W. D. Billings

Bio: W. D. Billings is an academic researcher from Stanford University. The author has contributed to research in topics: Germination & Alpine climate. The author has an hindex of 8, co-authored 8 publications receiving 1714 citations.

The ecology of arctic and alpine plants

Abstract: Summary ‘How are plants adapted to the low temperatures and other stresses of arctic and alpine environments ?’ At present it is not possible to answer this question completely. Much work remains to be done, particularly on low-temperature metabolism, frost resistance, and the environmental cues and requirements for flowering, dormancy, regrowth, and germination. However, in brief, we can say that plants are adapted to these severe environments by employing combinations of the following general characteristics: 1. Life form: perennial herb, prostrate shrub, or lichen. Perennial herbs have greatest part of biomass underground. 2. Seed dormancy: generally controlled by environment; seeds can remain dormant for long periods of time at low temperatures since they require temperatures well above freezing for germination. 3. Seedling establishment: rare and very slow; it is often several years before a seedling is safely established. 4. Chlorophyll content: in both alpine and arctic ecosystems not greatly different on a land-area basis from that in temperate herbaceous communities. Within a single species there is more chlorophyll in leaves of arctic populations than in those of alpine populations. 5. Photosynthesis and respiration: (a) These are at high rates for only a few weeks when temperatures and light are favourable. (b) Optimum photosynthesis rates are at lower temperatures than for ordinary plants; rates are both genetically and environmentally controlled with phenotypic plasticity very marked. (c) Dark respiration is higher at all temperatures than for ordinary plants; rate is both genetically and environmentally controlled, with phenotypic plasticity very pronounced, i.e. low-temperature environment increases the rate at all temperatures. (d) Alpine plants have higher light-saturation values in photosynthesis than do arctic or lowland plants; light saturation closely tied to temperature. (e) There is some evidence that alpine plants can carry on photosynthesis at lower carbon dioxide concentrations than can other plants. (f) Annual productivity is low, but daily productivity during growing season can be as high as that of most temperate herbaceous vegetation. Productivity can be increased by temperature, nutrients, or water. 6. Drought resistance: most drought stress in winter in exposed sites is due to frozen soils and dry winds. It is met by decreased water potentials, higher concentrations of soluble carbohydrates, and closed stomates. Little drought resistance in snowbank plants. Alpine plants adapted to summer drought stress can carry on photosynthesis at low water potentials; alpine or arctic plants of moist sites cannot do this. 7. Breaking of dormancy: controlled by mean temperatures near or above 0° C., and in some cases by photoperiod also. 8. Growth: very rapid even at low positive temperatures. Respiration greatly exceeds photosynthesis in early re-growth of perennials. Internal photosynthesis may occur in hollow stems of larger plants during early growth. Nitrogen and phosphorus often limiting in cold soil. 9. Food storage: characteristic of all alpine and arctic plants except annuals. Carbohydrates mostly stored underground in herbaceous perennials. Lipids in old leaves and stems of prostrate evergreen shrubs. Depleted in early growth, and usually restored after flowering. 10. Winter survival: survival and frost resistance are excellent after hardening. Cold resistance closely tied to content of soluble carbohydrates, particularly raffinose. 11. Flowering: flower buds are pre-formed the year before. Complete development and anthesis dependent upon temperature of the flowering year and also, in some cases, upon photoperiod. 12. Pollination: mostly insect-pollinated in alpine regions and even in Arctic, but to a lesser extent. Wind-pollination increasingly more important with increasing latitude. Diptera more important than bees in the Arctic and in the highest mountains. 13. Seed production: opportunistic, and dependent upon temperature during flowering period and latter half of growing season. 14. Vegetative reproduction: by rhizomes, bulbils, or layering. More common and important in Arctic than in alpine areas. 15. Onset of dormancy: triggered by photoperiod, low temperatures, and drought. Dormant plant extremely resistant to low temperatures.

Effects of Altitude on Carbohydrate Content of Mountain Plants

Abstract: Sugar and starch contents of roots or rhizomes of Polygonum bistortoides, Saxifraga rhomboidea, and Calyptridium umbellatum were measured at different altitudes in the Sierra Nevada of California and in the Medicine Bow Mountains of Wyoming. Carbohydrate reserves appear to be higher near the lower altitudinal limits of a species. Ploygonum bistortoides, Caltha howellii, and Sibbaldia procumbens transplanted to lower and warmer elevations used up stored carbohydrates more rapidly than at the elevation of origin. The higher carbohydrate content of individuals in natural populations near the lower altitudinal limits of an alpine species thus appears to be an ecotypic or ecoclinal adaptation. See full-text article at JSTOR

Evidence for the existence of three primary strategies in plants and its relevance to ecological and evolutionary theory

Abstract: It is suggested that evolution in plants may be associated with the emergence of three primary strategies, each of which may be identified by reference to a number of characteristics including morphological features, resource allocation, phenology, and response to stress. The competitive strategy prevails in productive, relatively undisturbed vegetation, the stress-tolerant strategy is associated with continuously unproductive conditions, and the ruderal strategy is characteristic of severely disturbed but potentially productive habitats. A triangular model based upon the three strategies may be reconciled with the theory of r- and K-selection, provides an insight into the processes of vegetation succession and dominance, and appears to be capable of extension to fungi and to animals.

Principles of Terrestrial Ecosystem Ecology

Abstract: I. CONTEXT * The Ecosystem Concept * Earth's Climate System * Geology and Soils * II. MECHANISMS * Terrestrial Water and Energy Balance * Carbon Input to Terrestrial Ecosystems * Terrestrial Production Processes * Terrestrial Decomposition * Terrestrial Plant Nutrient Use * Terrestrial Nutrient Cycling * Aquatic Carbon and Nutrient Cycling * Trophic Dynamics * Community Effects on Ecosystem Processes * III. PATTERNS * Temporal Dynamics * Landscape Heterogeneity and Ecosystem Dynamics * IV. INTEGRATION * Global Biogeochemical Cycles * Managing and Sustaining Ecosystem * Abbreviations * Glossary * References

Alpine plant life

Abstract: 1 Plant ecology at high elevations.- The concept of limitation.- A regional and historical account.- The challenge of alpine plant research.- 2 The alpine life zone.- Altitudinal boundaries.- Global alpine land area.- Alpine plant diversity.- Origin of alpine floras.- Alpine growth forms.- 3 Alpine climate.- Which alpine climate.- Common features of alpine climates.- Regional features of alpine climates.- 4 The climate plants experience.- Interactions of relief, wind and sun.- How alpine plants influence their climate.- The geographic variation of alpine climate.- 5 Life under snow: protection and limitation.- Temperatures under snow.- Solar radiation under snow.- Gas concentrations under snow.- Plant responses to snowpack.- 6 Alpine soils.- Physics of alpine soil formation.- The organic compound.- The interaction of organic and inorganic compounds.- 7 Alpine treelines.- About trees and lines.- Current altitudinal positions of climatic treelines.- Treeline-climate relationships.- Intrazonal variations and pantropical plateauing of alpine treelines.- Treelines in the past.- Attempts at a functional explanation of treelines.- A hypothesis for treeline formation.- Growth trends near treelines.- Evidence for sink limitation.- 8 Climatic stress.- Survival of low temperature extremes.- Avoidance and tolerance of low temperature extremes.- Heat stress in alpine plants.- Ultraviolet radiation - a stress factor.- 9 Water relations.- Ecosystem water balance.- Soil moisture at high altitudes.- Plant water relations - a brief review of principles.- Water relations of alpine plants.- Desiccation stress.- Water relations of special plant types.- 10 Mineral nutrition.- Soil nutrients.- The nutrient status of alpine plants.- Nutrient cycling and nutrient budgets.- Nitrogen fixation.- Mycorrhiza.- Responses of vegetation to variable nutrient supply.- 11 Uptake and loss of carbon.- Photosynthetic capacity of alpine plants.- Photosynthetic responses to the environment.- Daily carbon gain of leaves.- The seasonal carbon gain of leaves.- C4 and CAM photosynthesis at high altitudes.- Tissue respiration of alpine plants.- Ecosystem carbon balance.- 12 Carbon investments.- Non-structural carbohydrates.- Lipids and energy content.- Carbon costs of leaves and roots.- Whole plant carbon allocation.- 13 Growth dynamics and phenology.- Seasonal growth.- Diurnal leaf extension.- Rates of plant dry matter accumulation.- Functional duration of leaves and roots.- 14 Cell division and tissue formation.- Cell size and plant size.- Mitosis and the cell cycle.- From meristem activity to growth control.- 15 Plant biomass production.- The structure of alpine plant canopies.- Primary productivity of alpine vegetation.- Plant dry matter pools.- Biomass losses through herbivores.- 16 Plant reproduction.- Flowering and pollination.- Seed development and seed size.- Germination.- Alpine seed banks and natural recruitment.- Clonal propagation.- Alpine plant age.- Community processes.- 17 Global change at high elevation.- Alpine land use.- The impact of altered atmospheric chemistry.- Climatic change and alpine ecosystems.- References (with chapter annotation).- Taxonomic index (genera).- Geographical index.- Color plates.- Plant life forms.- The alpine life zone.- Environmental stress.- The human dimension.

Photosynthetic Response and Adaptation to Temperature in Higher Plants

Abstract: INTRODUCTION 492 ECOLOGICAL ASPECTS OF PHOTOSYNTHETIC TEMPERATURE ADAPTATION 493 Photosynthetic Temperature Dependence in Thermally Contrasting Climates ........ 493 Photosynthetic Temperature Acclimation 497 Seasonal acclimation in natural habitats ...... ....... 497 Studies in controlled environments 499 THE MECHANISTIC BASIS FOR PHOTOSYNTHETIC RESPONSE AND ADAPTATION TO TEMPERATURE 504 Reversible Temperature Respon.ses 505 Stomata! effec� o� the . temJH!.rature response 0/ photo.rynthesis ......... ....... 505 Interacttons with /lght mtenslty 507 C, photo.rynthesis (lM photorespiration 507 C, photo.rynthesis 515 Comparison 0/ plants from contrasting thermol regimes ...... ...... 517 ["eversible Temperature Respon.ses 519 Low temperature sensitMty ....... 519 High temperature sensitivity 524 Adoptive responses in the heat stability 0/ the photosynthetic apparatus 530 CONCLUDING REMARKS 532