Boundary Layer Climates.

. Abstract Research on fragmented ecosystems has focused mostly on the biogeograpbic consequences of the creation of habitat “islands” of different sizes and has provided little of practical value to managers. However, ecosystem fragmentation causes large changes in the physical environment as well as biogeograpbic changes. Fragmentation generally results in a landscape that consists of remnant areas of native vegetation surrounded by a matrix of agricultural or other developed land. As a result fluxes of radiation, momentum (La, wind), water, and nutrients across the landscape are altered significantly. These in turn can have important influences on biota within remnant areas, especially at or near the edge between the remnant and the surrounding matrix. The isolation of remnant areas by clearing also has important consequences for the biota. These consequences vary with the time since isolation distance from other remnants, and degree of connectivity with other remnants. The influences of physical and biogeographic changes are modified by the size, shape, and position in the landscape of individual remnant, with larger remnants being less adversely affected by the fragmentation process. The Dynamics of remnant areas are predominantly driven by factors arising in the surrounding landscape. Management of, and research on, fragmented ecosystems should be directed at understanding and controlling these external influences as much as at the biota of the remnants themselves. There is a strong need to develop an integrated approach to landscape management that places conservation reserves in the context of the overall landscape

Biological consequences of ecosystem fragmentation: a review

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Biological Consequences of Ecosystem Fragmentation: A Review

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.

Alpine plant life

Edges are presumed to have deleterious consequences for the organisms that remain in forest fragments. However, there is substantial discrepancy among recent studies about the existence and intensity of edge effects. Most studies have focused on seeking simplistic and static patterns. Very few have tested mechanistic hypotheses or explored the factors that modulate edge effects. Consequently,studies are very site-specifci and their results cannot be generalized to produce a universal theory of edges. Although estimates of the intensity and impact of edge effects in fragmented forests are urgently required, little can be done to ameliorate edge effects unless their mechanics are better understood.

Edge effects in fragmented forests: implications for conservation

Introduction 1 Introduction Part 1 2 Earth's Surface Energy Budget Part 2 3 The Air Layer over Level Ground without Vegetation Part 3 4 Influence of the Underlying Surface on the Adjacent Air Layer Part 4 5 Futher Analysis of the Energy Balance Part 5 6 The Effect of Low Plant Cover on the Surface Air Layer Part 6 7 Forest Climatology Part 7 8 The Influence of Topography on the Microclimate Part 8 9 Interrelation of Animals and Humans to the Microclimate

The climate near the ground

The Climate Near the Ground

The Climate near the Ground

THIS is the first part of vol. ii. of the third edition of Prof. Hann's “Handbuch der Klimatologie.” Vol. i. dealt with general principles, and we now come to the detailed consideration of the climates of different parts of the world. The volume before us concerns itself with the tropics, the consideration of temperate and polar regions being reserved for subsequent volumes. The author has not confined himself strictly to the area lying between 23½° north and south of the Equator. When desirable he has gone outside this region. Roughly speaking, he discusses that portion of the earth's surface which has an annual mean temperature of 20° C. or above. The isotherm of this value may be taken as marking the polar limits of the trade winds, when definable, and of the palm tree.Handbuch der Klimatologie.By Prof. Julius Hann. Band ii., Klimatographie. 1 Teil, Klima der Tropenzone. Dritte, wesentlich umgearbeitete und vermehrte Auflage. Pp. xii+426. (Stuttgart: J. Engelhorn, 1910.) Price 14 marks.

Rudolf Geiger

Papers

The climate near the ground

The Climate Near the Ground

The Climate near the Ground

Handbuch der Klimatologie

Das Klima der bodennahen Luftschicht