Orchid evolution and slash-and-burn in the Neotropics.-
By Alexander Hirtz
In:Â Proceedings of the Second International Orchid Conservation Congress, IOCC 2004. Marie Selby Botanical Gardens, Sarasota, Florida, USA in Selbyana 26(1,2) 2005.
At several previous orchid congresses, I have presented a novel hypothesis and supporting ideas about the relatively recent and rapid occurrence of orchid species as orthogenetic, punctuated mutations, possibly occurring in multiples of four. (Dodson & Gentry, 1987; Hirtz, 1996; Hirtz, 1999; Hirtz, 2003). This hypothesis has been formulated based on the latest information in archeology, paleontology, paleo-botany, anthropology, genetics, and other pertinent sciences. In this paper, I propose that the ancestral agricultural technique of slash-and-burn, which kept the potential primary forests from developing in the Holocene period, has been a major contributor to this course of orchid species evolution. Following the Spanish conquest, during which illnesses introduced from Europe drastically diminished the native American population, human demands on the natural resources significantly reduced pressures on the naturally exuberant vegetation; only then were the primary forests â€œpermittedâ€ to cover extensive territories. This phenomenon has had a major impact in the recent explosion in evolution in orchids, as well as in the species of other plant and animal families.
Most theories on evolution are based on Darwinâ€™s work: the lifespan of a single species is assumed to last about two million years, gradually mutating thereafter into a new one. Most still believe that the current biodiversity of the Amazon Basin has survived unchanged for millions of years. Others have explained the changes of the last 20,000 years as being the result of Â dramatic climate changes and suggest that current animal and plant species have been survivors during the Ice Age, existing in small refuges that expanded again geographically in the Holocene. In previous papers, I have presented several arguments against the refuge theory, along with many ideas why the extreme rich and endemic biodiversity might have evolved in the Holocene. Human presence during the dramatic transition between the Pleistocene and Holocene in the Neotropics is the key factor to support my present idea related to slash-and-burn, so I will start this proposal with an account of the early migrations of Indian tribes in America.
Between 17,000 BP (BP = Before Present) and 14,000 BP, near the end of the last glaciating in the Pleistocene, one or more migrations of tribes originating probably from west Siberia or even as far as from “Old Europe”, occurred across the Bering Straits.Â Descendants of the migration populated America in very short time, a continent that was geographically quite different then from that of the present day. Water levels of oceans were about 120 to 150 meters lower than today (Fiedel, 1987), and a great portion of the continental platform, now under water, was above sea level. The shorelines were sometimes several miles away from the present ones; hence the worldwide continental surface was several million square kilometers larger.
At the equator, the average temperature was about 5Âº to 8Âº Celsius cooler, and the permafrost line was about 1,000 meters lower, at about 3,600 meters above sea level. Rainfall in the tropical belt was at least 50% less than in present times, and the Amazon Basin and other current rainforests were mainly deciduous forests, savannas and desert. Several dozen species of large mammals inhabited those ecosystems including species related to the mastodon (Cuvieronius & Haplomastodon), the megadont & giant sloth (Eremotherium, Megatherium & Mylodontidae) and the paleo-llama and Andean horses (Colinvaux, P:A: 1985, 1987; Piperno, R.P. & Pearsall,D.M., 1998).
These immigrants to the American continent encountered a most favorable environment in which to settle and multiply. Hunters found meat in great abundance, e.g. buffalo, deer, horses and llamas, along with an incredible supply of large birds, e.g. turkeys, ducks and geese. Comparing those early societies with our present one that is afraid to try any new form of food, gatherers of the Pleistocene had a complete different attitude towards their surrounding environment and continuously ingested every part of every plant to discover its potential value as a food, medicine or hallucinogenic drug. Very early on, they discovered a large number of medicinal herbs, hallucinogenic drugs, nutritious tubers, beans and fruit.
The settlers, who found abundant food and encountered almost no diseases, increased dramatically the number of their people in few generations and soon settled all of the Americas from Alaska down to Tierra del Fuego.
Suddenly, around 10,500 BP, the current and ongoing ice age, which started 2.6 million years ago, is facing another inter-glacial cycle. In less than 100 years, the average temperature on planet Earth increased by 8Âº Celsius. This dramatic change in climate was probably related to a natural greenhouse effect apparently caused by upwelling ocean currents (North Atlantic Conveyor Belt) releasing impressive amounts of CO2 from decaying organisms which had accumulated over the millennia at the ocean floor (Broecker and Denton, 1990). Another maybe related theory is the so-called â€œMilankovitch cycleâ€, which refers to the variations in the earthâ€™s orbital geometry (Imbrie and Imbrie, 1979). The ice started to melt and the level of oceans started to rise at an incredible rate. The sea-level must have risen during certain periods by several meters in few decades, forcing the settlers along the coast to frequently move to higher ground, year after year, generation after generation. This ice melting must have come in cyclical sweeps, where some floods were very dramatic; in fact, such accounts of a â€œUniversal Floodâ€ are found in chronicles from cultures throughout the world, describing what happened in just a few weeks. The earliest account of a concerned conservationist in human history is recorded in the Bible, relating the story about Noah who built an arc to save a pair of every species of animal from impending doom.
Sea level did not stabilize, allowing the formation of the present tidal and estuarine ecosystems, until about 7,000 BP. The human settlements along the Paleolithic coastline are now under sandbars and coral reefs. At some places the uplift of the continental shelf was faster than the rising see-levels, allowing fisherman to remain at the same place over several millennia, as fortuitously happened with a local geologic anomaly at the Peninsula of Santa Elena in Ecuador, where the Las Vegas Phase had their settlements undisturbed from 10,800 BP to 6,600 BP (Stothert, K., 1988).
During the post-glacial period, as noted in tropical paleo-ecological records, temperatures increased by several degrees and rain became much more abundant. Not only did the Andean foothills turn into impenetrable rain-and-cloud forests, but so also did the vegetation in the hot and humid lowlands, particularly in the Amazon Basin, the ChocÃ³ in Colombia and the DariÃ©n in Panama evolve into dense tropical forests. The new ecosystems could not be accommodated by the mega-fauna, resulting in the extinction of such species as the mastodon, the Andean horse, and at least another 160 identified mammals. With the disruption of the Pleistocene ecosystems, not only did the mega-fauna become extinct, but so did innumerable plant and insect species as well. It follows, that many orchid species must have gone extinct then as well.
On the other hand, with the increase in temperature and rainfall, totally new habitats formed, some of which could not have existed at all during the Pleistocene. For example, the Darien and the Choco are currently the wettest regions in the world with rainfall up to 10,000 millimeters per year and temperatures 8Âº warmer than anyplace possible in the tropical belt during the Pleistocene. Hence, most of the flora and fauna endemic to this wet tropical belt from Costa Rica down to Ecuador must be new in evolution, because there were no equivalent refuges during the Ice Age. One can envision a similar panorama for the lower Amazonian Basin. The permafrost boundary at the Andean volcanoes during the Pleistocene started at about 3,500 masl (meters above see level). Currently, the upper end of the cloud forests containing epiphytes may grow as high as 4,200 masl and the tundra vegetation is found up to 5,000 masl where a large percentage of the flora is endemic to each volcano. If many of the orchids and other plants are isolated and endemic to each volcano, and this surface is only become habitable in relatively recent times, one should come to the conclusion that these endemics are new in evolution. This is particularly conclusion is even more compelling if one takes into account the fact that the volcanoes are only a few thousand years of age or had recent and dramatic eruptive events, as in Ecuador, for example, the volcanoes El Soche, Mojanda, Atacaso, Pichincha, Ninahuilca, Antisana, Tungurahua, Altar, Pululahua, or Quilotoa. These eruptions were not comparable to the small ones observed in recent decades, but rather were enormously powerful completely devastating thousands of square kilometers around the sites.
It is also important to point out that during the last ten thousand years, the newly formed ecosystems were exposed continuously to various climate cycles, each relatively nominal in comparison to the dramatic climate change 10,500 years ago; regardless, these must have had substantial impacts to the flora and fauna. For instance, prolonged periods of rain or drought caused by the El NiÃ±o phenomena do impact populations of delicate endemic species, e.g., species in the Pleurothallidinae. The cycle of the El NiÃ±o phenomena seems to have started only 5,000 years ago, based on geo-archeological data (Rollins et. al, 1986 and Sandweiss et.al, 1996). At this time severe draughts affected the Amazon Basin. It has been suggested that around the 8th to 11th century, rainfall in the Amazon Basin was several times greater than in present times, to the point that the Amazon River could not drain the water fast enough and that the whole basin became a big lake (Coulinvaux, 1987). During this time, global warming allowed temperate crops to be grown by the Vikings in Greenland, but these settlements eventually died out, due to another climate change to a mini-glaciation. This Â¨mini ice-ageÂ¨ incremented glaciers world wide, particularly in the Andes until the mid fourteen century, when once again global warming started melting these glaciers to our present time.
I think it is quite obvious that following the massive extinction of animals and plants, which started 10,500 years ago, a subsequent explosion in evolution must have occurred as well. In fact, a large number of the current mammalian species have not been found in the fossil record of the Pleistocene. Are these mammal new species in evolution? As long as there is no evidence as fossils in the Pleistocene of the current animal species, I have to assume that these are of very recent evolution. It has been established by Peruvian archeologists, that the American camel, the paleo-llama, became extinct, but that four new species actually mutated from this one mother species: the guanaco, the vicuÃ±a and the domesticated alpaca and llama. It would appear that the transition was not a gradual one, but rather a case of an orthogenetic punctuated mutation, occurring in a set of four.
Letâ€™s go back to the story related to the hunter-gatherers in the Neotropics, ten thousand years ago. With the extinction of the mega-fauna, the hunters had to look for smaller game, which also were many fewer and more difficult to locate in the newly grown, dense, tropical forests. But in an even more dramatic change, many of the plants known to the gatherers were also going extinct. The gatherers, mostly women under the guidance of female shamans, had to learn to grow these plants in their backyard. First, they saved the more important medicinal and hallucinogenic plants. Later, with the help of the male counterpart, most of who had stop being hunters and became farmers, the gatherers began to domesticate plants which were important food-crops, like edible tubers, beans and fruit.Â This all must have happened worldwide right after the dramatic climate change 10,000 years ago. From DNA studies made in the probable centers of dispersion for semi-domesticated plant species, it has been suggested that the dawn of agriculture must have occurred right at the beginning of the Holocene. Direct and indirect trade throughout South America soon spread many plants, which had to be at least semi-domesticated, as early as 8,000 BP, plants which eventually reached Meso-America at least 4,000 years ago by trade with the Valdivia culture of Ecuador. Due to the continuous dramatic climate changes, the rising sea levels and frequent volcanic eruptions, its most natural to assume that migrations were very common, where the horticulturists took the domesticated plants along with them.
There a very few archeological discoveries of settlements related to the tribes of the early Holocene, even less so, their possible trade routes. As already pointed out, all those tribes that were living at or near the coast, were in most cases inundated by the ocean; evidence of their civilizations is now tens of meters below sea level, buried under coral reefs. Direct evidence of inland trade is just as difficult to trace, because the main routes and settlements in the valleys to the Andean Cordillera have been covered several times in the last millennia by pyroclastic flows, volcanic ash and mud flows related to the seismic and volcanic activity of more than 80 active volcanoes in northern Ecuador and southern Colombia. For example, the Machalilla related ‘Cotocallao’ village in the highlands north of Quito was twice covered by a one-meter thick pyroclastic ash flow from the nearby Pululahua volcano around 1,600 BC and again in 355 BC (Isaacson, J. 1994).
Lacustrine deposits caused by rapid erosion due to the dramatic climate change and rainfall in the Andean mountains, over several thousand seasons, now cover most of the early Amazon settlements. The present clay cover over ancient settlements makes discovery by archeologists a difficult task. Perforations in the Amazon basin show an eroded surface beyond the 10,000 BP benchmark. Dr. Colinvaux discovered pollen of Zea mays in mud-core samples from lacustrine sediments in the Upper Amazon, which date back to 6,000 BP (Colinvaux).
Some examples of domesticated plants, which are not found anymore in the wild and probably became extinct at the end of the Paleocene, are the brugmansias, plants which were cultivated for their strong hallucinogenic properties; various species of cannas, cultivated for the starch in their tubers or the sweet potato Ipomoea Batatas or various species of caricas (papayas) or chili-peppers cultivated for their fruits. An example of early trade is for instance the bottle gourd (Lagenaria siceraria), a plant that definitely had its origins in Africa and arrived in the New World by ocean currents or brought over by African tribesmen via the Amazon Basin; there is adequate evidence that this species was already cultivated by the Las Vegas culture of the equatorial Pacific at about 8,000 BP, one of the earliest settlements where horticulture/agriculture began in America. These pre-Valdivias also cultivated a tuber related to the arrowroot (Calathea alloui) and maize (Zea mays), a plant which is of complex origin, the parental stock being either extinct or derived from mutations of Teosinte sp. introduced from Meso-America (Piperno, R.P. & Pearsall, D.M., 1998).
During the early Holocene, a dramatic decline in foraging return rates from the demise of the glacial-period resources took place in the new tropical forest ecosystem. One of its new hallmarks was the relative paucity of starch-rich foods as well as the high costs associated with collecting and extracting starches from wild plants. This phenomenon led to the early development of agricultural practices in the lowland Neoptropics, for as has been demonstrated over time, planned food crop cultivation is less labor intensive than collecting edibles in a tropical forest region.Â Natives were accustomed to deciduous forests and longed for a more arid climate. Slash-and-burn was favored to achieve this panorama as a primary subsistence mode, but it turned out that swidden cultivation was, and still is, an enormously successful adaptation to the rigors and constraints of the tropical forest; application of the technique soon led to a very high population density in the areas where it was practiced (Piperno & Persall, 1998).
During my expeditions into the tropics of Ecuador, on top of nearly every hill, big or small, either near or remote from current inhabited sites, I encountered ceramic potshards and waste dumps, evidence that someone had lived there in the past. Some archeologists estimate the population for coastal Ecuador at the time of the Spanish conquest to have been ten million people, twice the number of today (Norton,P.,1992) Other archeological studies infer for pre-colonial times that high population densities existed in coastal Peru, the Darien in Panama, the Magdalena, Orinoco and Amazon Basins, as well as in the Classic Maya heartland of northern Guatemala and Belize. For their subsistence, extensive and intensive agriculture was required.Â In many sites of the areas mentioned, most having returned to their current condition as pristine primary forests, drill-holes have been made down to bedrock for core that demonstrate within the clay layers, evidence of former human civilization in those locations. Most of this has been evidenced by ash and charcoal layers produced by slash-and-burn overlain by phytoliths of domesticated plants (picture #1).
Satellite imagery taken over the Darien, the Magdalena River or the GuaranÃ Forests in Paraguay, show extensive water-channel systems of irrigation installed for use over country-size districts which are now masked by primary tropical forests. I have concluded that there was much less primary forest in pre-colonial times than even today. What happened that resulted in these agricultural territories being abandoned and then invaded and overgrown by tropical vegetation?
Tribal inhabitants in the pre-colonial times experienced almost no diseases, with the consequence that their immune systems was not prepared for the devastating calamities introduced from Europe. Indians even died easily from common flu. But, of course, small pox, polio, malaria, typhoid, bubonic plague, and many other mortal diseases were brought to America; the native population was ultimately reduced to a relative â€œhandfulâ€ of people. Coastal cities like Manta in Ecuador, which had an initial population of 40,000 when the Spanish arrived, numbered its population at only 400, just ten years later (Cieza de Leon, 1553). The Spanish also eliminated the Indian leaders, priests, astronomers and shamans, and they took away their cosmology, religion, and in most Indian cultures, even their native languages; Quechua, the only other official language besides Spanish, replaced those native languages. Quechua was forced on the Andean Indian tribes, because that was the only language translation available for the Bible.
Today, new population estimates for Amazonian pre-colonial cities suggest that some of these may have harbored over one-half million inhabitants each. Nowadays, small tribes, consisting of primitive hunter-gatherers, inhabit these same areas. All of these tribes, after losing their leaders and their agricultural heritage, had to re-discover survival methods and ways of coping with the invading tropical forest, but probably are still much more primitive in their ways than thousands of years ago. It is only in these last 500 years that the Neotropics from Mexico down to Paraguay are almost devoid of the pre-colonial overpopulation of humans that had prevented the forests to develop. Only in these few centuries the primary ecosystems flourished allowing for an explosion in evolution.
In previous papers, I expanded on my original proposition that evolution among certain orchid genera has occurred very recently, based on the dramatic climate changes 10,000 years ago. There is evidence that the refuge theory did not explain the presence of many plants found today (Colinvaux et al, 1966a,b).Â Today, many endemic orchid species are found only on extensive volcanic surfaces that are only a few hundred or thousand years old. And science tells us that the Amazonian tropical forests are only one hundred tree generations old (Colinvaux, 1985). Plus, on a very practical empirical basis, it is undisputed that new orchid species have been found in the last few years in areas, thoroughly botanized in the relative recent past by the same botanists (Dodson & Gentry, 1987). Thus, using these criteria plus my own field observations, I propose that many orchid species must be very recent additions in evolution, some appearing only within the last few decades.Â In this paper, I am adding an additional factor to those previously proposed in my theories about reasons for the recent appearance of new orchid species the following: the primary habitats which allow for new orchid species to form are in many cases only 500 years old, because prior to that time, these areas were consistently slash-and-burned to optimize swidden agriculture; during the last 500 years, these formerly devastated ecosystems became pristine. And within these relatively new, extensive primary ecosystems in the ChocÃ³, Amazon Basin, Darien or Magdalena Basin, an explosion in the evolution of orchids has occurred, one that continues today.
In the past two and a half centuries, well-financed, large botanic and commercial orchid expeditions were undertaken, particularly in the areas listed above. From accounts of those expeditions and the detailed descriptions of their discoveries, including herbarium sheets and the drawings and discussions published in innumerable books and magazines, one can appreciate how professionally and meticulously their collecting efforts were in those early times. Even so, about 2,200 orchid species, new to botanical science, have been discovered in Ecuador in the past few decades; current, the record includes 4200 orchid species for Ecuador alone.Â I propose that many of these species were not discovered in the 18th and 19th century because these have only evolved in the last few decades. Many argue that these â€œnewâ€ orchids were not found previously because the collectors and botanists of those times did not have road access, the facilities or even the time to discover them. Yet, the newly discovered Ecuadorian orchids represent 60% of the total described orchids for entire country. If we accept the reasonable argument, that the newly discovered orchids were just â€œmissedâ€ in the past, then one should also expect that these new species would be distributed proportionately in every genus, implying that each orchid genus known in Ecuador would now include nearly 60% more species as a result of someone having recently found the previously â€œoverlookedâ€ species.
Presently, there are about 220 orchid genera listed for Ecuador. Interestingly, 90% of the new discoveries occur only within 12% of the genera, while fewer than 20% of new species occur acrossÂ 40% of the genera. Some might say that these new species were not found because they are rare or were of no commercial interest.
But these is not so. Collectors and botanist in the 18th and 19th century made herbariums of everything they came across. Often it is very surprising what orchids were found first and chosen as the type of the genus, sometimes â€œuglyâ€ species compared to their relatives. It is also argumented that the new discoveries were in fact already collected, pressed and often made drawings of, but were never described. An example is Dracula vampira collected by Consul Lehmann, a plant which was not described at his time.
Letâ€™s compare what orchids have been collected in the 18th and 19th century and what has been discovered in the last decades. For example, letâ€™s take a look at the terrestrial orchids. These have been in most cases of little commercial value and most species are rarely seen in flower. As a fact, a large number of the herbarium specimens collected in the last 40 years related to these Ecuadorian orchids carry my collecting numbers. Of the 433 classified species, only 129 species were new and about half were described by Leslie Garay from old herbarium sheets of terrestrials not described in the previous centuries (Garay, 1978). Summarizing, for the terrestrials in the subfamily Cypripediodeae, of the 14 species known, 5 are new; for the Spiranthoideae, of the 202 known, only 60 are new; for the Orchiddoideae, the comparable numbers are 27 and 3; for the Epidendroideae, 170and 59; for the Vandoideae, 20 and 2. One would expect that during the Ice Age, the terrestrials had the opportunity to populate larger geographic areas and that they flourished in the Pleistocene. This theory can be supported by the evidence showing that most terrestrials growing in the Andean paramo, or tundra, have wide geographic distribution, very often found from Colombia down to Bolivia. In these genera, almost no new species have been added in recent times, like the Aa, Altensteinia, Gomphichis, Myrosmodes, Prescotia, Pterichis, Habenaria and Malaxis, which together include 88 species in Ecuador where only 11 are new. Most of the new terrestrial species have been found in very humid environments growing in forest litter or certain species that have adapted to the Neotropic ecosystems have been found growing on trees. This can be particularly noted with the genus Erythrodes, Baskervillia, Ponthieva, Elleanthus, Liparis and Crossoglossa, and I propose that these newly found species are actually new in evolution.
Another group of orchids with few surprises include the genera that would appear to have favored the Pleistocene environment, as were the deciduous forests. Probably the genus Cattleya, Encyclia, Schomburgkia, Prostechea, Leochilus, Aspasia, Bifrenaria, Brassavola, Bulbophyllum, Campylocentrum, Catasetum, Caularthron, Dimerandra, Eriopsis, Galeandra, Lockhartia, Notylia, Octomeria, Oncidium, Pachyphyllum, Polystachia, Psygmorchis, Rodriguezia, Rudolfiella, Scaphyglottis, Trichocentrum, Trichopilia, Trigonidium and Xylobium did better during the Ice Age and are dormant in evolution in present times. Of these 29 genera with a total of 404 species in Ecuador, only 13% are new.
On the other hand, the explosion in evolution is most evident with the genera of orchids that favor very humid environments, habitats almost absent in the Pleistocene and which have reached their prime only in the last 500 years. In these genera, which account for over 90% of the new species discovered in recent times, particularly in the genera Epidendrum, Maxillaria, Telipogon and most of the Stanhopeinae, Zygopetalinae and Pleurothalidinae, the species evolution seems to have in many cases occurred within only in the last few decades. This assumption is based on the fact that commercially attractive floral qualities were earnestly sought after by the collectors in previous centuries and were missed in their expeditions (by some theorists); also, as noted by Dr. Dodson and Dr. Gentry (Dodson & Gentry, 1987) and myself (Hirtz, 1996, 1999, 2003), many new species have been discovered recently in areas which have been combed many times over for the last two hundred years by knowledgeable orchidists, including ourselves. To highlight some examples, we found 92% of the new species in 11 genera of the Pleurothalidinae, representing 1,377 new species of the 1,744 currently known: 31 new Brachionidium of 35, 48 Dracula of the 56 known, 320 of the 348 Lepanthes, 155 of the 213 Masdevallia, 51 of the 57 Platystele, 324 of the 468 Pleurothallis, 25 of the 32 Scaphosepalum, over 350 of the 450 Stelis (including unpublished species), 35 of the 47 Trichosalpinx and the spectacular examples of what are likely two new genera with 3 species in Epibatis, and over 35 species in Teaguea. InÂ Epidendrum, the largest orchid genus in Ecuador with over 250 new species of the 470 known, 26 of the 50 Telipogon, all three in the new genus Ackermania, the two species in a new genus Benzinguia, the two species in Bollea, the one species in the new genus Caluera, 4 of the 5 species in Chaubardiella, 12 of the 14 species in Chondrorhyncha, 4 of the 6 Cischweinfia, both species in the new genus Dodsonia, all three in the genus Eloyella, 10 of the 16 Gongora, the apparent two species of the new genus Hirtzia, 2 of the three Lycomormium, 6 of the 7 Macroclynium, 3 of the 4 Mesospenidium, the 2 in Oerstedella, all 6 in Paphinia, 2 of the 3 Plectrophora, 4 of the 6 Polycugnis, the one species in the new genus Raycadenco, 14 of the 19 Scelochilus, 3 of the 4 Schlimia, 4 of the 6 Sievekingia, 11 of the 18 Sygmatostalyx, the 2 in Sphyrastylis, 2 of the 3 Stenia, the one species in the new genus Suarezia, 4 of the 6 Teuscheria and the one new Warminguia for Ecuador.
The most spectacular horticultural discovery is found with the red Phragmipediums, orchids of such beauty that they could hardly have been overlooked in the past: P. besseae, dalessandroi and kovachii. Phragmipedium besseae, only discovered and described by Dr. Dodson in 1988, is now a relative common orchid found in all of southeast Ecuador and northeast Peru. This orchid, like its relatives of the Cypripediodeae in Ecuador, is a colonizer that invades the wet, rocky cliffs. Likewise, I predict that the newest slipper orchid in evolution, P.kovachii, will also soon be recognized as a colonizer in southern Ecuador.
There is a new explosion in Ecuadorâ€™s human population, which is taking us back to the desperate needs for new agricultural grounds. Ecuador is among the smallest countries in South America, along with the Guianas and Uruguay, but is at least twice as densely populated as the other countries in this continent. Every year 300,000 youngsters become adults who need a job want to raise their own family and maybe even have their own property. There is a current world recession, and certainly the countryâ€™s economy cannot provide this amount of new jobs, particularly not in the cities. To feed themselves and find a home for their new families, people either try to emigrate or they have to turn to the rural areas looking for cheap new ground. Of course, this would be the uncultivated areas in the tropical, rain or cloud forests which have been undisturbed for the past 500 years. After getting a fast income by selectively logging the best trees, they proceed with the ancestral agricultural technique of slash-and-burn. Piperno and Persall point out the reality in their book The Origins of Agriculture in the Lowland Neotropics:
â€œAlso part of the problem is that slash-and-burn cultivation is seen as a primary cause of the disappearance of the remaining forests by the well-intentioned conservationists and is viewed as a â€œwastefulâ€ and â€œdestructiveâ€ technique. We need to be reminded from time to time that swidden cultivation was, and still is, an enormously successful adaptation to the rigors and constraints of the tropical forest. It allowed effective food production to be practiced in highly diverse, and sometimes exceptionally poor, environments. It could be adjusted as needed to varying conditions of climate. In areas where dry seasons were long and marked, it could be practiced without the need for sophisticated and labor-intensive tool technologies. If practiced on fertile soils at high levels of intensity (with short fallow periods), it could, for a time, support high levels of population, and it did just that in at least two regions we know about â€“ central Pacific Panama and the Maya heartland and peripheryâ€ (Piperno & Pershall, 1998).
Regardless of the efforts of a handful of concerned conservationists and a few botanists to stop the ancestral practice of slash-and-burn, the overpopulation in Ecuador is a fact that will not change in the foreseeable future and soon the Neotropics of America will again be extensive areas of agriculture with little or no pristine forests. In lowlands of western Ecuador only a few percent of fragmented wet and dry forests remain. As a fact, these isolated areas are so small, that the extended droughts in the last three years have probably already caused major extinctions in epiphytes. Small primary forests that do not have surrounding buffer zones of secondary forests cannot harbor the original wealth of epiphytes. It is unthinkable that soft leaved orchids without succulent reservoirs in the stems like in the Pleurothalidinae or the Zygopetalinidae could survive for several months without any rain or evening moisture. I have personally visited many isolated forests in central west Ecuador where I found almost no orchids, areas of forests, formerly rich in epiphytes where I had found hundreds of orchid species only 20 years ago.
It is generally accepted that about 200,000 to 300,000 hectares of primary and secondary forests are destroyed yearly by slash-and-burn in Ecuador. If we use the conservative number of 100 plants per square meter, where often trees might harbor tens of thousands of plants on a small horizontal area (Hirtz, 1993), one arrives at the shocking number of 20 to 30 million plants burned every hour during the whole year. This implies that tens of millions of orchids are burned every day in Ecuador alone, certainly more plants destroyed in such a short time than were ever collected by orchid hunters worldwide in the past 200 years.
Ecuador has the highest biodiversity in the world in relation to its geographic surface. Ecuador is also among the most peaceful countries in the equatorial belt, and it is therefore favored by conservationists and scientists. At least a thousand non-government organizations are helping the country to preserve the natural habitats, in particular the areas considered as â€œhot spotsâ€ in biodiversity. The government has declared about 22% of the countryâ€™s land as untouchable areas, world patrimony, national parks and forest reserves. But there are also hundreds of smaller forests purchased by non-government organizations and private individuals, where many of these areas are not accounted for in the total preserved area of Ecuador, increasing the total closer to 30%.
With this conservation program, most of these forests will remain pristine for the future generations, particularly because most of the selected areas are presently inaccessible.
Unfortunately slash-and-burn and extensive agriculture is not the only threat to the pristine ecosystems. I have been in the past 15 years in several forests that probably have never been visited before by a botanist. To my great surprise and disappointment, these forests were almost barren of endemic orchids. I also re-visited other pristine forests where I collected many endemic orchids 20 or 30 years ago, and again, to my disappointment, many of these forests are now â€œemptyâ€ of the delicate orchid species like the Pleurothalidinae or the Zygopetalinidae. Offhand, this void in orchids will be blamed to over-collecting. Personally I do not believe that the Pleurothalidinae can be ever over-collected, because these species in the right environment are found in innumerable quantities and year after year the seedlings will replace the adult plants. Also, the areas where these plants grow are in most cases only accessible to very limited distances from the road. A most convincing argument that the delicate orchids have disappeared for reasons other than over-collection can be made since the non-commercial abundant orchids have disappeared as well, like common Stelis and certain Lepanthes, like L.mucronata. On the other hand, in these same forests one can still find the hardy species, but of great commercial value, like the showy Cyrtochilum.Â I also have noted that countrywide, pretty much all species of insects have diminished in the number of their population,Â down to a few percent compared to what I have encountered 20 or 30 years ago. If we use the â€œRed Listâ€ criteria, I would have to include all the insects in the category of endangered, including the common ones like the leave-cutter ants, wasps, house flies and even the common roaches. I have presented this potential path to â€œextinctionâ€ of insects under the heading â€œPortraits of the Last Insectsâ€ in the Pavilion of Nature at the World Fair Seville 1992 by invitation of the ICONA, the Institute of Conservation of Spain (Hirtz, 1992). Also, it has been recorded that in Ecuador, most of the species of frogs that occurred over 1,500 meters of elevation have gone completely extinct by 1987. For example, 22 species of the genus Atelopus, which had populations living in the Andean tundra by the tens of millions, are gone forever. Unfortunately not a single living Atelopus from these altitudes remains in captivity and can never be bred for re-introduction. All animals that feed on insects are also greatly reduced in the number of their population, like insect-feeding birds or bats. The chain reflects on other species too, where snakes are now scarce or orchids are rarely found with seedpods. What possibly could be the cause for this new threat for a massive extinction of species? A very probable cause could be acid rain. Studies undertaken worldwide and in southern Ecuador by the University of California (San Diego) suggest that certain nitrates, byproduct of the mega forest fires in Brazil and India, are dispersed over long distances by rain and might be the cause for â€œdead forestsâ€ in the Andean foothills (personal communication).
Â In Ecuador, the current count of the classified vascular plants borders 17,000 species (Jorgensen & LeÃ³n-Yepez, 1999). Of these, over 4,200 species are orchids, representing nearly one fourth of the total number of vascular plants. This large proportion of orchids to other plants can be justified as most work has been concentrated on orchids and many fewer botanists had the opportunity to collect and classify the other plant families. Worldwide the general proportion of orchids to other vascular plants is approximately one to ten. If we assume that there are at least 5,000 orchids to be found in Ecuador, one could expect a total of 50,000 vascular plants too. This implies that over 60% of the native flora of Ecuador has yet to be discovered. An example can be noted with the Araceae where 404 were described by 1999. But with the efforts of a handful of botanists, over 1,000 undescribed species have been recently collected and are currently awaiting publication by scientists at Missouri Botanical Gardens (personal communication). If we do not collect and describe these undiscovered species as soon as possible, a large percentage of the endemic species will be lost in the near future. Many species have a geographic distribution of only a few square kilometers. Even if they are currently still to be found in fragmented forests, these particular species should be considered as â€œliving fossilsâ€ (Leakey, 1995), because many of the large number of variables that sustain a plant population have already been broken. As mentioned, almost 30% of the Ecuadorian forests are now protected, but in most of those areas, accessibility to study plants there is literally impossible, either because the areas are impenetrable or because it is almost impossible to obtain a permit to collect plants in national parksâ€¦ even for scientific purposes. But of much greater concern is to study and rescue for ex-situ conservation, the endemic orchid and other plant species in the remaining 70% of Ecuador, of which about 55% is already completely destroyed. Botanic studies have been neglected in Ecuador since the 70â€™s, like in most other countries of the southern hemisphere, mostly because of prohibitive sovereign laws and foreign treaties like CITES. Rather then constituting instruments of obstruction, International Treaties should take into consideration the countries where the native habitats are critically endangered and should impose regulations upon those countries to allow the international scientific community to study and rescue the endangered endemic species for national and international ex-situ conservation. Wildlife should be considered world heritage and should not be subject to temporary local sovereign political rules and regulations. In any case, local and international legislations should be based on mutual collaboration built on common sense.
NOTE:Â A recent documentary by the BBC now confirms my proposal I have presented for the first time at Speakers Day in San Francisco in 1988. This documentary states that the forests in the Amazon Basin were never primary forests, but anthropogenic forests managed by a population which reached at least 6 million inhabitants in the early 16th century. The link for this documentary is HYPERLINK “http://www.youtube.com/watch?v=HUXLim2HIvU” \t “_blank” http://www.youtube.com/watch?v=HUXLim2HIvU
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