nl l 21 ) or to a combination of elevated CO 2 and ozone in controlled chambers. Lignification was analysed at different levels: biosynthesis pathway activities (enzyme and transcript), lignin content, and capacity to incorporate new assimilates by using 13 C labelling. Elevated CO 2 and ozone had opposite effects on many parameters (growth, biomass, cambial activity, wood cell wall thickness) except on lignin content which was increased by elevated CO 2 and/or ozone. However, this increased lignification was due to different response mechanisms. Under elevated CO 2 , carbon supply to the stem and effective lignin synthesis were enhanced, leading to increased lignin content, although there was a reduction in the level of some enzyme and transcript involved in the lignin pathway. Ozone treatment induced a reduction in carbon supply and effective lignin synthesis as well as transcripts from all steps of the lignin pathway and some corresponding enzyme activities. However, lignin content was increased under ozone probably due to variations in other major components of the cell wall. Both mechanisms seemed to coexist under combined treatment and resulted in a high increase in lignin content.