This article is a summation for teachers interested in the subject

Bio-diversity in Boreal Newfoundland-Labrador, Temperate Canada & Tropical Forests.
(published in The Osprey Magazine Oct. 2009)

Robin Tim Day cowboy4444@hotmail.com Little Eden Nature Reserve, Hostel & Organic Farm, 605 Gardiner Rd., RR3 North Augusta, Ontario, Canada, K0G 1R0

Intro
Big fleas have little fleas upon their backs to bite them, and little fleas have lesser fleas, and so ad infinitum (Jonathan Swift etc. 1733)

By doing without autos, running water and electricity I was able to retire from a string of international teaching contracts at age 50 and conserve 58 acres of Ontario forest & wetland. I´ve also visited a few more tropical and subtropical forests for comparison, my life data, in Trinidad-Tobago, Cuba, Cayman Islands, Yucatan Mexico, Ecuador, Peru, Brazil, Philippines, Cheju Island South Korea, Bali Indonesia and Thailand. Am struck that tropical forests are structurally very similar to Canada´s Boreal and Temperate forests. Trees do the same basic things everywhere. The differences in these forests are in the details, the big plant groups, families and genera and the size and elaboration of individual specimens. A humid day in Canada´s temperate forest is very similar to a humid day in the tropics surrounded by the unfolding greenery and the sounds of frogs, insects and birds, remembering that many of these birds in temperate forests are short term tropical visitors 1a.

There is no single explanation to high species diversity, or species richness, in tropical ecosystems, no Holy Grail. We know the influences are additive and interactive. Many explanations have been put forward and many of the influences on diversity I am going to describe could or should have been tested long ago in experimental microbial cultures, microbial ecological experiments with algae or bacteria to start with. Perhaps these microbial ecological experiments have been performed already but I am not aware of them (yet). We all have more reading to do. The classic population studies of G.R. Gausse, Russian ecologist, used Paramecium and Euglena to study population dynamics. I suggested using algae on petri dishes to Dr. Paul Keddy back in the early 1980s while doing graduate work at the U. of Ottawa but the idea was brushed off. He dumped his responsibilities and left the country. That ended my PhD studies. Universities in Canada allow this kind of behaviour and potential grad students need to hear how common this is.

In the following sections you will see that some controls of diversity are large scale and geographical as when two continents drift and join and others are small scale and very local like the competition of several plants growing in the same meadow. Keep this in mind.

Species on Gradients & Niche Partitioning & Total Radient Energy
Trees worldwide are usually responding to the same needed but dispersed resources above and below ground and so they branch like animal lung and vascular tissue above and below ground to increase surface area and absorb in fierce and deadly competition the limiting resources found there, scarce minerals, chiefly nitrogen below, and light above. Even the tall coastal mangrove forests of Ecuador are much like the Silver Maple freshwater swamps around Ottawa. Both have low oxygen soils but the mangroves have to deal with salt and tides as well. Tillman (1988) examines forest development in detail 1b. We all know that seedlings die annually in huge numbers in failed competition and in our maturing Boreal forests we see spindly dead and leaning and fallen trees that have been crowded (killed) by their neighbors. This struggle kills many seedling and young trees but also separates those that survive along gradients in the forest and this influences the diversity or species richness we observe and measure. Tree seedlings that survive are often spread, or partitioned across a soil nutrient or moisture gradient, a disturbance by grazers gradient or a light gradient across the landscape. Can, or should, this partitioning be considered cooperation? Probably not.

There is a great deal of work written about niche partitioning 2 especially by animal ecologists. The basic idea is that species have evolved slightly different specializations and thus compete best within these narrow limits of niche space 3. Animals ecologists studying niche partitioning are working with consumers not producers and have different approaches and methods. In their studies they often correlate the prey size and the predator mouth size for a series of potential competitors. I have not explored this area in animal ecology with much depth and will say no more, though I agree with the general idea. Instead I will comment mostly about the big trees and other plants, the big photosynthetic producers which give most structure to a forest.

All plants and animals evolve within a food chain and more broadly a niche 3a, and tropical food chains and webs tend to be longer and more complex with most of the species tiny invertebrates and parasites. Think of all the beetles on a huge old tropical tree. Being small is important. Tiny organisms are able to divide resources much more finely than the larger, thus they contribute much more to overall species diversity. Rarity is a common condition in forests. The majority of species in any given area are rare or uncommon and this has long been demonstrated by graphing species versus area curves. A small group of plants are common, others occasional and the majority rarely encountered as more area is searched.

Humid tropical forests capture much much more total radiant energy, 12 active growth months versus maybe 3 warmish months in Newfoundland (more slices of the energy pizza). The Boreal and Temperate forests have the obvious disadvantage of a major annual setback or disturbance in development, winter, and many also experience forest fire periodically 3b. The humid tropics have ongoing growth and the setback of wild forest fire is very rare. Think of tropical trees like a huge Manhatten office tower versus a simple boreal forest hut with much more space and energy to partition or subdivide. Even the tropical rivers can teem with fish, large shrimp and crab for 12 months providing foods, for example, for the 7 species of Egret-Heron and the Curlew and various Sandpipers outside my door on the Rio Jama, Ecuador. Shallow tropical coral reef systems can be equally rich in solar energy and species.

In the following notes I comment on two of the biggest differences in forest structure regarding vines and epiphytes and then mention some more general controls that foster or hinder plant and animal richness. Many will be familiar to readers already.

Vines
Tropical forests, wet or seasonally dry, have many vines and some become full size trees. These are plants that take a short route to the sunny tree canopy by climbing up and over bigger plants 4, 5. Newfoundland´s flora has very few vines and none of them are native to forests. Can you think of them? Black Bindweed, Polygonum convolvulus, Deadly Nightshade, Solanum dulcamara (mapped, Day 1978) Purple Vetch, Vicia cracca and Bindweed, Convovulus sepium and C. arvensis. All are confined to urban and disturbed habitats and were probably all introduced to the island with human activity. Near Ottawa Convolvulus sepium behaves like a tropical vine where it evades the intense crowding or competition from tall and dense herbaceous Cattail communities. It climbs the shoots and trails across the top in a single growing season, only 3.5 warm months versus 12 in the humid tropics. In this way it can catch the sun in a moist, fertile marsh habitat. The climbing Wild Cucumber, Echinocystis lobata, in the Saint John Valley of New Brunswick, does the same. Newfoundland does have one other herbaceous climber, a parasite, that feeds and climbs other herbs, the Dodder Cucuta. Wild Grape, Vitis riparia, and Bitter Sweet Vine, Celastrus scandens, grow in the warmer parts of Canada but not in Newfoundland. However, Farley Mowat in his 1965 Westviking book suggested that the Wild Grape may have grown here in isolated locations but has been killed out in the early colonial period by very cold winters. Maybe and maybe not with only written reports. There is no other evidence. I did not mention Lathyrus palustris, Marsh Pea. It is a small native Newfoundland herbaceous climber. Did you catch my omission? Thinking of others?

Woody plants overtop other woody plants in our Boreal Forest, shrublands and arctic vegetation, the normal competition for light, but none are vines though some like Twinflower, Linnea borealis, are trailing. We could think of them as horizontal vines on a miniature scale, as are the trailing runners of Strawberry plants. In the same line of thought plants with creeping underground rhizome stems can be thought of as subterranean vines pushing radially and horizontally through soil, moss, and litter, emerging in light gaps. Most of our perennials do this, like Cinnamon Fern, Osmunda cinamomea and two Aspens, mentioned later.

Epiphytes
The tropical forests often have large numbers of epiphytes. These too take a short cut to the canopy or subcanopy of woody trees, sometimes climbing, but mostly by seeds or plant fragments carried by animals or wind. Epiphytes even colonize electrical lines and have to be removed periodically. The main epiphytes in tropical forests are the Orchids, Bromelliads, Cacti and Ferns but they also have the ones common to our Boreal Forests as well, lower plants, the liverworts, mosses, lichens and algae. A lush growth of lower plants can be seen on big old Yellow Birch trees in southern Newfoundland 6 and the lichen Old Man´s Beard, Usnea sp., is common on conifers in more humid locals like St. Mary´s Bay, Salmonier Line. (I would very much like to know more about this mini ecosystem on tree bark from knowledgeable teachers.) If you look for a flowering epiphyte, an Orchid, Cactus or Bromeliad in Newfoundland you waste your time. You will not find one. All Newfoundland orchids are terrestrial and cannot tolerate the desiccation of an epiphytic winter. The closest Bromeliad can be seen growing in North Carolina State where evergreen Live Oaks are famously draped in Spanish Moss, Tilandsia usneaoides, a flowering Bromeliad (Pineapple family). This genus is widespread in the Neotropic cloud forests. I see it daily in the misty hills near Jama Ecuador. Look for an ephiphytic fern in Newfoundland-Labrador and you may find one. Can you think of it? The Rock Polypody Fern, Polypodium vulgare, can sometimes be found in the crotches of old hardwood trees, but is more common on large glacial boulders in forests where it has less competition and more light. There is only one other native flowering epiphyte in Newfoundland. Can you think of it? It is a semi-parasite actually, the Dwarf Mistletoe, Arceuthobium pusillium, and it derives its moisture and some food internally from Black Spruce bark. I have seen it sprouting a few millimeters out of branches near Corner Brook 7. It is hard to find and a guide is essential.

Other Influences on Diversity
The island area vs. continental effect and human imports and hunting of species

The tropics are famous for amazingly diverse floras and faunas but this is not always so. Many tropical Islands have few tree species, often only the coconut, and have never been colonized by 4-legged herbivores. The native mammals of North Island New Zealand are a bat and some seals. This was caused by ocean isolation and the small land size, the island area versus continent effect. Much of the tropical diversity we observe comes from the relative ease of dispersal of organisms through connected continental tropical forests. S.E. Asia, one of the richest areas, has organisms also found in India and Africa. Think of the wide ranging Leopard and Pangolin and our own dispersal, first Homo erectus and later H. sapiens out of Africa and across south Asia.

Newfoundland has a very low diversity of native trees, Balsam Fir, Black & White spruce, Larch, Red & White Pine, Black Ash (v. rare), White & Yellow Birch 6, 8, Trembling & Balsam Popular, Pin & Choke Cherry, eleven species. In the Humber Valley Speckled Alder can reach the stem diameter of 6 inches, a tree, but rarely so. Jack Pine managed to disperse to Labrador but not Newfoundland (Day 1995-98). Amelanchier, Service Berry, and Sorbus, Mountain Ash, also reach small tree size occasionally. Exotic trees and weeds have been brought in with European settlement, boosting diversity, and most of these are found in St. John´s and Corner Brook. The negative side of human influence is ecosystem disruption leading to loss or gain of diversity and many extinctions, local (extirpations) or total (global). Weeds are still invading the Goosebay area of Labrador, thousands of years since deglaciation. This area is a sandy hot pocket in spring and summer where many southern plants thrive (Day 1995 & 98). The Moose is also a new colonizer here.

The saltwater barrier around our island has cut us off from the continents of North American, Europe and Asia. This barrier has also kept out many animals, limiting diversity. The Porcupine, Groundhog squirrel or Marmot, Hare, Moose, Red and nocturnal Flying Squirrel colonized Labrador naturally but not Newfoundland and the Wolverine may have once been on the Island like the Wolf, Polar Bear, Walrus and Giant Auk. All have been killed out with European settlement. We have a lot of damage to restore.

We have no palms in Newfoundland. This group is tropical and subtropical and they have not evolved much tolerance to cold (limits diversity). As you can guess there is a very rough correlation between latitude (or altitude) and diversity. One short palm species get as far north as the Carolinas, the Palmeto Palm, Sabal serrulata 9. This cold limitation is the case for a very large numbers of plant and animal groups. No Tapir comes north, only one Hummingbird visits eastern Canada, no Begonias, which are largely South American, only one Cactus (exclusively of the Americas) made it to the Boreal region of south Manitoba, Opuntia fragilis, no Tree Sloth but Giant Ground Sloths (Yukon to Patagonia) and Capybara migrated across Panama, probably 3 million years ago (late Tertiary) and into North American. Several large mammals are thought to have been hunted to extinction by natives, using fire, traps and spear throwers (atlatl), as for the entire elephant family. The Pleistocene ice sheets and cold dry climate compressed many ecosystems into the American southwest, Florida and the Texas-Louisiana coast making large animals more vulnerable to hunting. Armadillo now exist as far north as Florida and Opossum just gets into south Ontario where they often experience frostbite on ears and tail. This is Canada´s only marsupial. Porcupine from S. America dispersed north to the arctic treeline. The Coyote recently got into Newfoundland, perhaps in the back of a transport truck left open at a truck stop in Nova Scotia. Raccoon will likely be next to arrive. Coyote have spread to all areas and we don´t know what effect this is having on our rare Pine Martin. The Coyote is not in South America yet, where small foxes and feral dogs are common, but will probably get there soon and perhaps drive some prey species to extinction. Sadly, most of S. America´s large mammals like the Giant Lama and Giant (herbivorous) Armadillo, Glyptodont, have been killed out. The Manatee, River Dolphin, Capybara (all aquatic), Tapir, Rhea, Spectacled Bear, White-Tail Deer and smaller Lamas remain. When cats (Jaguar (extirpated in the US early 1900s), Puma, Jaguarundi, Ocelotte etc.) finally migrated south with the formation of Istmus Panama they too likely played an important role in extinctions. No large marsupials remain.

Animal Effects on tree and soil cavities (niche space) and Geological Heterogeneity or Gradients
Animals, wind and tree fall all wound or excavate cavities in trees thus promoting diversity. Porcupine do this as well as woodpeckers and squirrels. Even marmoset monkeys bite tree bark to stimulate resin flow, a major food but also an entry point for tree decay and cavities. In Newfoundland´s Terra Nova Park I see ants excavating the dead heartwood of trees already weaked by fungi and then black bear excavate and eat them. These cavities are vital for many birds and others that cannot tunnel in wood like snakes, amphibians and bats. Animals that burrow (ground squirrels, badgers, termites) make vital refuges shared by those that cannot like the Burrowing Owl (seen on the Canadian Prairies and also at Arraial d'Ajuda, coastal grasslands of Brazil). These tunneling activities in trees and soil promote species richness, as does geological diversity or heterogeneity (tied in with gradients), the sink holes, boulders, spires and caves of limestone karst landscape, as an example. We see the same heterogeneity with the diversity of forms in coral reefs and coral sand, bio-generated geology.

Summing Up
Years back when looking at plant diversity in plant communities of Ottawa River marshes (Day et al. 1988), Paul Keddy and I were interested in fertility and disturbance gradients as major controls of species richness or diversity. We refined the Intermediate Disturbance Hypothesis, a family of hump-back curves. Moderate disturbance can boost local plant diversity (proposed in Grime´s 1979 influential book). Under very high disturbance plant diversity is supressed and low, and under low disturbance intense plant competition leads to monopolies and drives diversity down. Thus diversity is highest in intermediate conditions. We also re-confirmed that water depth had the greatest influence structuring river marsh vegetation. Water is a very strong physical gradient for plants and animals, a steep gradient for many things, oxygen, CO2, light, pressure etc.

As said in the introduction, the more elaborate tropical forests have a whole series of factors that add up or detract but also interact. Some are historial or geographical like the isolation of continents but others act on communities nearly every day like grazing disturbance in a pasture 10. We can all apply what we learn to boost or conserve diversity 11 on our own property.

All the trees and animals have things that eat or live upon or disperse or parasitize or bite them ad infinitum as noted in Johanathan Swift´s (1733) poem. My notes touch on much of the observed diversity. Eventually someone will write in a huge cumbersome equation, a computer model to explain diversity. It won´t be me but examples can be found in journals like American Naturalist. Fortunately for botanists, foresters, farmers and gardeners Tillman (1988) has identified limiting soil nitrogen and light at the soil surface as the major factors structuring well-watered plant communities. This is encouraging.

Finally, what are you doing to conserve Earth biodiversity?

Footnotes
1a. Cattail, Typha latifolia, Spikerush, Eleocharis, Water Rush, Scirpus, Water Smartweed Polygonum, and Willow, Salix, can be seen growing in Newfoundland and also in tropical wetlands. Are you surprised? Common weeds like Shepherds Purse, Capsella bursa-pastoris and Plantain, Plantago major, are also here, Brazil and Ecuador. Even our insectivorous Sundew, Drosera rotundifolia, has relatives in Venezula. The genus seems to have dispersed by island hopping through the Caribbean to the US Coastal Plain and then north to Newfoundland & Labrador. I have seen our Bladderwort genus, Penguicula, growing in pools outside Puket Thailand. The national bird of Brazil may surprise you. It is a thrush with a rusty red breast, hardly different from our common American Robin. What an adaptable bird. I´m wondering which group is ancestral North or South American?

1b. Tilman 1988 p. 222, citing Vitousek (1982), points out that most world forests are limited in growth by available nitrogen. This is certainly true in Newfoundland and Labrador where the half million citizens rarely make a practice of using dilute urine or wood ash on valued trees or use compost toilets to improve soils but instead flush all the nutrient into the sea or in deep underground septic beds below the reach of most plant roots. Flush toilets are wasteful, polluting techology (Hupping Stoner 1978). The same can be seen when we note that our province has more dogs and cats (fed imported food) than sheep, goats or cattle. We have thousands more imported lawnmowers, than haybailers or silage cutters, and the lawns they cut produce not a drop of milk or a gram of meat or cheese. Where is the leadership in the necessary cultural changes? It´s right here. Memorial University can easily offer a degree specialization in technical horticulture and soils with existing courses 10. Making sustainable farms in the Boreal forest takes generations of input for extensive fenced grazing land (except islands), or thousands of $ for intensive greenhouses, a double option. Farms are a success when they are married to market outlets, cafes, or bed & breakfast homes.

2. Niche partitioning is an unpopular term for many biologists (self included) as the word ¨partitioning¨ is an active verb and does not fit what is happening. The animals or plants as individuals adjust to their fluid niche and those around them, all part of natural selection and evolution.

3a. The biology concept of niche (French for gap or crack) is a difficult thing to wrap the mind around. It is a metaphor. It is the sum total of random events, space and place and time and resources used by a species in an environment (foods, nesting holes, food chain etc.). It is not exactly the same for all individuals (organisms all eat differently and have a different history) but approximately so and always changing. Excuse me for using the tired expression, it is multidimentional, and therefore difficult or exhausting to measure. Compare my definition with those used by others.

3b. Conifers that retain their needle-leaves (not Larch) lose much less biomass as a result of the winter disruption. True they must form buds and some root hairs die in the cold of winter but deciduous trees, herbaceous communities and especially annual herbs suffer a massive autumn dieback of biomass from which they must recover in spring. This is one major advantage to being evergreen.

4. Some places in SE Asia and S. America even have strange elongate climbing palms, the Ratan Vines (several genera), used to bind imported bamboo furniture. Ratan Palms have spines that aid climbing but tear flesh.

5. In South Korea some vines, like the legume Kudzu Vine, Pueraria lobata, are so agressive they climb light poles and support cables and the leading shoots have to be kept back by attaching conical excluders like the rat excluders often seen on ropes attaching ships in port.

6. The Yellow or Golden Birch forests common in the the river valleys of south coast Newfoundland are mostly restricted to the warmer south and west facing slopes while the north and eastern slopes are colder and all conifers. On these warmer slopes Yellow Birch can reach a magnificent size with branches draped in lichen. An example close to St. John´s is at the mouth of the Salmonier R. where artists John and Mary Pratt have a home. My father (from Galtoise, Long Island) and people of his region, called this tree Witchhazel for the wintergreen smell released from broken twigs. This Yellow Birch forest has deep brown soils over an active moss and humus layer, fine for agriculture, and is related to the more diverse Acadian Forest of NS NB and PEI. Our Yellow Birch forests were mapped by Damman (1976) and shown to have a higher than usual growing season heat or growing degree days. Tiny Yellow Birch seedlings can become established on bared mineral soil when trees fall over and rip up the moss and litter layer, or they may be perched on moist rotted stumps or fallen logs. Here they obtain a stable water supply which is critical for many Boreal tree seedlings (Day 1981)

7. Some believe that the Grey or Boreal or Canada Jay is responsible for dispersing the single sticky seed which can explode from the fruit. I know no more about this.

8. My own 58 acre forest organic farm and hostel, Little Eden Nature Reserve, south of Ottawa & Merrickville, has Yellow Birch and a whole range of trees never seen in Newfoundland. Some are found in the Acadian forest but more are part of the large number of species in the southern Appalachian Mountain system, a center of temperate biodiversity very closely related and once in contact with the forests of China, Korea and Japan (Arctotertriary Forest). I have fragrant Eastern White Cedar, Black Cherry (beautiful furniture), Basswood (attracts bees), Red Oak, Silver and Sugar Maple (can be tapped for sap), Beech, Ironwood, Elm, Ash, Musclewood and Hemlock as well as the common Newfoundland trees....... This type of forest is a treat to a Newfoundlander raised in the Boreal Forest, a treat and a challenge to understand.

9. Palms are macrophyls or big leaf plants, the largest leaves in the plant kingdom. They are close to the extinct Seed Ferns essentially like the surviving Cycads. Many like the spiny stemmed Chonta Palm, Aiphanes aculeata etc., make a mad dash to the canopy devoting most energy to a very active single apical meristem, a very special competitive strategy. They are so very specialized in their upward growth that they very rarely branch unless damaged. Flower stalks of palms do branch, as do the leaves, or rather they split while enlarging thus dispersing the energy of winds. Banana leaves do the same. The leaf stalk of many palms clasp the stem for mechanical support just like corn/maize and most other grasses.

10. In 2008 I visited a private botanical orchid forest restored over 25 years. It is just outside the town of Puyo on the eastern Andes of Ecuador. The owner and English guide, Omar Tello Benalcazar (jblorquideas@andinanet.net), has rebuilt a forest by collecting salvaged seedlings, cuttings and epiphytes and by daily bringing in bags of organic matter to improve the clay soil of a degraded cattle pasture. He told me is convinced that the carnivorous bugs which control the herbivorous species also control the health and diversity of the trees. The mechanisms were not explained exactly but these ideas need testing with hard science. Omar is also domesticating many delicious amazonian plants. He has found a very rare new cycad but only one sex, so cannot breed it sexually.
In coastal Brazil at Arriail d'Ajuda the grass airfield, now an informal municipal park has developed artificially in what was originally a tropical coastal forest. In 2007 I saw it was kept open by tree removal, patchy fires and grazing by mules and horses. Over many years it has been invaded by a huge variety of grasses, other herbs and shrubs. There has been no inventory of this remarkable field/prairie.

11. The Natural Hist. Soc. can offer workshops to landowners for enhansing wildlife. There are many useful techniques, most as simple as gardening or favouring hardwoods which promote soil fertility. For example I place logs on the east side of my tractor-made pond so Painted and Blanding´s Turtles and Northern Brown Water Snakes can warm in the morning sun. This modest pond provides water to the whole forest in dry summers.

Acknowledgements
I thank Fred Rayment (Agriculture Canada) and Fred Pollett (Forestry Canada) for giving me summer student employment many years back when I first studied pasture plants, then Lambkill, Kalmia angustifolia, and then Boreal forest regeneration after fire. I remember the friendship of potato specialist Ken Proudfoot who recently passed away. I thank my parents for giving me me the luxury of study. I also thank the people of the Jama River, Ecuador, where I had a small museum built in 3 days, opened in 2 months and now exhibits animal skulls and pre-Columbian artifacts. This was my writing home for a second winter. I tubed down the Rivers Jama & Mariano for 8.5 hours, saw clouds of butterflies but not a single turtle which are taken by children as pets, as in Canada. One-to-one education is sorely needed. In Ecuador one can see 83 % of Brazil´s biodiversity in a much smaller, fertile, volcanic country.
Incidentally, I saw the Scarlet Flycatcher here and in north coastal Peru. The male is red like a puff of fire. I suggest it mimics a red flower and attracts insects that it can then eat. The male is also likely noticed more and eaten by predators. These hypothesis can be tested experimentally.

Literature Cited
Damman A.W.H. 1976. Plant distribution in Newfoundland especially in relation to summer temperatures measured with the sucrose inversion method. Can. J. Bot. 61: 1564-1585.

Day R.T. 1978. Deadly Nightshade Solanum dulcamara L. and other Solanaceae in Newfoundland. The Osprey 9(2): 71-74.

Day R.T. 1981. The Vegetation and Organic Layer in Black Spruce-Kalmia Postfire Communities. MSc. thesis University of NB, Bio. Dept. (copies at Memorial U. etc.)

Day R.T., P.A. Keddy, J. McNeill & T. Carleton. 1988. Fertility and disturbance gradients: A summary model for riverine marsh vegetation. Ecology 69(4):
1044-1054.

Day R.T. 1995 & 98. The Atlas of Labrador Plants Vols. 1 & 2. Ubiquitous Publishing, cowboy4444@hotmail.com (M.U.N. has 6 copies)

Grime J.P. 1979 Plant Strategies and Vegetation Processes. Wiley.

Hupping Stoner, Carol (editor) 1978. Goodbye to the Flush Toilet: Water-Saving Alternatives to Cesspools, Septic Tanks, and Sewers. Rhodale Press.

Mowat F. 1965. WESTVIKING, The Ancient Norse in Greenland & North America. Little Brown, HB.

Swift J. 1733 Poems: On Poetry: Rhapsody, & later version by Augustus de Morgan, A Budget of Paradoxes, 1872, p.377.

Tilman, D. 1988. Plant Strategies and the Dynamics and Structure of Plant Communities. Monographs in Population Biology, Princeton University Press. 360 pp.

Vitousek, P. M. 1982. Nutrient cycling and nutrient use efficiency. Am. Nat. 119, 553-572.