Global Soil Changes (Report of an IIASA-ISSS-UNEP Task Force on the Role of Soil in Global Changes)

(1)

GLOBAL SOIL CHANGE

Report of an

International lnstitute for Applied System Analysis, International Society of Soil Science,

United Nations Environmental Programme

Task Force on the Role of Soil in Global Change

Editors:

R. W. ARNOLD, I. SZABOLCS, V. 0 . TARGULIAN

International lnstitute for Applied Systems Analysis Laxenburg, Austria

1990

(2)

(3)

...

⁷

Prefaae

...

⁹

Editorial Preface

...

¹¹

Q=@=I Chapter 11 Chapter I11 Chapterm Chapter

v

Chaptern Chapter VII Chapter VIII mpter IX I n -

...

¹⁵

Pedospkre

...

²¹

S o i l

axe.r

of t.h? Wrld

...

³¹

Types of Soil Prooesses and Changes

...

⁴¹

Pdleosols in the ca-ltext of Envirmm?ntal Changes

...

⁶³

...

Acn- Effects cm Soils 69 EUture Changes of t k Pedospkre

...

⁸⁷

Spatial Soil Databases ard kdeling

...

⁹¹

amclusions and &amendations

...

^lo3

(4)

(5)

FOREWORD

The I n t e r n a t i o n a l I n s t i t u t e f o r Applied Systems, is a non-governmental, i n t e r d i s c i p l i n a r y research organization founded i n 1972. Arrang i t s mst r e l e v a n t a b j e c t i v e s a r e "the i n i t i a t i o n and s u p p r t of individual and col- lakorative research on problems associated with environmental chanqe, and thereby t o a s s i s t s c i e n t i f i c c a m u n i t i e s throughout t h e world in t a c k l i n g such problems". One mans t o t h i s goal is by d i r e c t support of ICSU's In- t e r n a t i o n a l Geosphere-Biosphere P r c q r m , UNEP's I n t e r n a t i o n a l Panel on Climate Change, and s i m i l a r organizations.

IIASA's s i x t e e n national m d r organizations, located in e a s t e r n and western Europe, Asia and North Arrerica, are s c i e n t i f i c and professional bodies, r a t h e r than p o l i t i c a l ones.

me

I n s t i t u t e i s p a r t i c u l a r l y s u i t a b l e f o r bringing together t h e appropriate personnel t o solve s c i e n t i f i c research problems involving e a s t und *st. I t dces s o through the f o m t i m of program of study, presently a d d a t enhancing m t h d s of m t h e m t i c a l a n a l y s i s /System C e c i s i m Support Program/ and a t studying change i n global p p l a t i o n

/

P o p l a t i o n P r q r a r n / , technology /l'echnolog.i, Economy and Society Program/, and e n v i r o m n t / k v l r o m n t Program/.

Tne present environrrental ,=Flange i i c t i v i t i e s a t IIASA a r e centred on t h e Environment Program. Tne prcqran includes a group of 25 research schol- ars working on three desiyrated p r o j e c t s . The p r o j x t s concentrate on m- agerrent of l a r g e i n t e r n a t i o n a l r i v e s / I n t e r n a t i o n a l Water Resources P r o j e c t / ,

& e l l i n g of EuroFean a c i d r a i n d i s t r i b u t i o n s / T r a n s b u n d q Air Pollution P r o j e c t / , and ecolcqically sustainable d e v e l o p n t of Lye biosphere /Bio- sphere Dynamics P r o j e c t / . I t i s notable t h a t each of t h e proj,ects e r e developed inzependently of t h e o t h e r , b u t t h a t each of these p r o j e c t s i s a i m d d i r e c t l y o r i n d i r e c t l y a t d e v e l o p n t and use of m a t h m a t i c a l rrodels of e n v i r o m n t a l p h e n a n a . The models a r e desiqned s p e c i f i c a l l y t o be i n t e r r c q a t e d i n order t o r e ~ ~ e a l the options available t o p o l i t i c a l decision- rrakers on s p c i f i c envYrarmnta1 i s s u e s . Thus, t h e m i n g a l s of ea:A pro- j e c t a l s o are derived d i e c t l y f r m s p c i f i c i s s u e s of i n t e r e s t , r a t h e r than from e . g . a Fmdarrental c u r i o s i t y of how the e n v i r o m n t functions.

Global change issues which define both t h e nature of t h e Biosphere Project & e l l i n g aims, have a n-r of s o i l & e l l i n g r e q u i m n t s . Both s p t i a l and m r a l s c a l e s of t h e s o i l s i n f o m t i o n are needed. Tne pre- s e n t r e p r t gives s o m of t h e concepts underlying such s o i l s i n f o m t i o n .

A. M. SOLOMON

~ i o s p h e r e Dynamics P r o j e c t , IIASA, Vienna

(6)

(7)

PREFACE

'lhe present r e p o r t i s a l e o f a s e r i e s of documents by s o i l s c i e n t i s t s i n preparation of a coordinated input by t h e various national and interna- t i o n a l centres on s o i l research and m - n t into t h e International @o-

s@ere-Biosmere Programs /IGBP o r "Global Change" P r o q r m / i n i t i a t e d by the International Council of S c i e n t i f i c Unions / I C S U / . They are, i n chrono- l o g i c a l order;

-

TWO i n t e r n a t i o n a l task force rneetings on " W ~ p t of Global S o i l Change", taken place b e b e e n 24-25 April 1989 and 15-17 Lk&r 1989 i n Budapest /Hungary/ and W c o w /USSR/, r e s p c t i v e l y ; organized by IIASA, Vienna.

Proceedings, edited by R. W. m L D , I. SZABOLCS and V. TAFGULIA!!, published by I U S A / t h i s r e p o r t / .

-

^An i n t e r n a t i o n a l conference on "Soils and t h e Greenhouse Effect";

the present s t a t u s and future trends concerning t h e e f f e c t of s o i l s and t h e i r cover on the fluxes of greenhouse qases, t h e surface energy balance and the water balance, taken place between 14-13 August 1989 i n Wageninyen, the Netherlands; organized by the International S o i l Wference and Inform- t i o n Centre /ISFUC/.

Proceedings, e d i t e d by A.F. EOLW4?N, under the t i t l e "Soils and the Greenhouse E f f e c t " , published by John Wiley and a s , Chichester UK, e a r l y 1990.

- An i n t e r n a t i o n a l workshop on "Effects of Climatic Change on S o i l Processes i n the Trapics and Subtropics", t o take place between 12-14 February 1990 i n N a i r o h i , Kenya; organized by the International Society of S o i l Science /IsSS/ and the United N a t i m s EnvironnEnt P r o g r m / U N E P / .

Proceedings, e d i t e d by H.P. SCHARPENSm and M. SMO-R, t o

be

published in mid 1990 by Elsevier Science Publishers, h t e r d a m , the Netherlands.

-

A syrrposium on "Global S o i l Changes and t h e i r Dynamics in a Changing R x i m m m t " i n the f r a m m r k of the 14th International Congress of S o i l Sclence, 12-13 August 1990 in Kyoto, Japan.

P r o c e e h g s of the symposium to be edited by H. P. SWENSEEL and to be published by the J a ~ ~ ~ e ~ e Society of S o i l Science i n association with ISSS.

(8)

The four a c t i v i t i e s w e r e p r m t e d by t h e ISSS standing Cornnittee on International Programrres /CIP/ and w e r e f i n a n c i a l l y supported by

I i .

I t is the intention of ISSS t o prepare, m t h e b a s i s of all above proceedings, a separate Executive S m m r y m t h e Role o f S o i l s in Climatic Change, t o be s u b i t t e d t o t h e S c i e n t i f i c Advisory Council of IGBP and t o appropriate i n t e m a t i m a l fora, including the IN s s ~ c i a l i z e d Agencies concerned.

W . G . SOMBROEK Secretarq-CXneral of ISSS,

Wageningen

(9)

EDITORIAL PREFACE

By an agreemnt k t m e n I I A S A and the Hungarian a m n i t t e e f o r @lied Systems Analysis, a Task Force m e t i n g on the Concept of Global Soil h g e tcok place in Bdapest from 24 t o 27 April, 1989. T k participants agreed on the preparation of a publication on Global S o i l Change addressed to tk m r l d mmrunity of s c i e n t i s t s involved i n I m p , e.g. ecologists, climatolo- g i s t s , hydrologists, biologists, e t c . a s m11 a s decision- ad policy makers of high level, w b need t o e l a b r a t e the b l i s t i c and ccanpreknsive concept of global s o i l change a s a p a r t of the general concept of global geosphere- biosphere change.

The main s t u i f o r

tk

preparation of such publication =re:

a. tk extreme necessity of t3-e global and b l i s t i c spheric approach t o m r l d s o i l s and s o i l patterns, t h a t i s , t o land pedosphere and t o a l l interactions of t h e pedosphere with the other natural spheres and with a l l k i d s of human a c t i v i t y ad human l i f e :

b. the peculiarity of

tk

pedospkre a s an independent genetical, struc- t u r a l and functional subsystem within

tk

biosphere-geosphere with its own laws of evolution, d i s t r i b t i o n and functioning;

c. the international and interdisciplinary aspiration to urderstand the e s E n c e and s p a t i a l - t e n p r a l d i s t r i b t i o n of the m j o r m c h m i s n s of pedospheric changes due to b t h natural and anthro-ic f a c t o r s and forces;

d. the d e s i r e t o understand the major consequences and r e s u l t s of pedo- spheric c b n g e s on other V n e n t s of nature and society /feedback from -sphere t o biosphere-geosphere-society systems/;

e . and l a s t but not l e a s t : the feeling of resentn-ent f o r the lack of s c i e n t i f i c remgnition t h a t pedology i s such an i n t e r e s t i n g , a t t r a c t i v e , exciting and profound science, and f o r such an important and p l y f u n c t i o n a l natural M y a s s o i l and the m r l d ' s pedosphere.

T k publication slmuld k s c i e n t i f i c a l l y sound and based on f a c t s , but it i s interded to & e a s i l y read and c l e a r l y understood by b t h s p e c i a l i s t s and l a p n . The b k , b a a on an analysis of t h e e x i s t i n g kmwledge of t k p a s t , present and future of s o i l s of the m r l d , &sides the description of p r o c e s E s and situations, s b d d a l s include scme predictions and reoxm%m- dations.

After long discussions the s c k of the chapters of the " k s t - e l l e r n was accepted and the m r s of

tk

task force tcok t h e respcnsibility t o E r v e a s umrdinators and m n t r i h t o r s of the respective chapters.

(10)

It was also agreed that tk book should k available a t

the

14th Con- gress of

the

International Society of Soil Science t o k held in Kyoto, Japan in August, 1990, and k s i d e s

the

interested soil scientists an q l e n n h r of copies should k suhnitted t o interested international organizations as w l l as to

the

a m p t e n t agencies and projects /e.g. I-, UNEP, MAB or federal agencies/.

!RE second Task Farce U t i n g on

the

Concept of Global Soil Change was k l d in bbscow betwen 15 and 17 Decemter, 1989 ad was supported by UNEP and b s t e d by tk Centre for International Projects of

the

USSR State Onr mittee for Envimnmental Protection. A t t h i s meting tk chapters of tk publication wre presented

and

discussed and a final decision was made on

the

context of

the

book a s w l l a s on tk cwrdinators ad contribtors.

R. W. ARNOLD, I. SZABOLCS ad V. 0. TARGULIAN e r e appointed a s editors of

the

publication.

!RE coordinators and contributors of

the

different chapters are as follaus:

VII

VIII

Ix

Introduction

Soil carer of tk World Tylzs of soil processes ad changes

Paleosols in

the

context of envimnmntal changes Anthropqenic effects on soils

Future changes of

the

pedosphere

Spatial soil databases and d e l i n g

cBnclusions

and

recomnen- dations

V. 0. TAR-

v.

O. TAW;ULIAN R. J. DUDAL G. V A R W Y A Y D. H. Yz-mLN I. SZABOLCS

N. A. Karavaeva,

v.

0. TargLllian

J. Hrasko, B. G. Rozanov, H. W. Scharpenseel, V. 0. Targulian

G. W. Scharpenseel

!RE editors of this publication wish t o express

their

gratitude to a l l w r d i n a t o r s ardi ccmtributors of chapters for

tkir

k l p and understanding, which made it p s s i b l e to finalize tk publication in a comparatively short

th2.

The intention of tk task force was to give an overall picture on global soil c h g e based on a uniform use and m n technical understanding. S t i l l , due to

the

large number of autbrs,various opinions and scien-

(11)

t i f i c appmacks of saw questicns can possibly ke found i n different places of the

took.

Evidently, tk various parts of tk publication a r e i n t h e i r a u t b r ' s credit.

T ' k

editors had t o respect

thz

a u t b r s f opinions a s lona a s t k s e did not r e s u l t any misunderstardings o r confusion in tk interpreta- tion of & text. Consequently, tk editors mde no changes in tk m u - s c r i p t s w i t h & exception of inwitable, minor corrections necessary f o r a uniform structure.

~ c c o r i h g to the decision of the M3scow bleeting, t o eliminate the re- petitions, an integrated List of Selected ReferenQS was canpiled and pub- l i s k d from tk list of r e f e r e n ~ s suhnitted by

tk

coordinator of each chapter.

W e rmst achowledge

tk

assistance

and

c o n t r i h t i o n of m y persons.

A large number of colleagues took part i n the preparation of each chapter, besides

the

coordinators and contributors. Prof. M.

-,

a m d i n a t o r of Chapter VIII, wishes to extend appreciation to Dr. mrkerto FEIWWDEZ, -due Miversity, mA f o r h i s valuable contribution t o his chapter. T k undersigned wi&s to express h i s appreciation t o Dr. M. m L Y , who offered k r assistance i n tk f i n a l stage of tk e d i t o r i a l process.

We wish t o acknowledge the k l p and support of the International Insti- t u t e f o r &plied System Analysis ]IIASA/ and especially of Prof. D r . B. R.

W , bzider of

tk

hvircmmntal Programw,

and

Dr. Allen M. SOK@DN, W- e r of

tk

Biosphere Project i n tk preparation and realization of t h i s plb

lication.

Gratitude h l d ke expressed to

the

Mited Nations Environmental Prog- r m , and p a r t i ~ u l a r l y t o D r . S. A. EVTEEV, Assistant Executive Director

and

Dr. A. AYCUB, Senior Programne Offioer of Terrestrial Emsystems Branch, f o r tkir s u p p r t and financial assistanoe.

T ' k

President of the International Society of Soil Science, Prof. D r . A. TANAKA,

tk

Vice-President, Prof. D r . Y. TAKAI,

and

Secretary General, D r . W. G. SOMEROEK, offered tkir invaluable k l p during tk e n t i r e process of preparing and editinq the kmk, for which tk editors express their sincere thanks.

We are deeply indepted t o Dr. T. AsEOTfi, Secretary

and

Ms. Z s . ZibDRI from the Hungarian National Member Organization of IIASA, who supported

and

assisted the a c t i v i t y of tk Task Force f m

tk

very keginning.

Appreciation

should

also be extended toward tk USSR (Entre of Inter- national Projects,

and

particularly t o D r . T. A. SAIKO, Deputy -or-

dinator of Desertification Oxkrol projects, for b s t i n g & M~SCOW &eting.

Tl-e

loyal assistance of Dr. M. lDINAI, Director

and

Ms. I. IXIBI-NAGYI Business Executive of tk I n s t i t u t e for =search Organization of the Hun- garian k a d e m y of Sciences /Bulapest/ i n the realization and printing of this kmk should be admowledged.

Last ht not l e a s t ,

thz

edibors

are

deeply indebted t o tk c l e r i c a l s t a f f , which has engaged i n technical editing, i n preparing translations, drawings, typing, etc. and supplied long kcfurs of m r k i n & preparation of this book: MS. I. HETEI, MS. I. KEMENES, MS. S.

~ovAcs,

Ms. V. L A C Z K ~ ,

m.

Z. SZILX&SY, Ms. K. TEPLAN, and Ms. I. K?QI. Sincere thanks should be expressed a l s o t o Ms. Mwylin BRANDL, Secretary, Enviromntal P r o g r a m /IIFSA], who willingly cooperated with t'k W s of tire Hungarian group t h r o u g M t

thz

whole t h .

Fk~dapest, February, 1990 I . SZABOLCS

(12)

(13)

Chapter I INTRODUCTION

Theoretical and practical neQssity of studying qlobal s o i l change Landscapes developd l a g &fore the appearma? of man. W i n d has

&en altering

the

earth's envimnrrent f o r a t l e a s t t m millicm years. Dur- ing most of this the m ' s influence has

lzen

minor and local. He has

kid bath

~ o s i t i v e and negative e f f e c t s cm tk environmmt. But r e ~ n t l y his

im

pad has increased on a global scale, emtracing all regions ad a l l x n p - nents of

the

environment. We are now f a d with m y global issues a s a re-

sult of anthmpgenic.'changes of

the

wlrsle b i o s p w - g e o s p k r e system, each of i t s c m p n e n t s , and t h e i r linkages

and

f e d h c k s .

'IWay the situation is characterized by:

1. Increasing i n t e r e s t i n assessllents of global changes of t h i s very carr plicated system.

2. frbny kinds of human a c t i v i t y cm land and ocean have led to tk deterioration, degradation

and

even q l e t e destruction of the natural systems and/or t h e i r separate c m p n e n t s .

3. Realization that m has significantly i q m e d the envircmwnt t o provide t h e necessities of l i f e

and

the growth of civilization.

4. L%'s a b i l i t y to change the natural e n v b m m n t is creating uncertainty of our mderstarding ard canprehension of

the

earth as a system.

There is a need t o study the q l i c a t e d interacticms of nature and

the

interactions kt- nature and society in order t o adapt, o r mitigate various natural

and

man-made a g e s within the biosphere-geospkre-society system.

The system has developed

and

functions by tk s ~ t a n e c u s presence cm t h e earth's surface of t h e atrmspkre, hydi-osphere, l i t h s p k r e , biota and hmm activity. "Semndaq" spheres of interaction of t k s e o m p n e n t s also exist. Within such s p k r e s of i n t e r a ~ t i a n a l l the phases and fluxes of sh- stances /gaseous, liquid ad solid, organic ad inorganic, biotic and abio- t i c , natural

a d

a n h p o g e n i c / intersect, m i x

and

interact.

ImFortant i n t e r a c t h s occur i n the three m j o r b i o t i c a b i o t i c spheres:

w o s p h e r e / s o i l c a r e r / , and

the

p b t i c and h t i c zones of the ocean.

'R-ee spheres support

the

biota and serve a s the soure of nutrients for the functioning

and

f o r production of the b i m s s .

In Fig. 1 a s c h t i c nrdel on tk

abare

described functions of the pedosphere and of i t s interaction with o t k r systems i s d m n s t r a t e d .

(14)

Fiwe 1. Model of the natural ard hm-incuced interactims within the soil; and betwe soil an2 other tic-qeoqheric &systems

e T

4 at momhere

-

biota I s.energy, prec . O.M. ; I I \ gases biochem cycles

\

dust bioturba tiod T human activity agriculture I

.\ \ I

v

hydrosphere + field water balance forestry settlements

/&ZJH;Htl

chemistry of water industry recreation, etc.

1 A A

g% 3

ma rg Y pedosphere 1 I

1

-

A

1 t 1 V - -

transport and sedimentation

I

Lithosphere

"7

etc. a

I

parent materia1,texture

---

Amineralogy chemistry 4

7

1 '1

t

(15)

'RE pedospkre is

the

important natural r e s u r c e for growing f d , feed, timber and fiber. In a d d i t i m t o

the

physical s u p p r t of l i f e the pedo- s p k r e has many other important f u n c t h s , ach a s atrtospheric, hydrospher- i c , lithospheric. Soils f u n d i m not m l y a s a mter-nutrient-life m d i a hlt also a s r e d i s t r i h t o r s and regulators of mst of

the

important fluxes of mtter

and

energy.

Due t o

the

very cunplex /horizmtal and v e r t i c a l / heterogeneity of the pedosphere and t o tk high v a r i a b i l i t y of

soil

age

ard

duration of s o i l fonn- in9 processes, all s o i l functions and p r o p r t i e s vary b t h in space

and

time.

Knowledge of the m i n linkages and feedbacks bet- the pedosphere

and

other natural

and

rran-mde systems i s important t o understand and f o m l a t e the m e p t of global

soil

change.

Soils change because of t h e i r wer-intensifyinq use. T k changes m y be gradual, rapid, o r even catastrophic. Such changes in the pedosphere af- f e c t the i m d i a t e carrying capacity of the land, through t h e i r i n f l u e n e on

the

vegetation and land-use t y p s , run-off, evaporatim, graJndmter quality, and so forth. Directly o r jladirectly the s o i l changes have a substantial ef- f e c t m global c l i m t i c a n d i t i o n s , W h i c h in turn, i n f l u e n e soils.

It is W r t a n t t o study

the

pedosphere m e p t u a l l y a s w l l a s prac- t i c a l l y . 0-1 one hand studies &mld analyze past, m e n t and f u t m changes of tk pedosphere influenced by

the

other changing sphere, including different types of humm a c t i v i t i e s ; m the other h a d the influ- ence of a changing pedospkre cm other spheres and cm I-olroan l i f e s h a l d

be

quantified and evaluated.

"Ocncepts of Global Soil Change" attempts t o focus

the

a t t e n t i m of those who study

the

biosphere-geosphere m

the

global aspects of

the

@lo- s p k r e and on tk importance of describing

ard

widerstanding changes of the

@losphere f o r the functiming of

the

w h l e earth system

ard

the required knrman respcnses.

This publication r e f l e c t s a c a n e r n a b u t glabdl s o i l changes by m n - sidering the following questions:

-

^What^{is the}place

and

tk role of

the

@lospkre within

the

biosphere- geosphere system?

-

What are tk m i n £unctions of

the

pedosphere?

- What is global s o i l change?

-

What

are

the m i n factors and trends of pedospkre changes?

-

What i s

the

feedback from a changing pdosphere?

-.What are relevant apprcacks t o

the

s M y of those changes?

-

What important gaps e x i s t in

our

kmwledge abxt the qualitative

and

quantitative characterization of

the

structure a d functiming of tk pedospkre?

-

What databases are relevant for studying global s o i l changes?

-

What r e m a t i o n s can be offered t o help descrike

and

understard global sil c h g e ?

(16)

IIASA's interest i n environmntal change

~ ~ ~ 2 ~ ~ ~ ~ - - ~ ~ ~ ~ ~ ~ ~

The basic prohlem i s t o understad the role of the t e r r e s t r i a l biosphere in the global c a r b n cycle. s here are three p r i m r y sources of the large uncertainty:

a. inadequate estimates of the bicnnss amunts

and

variations character- i s t i c of varirxs biotic m i t i e s

and

t h e i r s o i l s ,

b. i n a b i l i t y to precisely m s u r e historic

and

present changes in land use

and

deforestatim, and

c. poorly understocd transients in carban dynamics of biotic a m u n i t i e s /decay

and

recovery r a t e s / .

The current uncertainties in estimates of biomss arrcunts

ard

_varia- t h s follow from too few f i e l d samples.

Additionally, msasurements of &low ground biamass w i l l require large e . i t u r e s of m m m r cn f i e l d studies, m y of

them

a t

the

spatial s d e of m t e r s t o kilometers. 'Re &low g r m d processes form ~ e r h p s the uncertainty of greatest potential e f f e c t m t e r r e s t r i a l carban cycling.

The r a t e of deforestaticn includes uncertainties in estimates of the t o t a l clearance rate, of permanent versus temprary clearing, of pr-

versus seccndary or fallow forests,

and

of current and historical land use.

Deforestaticn and afforestation a r e intimately linked t o s o i l features, especially t o e r o s i m and changing s o i l f e r t i l i t y . The d c a m n t a t i o n of current land use, and the prediction of f u b x e land u s

are

critical cxp- nents i n estimating future c a r h storage characteristics of the globe. In t h a t regard, s o i l properties provide the mst important local l i m i t , par- t i c u l a r l y t o the aupunt and kind of agriculture vhich can

take

place under climate characteristics.

Poorly understood transients in c a r b dynamics w i l l probably only be described accurately m c h n i s t i c d e l s can provide a spatially

a d

temprally-detailed accounting of both the loss

ad

recovery of c a r b storage which i s measurable i n the f i e l d .

The transients in vegetation follow from a m p t i t i o n arrong individuals.

Therefore, no mtter what aggregated variables may & r q u i r e d /e.g. bio- geochmical cycling phencarma, standing crop biamass, etc.

/ ,

d e l s them- selves mst encanpass processes m a s w e d for areas of no m r e

than

h u t one square k i l m e t e r a t which ocmpetitim for l i g h t , m t e r ,

ard

nutrients occurs m g the largest plants, i . e . trees.

T k replacerrent of t r e e s by new, lztter adapted species i s a m j o r point of uncertainty. m e c r i t i c a l question involves r a t e of climate change, not the eventual magnitude of climate change.

Soil infomation, ccanbined with general principles of plant growth and ecological i n t e r a c t i m s , prmides

the

basis for the required mchanistic d e l s .

Bicdiversity issues

Ourrent issues surrourding preservaticn of biodiversity

ad

endangered species r e l a t e t o

the

cxmtinums l o s s of

the

genetic resources of the earth.

The biota receiving most of the present m c e r n have k e n reduced by the d i r e c t actions of m: harvesting forests, replacing natural h i o t i c axmum-

(17)

i t i e s with agriculture, emitting dangerous p l l u t a n t s , and introducing spe- c i e s fran other regions. In tk future, biota w i l l likely be threatened also by chmging extrems in clirrate

an3

t r o p s p k r i c content.

The relevant t h and space scales are of quite fine resolution.

The

data s e t s mst include tk day-long o r wek-lcmg tim scales which contain extrems of wather /floods, drcllghts, late spring and early f a l l f r o s t s , winter low temperatures/ that

are

capable of destroying tk few scattered p p u l a t h s of a s p c i e s , o r

the

dominant individuals which m t r o l the character of a rare ammmity.

The nature of tk biotic data, too, i s quite precise, k i n g derived from a thorough understanding of the uniqw environrnatal variables h i c h determine the survival of

the

species o r m i t i e s . These variables d i f - f e r from m e species or a m u n i t y t o a n o t k r , hlt often cansist of unique ambinations of s o i l s and climate features.

Data a r e &st all of d l spatial areas, and m y of the tempral steps are quite &art a s ell. General principles are unlikely to be detailed enough t o a l l o w predicting the respcnse of biota t o s h i f t s in envi- r-tal variables by specific biosphere reserves and erdangered species.

Agriculture issues

Changing climate w i l l play an important role in tk future availabil- i t y of food, fiber,

ard

forest products of the earth.

There appears to te general agreerent that the geographic distrituticm of crop productivity is mre related t o humn actions than t o envircwoental canstraints. The problem for global change studies is t o define

the

a x r e n t e n v k m m n t a l constraints a c h define the potential presence or abssnce of each crop in differing regions of

the

_globe,and t o apply those canstraints under scenarios of changing geography of climate.

The s o i l s a s p & is particularly h p r t a n t in estimating tk future agricultural potential of crops kecause s o i l s unsuitable for growth of crops m y daninate regicms which k m o t h r w i s e climatically suitable.

The geographic implications t o agriculture of changing climate produce an issue of paramxlnt W r t a n c e t o a global populatj.cn which continues t o grow rapidly.

The t h d e s of tk is- are not easily determined tecause they depend cm hmm a b i l i t i e s t o adapt to ambiguous hlt clearly changing e a t k r . The space d e s of cancern are tens of mters t o kilaneters, defined by s o i l capability classifications.

Forestry issues

Future availability of forest products is very uncertain. Direct _choices by society w i l l determine hardwood forest product availability during the next few decades.

H m r , h m a c t i v i t i e s which produce changes i n climate and a t m - spheric chemistry my indirectly define softwood futures. The circurqmlar bred forest in the n o r t k m h e s n i s p b m t a i n s mst of tk softwood grow- ing stock of the m r l d . Climates that occur n-e today in the breal f o r e s t s m y soan displace

the

boreal temperature and precipitaticn r e g h s under vhich tk northern ecosystems curxently exist.

(18)

T k critical datum determining this issue w i l l be tk r a t e of climate change. The critical process to be u n d e r s t d w i l l be f o r e s t s u c e s s i m h i c h d e f d s

tk

r a t e of forest r e s p n s e to climate change. Depending upm migraticm r a t e s , species adapted to changed ccPlditions may a l s o not

te

cxpable of migration to

t k

newly available sites.

Th?

spa^ scales are those of perhaps t e n s of kiloneters in terms of d i s t r i f u t i m s of climate,

and

s o i l s features. tine scales are years t o t e n s of years, a x r e e d i n g t o transient respcnses t o changing climate by long-lived trees and forests. The m a l l s p a t i a l area is

required

to handle the causes and consequences of

tk

processes of f o r e s t accession

and

spe- c i e s migration.

(19)

Chapter II PEDOSPHERE

k f i n i t i c n of s o i l s ard peCiosphere

Of course everybody seems to know what s o i l s are, but not many people knm why they e x i s t on the e a r t h o r what t h e i r important functions are.

From e a r l i e s t childhood, we walk on s o i l and think 05 it a s a s o l i d founda- t i o n o r dirt under m r f e e t . (3n the other hand, we know t h a t s o i l s a r e hab- i t a t s f o r l i v i n g plants, providing trees and grasses w i t h rooting space and anchorage. Many even knm t h a t s o i l s provide p l a n t s with n u t r i e n t s and water f o r t h e i r l i f e . ^{A n}a g r i c u l t u r i s t o r a gardener w i l l further knm that s o i l s a r e the surface layer of the e a r t h which r u s t be ploughed, f e r t i l i z e d , irri- gated o r drained, and kept f r e e of weeds in order t o grow cultivated plants.

But knowing a l l these simple f a c t s is not enough t o understand. these s p c i f - i c bodies of nature, t o m a w them, _{t o}irtprave t h e i r natural capability, to increase and m i n t a i n t h e i r productivity, and t o sustain t h e i r diverse ecological and economic functicms f o r the benefit of the biosphere and man- kind. We have t o know rmch more about s o i l s , looking a t them f m d i f f e r e n t p i n t s of view, t o h a w

and

understand them a / a s natural bodies, b / as ccmponents of the geosphere-biosphere system, and c / as natural resources f o r economic d e v e l o p m t .

Such an integrated view of s o i l becarre possible only w i t h the develop- m n t of s o i l science a t the end of the l a s t century, when DOKUCHAEV, HILGARD and others p r o p s e d a new s c i e n t i f i c concept of s o i l a s a s p e c i f i c body of nature which developed h i s t o r i c a l l y in tim and space a t the land surface due t o continuous and s h l t a n e o u s interactions through

time

of t h e follawing soil-forming factors: a / the lithosphere, b / the atmsphere, c / t h e hydrosphere, d / l i v i n g organisms and products of their l i f e , and e / landform o r the r e l i e f of the l o c a l i t y . Presently, man is m s i d e r e d to have a s i q n i f i - cant influence cm s o i l s .

Tbroughout history, *re was no s p c i f i c definition of s o i l s i n t h e i r many-sided t o t a l i t y because it was not required. Instead there existed a sirrple comnon understanding of s o i l s , which f u l l y s a t i s f i e d the users. It w a s enough t o define them as the surface layer of the e a r t h capable of producing and s u p p r t i n g p l a n t Hmever, with the developwnt of:

s o c i a l , economic and ecological problems of the last century, with the progress of p r d u c t i o n and technology caused by the technological revolu- t i o n , and with the advance of mchines and chemicals i n agriculture, the need f o r a new s c i e n t i f i c approach and. definition of s o i l s has becane pressing. The developmnt of s o i l science b e c m an answer t o this growing need, and w i t h this c m a new definition of s o i l s .

(20)

W currently describe a s o i l as having e been form4 in s i t u with strata or horizons of earthy m t e r i a l that have properties and qualities which have developed under a cQnbined effect of parent rock, climate, living matter, relief, and age of landform. The widest definition of soil might be made using the system apprcach: s o i l is a canplex, polyfunctimal, open, p l y - phased, structural system within the surface part of the litbsphere.

Soils ' m e r the earth's land surface

and

the bottcm of shallow m.ters as part of a continuum or mantle, except on bare rock. ?his continuum i s called

the

pedosphere /from G r e e k , pedm'graund/. The pedosphere functions as the earth's geom?mbrane, which i s , up t o a ~ r t a i n deqree, analogous to biQwT33ranes of living organisms IFOZANOV, 19881. I t i s the skin of the earth, through which the perpetual exchange of substance and energy between other geospheres proceeds. A s a g e o d r a n e , the soils regulate t h i s exchange, passing through saw substances and flows of energy, reflecting or retaining, and accumlating others by i t s surface, or thickness.

The pedosphere in the biosphere-geosphere system

The earth's biosphere-geosphere system mnsists of several interacting strata covering the nucleus of

the

globe: outer space, atrmsphere, hydrosphere, biosphere, pedosphere, lithopphere, mantle /see Figure 21. T k earth's biosphere i s mde up of t e r r e s t r i a l and aquatic biospheres. Iand only has t w ~ -in structural and functional layers: the abwe ground bio- amsphere and below ground biolithosphere.

This ccncept a s s m s that

the

below ground biolithospheric layer of the land's biosphere i s the pedosphere, which develops and exists a t a junction and as a result of interaction betwen the lithosphere, atmosphere, hydrosphere and the biota of the planet /Figure 21. The pedosphere i s simul-

Figure 2 . The Wosphere in the biospherweosphere system 22

(21)

taneously a conpment of the lithosphere and of

the

biosphere, a m j o r support, and the result of l i f e .

Using t h i s approach, it i s possible t o give descriptim of the

w-

sphere according to i t s function and structure. Functionally, the pedosphere, as the upper layer of

the

lithosphere, i s loose and porous, inhabited by biota, and pemable for abmspneric gases and misture. Wcause of i t s porosity, soil i s habitable for organisms, and it exercises i t s g=mmbrane function as a regulating ~nechanim within the biosphere-wsphere system.

As a subsystem of the land biosphere, the m s t important and rmst intensive interactions between biota and a l l kinds of abiotic substances take place within the pedosphere. ??unctionally,

the

pedosphere i n c l u k s any solid-phase substratum which i s capable of exchanging gases and misture with the atrro*

sphere, hydrosphere, and lithosphere, and of supporting the l i f e of auto- trophic and heterotrophic biota. So the pedosphere i s

the

strata of below gromd functional layer of the land biosphere.

The majority of the processes within the pedosphere are not ccslrpletely reversible. Same are irreversible processes such as weatherha of silicates and leaching. Others are cyclic but not mrrpletely reversible processes such as biological turnover, and f o m t i o n and mineralization of h m s . Due t o such irreversibility of soil processes, m y residual or new solid-phase compounds occur within the pedosphere /EihlDE 1947; YAAU=N 19711. 'Ihe annual formation of such ampunds i s very small and can hardly be detected. But i f these processes function for a long tim /n.102-lo5 years/, these solid- phase compunds gradually acamdate witkin

the

pedosphare and form the pronounced pedogenic features of s o i l formtion such as h m s , salic,

a r g i l l i c , carnbic, and other horizons.

The process of the accumulation of the various canbinations of these pedogenic macrofeatures i s usually called a soil-forming process, that mans, a process which changes the i n i t i a l solid-phase lithospheric structure and c a p s i t i o n into the newly f o m d pedospheric solid-phase structure and composition /JENNY, 1941;FODE 19471. These pedogenic features are m s t p r o - nounced in those cases when the upper layer of the lithosphere i s neither renewed by erosion or &imntation nor mixed with the deeper layers. In the cases of stable landscapes and long-term functioning of the processes in the pedosphere, the gradual accumulation of solid-phase results takes place and forms wll-differentiated soils,/JOHNSCN

and

WATSON-S-R, 19871.

It i s important to note that

t k

pedosphere functioning as a zone of below ground biosphere forms rapidly

-

a few m t h s and years. The pedo-

sphere as a s p c i f i c structural solid-phase anisotropic subsystem needs much m r e time /n.ld-lo5 years/ t o a well-develo~ed, vertically and bri- zontally differentiated m t l e which e c a l l the pedosphere. So, when we consider the pedosphere in a structural sense we usually man the attributes of the solid phase of the s o i l profiles and bodies.

The general developwnt of the pedosphere can be visualized as a

sequence. The i n i t i a l contact and interaction of the abmsphere, hydrosphere, biota with

the

upper lithaphere layers distinguish the pedosphere as a zone of biosphere functions. With longer-term biosphere interactions the =dosphere kvelops a three-dimnsional anisotropic structure. A f t e r i t s formation, the pedosphere strangly regulates and controls the present and future functioning of

the

biosphere.

(22)

Vertical structure of the pedosphere

The pedosphere has i t s a m specific structure. W r y natural soil has a vertical pedogenetic anisotropy as the result of the depth of action in s i t u of the f a c a r s and processes of soil formation. The vertical sequence of different layers in a natural s o i l i s the system of genetic s o i l horizons that canprises a genetic profile, or soil body.

In general each s o i l , as a polyphase body within the psdosphere, consists of different t y p s of depth distributions in any given r r m t . There are temprature profiles, moisture profiles, s o i l solution profiles, macro and microbiota profiles, and solid-phase profiles. The f i r s t

three

are mainly functional; they

are

very labile and change very fast / n . 1 0 - ~ 1 0 ~ years/ in the prccess of biosphere functioning. The solid-phase forms the m r e stable s o i l f r m o r k and i s characterized by

the

d i n a t i o n of inter- related horizons which generally differ in s o i l texture, s o i l structure, mineralogical and chemical a m p s i t i o n . Many kinds of s o i l horizons are recognized and d i n a t i o n s and sequences of horizons give rise t o a large nwlber of unique soils.

Soil as a "block of m r y " of the biosphere-geosphere system

Soils and the pedosphere as a whole, are not only a m t i n g rrediw, for plants and a source of bioprductim; they are also organized and struc- tured natural entities. The main features of enviromrents that existed

&ring s o i l formation and subsequent changes are reflected and recorded by the pedosphere in i t s a m properties. Every soil body i s a "block of m r y "

of past and present a m - , hydro-, bio- and lithospheric interactions. I t can

be

said that the pedosphere i s the product and block of m r y of biosphere-geosphere functioning ITAFGULIILU e t a l . 19791.

Soi'l properties have different capacities for recording past and present e n v i r m n t s . This strongly depends on the characteristic respnse time /CRT/ of the individual features and processes, and refers t o the t h required for a given soil feature t o ^CXXE into quasiequilibrium with the environmtal conditions / Y ~ N , 19711. ?he general scheme of the CKC in soils i s as follows /ARMAND and TAFGULIATJ, 19741:

CRT of s o i l gaseous phase

-

t o 10-1 years CW of soil liquid phase

-- lo-z

t o

lo0

years CRT of s o i l micro- and macrobiota

-

^10-1^to

^lo2

^years

CRT of s o i l solid phase /mineral and

organic/

-

¹⁰⁰

ⁱ ^a ^loG

^years

The t h spans sham as orders of magnitude are only illustrative of the wide range of t h s involved. For example, sorre biotic attributes can change much slowr than s m solid-phase features. It i s concluded that the gaseous, liquid, and biotic s o i l features w i l l reflect the e n v i r m t a l changes mch faster than the solid-phase s o i l features. Although the solid- phase features w i l l reflect the e n v i m n t a l changes s l m r , they retain a record of e n v i m n t a l changes mch longer than gaseous, liquid and biotic attributes.

Thus the solid-phase features of s o i l profiles are the more important recorders .of e n v i r o m t a l m d i t i c n s . Different s o i l solid-phase properties have different CRT and consequently differ i n their capacity to record prior change. The faster soil-forminq processes and c o r r e s p d i n g s o i l properties

(23)

m y record p a s t environrrental changes f o r years, decades, and even centuries.

Examples

are

litter-leaching and decamposition, s o i l s t r u c t u r e f o m t i m and d e q r a d a t i d , salinization and desalinization, gleyzation and oxidation, hums f o r m t i o n and deccpnposition. The slower p r o ~ s s e s and t h e i r correspnd- ing s o i l properties m y record envirunn-ental changes f o r millennia to m i l - lions of years. Examples a r e clay t r a n s f o m t i o n and translocation, rubifica- t i o n , and d i f f e r e n t types of deep w t h e r i n g . The age of s o i l m r y depends m the age of a s o i l , t h a t i s , the duration of s o i l forming and e a t h e r i n g processes which acted i n s i t u i n each s p e c i f i c place.

Many buried s o i l bodies and patterns r e f l e c t past geological environ- m n t s /see Chapter V / . The s o i l s of the existing pecosphere qenerally ccmsist of conplex carbinations of s t a b l e , inherited and often r e l i c t properties of pre-Pleistocene and P l e i s t o ~ n e weathering, lithogenesis and pedogenesis, inherited and/or evolvinq properties of Holocene weatherina and s o i l f o m - t i o n , and more recent properties caused by human-induced transformation.

These very camplicated carbinations serve a s records of the processes of biosphere-geosphere interactions and t h e processes of the evolution of these interactions aver

time.

Pedologists

are

learning, s t e p by s t e p , to "decode"

t h e s o i l p r o p r t i e s informaticm into envimnmmtal change information /TAFGULIAN and SOKOLOV, 19781.

The recognition and g e q r a p h i c delineation of s o i l a s a "block of m n ~ r y " has g r e a t inportance not cmly i n pedology and s o i l science but a l s o i n paleoqeography

,

ecology, geology and other e a r t h s c i e n e s . The correct

"reading" of s o i l - m r y informaticm w i l l ke useful to separate past and present s o i l changes and to assist in forecasting the future changes.

Knowledge of d i f f e r e n t c m p n e n t s of a s o i l as "block of m r y " and of t h e r a t e s of changes of solid-phase properties i s cme of the mst challengina tasks f o r understanding future pedosphere changes.

Main functions of the pedospkre

'Jhe biospheric, hydrospheric, atmos&eric and l i t h o s & e r i c functions a s we11 a s the f e r t i l i t y of s o i l s

are

determined by t h e properties and a t t r i b u t e s of t h e *ole s o i l body.

The f i r s t most irrportant function of the pedcs@ere is biospheric.

The pedas@ere s u p p r t s and regulates m y b i o t i c processes. Plants r e e i v e t h e i r mineral n u t r i e n t s and water from s o i l s to build up t h e i r biomass.

This plant bicmass b e c a ~ s the source of nutriticm f o r a n h l 4. m.

Biogenic chemical elerrents accurmlate i n a s o i l i n t h e form of available chemical campounds. The bios&eric functicm gives rise t o the s ~ c i f i c s o i l q u a l i t y c m l y h a m a s m i l f e r t i l i t y , which is

t h

a b i l i t y of a m i l to regularly supply plants with e i e m n t s of mineral n u t r i t i o n and water, i n addition to sirrolltaneously providing favorable &ysical and chemical ccmdi- ticms f o r p l a n t grudth. S o i l f e r t i l i w i s absent m hard rocks and cmly weakly expressed on loose nxks of t h e lithosphere f m w h i c h s o i l s

are

developing. Natural s o i l s vary widely in t h e i r f e r t i l i t y . Gradually mm has learned how to m g e s o i l f e r t i l i t y and s o i l s with l m productim capacity to transform i n f e r t i l e s o i l s i n t o more productive ones. I r r i g a t i n g deserts, draining swanps, leaching e x e s s s a l t s and adding f e r t i l i z e r s a r e -1es of such t r a n s f o m t i o n s .

Although s o i l s have t h e capability to s w r t l i f e , they m y a l s o have certain p m p r t i e s detrimmtal f o r s a w organism. They m y be too s h a l l m ,

too

_dense,too acid o r too alkaline, too dry o r

too

_wet,

too

_deficientin n u t r i e n t s o r

too

toxic i n soluble salts to p r w i d e a favorable envinmmnt

(24)

f o r plants and animals. ?he distribution and gecga& of natural vegetation is closely connected with the d i s t r i b u t i m and ccqxJsitim of s o i l cover.

?he p e d o s p h e ~ accumlates active organic matter / h m s / and the chemical energy bound t o it. Living organic matter r a t h e r quickly deonn- poses i n t o simple chemical mmpunds a f t e r the death of the organism. Part of the &ad organic mtter is t r a n s f o m d i n t o s o i l h m s o r ccmplexed with clay and oxides, which m y be preserved f o r hundreds and thousank of years.

?he second global f u n c t i m of the pedosphere i s t o be an interface and a zone of interaction i t s e l f . Due t o its "boundary" position w i t h i n 'Lhe biosphere-geos@ere system, the pedosphere sustains, regulates and controls many b i o t i c and a b i o t i c turnovers and fluxes of substances. ?he important p a r t of biogecchemical turnover of substances takes place between plant and s o i l and has an ascending-descending character /so-called smll biological turnover/. ?he plants take from the s o i l the e l e n t s of mineral n u t r i t i o n which, through a n m h r of i n t e m d i a t e stages /plants-animals-micmrgan- i s m s / , a r e again returned i n t o the s o i l a f t e r b i o t i c , p r o t o l i t h i c , and photochemical organic mtter decanpositicm.

A t t h e s m tirre s o i l s a r e the s t a r t i n g point f o r the migration of

the

soluble and nonsoluble substames within and through ecosystems. A l l these subskhnces m y be rmbilized and leached out of the s o i l by atmospheric p r e c i p i t a t i m into the ground and surface waters, sore t o

the

ocean, where the aquatic biota use som transported nutrients. Most sediroentary rocks a r e f o m d £ran materials derived £ran t h e pedosphere. A t a l a t e r t i n e , these rocks m y be exposed, undergo ~ t k r i n g , and give rise t o new s o i l s . This is the so-called big geological turnover of substances.

The t h i r d global function of t h e pedosphere is a m s p h e r i c . Soils contribute to t h e chemistry, moisture and heat balance of the atm3sphere.

A s a porous system, t h e s o i l contains pores of d i f f e r e n t s i z e s and config- urations forminq a network of interconnected channels throughout the s o i l volurre. A large p a r t of the pore space i s inhabited by roots and by mzo- and microbiota. Due to s o i l porosity and high density of i n t r a s o i l b i o t i c p p u l a t i o n , t h e pdos@ere exchanges various gases w i t h t h e near-surface atnosphere: absorbing oxygen, and exuding carbon dioxide and a n m h r of other gases such as rethane, hydrogen, hydrogen sulphide, nitroqen oxides, and a m n i a . S o i l respiraticm has d a i l y , seasonal and mualdynamics spe- c i f i c f o r each s o i l ecosystem. Soil evaporation influences m t e r vapour of t k a t m o m e r e and m i l a l M o .

?he fourth global function of the ~edosphere is hydrospheric. ?he pedos@ere r e d i s t r i b u t e s water i n t o various land hydrological fluxes. Due i n p a r t t o porosity and water perrreability, s o i l s d i f f e r t h e i r a b i l i t y t o transform precipitation i n t o i n f i l t r a t i o n , surface runoff, subsurface intra- s o i l runoff, and groundwater runoff. ?he chemical o m p s i t i o n of precipita- t i o n is a l s o a l t e r e d when it comes i n contact with t h e s o i l surface and percolates through t h e s o i l body. Due t o its porosity, f r i a b i l i t y , s p e c i f i c surface area and surface a c t i v i t y of s o l i d p a r t i c l e s , tk -sphere serves a s source, f i l t e r and sink of substances during amsphere-pedosphere-hydrosphere interaction. Soluble mineral and organic substances a r e realized t o percolating and b e m part of the hydrogecchemical, v e r t i c a l and l a t e r a l fluxes within and through s o i l . The pedos@ere is a l s o t h e source of s o l i d p a r t i c l e s remJved by erosion and is often t h e sink where t h e m t e r i a l s are d e ~ s i t e d .

(25)

Because of the sorption and exchange capacity of s o i l s , they f i l t e r and absorb many substances frcm the waters passing through. The hydrospheric functians of t k pdosphere a f f e c t b t h t h e l a t e r a l d i f f e r e n t i a t i o n of t h e geochemical s o l i d substances a t the earth's surface and t k chemical canpsi- tion of the hydmqhere i t s e l f .

The

f i f t h function of the pedosphere i s lithospheric. A s a naturally

£om& and s t r a t i f i e d solid-phase r m t l e , the pdosphere protects t k e a r t h ' s lithosphere £ran destructive impacts of the exogenic forces. I t buffers and regulates these destructive processes, by acting as the "dynamic"

geoderrna o r skin of the earth. The developmnt of t h e pedcsphere r e f l e c t s the mtual relations and dynamic equilibrium betw=en d i f f e r e n t forces and processes: a / t h e vertically-acting exoqenic processes /weathering and s o i l formation/, b / the laterally-acting exoqenic processes /denudation, trans- portation and deposition of the s o l i d p a r t i c l e s / , and c / t h e endogenic forces / t e c t o n i c u p l i f t and subsidence, volcanic a c t i v i t y / .

In each c l h t i c and g e m r p h i c s e t t i n g , the presence and degree of expression of many s o i l properties strongly depend u p the r e l a t i o n s of

the

i n t e n s i t i e s of these g r o u p of processes. Those mst d i f f e r e n t i a t e d and deeply weathered s o i l s , i . e . f e r r a l s o l s , usually develop when weathering and s o i l f o m t i o n processes have been active f o r a longtime. Shallow, stony and wakly-developed s o i l s occur mainly where the land surface has keen periodically rejuvenated e i t h e r by erosion o r by a c c m l a t i o n of recent sediments.

A l l these global functions of the pedosphere are realized in d i f f e r e n t q u a l i t a t i v e and quantitative terms i n d i f f e r e n t p a r t s of t h e globe, depending on the natural o r anthropgenic landscape of the area, on the natural zone. The t o t a l i t y of the mll s i t e s p e c i f i c s o i l proczsses m i n e t o form t h e p e r k 1 process of global functioning of the pedos&ere.

Spatial and tenpral limitations of tk p d o s p k r e : S o i l a s a f i n i t e and conditionally renewble natural resource

Soils represent a high capacity buffer m d i a of the biosphere, which m y buffer am3 can na3derate

-

up t o a c e r t a i n Limit

-

the various s t r e s s e s caused by:

-

e n v i m m n t a l f a c t o r s , a s climatic droughts o r t m humid m d i t i o n s , natural a i r pollution, volcanic a c t i v i t i e s , t a p z r a t u r e e n s , e t c . , and/or

-

human influences, a s intensive, fully-n-echanized and chemically con- t r o l l e d crop prcduoticn; liquid mure of large-scale a n h l husbandry farms;

wastes and waste waters originating frcm industry, transport, s o c i a l and r u r a l &:velownt, urbanization, recreation; pollution frcm~various sources, e t c .

The pedos&ere, according t o its functional and s t n ~ c t u r a l peculiari- t i e s , has its om s p e c i f i c s p a t i a l and temp3ral limitations. Thickness a n 2 area a r e its m i n s p a t i a l c h a r a c t e r i s t i c s . In canparison with the atmsphere, hydrosphere and lithosphere, t h e thickness of We pdosphere is very s h a l l a i , because the pedosphere i s mrked out from the q e ~ r a l biosphere-geosphere s y s m n o t as a sphere with

the

prevalence of me &ysical phase /gaseous, water, s o l i d phase/, but as a r e l a t i v e l y s h a l l a i sphere of atnuspheric, hydrospheric, biospheric and anthropospheric interaction w i t h i n

the

upper layers of the lithosphere.

(26)

Functionally, t h e thickness of the -dosphere equals the thickness of the upFer layer of the lithosphere involved i n such regular annual interactions. Often s o i l thickness is defined a s the thickness of the rooting z m . I t is a p r a c t i c a l l y important, but rather n a r r m , c r i t e r i m when taking i n t o consideration only the b i o p r d u c t i v e

and

biogeochemical functions of the s o i l . It is c l e a r t h a t not only b i o t i c but all of the m i n s o i l functions

/atnospheric, hydrospheric and lithospheric/ should be taken i n t o considera- t i o n when defining the functional s o i l thickness.

The f i r s t s p a t i a l pedospheric paramter i s t o t a l s o i l thickness. In s p i t e of the s h a l l w thickness the whole - d o s @ ~ r e strangly cantrols and regulates the interactions betwen all spheres, as the r e a l g e a m b r a n e or geoderrra. It should be stressed t h a t t h i s very t h i n sphere w i t h i n the whole biosphere-geosphere system is very vulnerable because it is influenced by all emir-ntal changes and can be e a s i l y deteriorated and even destroyed.

The most f e r t i l e topsoil labout 0.1-0.5 m/ l i m i t s the depth of possible a g r i c u l t u r a l a c t i v i t y and leads t o cantmination by p l l u t a n t s , d e s t r u c t i m and even ccmplete s o i l rerroval of the land surface due t o h m - i n d u c e d erosion.

The s e c d s p a t i a l pdospheric limitation is area. The t o t a l area of the pdosphere d e w c i s on the e a r t h ' s land area 1149 *]lion

&/.

But

the

real area of the W o s p h e r e is limited. t y 95 n i l l i o n km2, that is, 64% of the land area is n w covered by m r e o r l e s s hioproductive landscapes and s o i l s . Tne m d e r of the land area /36%/ is occupied by g l a c i e r s , lakes, rivers, l i f e l e s s deserts, rocks, sands, h m settlemats and constructions, h m - m d e badlands, etc. /E1OZANOVt 1977

/ .

The pedosphere has f i n i t e s p a t i a l limitations i n depth a s wll a s in area.

The t h i r d important Limitatim of the pedosphere is

the

temporal limita- t i o n of s o i l functioluring, forrratim and evolution. This problem is clasely cannected to the very s i g n i f i c a n t problems of s o i l and pdosphere renewal a f t e r natural and h m - m a d e deterioration and d e s t r u c t i m . The t.im _needed f o r the natural formatim of a m t u r e and w11-developed s o i l k d y , which has reached / q u a s i / e q u i l i b r i m with the environmnt, varies d e w d i n g on s o i l features, s o i l type, s o i l prccesses and e n v i r o m t . The whole set of r a t e s and c h a r a c t e r i s t i c times of s o i l functiming, s o i l f o m t i o n and evolu- t i o n prccesses &races nine orders : f m the f a s t e s t 110-3 years/ t o the s l m s t

/lo6

years/, as mntioned above.

The whole amplitude of soil-functioning and soil-forming process r a t e s keeps p a r t l y wi% the bioecolcgical and p a r t l y within the geological t.im scales. Only p a r t of the s o i l features can be forn-ed, changed and renewed by natural prccesses within the biota- and h m - l i f e tirre scales. I t a l s o mans t h a t s i g n i f i c a n t s o i l pro-rties /such a s organic mtter content and d i s t r i b u t i o n , texture and clay minerals d i f f e r e n t i a t i o n , total depth of the topsoil and whole s o i l p r o f i l e , and total content of clay w i l l have no chance f o r renewal by natural processes i f they becarre changed and deteriorated by h m action. In other words, s o i l f e r t i l i t y is exploited by a q r i d t u r a l h m a c t i v i t y based on s m basic s o i l properties which have

been

formed by very l m g - t e r n prmesses of weathering and s o i l f o m t i m and could not be renewed i n a h m - l i f e scope. In f a c t , in the pas.t and a t present mn exploited and e x p l o i t s the world's " s o i l treasures" accurmiLated over millennia and hundreds of thousands of years of natural s o i l forrration and evolution;

these treasures should not be exhausted.

(27)

W e now know of the many types of h m inpacts which have, p a r t i c u l a r l y over the l a s t f i f t y years, affected not only l a b i l e and dynamic s o i l pr-r- ties but a l s o the m r e stable and long-term f o m d properties. These may be very f a s t , sharp, and &p changes of the s o i l body and cover during one-two years / i r r i g a t i o n o r drainage, corbined with deep t i l l a g e and strong chemical a t t a c k / , o r very gradual, l a t e n t changes which can h r p r c e p t i b l y a c m l a t e f o r a long-tirre, and

tben

suddenly blow up a s a " s o i l degradatim

bcmb"

/ck&cal s o i l pollution, hums and s t r u c t u r e degradation, deep erosion, e t c . / . In a l l these cases, it should be stressed t h a t h m - i n d u c e d forces an s o i l s and the whole pedosphere are often accoqanied by d e t e r i o r a t i m o r even canplete l o s s of very s i q n i f i c a n t long-forrred natural s o i l properties and even s o i l bodies and s o i l patterns.

Cne can conclude t h a t the peclos@~re a s a whole, as we'll as the separahe s o i l bodies and s o i l patterns, cannot

be

considered a s a q l e t e l y renewable natural resource.

The pedosphere is f m t i o n a l l y and s t r u c t u r a l l y a very important and obfigatory subsystem within the biosphere-qeosphere system, and a t the s m tin-e, a necessary conditionally and p a r t i a l l y renewable natural resource f o r h m society. A l l i3-e usefiul properties of the pedosphere, p a r t i c u l a r l y the m e w a b l e ones, should be carefully protected and saved f o r fukure genera- tions.

(28)

(29)

Chapter Ill

SOIL COVER OF THE WORLD

H i s t o r i c a l evolution in t b ? and space

The s o i l cover is characterized by i t s composition, i . e . t h e set of s o i l s t h a t c o n s t i t u t e the cover, and by its s p a t i a l orqanization, i.e. t h e d i s t r i b u t i o n and conbination of d i f f e r e n t s o i l s in accordance with horizon- tal and v e r t i c a l hydro-geochemical i n t e r r e l a t i o n s h i p s .

The beginning of the formation of the earth's s o i l cover apparently coincides with t h e i n i t i a l phases of pedcgenesis as a global process IGERPSSIMOV and GLAZOVSKAYA, 1960; YA?XCN, 1963; TAXULIAN e t a1.

,

19861.

The i n i t i a l expansim of b i o t a from the sea t o the land a d supposedly take place a s e a r l y a s the Imer Paleozoic, lrpre than 503 mln years hefore present /SINITSIN, 19671. These b i o t a wre micro-organism, t h a t could only produce a primitive s o i l formation, s o i l - f i b s , a few mn deep. These t h i n films apparently f o m d , a s microspots over t h e a b i o t i c land surface. A r e a l s o i l cover was i n e x i s t e n t . It w a s a 'primary' phase of s o i l developrrent.

A t the end of the S i l u r i a n , about 400 mln years before p r e s e n t , b i o t a wre a c t i v e l y c o n w r i n g land, Psilophytes, 6evoid of r c o t s y s t e m and adapted to hig-h humidity of the s e a coasts. F l w i s o l s were forming, charac- t e r i z e d by surface a c c m u l a t i m of organic mtter, g l e y i f i c a t i m , and constant inflow of mineral sedimnts f r m water stream IFRIDLAD and BUYANOVSKIY, 19771. &her weakly-developed s o i l s , F&gosols and Leptosols, were f o m d t-ther with the Fluvisols. They are the earliest s o i l £ o m -

t i o n s of t h e earth. lhis phase of evolution of the s o i l

cover

can be narred 'sporadic' a s the s p o t s dnd s t r i p s of Fluvisols wre sporadically d i s t r i b - uted over the a b i o t i c o r weakly b i o t i c background.

By the end of the D e m i a n , about 350-360 mln years before present, there was a d r a s t i c change of t h e earth's veqetation: f e r n s and horsetail, KOt-possessing p l a n t s with high b i ~ l l a s s production, spread in subtropical and t r o p i c a l conditions. It is probably during the Devonian-Carhiferous t h a t s o i l s r e l a t e d t o the F e r r a l s o l s have appeared f o r the f i r s t time. The s o i l cover kcam mre complex in ccmposition, b u t s t i l l d i d not e n t i r e l y cover the land s u r f ace. This phase of evolution of t h e s o i l cover can be MnEd ' i n t e r m i t t e n t ' .

In the Permian, 285-240 mln years before present, in correspondence wlth the d i f f e r e n t i a t i o n of the earth's climates

and

landscapes, t h e s o i l cover was enriched by new s o i l groups. Concurrently, there w a s a f u r t h e r d i f f e r e n t i a t i a n of the already e x i s t i n g groups. Thus, t h e F&gosols and

Global Soil Changes (Report of an IIASA-ISSS-UNEP Task Force on the Role of Soil in Global Changes)