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Im Rekultivierungsbereich des Braunkohletagebaus Welzow-Süd wurde der Einfluss der Schnitttechnik auf die Biomassequantität, die Stockausschlagfähigkeit und die Entwicklung von Robinien Wurzelbrut untersucht.
Für diesen Zweck wurden die Folgen der Holzernte mittels Forstmulcher und Motorsäge miteinander verglichen.
The production of energy wood on arable land increased in Germany during the last years. Black locust (Robinia pseudoacacia L.) is a suitable tree species in order to ensure substantial woody biomass yields on agricultural sites in eastern Germany. Arranged in hedge structures (alley cropping) positive effects on wind velocity and hence on soil erosion can be expected for the whole agricultural production area.
Results of field measurements carried out in several alley cropping sites located in eastern Germany show that wind velocity can be reduced by more than 50 %, even though tree hedgerows were not higher than four meters. Here, the reduction of wind speed was dependent on the distance to woody crops, the width of the crop alleys and the orientation of hedgerows. As a result of wind speeds reduction the potential of soil erosion by wind decreases considerably. The risk of wind erosion is even nearly negligible for 24 m wide or smaller crop alleys.
The establishment of short rotation hedgerows could contribute to an enhanced protection against wind erosion and thus to an ecological and possible long-term economic appreciation of agricultural sites. Aside from erosion control, further advantages such as a lower evaporation rate, and thus a crop yield increase, may be connected to the establishment of such agroforestry systems. Against the background of the increasing demand for woody biomass for bioenergy, the cultivation of fast growing trees on agricultural sites can furthermore result in an additional incomefor farmers. This is a prerequisite for the spread of this kind of agroforestry in Germany, because a comparable large share of an unprotected field has to be planted with trees in order to ensure an efficient windbreak.
Die Agroforstwirtschaft, also die kombinierte Nutzung von Bäumen und Feldfrüchten auf einer landwirtschaftlichen Fläche, gewinnt vor dem Hintergrund der steigenden Holznachfrage sowie diverser ökologischer Vorteilswirkungen auch in Deutschland
zunehmend an Bedeutung. Verglichen mit den bereits bekannten Umweltleistungen, wie etwa einer erhöhten Biodiversität sowie dem Schutz vor Winderosion, ist der potenzielle Einfluss der Gehölzstreifen auf das Wachstum bzw. die Nährstoffversorgung von angrenzenden Feldfrüchten in Agroforstsystemen noch weitestgehend ungeklärt. Zur Quantifizierung dieser möglichen Interaktion wurden im Jahr 2013 auf einem etwa 40 ha großen Agroforst-Versuchsstandort nahe der Stadt Forst (Lausitz) umfangreiche Nährstoff- und Ertragsuntersuchungen durchgeführt.
ln der Region Südbrandenburg herrschen ertragsschwache, sandige Böden vor, die von Natur aus ein geringes Wasserhaltevermögen und ein hohes Degradationspotential durch Winderosion aufweisen. Zudem existiert hier ein
vergleichsweise großer Flächenanteil an strukturarmen, großflächigen Bergbaufolgelandschaften, die sich zume1st durch eine geringe Standortsgüte auszeichnen. In diesem Beitrag werden Ergebnisse aus versChiedenen Studien vorgestellt, in denen untersucht wurde, ob und in welchem Ausmaß durch im Kurzumtrieb bewirtschaftete Agroforstsysteme die Anfälligkeit dieser Ackerstandorte gegenüber Winderosion gemindert und die im Boden bzw. Kippensubstrat vorhandene Menge an organischer Substanz erhöht werden kann.
The aim of this study was to evaluate the potential of short rotation alley cropping systems (SRACS) to improve the soil fertility of marginal post-mining sites in Brandenburg, Germany. Therefore, we annually investigated the crop alleys (AC) and black locust hedgerows (ABL) of a SRACS field trail under initial soil conditions to identify the short-term effects of tree planting on the storage of soil organic carbon (SOC) and its degree of stabilization by density fractionation. We detected a significant increase in SOC and hot-water-extractable organic C (HWEOC) at ABL, which was mainly restricted to the uppermost soil layer (0–10 cm). After 6 years, the SOC and HWEOC accumulation rates at ABL were 0.6 Mg and 46 kg ha−1 year−1, which were higher than those in the AC. In addition, comparatively high stocks of approximately 4.6 Mg OC and 182 kg HWEOC ha−1 were stored in the ABL litter layer. Density fractionation of the 0–3 cm soil layer at ABL revealed that the majority of the total SOC (47%) was stored in the free particulate organic matter fraction, which was more than twice that of the AC. At the same time, a higher and steadily increasing amount of SOC was stored in the occluded particulate organic matter fraction at ABL, which indicated a high efficiency for SOC stabilization. Overall, our findings support the suitability of black locust trees for increasing the soil fertility of the reclaimed mining substrate and, consequently, the high potential for SRACS to serve as an effective recultivation measure at marginal sites.
Der folgende Beitrag widmet sich der Frage, inwieweit sich mikroklimatische Änderungen in einem Agroforstsystem (AFS) bedingt durch die Gehölzkomponente kleinräumig auf die gemessene Evaporation sowie auf die Produktivität von Winterweizen (Triticum aestivum) auswirken. Hierfür wurden im Zeitraum von März bis August 2016 Untersuchungen auf einem ca. 40 ha großen Agroforstschlag und einer angrenzenden, konventionell bewirtschafteten Freifläche bei Neu Sacro (Landkreis Spree-Neiße, Brandenburg) durchgeführt. Neben mikroklimatischen Kenngrößen wie der Lufttemperatur, der relativen Luftfeuchte, der Windgeschwindigkeit und der Globalstrahlung wurde auch die Evaporation nach Piche bestimmt. Ergänzend wurden Ertragsmessungen zum Kornertrag und Messungen zum Blattflächenindex (LAI) des angebauten Winterweizens durchgeführt. Neben Änderungen der Tagesminima der relativen Luftfeuchtigkeit im Nahbereich der Gehölzstreifen wurde eine Reduktion der durchschnittlichen Windgeschwindigkeit von bis zu 51 % gegenüber der Freifläche festgestellt. Die Minderung der Evaporation im Vergleich zur Freifläche betrug je nach Witterung bzw. Nähe zum Gehölzstreifen bis zu 58 % und wurde dabei maßgeblich durch die Windgeschwindigkeit beeinflusst. Räumliche Unterschiede ergaben sich auch bezüglich des Kornertrags sowie beim LAI. So fielen die Kornerträge im Agroforstsystem mit bis zu 9,2 t ha-1 gegenüber ca. 7,0 t ha-1 für die Referenzfläche überwiegend höher aus. Mit Ausnahme des Leebereichs in 3 m Entfernung zum Gehölzstreifen lagen auch die LAI-Werte des AFS über jenen der angrenzenden Freifläche. Diese ersten Ergebnisse deuten darauf hin, dass in AFS durch Gehölzstrukturen neben der Windgeschwindigkeit auch die Wasserverdunstung im Bereich der angrenzenden Ackerkulturen gemindert werden kann. Die mikroklimatischen Unterschiede wirkten sich dabei potentiell auch positiv auf das Wachstumsverhalten bzw. den Ertrag des Winterweizens aus. Vor dem Hintergrund einer Verringerung der potentiellen Evaporation und einer hieraus resultierenden höheren Wasserverfügbarkeit für die Ackerkulturen könnte die agroforstliche Landnutzung zukünftig auch für trockenheitsgefährdete Gebiete Mitteleuropas eine vorteilhafte Anpassungsstrategie des Ackerbaus an den Klimawandel darstellen.
Agroforestry for arable farmers is not a common practice in Germany. However, alley cropping for woody biomass production is of interest because of its high potential to concurrently provide a biomass feedstock and an arable crop. One of the systems that exists, although at an experimental level, is the integration of rows of fast growing trees, such as poplar or willow, with arable crops.
The experimental plots were initially established as part of the German joint research project “AgroForstEnergie - Economic and Ecological Evaluation of Agroforestry Systems in Farming Practice“, funded by the German Federal Ministry of Food and Agriculture (AgroForstEnergie 2015). The goal of this project was to study alley cropping systems, which concurrently produce a woody biomass feedstock and conventional agricultural crops. Currently the work is continued through the AGFORWARD Project.
The State of Brandenburg is known for its light sandy soils that are prone to wind erosion. The introduction of tree hedgerows within the agricultural landscape can reduce wind erosion (Böhm et al. 2014). In addition, microclimatic conditions such as soil moisture, wind speed reduction, relative humidity and air temperature have been more favourable for plant growth in crop alleys compared to reference crop areas (Böhm et al. 2014; Quinkenstein et al. 2009).
Sugar beets are a common crop for conventional agricultural systems in Western Europe. As part of agroforestry systems, sugar beets have rarely been studied. Even though sugar beets can root up to a depth of 2 meter, their yields can be significantly reduced due to a lack of water (Hoffmann 2010; Bloch et al. 2006). Agroforestry systems that consist of tree hedgerows and crop alleys, also known as Alley Cropping Systems, have the potential to increase plant moisture in comparison to conventional agricultural systems (Quinkenstein et al. 2009).
This study aims to assess tree hedgerow effects on sugar beets. The objectives of this study were to; 1) assess how tree hedgerows planted at three distances affected sugar beet yields; 2) to correlate soil moisture values of the top 15 cm with sugar beet yields at the same distance of the tree row; 3) to assess the effects of drought stress on sugar beet yield.
Agroforestry (the integration of trees with crop and/or livestock production) offers a pathway to diversify agricultural production. Agroforestry systems have the potential to improve on-farm use of water through enhanced soil water holding capacities, the provision of shade, and the creation of wind shelter. These three characteristics can also improve the resilience of agricultural production in response to changing weather patterns. The objectives of this study were: 1) to measure how alley cropping systems with varying alley widths affect crop microclimate, 2) to measure the effects of this microclimate on sugar beet (Beta vulgaris) yields, and 3) to assess how moisture availability affects sugar beet growth patterns. Measurements were made in a 70 ha alley cropping system comprising black locust (Robinia pseudoacacia L.) and hybrid poplar Max1 (Populus suaveolens subsp. maximowiczii x P. nigra). A sugar beet crop was grown during the relatively dry growing season of 2015. Sugar beet yields were reduced in close proximity to the hedgerow, but yields were higher at and beyond an intermediate distance when compared with those in a nearby conventional agricultural field. Moisture availability significantly affected growth patterns of sugar beet roots.
Multifunctional land use systems, such as agroforestry, are able to deliver several ecological services to agriculture in addition to the concurrent production of woody biomass and arable crops. For example, trees in agroforestry systems can provide shelter for wildlife and supply additional nutrients to adjacent arable fields through leaf litter inputs and fine root turnover. In addition, tree-strips have the ability to improve the groundwater quality underneath the tree-strip itself and possibly underneath adjacent fields. Unlike these commonly measured ecosystem services the microclimate conditions in temperate agroforestry systems are still a comparatively new study area (Kanzler et al. 2015, Böhm et al. 2014). This might be due to the complexity of the microclimate, which depends on various parameters such as the plant height, the planting density, and the orientation of the tree-strips. The objective of this study was to investigate the potential influence of tree-strips on microclimate using high resolution data loggers.
Blattstreumengen in Gehölzstreifen und angrenzenden Ackerbreichen innerhalb eines Agroforstsystems
(2015)
Since the 1920s, more than 80.000 ha of land have been affected by lignite opencast mining activities in the Lusatia region (Eastern Germany), resulting in the evolution of large post-mining landscapes with substrates poor in humus and nutrients. As a consequence, the current conventional crop production on these post-mining areas is restricted. Against this background, the increasing demand for woody biomass for bioenergy, and thus the cultivation of fast growing trees for woody biomass production, could represent a promising option to enhance the productivity of land reclaimed from mining. Accordingly, considerable research has been carried out over the last two decades on reclamation technology, in addition to attempts to improve the soil quality through the use of different fast growing tree species in the Lusatia lignite region. Through such studies, it has been shown that it is possible to cultivate a sustainable supply of bioenergy wood through the use of black locust (Robinia pseudoacacia L.) trees, even under the unfavourable growth conditions of the marginal post mining areas. Since this knowledge is mainly based on studies of monocultural plantations (SRC), in 2007 a short rotation alley cropping system (SRACS) was established in the reclaimed lignite mining site “Welzow-Süd” with the purpose of obtaining fresh insight. The present paper evaluates the positive impacts of agroforestry land-use in terms of soil fertility, agricultural crop production, and soil protection against wind erosion based on the results of several years of examination made in this degraded area.
The cultivation of fast growing trees on agricultural sites is an area undergoing a growth in interest due to the rising demand for woody biomass as a source of bioenergy. Short rotation alley cropping systems (SRACS) represent a promising possibility to combine annual crops for food, fodder or bioenergy with woody plants for biomass production, doing so through an integration of hedgerows of fast growing trees into conventional agricultural sites. Against such developments, the question has arisen as to what extent hedgerows in SRACS can act as an effective windbreak despite their management-related low height of only a few meters. On the basis of multiannual recorded wind velocity data in high resolution at two sites in Germany, it could be shown that the wind speed on crop alleys was reduced significantly by such hedgerows. At the central point of 24 m wide crop alleys, the wind speed decreased on an annual average basis by more than 50 % when compared to the wind speeds of open field. The overall amount of reduction was strongly dependent on the location within the crop alleys, the height of trees, the distance between two hedgerows, and their orientation. In reflection upon these results, it was concluded that the establishment of SRACS could lead to enhanced soil protection against wind erosion and thus to ecological and economic benefits for agricultural sites.
Due to its ability to grow on marginal sites black locust (Robinia pseudoacacia L.) has been widely planted as a short rotation coppice (SRC) system that produce a renewable biomass feedstock in several post-mining areas of East Germany. However, as most of these sites are still in an initial stage of reclamation with low humus and nutrient contents, phosphorous can play a significant role as a plant limiting factor, because legumes require more P than other plants for their development. In April 2011, two experiments were conducted to evaluate the influence of higher rates and different applications of phosphorus fertiliser on the nutrition, survival, and biomass production of two different-aged black locust SRC plantations on the post lignite-mining site “Welzow-Süd”, situated in NE Germany. Treatments were applied as triple superphosphate (30, 60 and 120 kg P ha-1) and PK fertiliser (60 kg P ha-1) through broadcasting or banding on recently harvested or planted trees, respectively. Soil, leaf and woody biomass data were analysed utilising the Mann-Whitney U test and the Spearman correlation coefficient (rS). Following two growing seasons, it was observed that the total dry weight yields of the black locust seedlings were increased strongly by up to 8 times when compared to the control group, particularly when TSP was applied through banding. P fertilisation, however, did not affect the biomass yield of six-year-old black locust trees, but P concentration in leaves among treatments of both sites was still significantly increased and sufficient from a quantity upwards of 60 kg P ha-1. Taken together, a comparably moderate amount of P fertiliser (60 kg ha-1) had a strong impact on P uptake and growth performance in the examined black locust seedlings, which reveals a high potential to improve the current fertilisation practices for SRC black locust plantations grown on our research site.
A leaf net photosynthesis model is presented driven by light and modulated by temperature 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, and highest observed daily carbon gains in sun leaves amounted to 748.9 mmol CO2 m-2 day-1 in poplar and to 536.3 mmol CO2 m-2 day-1 in black locust, while the annual carbon gains amounted to 46,824 mol CO2 m-2 in black locust and 66,803 mol CO2 m-2 in hybrid poplar. Results obtained via gas exchange measurements and from the leaf model clearly indicate a potentially better growth performance of the poplar compared to black locust on the investigated site. The presented photosynthesis model provides a good and realistic estimation for seasonal carbon balances on the leaf level for both species.