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tilling emergence growth in height-ear emergence o yellow ripeness -harvest Figure 4.9 Mean onset of phenophases of winter wheat observed in Germany (1951-1998) (after Menzel, 2000b). P < 0.01), beginning of ear emergence (mean June 9, -0.10 days year, P < 0.05) and beginning of yellow ripeness (mean August 1, -0.30 days year, P < 0.01) in spring and summer, as true phases which react to temperature changes, have clearly advanced. In contrast, the beginning of harvest (mean August 14,...

Temperature and plant development phenology and seasonality

The recording of the timing of life-cycle events has only recently been considered as an area of climate impacts research. For a much longer period, phenology has been recorded by those with an interest in natural history, by those engaged in agriculture and horticulture and where traditional local festivals have been associated with plant phases. Some plant species and some phases are more apparent than others. Hence the brilliant displays of cherry flowering at the Royal Court in the former...

References

Atkin, O.K., Bruhn, D., Hurry, V.M. & Tjoelker, M.G. (2005) The hot and the cold unravelling the variable response of plant respiration to temperature. Funct. Plant Biol., 32, 87-105. Aubinet, M., Grelle, A., Ibron, A. Rannik, U., Moncrieff, J., Foken, T., Kowalski, A.S., Martin, P.H., Berbigier, P.H. & Bernhofer, C. (2000) Estimates of the net carbon and water exchange of forests the EUROFLUX methodology. Adv. Ecol. Res., 30, 113-175. Baldocchi, D. Falge, E., Gu, L., Olson, R.,...

Modeldata fusion techniques

The results in Table 8.2 show that predicted responses of plant ecosystems to increasing CO2 are subject to considerable uncertainty, because our understanding of the interactions between plant growth and soil nitrogen availability is still incomplete. We can only reduce this uncertainty by incorporating additional experimental evidence into our models. Sometimes it is possible to directly test model assumptions experimentally. For example, the 'litter quality' hypothesis has been refuted based...

Overview of ecosystem models

A large number of models of plant growth have been used to study responses to climate change. These models cover a wide range of time and space scales (Nightingale et al., 2004), but most of the models can be broadly classified into three different types stand-scale models, regional-scale models and dynamic global vegetation models. Stand-scale models are applied to homogeneous areas of crops or forests - they are parameterised for a single plant type and soil type. Typically, such models...

Preface

Evidence grows daily of the rapid changes in climate due to human activities and their impact on plants and animals. Plant function is inextricably linked to climate and atmospheric carbon dioxide concentration. On the shortest and smallest scales the climate affects the plant's immediate environment and thus directly influences physiological processes. On longer and larger time and space scales climate influences species distribution and community composition and determines what crops can be...

Is community change already happening

Is there any evidence that communities and distributions are starting to change in response to the (comparatively small) changes in climate that have already been recorded The last few years have seen a number of important studies investigating whether ecological changes consistent with the impacts of climate change can be detected, including some major reviews and meta-analyses (Walther et al., 2002 Parmesan & Yohe, 2003). Phenological changes, such as earlier leafing are perhaps the...

Christian Korner

Life is inevitably tied to certain temperature conditions that facilitate metabolism. Since plants are poikilothermic organisms (i.e. organisms whose body temperature varies with the temperature of their immediate environment) and since they commonly cannot move, except through reproduction, they have to cope with whatever the environment offers. In this overview, I will first revisit classical responses of plant metabolism to temperature (T) and will then explore the significance of such...

Introduction

The response of a plant community to climate change is not simply the sum of the responses of the component species. It will also be determined by interactions between species (animals as well as plants), colonisations and changes in soil processes and microclimate. The importance of these factors is illustrated by the fact that many species can be successfully cultivated outside their natural climatic limits, provided other conditions are suitable and the plant is freed from competition...

Biological Sciences Series

A series which provides an accessible source of information at research and professional level in chosen sectors of the biological sciences. Professor Jeremy A. Roberts, Plant Sciences Division, School of Biosciences, University of Nottingham. UK. Biology of Farmed Fish Edited by K.D. Black and A.D. Pickering Stress Physiology in Animals Edited by P.H.M. Balm Seed Technology and its Biological Basis Edited by M. Black and J.D. Bewley Leaf Development and Canopy Growth Edited by B. Marshall and...

Definitions and conceptual framework

The transfers of carbon between the biosphere and atmosphere may be expressed by four related terms. These can be considered on a 'per area of land' basis or on a 'whole world' basis, as follows i. Gross primary productivity (GPP) is the rate of transfer of carbon from atmosphere to biosphere by photosynthesis. For the world as a whole it is about 120 Pg C year-1, although this widely accepted value is sometimes questioned and may be higher (Saugier et al., 2001). GPP includes the 'hidden' term...

Conclusions

It is widely accepted that CO2 concentrations, temperatures and rates of nitrogen deposition will continue to increase over the century, despite the efforts to limit emissions (IPCC, 2001). The changes in temperature and nitrogen deposition will increase photosynthesis, especially in northern forests that are warming faster, although they are currently limited by cold winter conditions and by nitrogen supply. A model analysis shows, however, that the response to elevated CO2 is likely to reach...

Discussion

This study highlights the transient nature of the responses of terrestrial ecosystems to increased atmospheric CO2 in N-limited environments, and emphasizes that the response on the decadal timescale is related to the turnover rate of 'slow' SOM. Simulations of different scenarios also show a wide range of responses to increasing atmospheric CO2 by a terrestrial ecosystem. This uncertainty depends on nitrogen availability and how quickly various pools equilibrate with increased CO2 . Since most...

Overview of plant biology

Currently, there is unprecedented scientific and societal emphasis on assessing future anthropogenic changes in global temperature and the subsequent impacts on managed andunmanaged systems (Houghton etal., 2001). Yet, the principle anthropogenic gas associated with this potential warming, carbon dioxide, is also one of the four abiotic requirements necessary for plant growth (i.e. light, nutrients, water, and CO2). Any change in the availability of these abiotic parameters, particularly on a...

William J Davies

5.1 Introduction a changing climate and its effects on plant growth and functioning 96 5.2 Growth of plants in drying soil 97 5.2.1 Hydraulic regulation of growth 97 5.3 Water relations of plants in drying soil 100 5.3.1 Water movement into and through the plant 100 5.3.2 Control of gas exchange by stomata under drought 102 5.4 Water relation targets for plant improvement in water scarce 5.5 Control of stomata, water use and growth of plants in drying soil hydraulic and chemical signalling 106...

D

Apricot and cherry from central Asia, but also horse chestnut. Once they have experienced some (limited) frost, they flower whenever temperature permits (even in mid winter) - and then commonly lose all flowers or young fruit when winter returns with freezing temperatures (Figure 3.5B). Apple and pear, however, cannot be 'tricked' to the same extent by warm spells, and photoperiodism protects them from premature bud-break. However, some cultivars are at great risk of frost damage in a warmer...

How uncertain assumptions affect model predictions

In this section we quantify the effect of the uncertainties described above on model predictions. We focus on the G'DAY model's predictions of net primary production (NPP), net ecosystem production (NEP), annual N uptake, nitrogen-use efficiency (NUE) and ecosystem carbon storage (AC) under alternative assumptions about the impact of elevated CO2 on nitrogen cycling processes. We ran simulations of G'DAY with parameters representing seven alternative scenarios for how high CO2 affects litter...

Photosynthesis

Photosynthesis is a relatively well-understood process, which can be represented by biochemical equations. For C3 plants the equations were first proposed by Farquhar et al. (1980) and were known as the 'Farquhar model'. The model describes the activity of rubisco in relation to its two competing substrates carbon dioxide and oxygen, in terms of classical Michaelis-Menten enzyme kinetics. For carboxylation activity we have where Vcmax is the maximum carboxylation rate, C and O are the carbon...

Species interactions with limiting water resources

Species coexistence in a situation of limiting water resources implies either avoiding interactions (niche segregation) or allowing some interaction (niche overlap). For example, the coexistence of different functional types regarding water resources enables plant communities to occupy a larger amount of physical space, exploring more resources (McConnaughay & Bazzaz, 1992). The exploitation of spatially and or temporally distinct water resources by plants allows the coexistence of different...

Plant communities facing drought

Adaptation to semi-arid environments, namely in the Mediterranean, may be used as a paradigm for the range of plant traits adaptive to water scarcity. In Figure 6.3a, plants of group I have drought-avoiding behaviour without photosynthetic active parts during dry periods but survive in a resistant form. These are a majority in the flora of most semi-arid and arid environments (e.g. annuals, chamaephytes). Another extreme is plants of group II, which are water spenders without tolerance of...

Droughts and wildfires

Fire is a natural component of many ecosystems. Often, it is the fire regime (frequency, intensity and timing) rather than drought that determines primary productivity as well as plant community (Pyne, 1997 Bond et al., 2005). Nevertheless, dry weather enhances the risk of biomass burning. For example, the severe drought of 1994 that damaged large amounts of woody plants in central and southern Spain (Penuelas et al., 2001) also resulted in major forest fires, which burnt approximately 1.6 of...

A word about methodology

As new methodologies become available for doing CO2 fumigation, it is tempting to focus only on results obtained from newer methods and to ignore or reinterpret previous findings. We would caution that all methodologies used to ascertain plant responses to CO2 have both positive and negative attributes, and data obtained from a given experiment should not be judged 'superior', based solely on methodology. For example, environmental growth chambers (EGCs) are useful in evaluating the impact of...

Conclusions a strategy for plant improvement and management to exploit the plants drought response capacity

We have suggested above that it may be possible to use deficit irrigation to exploit the plant's long-distance signalling networks to enhance WUE in agriculture and to increase reproductive crop quality, in part by restricting vegetative crop development and the commitment of resources to this end (Yang et al., 2001 Davies et al., 2002). As soil dries, shoot water status can be sustained by signalling-induced restrictions in stomatal aperture (e.g. Mingo et al., 2003 Sobeih et al., 2004)...

Variability in water resources and plant productivity

6.3.1 Temporal variability in water resources Some biomes are characterised by the strong seasonality of water availability. For plant productivity it is not indifferent if the water comes continuously in a regular fashion, or if it comes in widely separated instalments (Harper et al., 2005). In tropical savannas, grasslands and regions with Mediterranean climate, there are several months without rain, occasionally interrupted by sporadic rainfall events. In Table 6.1 NPP, annual water supply...

To changes in water supply in a changing climate

5.1 Introduction a changing climate and its effects on plant growth and functioning As rainfall patterns become more unpredictable as climate changes, plants will be subjected to increasing fluctuations in soil moisture availability. These fluctuations are likely to have substantial impacts on plants in natural communities and on crop plants in agriculture (Davies & Gowing, 1999). For example, Silvertown etal. (1999) have shown how sensitive plant community composition can be to small...

David Viner James IL Morison and Craig Wallace

The geographic distribution of plant species, vegetation types and agricultural cropping patterns demonstrate the very strong control that climate has on plant growth. Solar radiation, temperature and precipitation values and seasonal patterns are key determinants of plant growth through a variety of direct and indirect mechanisms. Other climatic characteristics are also major influences, such as wind speed and storm frequency. There is a rapidly growing number of well-documented instances of...

Net primary productivity

Net primary productivity (NPP) may be quantified as a linear function of the pho-tosynthetically active radiation absorbed by the canopy (APAR) where e the radiation conversion efficiency into biomass. The value of APAR depends on incident short-wave solar radiation, leaf area index (LAI) and the canopy structure, which affects the light extinction coefficient (k). The slope of the relationship between plant productivity and APAR, i.e. e, varies with plant type and environmental conditions...

Wateruse efficiency

The quantification of the dependence of plant productivity on water resources may be viewed as the slope of the relationship of net primary production and the amount of water actually lost by transpiration (T) over the year as NPP WUEt x water supply x proportion of water used by plants, where the season-long water-use efficiency (WUEt) or transpiration efficiency is the ratio of biomass produced to the corresponding plant transpiration in g (dry matter) kg-1 H2O or mmol C mol-1 H2O (Jones,...

Agriculture

The world cultivated land is 80 dedicated to rainfed agriculture, with the remaining 20 allocated to irrigation (Rockstrom, 2003). Nevertheless, irrigated agriculture is a major consumer of water resources and 40 of the food and agriculture commodities are produced in irrigated areas. With the predicted growth in human population and climate change scenarios of increasing water scarcity, especially in the interior of continents and semi-arid regions, achieving a better efficiency of use of...