Tree Physiology

Tree loss and its effect to well-being, society, and energy are the inevitable results of rapid economic breakthroughs. Civilization has to constantly adapt to change, and while economic modifications commence society has to deal with preexisting issues on environmental health decline. While Amy Chillag’s CNN Article provides facts, allusions and statistics, there are particular details in the article that needs to be considered...

In urban environments, long-term tree survival and performance requires physiological tolerance or phenotypic plasticity in plant functional traits. Knowledge of these traits can inform the likely persistence of urban forests under future, more severe climates. We assessed the plasticity of morphological and physiological traits of tree species planted along an urban climatic gradient in the Greater Sydney region during a severe, multi-year drought in eastern Australia. We selected four sites along a~55 km east-west transect, ranging from the cool/wet coast to the warm/dry inland. We assessed five tree species (four natives, one exotic) with different predicted climatic vulnerability based on climate-origins, estimating functional traits indicative of drought tolerance: carbon isotope composition (δ 13 C), Huber value (HV), specific leaf area (SLA), wood density (WD), and leaf turgor loss point (π tlp). Broadly, trees planted in warm/dry sites had more negative π tlp , higher WD, δ 13 C and HV, and lower SLA than cool/wet sites, indicating phenotypic plasticity to drought. The leaf-level traits π tlp , δ 13 C and SLA were more strongly correlated with temperature and precipitation, compared to HV and WD. Species differed in the extent of their trait shifts along the transect, with greater plasticity evident in the exotic Celtis australis and the more temperate cool-climate Tristaniopsis laurina, compared to the more tropical, warm-climate Cupaniopsis anacardioides, which showed limited plasticity and lower drought tolerance. Our findings reveal adaptive capacity of urban trees to climate via plasticity in drought tolerance traits, which can direct species selection to improve urban forests resistance to climate change.

In pedunculate oak (Quercus robur L.) the architecture of the crown is strongly influenced by age and vigour of the tree. In old oak trees cladoptosis is a major mechanism on the transformation of crown architecture. Although it can be seen quite regularly, the causes and timing of shedding of twigs as well as the quantity of affected branches remain unclear. Because abscission is often used as an indicator of reduced vigour or stress in the assessment of stand and ornamental tree health, it deserves detailed investigation, especially in the context of oak decline. We studied the inter- and intra-annual variation of abscission in six stands across the eastern part of Germany in order to identify possible triggering events and controlling factors of abscission.On average, the number of twigs abscised per year increased from 1999 to 2001. While in 1999 approximately 100 abscised twigs per m2 per year were shed, this number increased to 250 per m2 in 2001. The majority of twigs was actively shed, a significant proportion of the remaining twigs was partly abscised. Only a small part of the abscised twigs had leaves attached to them. From June to September 20 per cent of the twigs had leaves, in the remaining months of the year less than 10 per cent.The analysis of almost 30,000 twig fragments over the course of 3 years demonstrated at least partial control by the tree of the process of abscission. The loss of the terminal bud and the formation of a male flower are traits correlated with abscission.Our data do not support the widely held belief that cladoptosis is mainly an immediate reaction to drought stress that reduces transpiring leaf area. The proportion of leafy twigs was quite low and the main peak of abscission occurred in late autumn, thus having little immediate effect on transpiration. In addition, we observed a time lag of 3 weeks between the onset of drought stress and increased levels of abscission.Gegen die verbreitete Annahme, die Kladoptosis sei eine Reaktion auf Trockenstress und diene unmittelbar der Verminderung der transpirierenden Blattfläche, sprechen der geringe Anteil belaubter Absprünge sowie der Schwerpunkt der Kladoptosis im Spätherbst. Auch bei direkter Beobachtung zeigt sich eine ungefähr dreiwöchige Verzögerung, bis es nach einer Trockenphase zur verstärkten Abgliederung kommt. Zur Verminderung der Blattfläche in der Stressperiode kann die Kladoptosis in dieser Weise kaum beitragen.Die Auswertung der annähernd 30000 Zweigfragmente, die im Laufe von drei Jahren gesammelt wurden, lässt deutliche Schlüsse darauf zu, dass der zeitliche Verlauf der Kladoptosis vom Baum wenigstens teilweise kontrolliert wird. Darauf lassen insbesondere die Unterschiede in der Dynamik der abgetrennten und der abgerissenen Zweige schließen. Obwohl natürlich die endgültige Abgliederung durch starke Winde befördert wird, gab es deutliche Unterschiede beim zeitlichen Ablauf zwischen diesen Fraktionen.Die Zahl der abgetrennten Zweige stieg von 1999 bis 2001. 1999 wurden etwa 100 abgetrennte Zweige je m2 gezählt, 2001 waren es 250 je m2. Die Mehrzahl dieser Zweige war aktiv abgetrennt worden, ein Großteil der verbleibenden wies eine teilweise ausgebildete Trennschicht auf. Nur ein kleiner Teil der abgetrennten Zweige war belaubt. Zwischen Juni und September waren dies 20 Prozent, in den restlichen Monaten weniger als 10 Prozent. Die Unterschiede zwischen den abgetrennten und den abgerissenen Fragmenten lassen ferner den nahe liegenden Schluss zu, dass die Abgliederung nicht zufällig, sondern aufgrund bestimmter Eigenschaften der betroffenen Zweige erfolgt. Den größten Einfluss hatte dabei das Vorhandensein einer männlichen Blüte. Allerdings könnte das Auftreten einer männlichen Blüte im Jahr der Abgliederung nur einen geringen Teil der so genannten Absprünge erklären.Das Schicksal der Jahrgänge 1999 und 2000 zeigt allerdings, dass eine mittelbare Reaktion auf Umweltbedingungen zu erfolgen scheint. Während die Absprünge der Jahrestriebe von 1999 überwiegend im Jahr 2000, also im zweiten Jahr erfolgten, geschah dies beim Jahrgang 2000 bereits im selben Jahr. Die Kladoptosis verringert zwar nicht unmittelbar die verdunstende Blattfläche, reduziert diese aber mittelfristig, also im nächsten Jahr. Bis zu einem gewissen Grad ist diese Abtrennung unproduktiver Zweige sicher von Vorteil für den Baum. Wirken die ungünstigen Faktoren jedoch über eine längere Zeit an, verliert der Baum durch die Abgliederung der Zweige unter Umständen zuviel photosynthetisch aktive Fläche, um sich danach wieder zu erholen.

Opracowana w ramach programu „Drogi dla Natury” książka przeznaczona jest dla tych, którzy w ramach swoich obowiązków odpowiadają za drzewa, a także dla tych, którzy je po prostu kochają i pragną je lepiej poznać i chronić. Jest ona połączonym drugim wydaniem książek „Aleje – skarbnice przyrody” oraz „Aleje – podręcznik użytkownika” opublikowanych w roku 2012. Ich zawartość została gruntownie zweryfikowana – zwłaszcza rozdziały o podstawowej diagnostyce i pielęgnacji drzew. Proponujemy także nowy, znacznie bardziej użyteczny formularz oceny drzewa. Mamy nadzieję, że książka będzie praktyczną pomocą dla pracowników służb drogowych i samorządów, gospodarzy nieruchomości oraz społeczników.

The aim of this book is to give a contemporary review of tree growth modelling and represent our own results in this field. We demonstrate that the growth inhibition can be a result of a systemic level effect, which can be seen in a whole-tree physiological model which includes submodels for the processes of photosynthesis, mineral nutrition, respiration, phloem and xylem transport, and growth of roots, stems, and leaves. 

The parts 1, 2 and 3 represent the review and analysis of existing models, beginning with simple growth formulas and then concentrating in contemporary dynamic (ecophysiological) models which contain many state variables and tens of parameters. The analysis of these models is given by the main components of growth process.

Part 4 deals with the most important problem of causal tree growth analysis – the reason of growth cessation (self-inhibi­tion) of too big tree. The arguments are given, showing the inadequacy of explanations which are based on Pütter-Bertalanffy equation. In the fig. 4.5 the numerical scheme of carbon balance for whole tree is represented, based on the experimental results of Estonian researchers.

In part 5 the description of our model PUU-1 is given. It contains 9 state variables (see List of symbols), 6 driving variables (table 6.1) and 43 parameters (table 6.3). The model enables to analyze both seasonal and ontogenetic dynamics of evergreen tree growth. The summary of all equations of the model is represented in ch. 5.9.

Part 6 deals with identification of the model: getting initial values of state variables and values of parameters and driving variables. More than half of them are based on the measu­rements made by Estonian researchers in Picea abies, others are taken from literature.

Part 7 gives the results of numerical experiments with our model – analysis of sensitivity of model variables and parameters, examples of growth dynamics, including numerical experi­ments with fertilization. The model fits satisfactorily with measured data. The comparison of calculated tree ring dynamics with dendrochronological data shows great perspectives in applying dynamical growth models of whole tree in dendrochronology, as well as in growth analysis and prediction, including situations
and problems which arise in agroforestry.

The most important theoretical result of our modelling is connected with self-inhibition of growth in tree ontogeny. It is shown, that self-inhibition of growth is taking place even without any aging factor, only because of size effects, which are mostly connected with changes in tree water exchange and trans­ port of assimilates (supplying of roots with assimilates becoming worse according to monotonous growth of cambium area). In the last chapter (7.6) the perspectives of tree growth modelling are discussed.

The authors of this edition propose a novel and inspiring research approach to the subject of plants, which – being a form of life that is different, yet akin to us – is a constant source of nourishment and metaphors, decoration and obsessions. The articles included in this thematic block on plants enter into lively ongoing debates on genetics, feminism, ecology and plant ontology. They are excellent examples of the fact that in Polish philosophical and cultural reflection there was an understanding very early on of the challenges that posthumanism poses to our anthropocentric intellectual habits. Foreign readers will recognize in these Polish reflections a bold willingness to ask ethical and aesthetic questions of great relevance to the modern world that go far beyond the safe, though most likely imagined, limits of what it is to be human.

In old Javanese and Chinese texts there are various references made to ‘Javanese paper’. This immediately gives rise to the question of whether paper was ever actually produced in Indonesia in the distant past. In theory this is possible because from earliest times a thriving trade existed between the islands of Indonesia and both India (where paper had been made autonomously since the year 1000) and China (where paper was invented well before the birth of Christ). Yet there has never been any sign of a ‘Javanese paper’ Dutch literary theorists and linguists discovered a number of Javanese manuscripts in Oriental library collections, written on material called dluwang, but were unable to identify it. It was botanical identification and physicochemical analysis that provided the initial answers to these questions. Dluwang is most renowned as a writing material. Handwritten manuscripts on dluwang in public collections are mainly Javanese, with one or two Malay or Madurese examples. It is not uncommon for these manuscripts to be compilations of texts in more than one language and in different scripts. There also seems to have been no inhibition about habitually binding European paper together with dluwang into one single book.

Recent large-scale studies of tree growth in the Iberian Peninsula reported contrasting positive and negative effects of temperature in Mediterranean angiosperms and conifers. Here we review the different hypotheses that may explain these trends and propose that the observed contrasting responses of tree growth to temperature in this region could be associated with a continuum of trait differences between angiosperms and conifers. Angiosperm and conifer trees differ in the effects of phenology in their productivity, in their growth allometry, and in their sensitivity to competition. Moreover, angiosperms and conifers significantly differ in hydraulic safety margins, sensitivity of stomatal conductance to vapor-pressure deficit, xylem recovery capacity or the rate of carbon transfer. These differences could be explained by key features of the xylem such as non-structural carbohydrate content (NSC), wood parenchymal fraction or wood capacitance. We suggest that the reviewed trait differences define two contrasting ecophysiological strategies that may determine qualitatively different growth responses to increased temperature and drought. Improved reciprocal common garden experiments along altitudinal or latitudinal gradients would be key to quantify the relative importance of the different hypotheses reviewed. Finally, we show that warming impacts in this area occur in an ecological context characterized by the advance of forest succession and increased dominance of angiosperm trees over extensive areas. In this context, we examined the empirical relationships between the responses of tree growth to temperature and hydraulic safety margins in angiosperm and coniferous trees. Our findings suggest a future scenario in Mediterranean forests characterized by contrasting demographic responses in conifer and angiosperm trees to both temperature and forest succession, with increased dominance of angiosperm trees, and particularly negative impacts in pines.

Future climate regimes characterized by rising [CO2], rising temperatures and associated droughts may differentially affect tree growth and physiology. However, the interactive effects of these three factors are complex because elevated [CO2] and elevated temperature may generate differential physiological responses during drought. To date, the interactive effects of elevated [CO2] and elevated temperature on drought-induced tree mortality remain poorly understood in gymnosperm species that differ in stomatal regulation strategies. Water relations and carbon dynamics were examined in two species with contrasting stomatal regulation strategies: Pinus radiata D. Don (relatively isohydric gymnosperm; regulating stomata to maintain leaf water potential above critical thresholds) and Callitris rhomboidea R. Br (relatively anisohydric gymnosperm; allowing leaf water potential to decline as the soil dries), to assess response to drought as a function of [CO2] and temperature. Both species ...

Savernake Forest and Tottenham Park, Wiltshire, is an extensive designed landscape established on the remnants of a medieval hunting forest and best known for its concentration of veteran trees. Between 2006 and 2009 seven thousand large trees were located and measured in a survey carried out by the Forestry Commission. The data are here stratified and analysed using the normal distribution curve to identify populations
and compared with archival material. It is suggested that the majority of veteran trees
date from the late eighteenth century. A small number of oaks are indicated as being of
older cohorts in the medieval period. Three may have their origins before the Norman
Conquest.