1. Lugo and Brown start off by suggesting that I view human beings in tropical forest ecosystems as, by definition, "destructive and wrong," and as "a nuisance." My brief from the National Academy of Sciences' Committee was to describe a situation - not to go into the whys and wherefores of the situation, or to present proposals to resolve problems. Since my survey's time-frame was critically short, and its budget unusually limited, I was required to confine my activities to documenting conversion rates of tropical moist forests, with focus on primary, i.e., undisturbed, forests. In other words, I was to concentrate on the degree to which primary forests are being converted from their "natural" form by the hand of man; and I was precluded from evaluating the repercussions of man's significant impact on forest ecosystems.
This is not to say that I do not hold pronounced opinions on man's role, both actual and potential, in tropical forests. I have set out my views on this topic in a series of papers, of which a selection is listed at the end of this text. As a summary of these views, I have stated, in an overview document that I prepared for UNEP's Meeting of Experts on Tropical Forests (to which FAO, together with Unesco, contributed) that "Tropical forests represent some of the most valuable natural resources on earth. They can supply goods and services of many kinds to human communities both in the countries of the biome and to the rest of humankind, now and forever. They can contribute not only to immediate material advancement but to long-term improvement in quality of life. Hardly any other stock of natural resources offers such a range of potential benefits to so many people. Yet tropical forests rank among the least developed of all natural resources on earth. They have not generally been subject to integrative strategies for their optimum utilization. They have not generally been managed with regard for all their diverse goods and services. They have not generally been exploited through systematic planning for sustained productivity. Thus their potential contribution to humankind's welfare has scarcely been tapped. This surely presents one of the most promising challenges for the International Development Strategy of the 1980s."
2. Lugo and Brown assert that my report overstates its capacity to resolve problems encountered by earlier surveys, and that my documentation methods are no different from earlier approaches. No earlier biome-wide survey that I am aware of, and particularly not those of Sommer (1976) and Persson (1974) referred to by Lugo and Brown (why not, in addition, Persson 1975 and 1977?), had access to remote sensing data. Appreciable sections of my report depend in part if not in whole on statistical information sup plied by satellite imagery' aerial photography, side-looking radar and other remote-sensing technologies; and I devote eight pages to a specific evaluation of remote-sensing capabilities. The proportion of the biome that 1 deal with in terms of remote-sensing findings amount to 42 percent surely a significant advance upon our state of knowledge in the mid-1970s.
3. Lugo and Brown go on to state that my work is "less quantitative and less analytical than earlier surveys." I believe that my report, with its extensive documentation of quantitative surveys, contains more quantified findings of substantive and authoritative kind than is the case with previous reports. As Sommer and Persson frequently admit, their documentation was perforce drawn from what Sommer describes as "a mass of incomplete data and a number of assumptions... yielding rather rough results and very few facts... and no clear answers." Persson comments in very similar terms. These two workers simply did not have access to comprehensive and systematic surveys of the sort made available through remote-sensing techniques. Nor could they benefit from the large number of field reports prepared by professional persons in recent years, several hundred items in all (the scale of this outburst of information is indicated by my 21 pages of references).
At the same time, I have been careful to avoid quantitative material for the sake of quantification. In many instances, I consider that a qualitative statement can be at least as sound as, and less likely to be unwittingly misleading than, a quantitative evaluation. Lugo and Brown try to remedy the supposed quantitative deficiencies of my report by assembling published data from my own and Sommer's reports (why not Persson's, whose data were far more extensive than Sommer's?) in their Table 1. But the data they use from my report vary in reliability from 90 percent confidence level for a few countries to only 60 percent or less for several countries - a differentiation that Lugo and Brown do not point out in their notes to the table, implying that the data are of consistent accuracy. Moreover, and for reasons they do not explain, Lugo and Brown do not incorporate data from all countries for which I present statistical evidence in my report; and for certain countries they imply that I had no data to offer, even though relevant sections of my report plainly specify the data in question. Why are Lugo and Brown so selective in compiling their table?
4. Lugo and Brown allege that my definition of tropical forests does not concur with certain of the Holdridge life-zone criteria, which they ostensibly prefer. I utilize a summary classification drawn from publications of Unesco, FAO and 10 other scientific authorities in this field, details of which are incorporated in my text.
"My brief... was to describe the situation - not to go into the whys and wherefores of the situation."
5. As regards my use of the term "conversion," Lugo and Brown assert that while I go to great lengths to define this term, as many other of my terms, I appear to make little use of definitions in the text. In my chapter on methods, I state that I have tried to take account of many meanings of "conversion." among other terms; and that, nonetheless, a survey that must take account of many other variables was not able to classify all changes in forest formations in accord with forest land-use patterns occurring in all countries of the biome but where possible, the scale of differentiation in question has been described in the country profiles that make up the main body of my report. In point of fact, I draw distinctions between forest types, communities, levels and consequences of human exploitation, etc., in explicit and often lengthy detail in more of the country profiles than not.
In support of their criticism, Lugo and Brown state that in my discussion of timber harvesting I do not differentiate between the many degrees of logging. In my chapter on the role of the timber trade, I point out that the number of commercial tree species in Southeast Asia is almost three times larger than in Africa; and that irreversible damage to residual trees can vary from one third to two thirds. In summary of the two pages that I devote to this topic, I state, "Clearly, logging impact varies from area to area. In some places, the consequence is only light modification of the forest, while in other places it amounts to gross degradation."
Lugo and Brown likewise charge that I do not distinguish between those forest areas where several trees are cut and those where all trees are cut. Apart from my treatment of widely divergent extraction rates for commercial logging in each of the three main regions in question, I indicate, in the chapter on the role of cattle raising, that livestock husbandry as a mode of forest-land exploitation obviously entails entire elimination of the forest in order to make way for man-established pasturelands; and that cattle raising is practiced in several sectors of Central America and Amazonia, but hardly at all in the other two main regions. I cite data and statistical indications of the amount of forest lands involved in each of the eight main cattle-raising countries of Latin America.
In similar style, I treat forest farming, viz. small-scale cultivation, as a type of forest-land exploitation that likewise entails elimination of the original forest cover. I present documentation to the effect that this type of conversion is pervasive in Southeast and southern Asia, and in West Africa, but less so, sometimes much less so, in Central Africa and in much of tropical Latin America.
In short, I present substantial amounts of documentation and analysis of the types and degrees of conversion in various sectors of the biome - by contrast with the Lugo and Brown assertion that my estimate of overall conversion is not subject to detailed appraisal in any part of the book except the single instance when I propose a figure for total conversion rare.
Moreover, on the single occasion when I propose a figure for overall conversion rate for the biome, viz. 20 million hectares per year, I propose this solely - as I point out in the text - with a view to throwing light on the possible scale of man's activities in the biome, with all that that implies for enhanced development policies and management planning for forest resources. Far from this being a "casual calculation," I emphasize, at the beginning of my report, that I do not believe it would be professionally pertinent to propound, throughout the text, some "grand figure" for forest area converted each year, on the grounds that such statistical conclusions often reflect little more than "bogus accuracy."
6. Lugo and Brown charge that "No consideration is given to the rapid regeneration of tropical forests." I state, in the second chapter, that, "After a tropical primary forest has been cleared, and the plant life left to regrow, there is a rapid accumulation of new biomass until it peaks at roughly 15 years." Further on, I state that. "A number of relevant questions arise.... for example, how much modern disruption, as compared with man's previous activities, leads to significant big-ecological impoverishment, and how fast can different sorts of forest recover from different sorts of intrusion?" I return to this topic in several of the country profiles.
7. Lugo and Brown consider that "Myers' discussion is mostly anecdotal." My survey depended on interviews with some 300 professional workers in tropical forestry, many of them with years of field experience. My survey further drew on almost 1000 pieces of correspondence with recognized authorities in tropical forestry. My report presents a reference list of over 400 items taken from the professional literature, almost all of them of post-1975 vintage and hence serving as up-to-date sources of information.
In the particular case of forest farmers, Lugo and Brown state that "Much of Myers' estimate is based solely on opinion, and thus subject to serious error." On the pages in question, I cite over 20 reports in support of my estimate - several of the items having met professional standards for FAO publications. Moreover, I recognize that some of the reports may be less than definitive, by inserting qualifications such as "According to preliminary reckonings" etc.
As concerns the general accuracy of information collated for a survey such as this, I state, right at the beginning of my report, that "Much information, while apparently plausible at face value, is quite likely to be little more than an educated estimate. Such information must be checked against its source, and preferably against other independent sources, before it can be accepted as fact. In short, any information about which one has doubts must be regarded as guilty until it can be proved innocent. Put another way, this approach means that many statistical assessments cannot be taken as precise accounts, though they may have value as indicators of the situation's general dimension." I reiterate this key constraint at frequent points throughout the text.
Lugo and Brown go on to state that "Also, for countries like Brazil, the estimate of deforestation is based on 'several officials and authorities consulted, and on unpublished agency reports.'" The officials and authorities in question included leading representatives of all the main government organizations active in Brazilian Amazonia; and persons who are generally accounted, both within Brazil and outside, to represent responsible professional opinion. The agency reports were documents published by the national bodies for development in Amazonia, for forestry development, for space research and other forestry activities. None of the 20-odd referees who scrutinized my manuscript, several of them with extensive experience in Brazilian Amazonia, questioned the reliability of these persons; nor do Lugo and Brown propose any alternative sources of information, much less do they present divergent findings for Brazil.
8. Lugo and Brown state that "One cannot be comfortable with Myers' predictions of total devastation of tropical forests in 20 years." In my chapter on methods, I state that "conversion" can include not only "fundamental transformation" but "marginal modification," and I go on to demonstrate that some changes can be of short duration, allowing the former forest to be restored within just a few years. I was careful throughout the report to avoid terms with loaded connotations such as "total devastation;" and in the summation chapter, I state, "In short, the overall outcome (of future land-use trends in tropical forests) is likely to be extremely patchy, both in terms of geographic areas and degree of conversion... In Central Africa, these could well remain large expanses of little-disturbed forest by the end of the century. Similarly, the western portion of Brazil's Amazonia could undergo only moderate change... The situation is highly differentiated, between and within the three main regions, as well as within some individual countries... It is necessary to bear in mind that exploitation patterns can change. It would be a mistake to suppose that the future will amount to a simple extrapolation of the present situation."
9. Lugo and Brown state, "In places such as Puerto Rico, in spite of the loss of 90 percent of the original forest cover, there has not been a significant loss of species." They do not indicate whether they base their assertion on comprehensive inventories of species stocks in the original forests and in today's forests. As an across-the-board reckoning, based on sample surveys, taxonomists and systematists believe that only one sixth, possibly even less, of tropical species have hitherto been identified. Lugo and Brown ponder whether 'this resiliency (in Puerto Rico) is a property of islands.' They appear unaware of the large literature on island biogeography which, drawing on experience in many parts of the world, demonstrates that when a piece of natural habitat is reduced to an island, through geophysical processes or man's activities or whatever, there is a marked fall-out of species - and the most sensitive "islands" are located in the tropical forest biome.
10. Lugo and Brown state that changes to tropical forests "do not necessarily alter carbon pools or forest areas because the forests are not being converted to bare soil but to secondary forests that grow rapidly and store significant amounts of carbon." As indicated, my report recognizes that forest re-growth can sometimes be very rapid. But in many instances, man's intrusion on tropical forests, especially in small-scale farming, can become so intensive as well as extensive that forest cover is left with all too little chance to regenerate. This accelerating trend has been widely documented at- a workshop on Tropical Forests and Carbon Dioxide, held near Boston last December - a meeting attended by both Brown and me. The deforestation pattern appears to be established, through abundant detail from case reports, for a large number of tropical-forest countries. Across large territories (e.g. between 280000 and 370000 km2 in Indonesia alone by the mid-1970s), much forest biomass has been converted into atmospheric carbon, leaving a subsequent vegetation cover that features only a fraction as much biomass and carbon content.
11. For reasons of space, I cannot present detailed responses to all the criticisms raised by Lugo and Brown. Any reader seeking further clarification is welcome to write to me at P.O. Box 48197, Nairobi. Kenya.
As a concluding comment, I find that Lugo and Brown confine virtually their entire critique to pointing out how they consider my findings are inadequate. They present next to nothing in the way of alternative findings. Indeed, in response to their question, "Are the tropical forests endangered ecosystems, or are scientists misleading the public?... To what degree can we utilize these magnificent ecosystems without harming them or ourselves?" - they concede that they have no answer to offer. In their final sentence, they express the hope that when future attempts are made to assess tropical forests, there will be "less time spent on rhetoric and more given to analysis:" could this final comment reflect as much on the writers as on their subject?
10 February 1981
DR NORMAN MYERS
Consultant in Environment and Development
P.O. Box 48197
1978a Forests for people. New Scientist, 80: 951-953.
1978b Foresters and tropical forests. Editorial in New Scientist, 30, 666, November.
1978c Whose hand on the axe? Mazingira, 6: 66-73.
1979 Tropical moist forests: we all gain or lose together. Reports (periodical publication of International Development Research Center, Ottawa), 8(3): 3-5.
1981 Development rather than depletion for tropical moist forests? (In press)
Tropical forest resources regional and world assessments
4 important reports
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