Der große Artenreichtum der mitteleuropäischen Kulturlandschaften ist zu weiten Teilen unmittelbar von bestimmten extensiven Formen der Landbewirtschaftung abhängig. Vielfältige, artenreiche Biozönosen waren und sind ein wichtiger Bestandteil landwirtschaftlicher Nutzflächen. Sie haben sich seit dem Neolithikum im Wechselspiel mit den landwirtschaftlichen Wirtschaftsweisen kontinuierlich weiterentwickelt. Erst als synthetische Pflanzenschutzmittel, Mineraldünger und leistungsstarke Landmaschinen in der zweiten Hälfte des 20. Jahrhunderts weite Verbreitung erfuhren, setzte ein bis dato beispielloser, stetiger und schneller Rückgang der Artenvielfalt von Äckern, Wiesen und Weiden ein. Trotz politischer Absichtserklärungen den raschen Artenschwund zu stoppen, hat sich der Druck auf die verbleibenden Populationen auch in den letzten Jahren weiter erhöht. Der Klimawandel und der Wunsch die Abhängigkeit von endlichen fossilen Energieträgern zu reduzieren, haben dazu geführt, dass die Nachfrage nach Ackerland zum Anbau von Energiepflanzen, bedingt durch einschlägige Subventionen, stark gestiegen ist. Nur wenige wissenschaftliche Publikationen haben sich bisher mit den Folgen der schnellen Ausweitung des Energiepflanzenanbaus Ackerflora beschäftigt. Diese Dissertation soll dazu beitragen, diese Lücke durch Untersuchungen der Habitatbedingungen (Bewirtschaftungsmethoden, Lichtklima im Bestand, Bodenchemie) und der Phytodiversität in verschiedenen Energiepflanzenbeständen (Silomais zur Biogaserzeugung, Winterraps zur Biodieselherstellung, Kurzumtriebsplantagen (KUP) aus Pappeln oder Weiden zur Hackschnitzelverbrennung) zu schließen. Die Energiepflanzenbestände wurden zudem mit konventionellem Wintergetreide zur Nahrungs- und Futtermittelproduktion (Winterweizen und -gerste) und mit extensiven Weizenbeständen aus Agrarumweltmaßnahmen (AUM) verglichen. Die Untersuchungsergebnisse weisen eindeutig darauf hin, dass die eigentlichen Ursachen des starken Phytodiversitätsverlustes auf Äckern weiter reichen und grundlegender sind als der Anbau von Energiepflanzen. Es wurde gezeigt, dass die Phytozönosen im Inneren von Bioenergiemais- und Rapsäckern sowie auch in Wintergetreidebeständen extrem verarmt sind (im Mittel 3–6 Arten 100 m 2). Die durchschnittliche Stickstoffdüngung (195 kg N ha-1 a-1) und der Herbizidbehandlungsindex (HI = 1.8) waren sowohl in Mais- als auch in Winterweizenbeständen ähnlich hoch. Eine Bedrohung für die Pflanzenartenvielfalt durch übermäßige Phosphatdüngung (im Mittel 96 kg P2O5 ha-1 a-1) wurde jedoch vor allem beim Maisanbau festgestellt. Zudem war die Beschattung in Maisbeständen erhöht (11 % PAR Transmissivität im Vergleich zu 19 % in Wintergetreide), was mit einem Rückgang der mittleren Artenzahlen am Feldrand einherging (11 Arten 100 m-2 im Mais, 15 Arten 100 m-2 in Wintergetreide). Die Pflanzengesellschaften konventioneller Äcker wurden regionsübergreifend von nur 5–10 häufigen Problemunkrautarten dominiert. Maisbestände wiesen als Sommerkulturen eine von Winterkulturen leicht abweichende Artenzusammensetzung auf. Eine ausgeglichene Mischung von konventionellem Mais, Winterraps und Wintergetreide in der Agrarlandschaft bietet mehr Arten einen geeigneten Lebensraum als jede dieser Kulturen für sich genommen. Insgesamt waren die Habitatbedingungen auf den im Rahmen von AUM extensiv bewirtschafteten Äckern jedoch wesentlich heterogener und boten einer weitaus größeren Zahl von Pflanzenarten (darunter auch seltene und bedrohte Taxa) geeignete Lebensbedingungen. Im Mittel wurden 21 Arten 100 m-2 im Inneren und 33 Arten am Feldrand gezählt. Auch die Regressionsmodelle weisen darauf hin, dass moderate Beschränkungen der Herbizidbehandlungsintensität oder der Düngung, die sich im Rahmen der zur Zeit üblichen konventionellen Bewirtschaftungspraktiken bewegen, kaum dazu beitragen den Rückgang der Ackerflora zu stoppen. Neue, an die jeweiligen regionalen Gegebenheiten angepasste Konzepte und extensive Ackerhabitate sind hierzu unerlässlich.  Die Vegetationsaufnahmen zeigen zudem, dass die Phytodiversität von KUP mit dem Alter der Plantagen stark zurückgeht. Junge KUP, ohne Düngung und mit nur geringem Herbizideinsatz, wiesen eine mit frühen Sukzessionsstadien von Ackerbrachen vergleichbare Artenzusammensetzung auf. Im Gegensatz hierzu wurden die 5–8 jährigen, dichtgepflanzten Plantagen von wenigen stickstoffliebenden Habitatgeneralisten dominiert. Obwohl sie seit mehreren Jahren weder gedüngt noch mit Herbiziden behandelt wurden, waren diese Bestände zudem dunkler (1–4 % PAR Transmissivität) und nur wenig artenreicher (8–19 Arten 75 m-2) als einjährige Energiepflanzenkulturen. Die Pflanzung von 5–20 m breiten Energieholzstreifen zur Zerteilung großer Schläge in strukturarmen, landwirtschaftlichen Intensivregionen kann jedoch aus naturschutzfachlicher Sicht empfohlen werden, insbesondere wenn Maßnahmen nur Erhöhung der Habitatvielfalt in den Plantagen ergriffen werden. Um die grundlegenden Ursachen des Pflanzenartenschwundes in Agrarlandschaften zu beheben, erscheint es jedoch darüber hinaus dringend notwendig, ein langfristig angelegtes Netzwerk extensiver Feldflorareservate zu begründen, um dauerhaft überlebensfähige Ackerwildkrautpopulationen zu erhalten und eine Ausbreitung dieser Arten in die weitere Agrarlandschaft in Zukunft wieder zu ermöglichen. Um politische Entscheidungsfindungen zu unterstützen, erscheint es notwendig im Rahmen von zukünftigen Forschungsprojekten den Blickwinkel vom Feld auf die Landschaftsebene zu erweitern und verbleibende offene Fragen über die Wirkungen der Ackerflora auf andere taxonomischen Gruppen zu klären.

Magistro darbe tiriama paliktų biologinei įvairovei medžių plyno kirtimo biržėse būklė ir išlikimas. Darbo objektas – plyno kirtimo biržės ir jose palikti biologinės įvairovės medžiai. Darbo tikslas – nustatyti plynose kirtavietėse paliekamų biologinės įvairovės medžių būklę, rūšinę sudėtį, kiekį ir pasiskirstymą bei išlikimą kirtavietėje. Darbo metodika – atliekant tyrimą, dėmesys buvo kreipiamas į du skirtingus parametrus. Pirmiausia buvo išsiaiškintas atskirų medžių atsparumas aplinkos poveikiams, priklausomai nuo jų individualių savybių. Kitas tyrimas, kuriame buvo apskaičiuota žuvusių medžių dalis kirtavietėje, priklausomai nuo kirtavietės parametrų ir medžių išsidėstymo joje. Darbo rezultatai – Plynose kirtavietėse vidutiniškai paliekama 11 medžių hektare, iš kurių per pirmuosius šešerius metus 14 procentų žūsta. Didėjant kirtavietės dydžiui bendras išlikimo procentas mažėja. Geriau išlieka grupėmis paliekami medžiai nei medžiai paliekami pavieniui. Didelę reikšmę medžių išlikimui turi vėjas - du trečdaliai žuvusių medžių žuvo dėl vėjo, buvo išversti arba nulaužti. Didžiausią poveikį vėjas turi medžiams, kurių paviršinė šaknų sistema, ir medžiams, kurių storio ir aukščio santykis mažesnis. Didėjant atstumui nuo kirtavietės krašto, dėl didesnio vėjo poveikio, medžių išlikimas mažėja. Atskirų medžių rūšių išlikimas priklauso nuo augavietės atitikimo medžių rūšiai ir paliekamų medžių individualių parametrų. Atrenkant paliekamus biologinei įvairovei medžius didesnis... [toliau žr. visą tekstą] / The master thesis presents evaluation of the trees condition and ability to survive, which are left for biological diversity in the clear cutting areas. Object of the work – trees left for biological diversity in clear cutting areas Aim of the work – to evaluate the condition, variety, quantity and layout of the trees, left for biological diversity in clear cutting areas. Methods of work- attention were paid to two different indicates: first, it has been investigated trees ability to resist environmental factors, depending on individual aspects of each tree. Second, it has been investigated area of coppice, where it was examined fraction of dead trees depending of trees layout and different factors in the coppice. Result of the work – there are approximately eleven trees left in each hectare and 14 percent of them do not survive during the first 6 years. The more the coppice expands the less possibility of tree to survive. The trees are more likely to survive when they are left in groups rather than on their own. The wind has important implication to the trees; two thirds of the trees get destroyed by the wind. The trees that are mostly in danger due to the wind are the ones that have roots spread out close to the ground surface and which have a reduced diameter and height ratio. Trees that are in the middle of the coppice have an increased risk to die from wind. Various trees survive depending on the type of the tree specification and its environmental... [to full text]

The cultivation of fast growing tree species on arable land is deemed to be one of the most promising alternatives amongst the approaches to the cultivation of renewable resources currently available. As the site factors influencing the growth of poplar and willow have not yet been sufficiently identified and quantified, it is not possible to provide reliable national yield expectations as a function of the prevailing soil and climate conditions at a particular site on the basis of the data currently available. The main objective of this study, therefore, was to develop a supraregional site-based yield model for the assessment of yield expectations for poplar and willow grown on arable land over short rotations. In order to achieve this goal, a total of 38 research sites were established across as many regions of Germany as possible. The clones selected for the experiment were the poplar clones Max 1, Hybride 275 (H 275) and AF 2, and the willow clones Inger and Tordis. Each site was also characterised, on the basis of climate and soil data. From the site parameters recorded, variables were defined for modelling purposes. The climate variables comprised temperature (T), precipitation (N) and aridity index (TI) derived from total or average values from selected periods during the year and during the vegetation period. Within the variables the months were indexed as numbers (January = 1), periods were separated by comma. Parameters of the German soil appraisal such as the condition grade (ZS), the soil quality index value (BZ) and the arable land quality index value (AZ) were used as soil variables. The selected texture parameters were the proportions of sand (S[%]), silt (U[%]) and clay (T[%]). Variables of the pore space parameters were the available field moisture capacity (nFK), the air capacity (LK) and the dry bulk density (TRD). Both the texture and the pore space variables referred to a soil depth of 0 to 60 cm. To increase the precision of the results, site clusters were derived, differentiated by main soil type, and the variables were aggregated. The dGZ, measured in odt ha-1 a-1,at the end of the first three-year rotation was chosen as the dependent variable. The main results of the study are outlined in the following: Negative correlations between dGZ and temperatures in the vegetation period, especially in the months July to September, were observed on the sandy and loamy soils. Precipitation variables always had a positive effect on the growth of poplar and willow across all clones and site clusters. Taking into consideration all experimental sites, precipitation in the period from May to July was most important. The parameters of the German soil appraisal revealed a moderate correlation with growth for all sites. From the appraisal of all sites and of the individual site clusters it became apparent that U[%] represents the most important texture variable for poplar and willow growth. Considered for all sites simultaneously, the nFK had the greatest significance for growth across all of the parameters examined. The site-based yield models were all univariate and often comprised aggregated variables. Under consideration of all sites, the model predictors for Max 1, Inger and Tordis were (nFK * TI5.7) and (nFK * N5.7) for AF 2. Each model was calculated with the inverse or sigmoid approach and revealed an R²korr between 0.45 and 0.64 with a RMSE of an average of 2.0 odt ha-1 a-1. The division into site clusters improved the accuracy of the models considerably. In the sandy site cluster, the models exhibited an R²korr of 0.77 to 0.97 and an RMSE of 0.95 to 1.36 odt ha-1 a-1. These comprised (U[%]* N6.7) for Max 1 and F 2, (S[%]/ TI6.7) for H 275 and (S[%]* T7.8) for Inger and Tordis. For the silty site cluster, significant models could only be determined for the clones Max 1 and Tordis. The model predictor for Max 1 was (BZ * TI4.5) and for Tordis solely (BZ). The calculated R²korr values were 0.84 and 0.95 with a corresponding RMSE of 0.22 and 0.62 odt ha-1 a-1, respectively. For the loamy soils the models for Max 1 and Inger comprised the variable nFK, for AF 2 the variables (nFK * N5.6). R²korr varied between 0.86 and 0.98 with RMSE between 0.56 and 1.21 odt ha-1 a-1.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 4 uppsatser.

During the last century the forests of Central Europe changed from open woodlands to even-aged stands with closed-canopy. This change resulted in severe decline of forest biodiversity. This study examines how, and why such change affected xylophagous insects. I have studied microhabitat preferences, i.e. distribution of xylophagous insects in canopy and understorey of closed forests, forest edges and wooded meadows. I used method of rearing insect from timber baits exposed to ovipositing females of xylophagous insects in different situations in the forest at the beginning if vegetation season. After one season of exposition,the baits were collected enclosed in fly-wire cages, where emerging insects were collected for two seasons. This thesis consists of two parts: The first part is an unpublished manuscript dealing with effect of habitat insolation, vertical stratification, forest structure and amount of dead wood on community of long-horned beetles (Cerambycidae) and jewell beetles (Buprestidae) feeding on wood of pedunculate oak (Quercus robur). Baits were exposed in the canopy and the understorey of forest interior, the canopy and the understorey of forest edge and on solitary trees on wooded meadows. Most insect species do prefer insoled wood for their development, and were more common in the understorey than in the canopy. Insolation of bait was thus the prime factor affecting composition of reared insects. No relation was found between dead wood volume and species composition or abundance of reared insects This shows that insolation of the dead wood is crucial to conservation of most xylophagous insects. The second part of the thesis studies effect of vertical stratification and insolation on distribution of xylophages feeding reared from wood of 8 tree species (Alnus glutinosa, Populus alba, P. x canadensis, Salix alba, Carpinus betulus, Quercus robur, Tilia cordata, Ulmus laevis) and host specificity of xylophages. Results show that: (i) community composition of xylophages reflects evolutionary history of their host plants; (ii) communities reared from different trees exhibit different preferences for forest strata and insolation of the habitat, probably in connection to preferred growth conditions of the host plant, (iii) many xylophagous insect species exhibit strong preferences to insoled habitats, and are thus confined to forest edges in extensively managed forests as well as in unmanaged forest reserves.

Durch das Ansteigen der Weltbevölkerung und das wirtschaftliche Aufstreben insbesondere der Entwicklungs- und Schwellenländer wird die Nachfrage nach dem Rohstoff Holz beträchtlich wachsen. Gleichzeitig ist die Entwicklung der weltweiten Waldfläche rückläufig. Eine wesentliche Frage für die nationalen Volkswirtschaften wird in der Zukunft sein, den bereits jetzt knapp werdenden Rohstoff Holz in ausreichendem Maße zur Verfügung zu stellen. Vor diesem Hintergrund beschäftigt sich die vorliegende Arbeit mit ertragskundlicher Analyse von Gehölzsystemen und den Möglichkeiten der Ertragssteigerung am Beispiel des Bundeslandes Sachsen. Im Zentrum stehen vor allem Kurzumtriebsplantagen im Vergleich mit Schlagweisen Hochwäldern. / The rise in the global population and in the economic ambitions of the developing and newly industrialising nations in particular will prompt a significant increase in the demand for wood. While these developments are taking place, however, the area of forest cover globally is in decline. An issue of central importance for national economies in the years to come will concern their ability to secure an adequate supply of the already limited raw material wood. Against this background, the study presented herein focuses on analyses of the yields provided by certain wood production systems and on the options to increase this yield. The study addresses the issue on the basis of the example of the German federal state Sachsen. A focal point of the study is short rotation coppice plantations, contrasted against age-class high forest stands.

Neste trabalho foi avaliada a variação espacial da regeneração natural das espécies nativas no sub-bosque de um povoamento de Eucalyptus saligna Smith. localizado na Estação Experimental de Itatinga do Departamento de Ciências Florestais da Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, que vem sendo manejado ha 50 anos pelo sistema de talhadia simples. A Estação Experimental de Itatinga ocupa uma área aproximada de 675 ha localizados na região fisiográfica denominada Planalto Ocidental Paulista. O uso da terra é caracterizado pelos plantios monoculturais de espécies exóticas, principalmente Eucalyptus sp. e Pinus sp., e fragmentos florestais naturais representativos de floresta estacional semidecidual, floresta ripária, cerradão e cerrado, em diferentes níveis de perturbação. A área experimental compreende 2 sítios distantes entre si em aproximadamente 250 metros e com desnível topográfico de 30 metros, diferenciados principalmente pela fitofisionomia da vegetação, declividade do terreno e pelas diferentes características de fertilidade e capacidade de retenção hídrica dos solos. Foram alocadas aleatoriamente 8 parcelas permanentes de 625 m 2 em cada sítio. Em cada parcela foi realizado o inventário das espécies nativas arbóreas ou arbustivas em via de regeneração, abrangendo os indivíduos com altura maior que 1,5 metros, bem como as brotações das cepas de Eucalyptus saligna existentes. No sítio de solo Latossolo Vermelho Amarelo (LVA), que apresentou área basal média de 6,12 m 2 /ha para as brotações das cepas de Eucalyptus saligna, foram amostrados 92 indivíduos distribuídos em 24 espécies, com destaque para Pouteria torta, Didymopanax vinosum, Ouratea spectabilis , Piptocarpha rotundifolia , Pouteria ramiflora e Anadenanthera falcata. No sítio de solo Latossolo Vermelho (LV), que apresentou área basal média de 13,81 m 2 /ha para as brotações das cepas de Eucalyptus saligna, foram amostrados 991 indivíduos, distribuídos em 90 espécies com destaque para Copaifera langsdorffii, Psychotria sessilis , Pithecolobium incuriale, Myrcia rostrata e Actinostemum communis. No total foram identificadas 107 espécies, sendo 7 espécies comuns aos dois sítios, distribuídas em 72 gêneros e 34 famílias. Os índices de diversidade de Shannon-Wienner (H’) obtidos para o sítio LVA e LV foram respectivamente 2,51 e 3,75. Embora os dois sítios estudados estejam espacialmente próximos, as diferenças com relação a quantidade de indivíduos amostrados e o número de espécies identificadas foram significativas. Analisando-se os resultados pode-se concluir que as variações quantitativas e qualitativas da regeneração natural entre os dois sítios dependem principalmente das condições de umidade e fertilidade do solo. A influência das brotações do Eucalyptus saligna ocorre principalmente no sítio LV em decorrência das condições microclimáticas determinadas pelo dossel desuniforme existente, promovendo diferentes condições de sombreamento e umidade do ar e do solo, as quais possibilitaram o crescimento de espécies de diferentes estádios de sucessão. No sítio LVA, onde as brotações de Eucalyptus saligna ocorreram em menor densidade e tamanho, promovendo menor variação nas condições microclimáticas, pode-se concluir que houve pequena influência sobre a regeneração natural. / This study was carried out to evaluate the spatial variation of the native species naturally regenerating in Eucalyptus saligna stand understory. This stand which is located at Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo (Itatinga Experimental Station, Forest Sciences Department), has been managed through lopping system for fifty years. The Itatinga Experimental Station, with an area of 675 hectares, is located on the physiographic region named São Paulo West plateau. This region is characterized by monoculture plantations of exotic tree species, mainly Eucalyptus sp and Pinus sp, besides representative remnants of natural forest formations like semideciduos seasonal forest, riparian forest and savannah (Cerradão e Cerrado) with different dis turbance degrees. The experimental area encompasses two sites separated from each other around 250 m, differing 30 m in altitude. These two sites are different mainly in phytophysionomy, land slope and soil fertility and soil hydric retention capacity. Eight permanent plots of 625 m 2 in each site (LVA and LV) were randomly sampled. The woody species individuals with height equal or bigger than 1,5 m and the Eucalyptus saligna coppicings were surveyed in each plot. On the LVA site, with an average basal area of Eucalyptus coppicings of 6,12 m 2 /ha, 92 individuals were sampled, distributed in 24 species and the most important ones were Pouteria torta, Didymopanax vinosum, Ouratea spectabilis, Piptocarpha rotundifolia, Pouteria ramiflora and Anadenanthera falcata. On the LV site, 991 individuals were sampled, distributed in 90 species and the most important ones were Copaifera langsdorffii, Psychotria sessilis, Pithecolobium incuriale, Myrcia rostrata and Actinostemum communis. A total of 107 species were identified and 7 species were common to both sites, distributed into 72 genera and 34 families. The Shannon-Wiener (H´) diversity indexes obtained for LVA and LV site were respectively 2.51 and 3.75. Although both studied sites were close to each other, the differences related to the abundance of the sampled individuals and the number of species were significant. Based upon the results it is possible to conclude that the quantitative and qualitative variations of the natural regeneration between the two sites depend mainly on the soil humidity and fertility. The Eucalyptus saligna influence occurs mainly on site LV due to the different microclimate conditions promoted by the uneven canopy, generating different conditions of shading, soil and air humidity, allowing the growth of species of different successional stages. At the LVA site, were the Eucalyptus saligna coppicing were at a smaller density and size, promoting a smaller variation at the microclimatic conditions, we may conclude that the influence at the natural regeneration was also smaller.

Worldwide there is an increasing demand of natural resources. In future, non renewable resources get substituted by renewable resources in the energetic sector as well as in the material sector. That implies a stronger usage of renewable resources especially - wood. In 2009 there was a usage of 77 million cubic meters of wood for material applications and a quantity of 55 million cubic meters for energetic applications in Germany alone. Furthermore, there is an increasing demand on wood for energetic purposes. In 2007 this problematic development led to the first supply bottlenecks. To meet the increasing demands of the future, Short Rotation Coppices (SRC) can help to improve the wood provision. An SRC is a planting of fast growing coppice on agricultural areas, which is managed more intensively than usual forestry practices for a quicker production of wooden biomass. With a comparative LCA of conventional wood and wood from SRC the present study evaluates if wood from SRC is reasonable to cover the increasing demand of wood for material and energetic purposes in an environmental friendly way. A comprehensive literature research regarding LCAs of wood and wooden products shows that there are no previous studies comparing the two types of wood. Hence, the present study examines a particleboard production as the material scenario and the combustion of woodchips in a firing system as the energetic scenario to compare the ecological advantages and disadvantages of wood from SRC and conventional wood. The LCA is implemented with the Gabi software designed by PE International. Data is obtained from previous LCA studies evaluating the production of wood, the particleboard production and the combustion of wood. Additionally, data from the Ecoinvent database is used. Functional units are the production of 1m3 particleboard and the production of 1 MJ of thermal energy. The LCIA is implemented with the “Ecoindicator” as endpoint- and “CML 2001” as midpoint approach to cover broad range of environmental issues. Moreover a sensitivity analyses shows the impact of decisive variables on the results of “Ecoindicator” and “CML 2001”. Results reveal that outcomes of the LCIA are dependent of the assessment method and the processed part of trees from conventional forestry. The present study shows, that with an efficient land use, wood from SRC can help to cover the increasing demand of wood for material and energetic purposes in a sustainable way. However, an immediate usage of wood for energetic purposes has to be seen critical. Instead, a cascaded and sustainable utilization of wood is recommendable to counteract climate change and to improve the efficient use of the renew-able resource - “wood”.

The cultivation of fast growing tree species on arable land is deemed to be one of the most promising alternatives amongst the approaches to the cultivation of renewable resources currently available. As the site factors influencing the growth of poplar and willow have not yet been sufficiently identified and quantified, it is not possible to provide reliable national yield expectations as a function of the prevailing soil and climate conditions at a particular site on the basis of the data currently available. The main objective of this study, therefore, was to develop a supraregional site-based yield model for the assessment of yield expectations for poplar and willow grown on arable land over short rotations. In order to achieve this goal, a total of 38 research sites were established across as many regions of Germany as possible. The clones selected for the experiment were the poplar clones Max 1, Hybride 275 (H 275) and AF 2, and the willow clones Inger and Tordis. Each site was also characterised, on the basis of climate and soil data. From the site parameters recorded, variables were defined for modelling purposes. The climate variables comprised temperature (T), precipitation (N) and aridity index (TI) derived from total or average values from selected periods during the year and during the vegetation period. Within the variables the months were indexed as numbers (January = 1), periods were separated by comma. Parameters of the German soil appraisal such as the condition grade (ZS), the soil quality index value (BZ) and the arable land quality index value (AZ) were used as soil variables. The selected texture parameters were the proportions of sand (S[%]), silt (U[%]) and clay (T[%]). Variables of the pore space parameters were the available field moisture capacity (nFK), the air capacity (LK) and the dry bulk density (TRD). Both the texture and the pore space variables referred to a soil depth of 0 to 60 cm. To increase the precision of the results, site clusters were derived, differentiated by main soil type, and the variables were aggregated. The dGZ, measured in odt ha-1 a-1,at the end of the first three-year rotation was chosen as the dependent variable. The main results of the study are outlined in the following: Negative correlations between dGZ and temperatures in the vegetation period, especially in the months July to September, were observed on the sandy and loamy soils. Precipitation variables always had a positive effect on the growth of poplar and willow across all clones and site clusters. Taking into consideration all experimental sites, precipitation in the period from May to July was most important. The parameters of the German soil appraisal revealed a moderate correlation with growth for all sites. From the appraisal of all sites and of the individual site clusters it became apparent that U[%] represents the most important texture variable for poplar and willow growth. Considered for all sites simultaneously, the nFK had the greatest significance for growth across all of the parameters examined. The site-based yield models were all univariate and often comprised aggregated variables. Under consideration of all sites, the model predictors for Max 1, Inger and Tordis were (nFK * TI5.7) and (nFK * N5.7) for AF 2. Each model was calculated with the inverse or sigmoid approach and revealed an R²korr between 0.45 and 0.64 with a RMSE of an average of 2.0 odt ha-1 a-1. The division into site clusters improved the accuracy of the models considerably. In the sandy site cluster, the models exhibited an R²korr of 0.77 to 0.97 and an RMSE of 0.95 to 1.36 odt ha-1 a-1. These comprised (U[%]* N6.7) for Max 1 and F 2, (S[%]/ TI6.7) for H 275 and (S[%]* T7.8) for Inger and Tordis. For the silty site cluster, significant models could only be determined for the clones Max 1 and Tordis. The model predictor for Max 1 was (BZ * TI4.5) and for Tordis solely (BZ). The calculated R²korr values were 0.84 and 0.95 with a corresponding RMSE of 0.22 and 0.62 odt ha-1 a-1, respectively. For the loamy soils the models for Max 1 and Inger comprised the variable nFK, for AF 2 the variables (nFK * N5.6). R²korr varied between 0.86 and 0.98 with RMSE between 0.56 and 1.21 odt ha-1 a-1.:Inhaltsverzeichnis 1 Einleitung 1 1.1 Problemstellung 1 1.2 Zielstellung 3 2 Hintergrund 4 2.1 Energieziele Deutschlands 4 2.1.1 Flächen- und Nutzungskonkurrenz mit der Forstwirtschaft 4 2.1.2 Flächen- und Nutzungskonkurrenz mit der Landwirtschaft 5 2.2 Anbau schnellwachsender Baumarten 6 2.2.1 Anbau im Kurzumtrieb 7 2.3 Verwendete Baumarten in Kurzumtriebsplantagen 11 2.3.1 Pappel 11 2.3.2 Weide 13 2.3.3 Anmerkung Züchtung 14 2.4 Leistung von Kurzumtriebsplantagen mit Pappel und Weide in zwei- bis dreijähriger Umtriebs-zeit 15 2.5 Ertragsdynamik und leistungsbeeinflussende Faktoren von Kurzumtriebsplantagen 17 2.5.1 Baumart und Klon 18 2.5.2 Umtriebszeit und Bestandesdichte 19 2.5.3 Standortanforderungen 21 2.5.3.1 Reichliche Wasserversorgung 21 2.5.3.2 Lockere Böden 22 2.5.3.3 Ausreichende Mineralstoffzufuhr 23 2.5.3.4 Wachstumsangepasste Bodenreaktion 23 2.5.3.5 Wärme 23 2.5.3.6 Bodenschätzungskennwerte 24 2.5.3.7 Textur 24 2.5.3.8 Standorte der Pappel 24 2.6 Waldwachstumsmodellierung mit Schwerpunkt in Kurzumtriebsplantagen 25 2.6.1 Empirische Modelle 26 2.6.1.1 Pappelmodell nach ALI (2009) 26 2.6.1.2 Pappel- und Weidenmodell nach AYLOTT et al. (2008) 27 2.6.1.3 Leistungsbeeinflussende Standorteigenschaften für Pappel und Weide nach BERGANTE et al. (2010) 28 2.6.2 Mechanistische Modelle 29 3 Material und Methoden 33 3.1 Flächenanlage und Versuchsdesign 33 3.1.1 Flächenvorbereitung und Pflegemaßnahmen 37 3.1.2 Prüfglieder 39 3.1.2.1 Pappelklon Max 1 39 3.1.2.2 Pappelklon H 275 39 3.1.2.3 Pappelklon AF 2 40 3.1.2.4 Weidenklon Inger 41 3.1.2.5 Weidenklon Tordis 41 3.2 Klimatische Standortcharakterisierung 42 3.2.1 Temperatur 44 3.2.2 Niederschlag 46 3.3 Bodenkundliche Standortcharakterisierung 47 3.3.1 Profilansprache und allgemeine Standortinformationen 48 3.3.2 Durchführung der Probennahme 48 3.3.3 Bodenphysikalische Untersuchungen 49 3.3.4 Grundwassereinfluss 49 3.3.5 Bodenchemische Untersuchungen 50 3.3.6 Bodenschätzungskennwerte 50 3.3.7 Zusammenfassende Betrachtung der bodenkundlichen Charakteristika 51 3.4 Bestandesaufnahmen und Ernte 55 3.4.1 Anwuchs- und Überlebensrate 55 3.4.2 Anzahl an Höhentrieben 55 3.4.3 Höhe 55 3.4.4 Durchmesser 55 3.4.5 Ertragsbestimmung 55 3.4.5.1 Biomassefunktionen 56 3.4.5.2 Systematische Teilbeernteung der Kernparzelle 56 3.5 Identifizierung von leistungsbeeinflussenden Standorteigenschaften und Entwicklung standortbasierter Ertragsmodelle 57 3.5.1 Variablenwahl und -bildung 58 3.5.1.1 Klima 58 3.5.1.2 Bodenschätzung 59 3.5.1.3 Textur 59 3.5.1.4 Porenraum 59 3.5.1.5 Aggregierte Variablen 60 3.5.1.6 Weitere Einflussgrößen 60 3.5.1.7 Abhängige Variable 61 3.5.2 Standortcluster 61 3.6 Datenbasis der standortbasierten Ertragsmodellierung 61 3.7 Ertragsteigerungfaktor 63 3.8 EDV und Statistik 65 3.8.1 Varianzanalyse 65 3.8.2 Korrelationsanalyse 66 3.8.3 Regressionsanalyse 66 3.8.3.1 Nicht-lineare Regression 68 3.8.3.2 Evaluierungsgrößen 69 4 Ergebnisse 71 4.1 Waldwachstumskundliche Ergebnisse 71 4.1.1 Anwuchs- und Überlebensrate 71 4.1.2 Anzahl an Höhentrieben 72 4.1.3 Übersicht Bestandesdimensionen und Wuchsleistung 73 4.1.4 Höhe 75 4.1.5 Durchmesser 77 4.1.6 Durchschnittlicher Gesamtzuwachs 81 4.1.7 Biomassefunktionen 84 4.1.7.1 Wahl der unabhängigen Variablen 84 4.1.7.2 Einfluss der Gattung und des Klons 85 4.1.7.3 Einfluss der Bestandesmittelhöhe 85 4.1.7.4 Allgemeingültige Biomassefunktionen 87 4.2 Leistungsbeeinflussende Standorteigenschaften 88 4.2.1 Temperatur 88 4.2.2 Niederschlag 90 4.2.3 Trockenheitsindex 92 4.2.4 Bodenschätzungskennwerte 94 4.2.5 Textur 96 4.2.6 Porenraum 99 4.2.7 Korrelation zwischen unabhängigen Variablen 102 4.2.8 Aggregierte Variablen 102 4.2.9 Weitere Einflussgrößen 105 4.2.9.1 Vornutzung 105 4.2.9.2 Bodentyp 106 4.2.9.3 Grundwasser 106 4.3 Standortbasierte Ertragsmodellierung 107 4.3.1 Standortcluster ALL 107 4.3.2 Standortcluster S 110 4.3.3 Standortcluster U 113 4.3.4 Standortcluster L 115 4.4 Ertragssteigerungsfaktoren und Ertragssteigerung in Folgerotationen 118 5 Diskussion 122 5.1 Material und Methodik 122 5.1.1 Versuchsflächen 122 5.1.2 Modellierung und Variablenbildung 123 5.2 Waldwachstumskundliche Ergebnisse 124 5.2.1 Anwuchs- und Überlebensrate 124 5.2.2 Anzahl an Höhentrieben 125 5.2.3 Höhe 125 5.2.4 Durchmesser 126 5.2.5 Durchschnittlicher Gesamtzuwachs 126 5.2.6 Biomassefunktionen 128 5.3 Leistungsbeinflussende Standorteigenschaften 129 5.3.1 Temperatur 129 5.3.2 Niederschlag 130 5.3.3 Trockenheitsindex 132 5.3.4 Bodenschätzungskennwerte 132 5.3.5 Textur 133 5.3.6 Porenraum 134 5.3.7 Aggregierte Variablen 135 5.3.8 Weitere Einflussgrößen 136 5.4 Standortbasierte Ertragsmodellierung 136 5.4.1 Standortcluster ALL 137 5.4.2 Standortcluster S 138 5.4.3 Standortcluster U 138 5.4.4 Standortcluster L 138 5.4.5 Vergleich mit anderen Modellen 138 5.5 Ertragssteigerungsfaktoren und Ertragsteigerung in Folgerotationen 140 6 Schlussfolgerungen und Ausblick 141 7 Zusammenfassung 144 8 Literatur 156 9 Anhang 176

Durch das Ansteigen der Weltbevölkerung und das wirtschaftliche Aufstreben insbesondere der Entwicklungs- und Schwellenländer wird die Nachfrage nach dem Rohstoff Holz beträchtlich wachsen. Gleichzeitig ist die Entwicklung der weltweiten Waldfläche rückläufig. Eine wesentliche Frage für die nationalen Volkswirtschaften wird in der Zukunft sein, den bereits jetzt knapp werdenden Rohstoff Holz in ausreichendem Maße zur Verfügung zu stellen. Vor diesem Hintergrund beschäftigt sich die vorliegende Arbeit mit ertragskundlicher Analyse von Gehölzsystemen und den Möglichkeiten der Ertragssteigerung am Beispiel des Bundeslandes Sachsen. Im Zentrum stehen vor allem Kurzumtriebsplantagen im Vergleich mit Schlagweisen Hochwäldern. / The rise in the global population and in the economic ambitions of the developing and newly industrialising nations in particular will prompt a significant increase in the demand for wood. While these developments are taking place, however, the area of forest cover globally is in decline. An issue of central importance for national economies in the years to come will concern their ability to secure an adequate supply of the already limited raw material wood. Against this background, the study presented herein focuses on analyses of the yields provided by certain wood production systems and on the options to increase this yield. The study addresses the issue on the basis of the example of the German federal state Sachsen. A focal point of the study is short rotation coppice plantations, contrasted against age-class high forest stands.