Ecology of black locust (Robinia pseudoacacia L) in post-mining ecosystems

More than 250 years ago black locust (Robinia pseudoaccacia L.) was introduced to Brandenburg. The native range of black locust is classified by a humid to sub-humid climate with normal annual precipitation of 1,020 to 1,830 mm. However, in Central Europe, black locust is known to be relatively drought tolerant compared to other temperate deciduous tree species. As a pioneer species the tree grows under a wide range of conditions and is used for reclamation of former open-cast lignite mining areas in Brandenburg). Here, due to the ongoing mining activities, the groundwater table is lowered, and therefore plant growth depends mostly on the amount of rainfall. In those areas characterized by unfavourable edaphic conditions , the soil is mostly an unstructured clayed-sandy material, extremely heterogeneous and poor in organic materials and nutrients. The soil water availability during summer is more prone to water deficit than in agricultural soils under the same climatic conditions. Since water and nutrient availability are the main limiting factors for primary production, there is a need to evaluate the  impact on the black locust growth performance, taking into account the response of the plant to different edaphic conditions. 

Robinia plantation on reclaimed post-mining soils in Welzow SüdEcological invesitigations of Robinia at post-mining sitesRobinia stands on reclaimed post-mining sitesInvestigation of light environment in Robinia standsEcophysiology - photosynthesis and water use efficiencyDetermination of water use efficiency of Robinia on post-mining soils with lysimeters

Ecophysiological and morphological adaptations of black locust to drought stress

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The tree showed different ecophysiological and morphological adaptations and  to cope with a long-term drought stress The photosynthetic performance of Robinia  was studied with chlorophyll  fluorescence systems and net CO2-exchange and transpiration were determined with a minicuvette system CMS 400. Under drought stress net photosynthesis and transpiration were reduced due to stomatal closure. The measured electron transport rate of the photosystem II showed an opposite trend to the net photosynthesis and increased also under drought stress and increasing temperature up 30 °C. This indicates a higher fraction of energy dissipation of electrons to photorespiration and the Mehler reaction to avoid photoinhibition under limited CO2-uptake under drought stress und high temperatures. To minimize transpiration on the plant level leaf area was drastically reduced during drought stress. Furthermore, we develope and photosythesis model. A leaf net photosynthesis model is presented driven by light and modulated bytemperature and air humidity. From this the seasonal variation of CO2 uptake and release could be modelled to estimate the annual carbon fluxes of sun and shade leaves. In fully expanded leaves light is the major factor determining daily carbon balances. The presented photosynthesis model provides a good and realistic estimation for seasonal carbon balances on the leaf level for both species.

Evaluation of transpiration and growth under different soil moisture regimes using lysimeters

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Information about the water use efficiency of Robinia pseudoacacia in combination with the ecophysiological response to drought stress is still incomplete. he response of black locust to water limitation was investigated in a lysimeter experiment. Plants were grown under three different soil moisture regimes, with values set at 35%, 70%, and 100% of the soil water availability, namely WA35, WA70, and WA100. Their morphological adaptation and productivity response to water constraint were assessed together with their water-use efficiency. Furthermore, the ecophysiological adaptation at the leaf level was assessed in terms of net photosynthesis and leaf transpiration. During the growing season, plants in the WA35, WA70, and WA100 treatments transpired 239, 386, and 589 litres of water respectively. The plants subjected to the WA35 and WA70 treatments developed smaller leaves compared with the plants subjected to the WA100 treatment (66% and 36% respectively), which contributed to the total leaf area reduction from 8.03 m2 (WA100) to 3.25 m2 (WA35).The water-use efficiency across all treatments was 2.31 g L−1. 

Black locust plants can adapt to prolonged drought conditions by reducing water loss through both reduced transpiration and leaf size. However, under well-watered conditions it does not regulate its transpiration, and therefore it cannot be considered a water-saving tree species.

Biological nitrogen-fixation by Robinia pseudoacacia

Robinie (1)

The pioneer tree black locust (Robinia pseudoacacia L.) is a drought-resistant tree and, in symbiosis with Rhizobium, able to fix dinitrogen from the atmosphere.  However, the interaction between soil water availability, carbon allocation and nitrogen fixation is important for a successful establishment of trees on marginal lands and has not yet been investigated for black locust. Twoyear-old trees were grown under various soil water conditions and drought cycles. The stable isotopic composition of C (δ 13C) and N (δ 15N) of the leaves was used to identify i) the effective drought condition of the treatments and ii) the portion N accrued from the atmosphere by the biological nitrogen fixation. Drought-stressed plants significantly reduced their total aboveground biomass production, which was linearly linked to tree transpiration. The shoot:root ratio values changed from 2.2 for the drought-stressed to 4.3 for the well-watered plants. 

In order to estimate the N2-fixation potential of black locust at post-mining sites leaf samples were taken from black locust trees in short rotation plantations planted between 1995 and 2007 in post mining sites south of Cottbus (Brandenburg, NE Germany). The estimated percentage of nitrogen derived from the atmosphere (% NdfA) in black locust was 63% – 83% compared to 56% in seabuckthorn (Hippophaë rhamnoides) and 79% in common broom (Genista scuparia). The annual leaf biomass production of black locust varied between 1325 (2 years old trees) and 2576 kg/ha a (4 years old trees). The estimated leaf nitrogen fixed by Robinia was approx. 30.5 - 59.2 kg/ha a. From the results, we can conclude that the biological nitrogen fixation by Robina is an important factor for the nitrogen balance of short-rotation plantations on nutrient poor-soils. Under drought stress the nodule biomass increases in order to maintain biological nitrogen fixation and to counteract the lower soil nitrogen availability. 

Published papers

Küppers, M., Schmitt, D., Liner, S., Böhm, C., Kanzler, M., Veste, M. (2017): Photosynthetic characteristics and simulation of annual leaf carbon gains of hybrid poplar (Populus nigra L. x P. maximowiczii Henry) and black locust (Robinia pseudoacacia L.) in a temperate agroforestry system. Agroforestry Systems.

Mantovani, D., Veste. M., Böhm, C., Vignudelli, M., Freese, D. (2015): Spatial and temporal variation of drought impact on black locust (Robinia pseudoacacia L.) water status and growth  iForest - Journal of Biogeosciences and Forestry 8: 743-747

Mantovani, D., Veste. M., Boldt-Burisch, K., Fritsch, S., Koning, L., Freese, D. (2015): Carbon allocation, nodulation, and biological nitrogen fixation of black locust (Robinia pseudoacacia L.) under soil water limitation. Annals of Forestry Research 58 (2): 259-274.

Mantovani, D., Veste, M., Freese, D. (2014) Black locust (Robinia pseudoacacia L.) ecophysiological and morphological adaptations to drought and their consequence on biomass production and water use efficiency. New Zealand Journal of Forestry 44: 29.

Mantovani, D., Veste, M., Freese, D.  (2014): Effects of drought frequency on growth performance and transpiration of young  black locust (Robinia pseudoacacia L.). International Journal of Forestry Research, 2014, Article ID 821891: 11 pages. 

Mantovani, D., Veste, M., Badorreck, A., Freese, D. (2013): Evaluation of fast growing tree transpiration under different soil moisture regimes using wicked lysimeters. iForest - Journal of Biogeosciences and Forestry 6: 190-200.  

Veste, M., Böhm, C., Quinkenstein, A., Freese, D., (2013): Biologische Stickstoff-Fixierung der Robinie. AFZ-Der Wald 2/2013: 40-42.

Veste, M., Kriebitzsch, W.-U. (2013): Einfluss von Trockenstress auf  Photosynthese, Transpiration und Wachstum junger Robinien (Robinia pseudoacacia L.). Forstarchiv 84: 35-42.

© Maik Veste 2018 - Update 05JAN2018                                          Impressum