Trees in the ecosystem pt IV: Trees & arthropods

The arthropods are vast in terms of species, and include ants, beetles, butterflies, mites, moths, spiders, and so on. Therefore, covering the entire spectrum of arthropods in this section is impractical, though the general provisioning by trees will be outlined and species will be used to illustrate given examples.

Many arthropods are considered to be saproxylic in nature – they principally utilise dead woody material (both standing and fallen, in both dead and living trees) as habitat, for at least part of their life cycle, though they may also rely upon fungal sporophores associated with the presence of deadwood, as is to be detailed below (Gibb et al., 2006; Harding & Rose, 1986; Komonen et al., 2000). Of all the saproxylic arthropods, beetles are perhaps the most significant in terms of the proportion occupied of total saproxylic species worldwide (Müller et al., 2010), though saproxylic flies also feature in great numerical abundance (Falk, 2014; Harding & Rose, 1986).

Beetles may be either generalist or specialist in nature (on either broadleaved or coniferous hosts), and they will normally require a host with an abundance of deadwood (or large sections of coarse woody debris) usually over 7.5cm in diameter that resides within an area typically not heavily shaded (Müller et al., 2010; Siitonen & Ranius, 2015). This may be, in part, due to many beetle species (in their adult stage) requiring nectar from herbaceous plants, which would be lacking in woodland with significant canopy closure (Falk, 2014; Siitonen & Ranius, 2015). This means that veteran trees amongst wood pasture and parklands (including in urban areas) may be particularly suitable (Bergmeier & Roellig, 2014; Harding & Rose, 1986; Ramírez-Hernández et al., 2014; Jonsell, 2012; Jørgensen & Quelch, 2014), though this is not at all a steadfast rule as species may also be found abundantly in (perhaps more open) woodland, and particularly where there are large amounts of veteran trees and deadwood – around 60 cubic metres per hectare, according to Müller et al. (2010). Granted, they are found particularly in older (mature to veteran) trees, including within cavities that possess wood mould, water-filled rot holes, dead bark, exposed wood, sap flows, fruiting bodies (of fungi and slime moulds), mycelia of fungi, dead branches, and dead roots (Carpaneto et al., 2010; Falk, 2014; Harding & Rose, 1986; Siitonen & Ranius, 2015; Stokland et al., 2012). Beetle species may also not necessarily associate preferentially with a species (or group of species), but with the conditions aforementioned that are present within a tree (Harding & Rose, 1986; Jonsell, 2012). At times, preferable conditions may be an infrequent as one veteran tree in every hundred (Harding & Rose, 1986).

A veteran oak tree that is of prime habitat for a variety of organisms.

Despite this, species preference is observed. For broadleaved obligates, heavier shade may be more necessary, and in such instances there is a closer affinity of the beetles with fungal mycelium. Because fungi tend to produce more mycelium in cooler and more humid conditions (though this does, of course, vary with the species), the broadleaved obligates may therefore be found normally in greater abundance where conditions are more suited to fungal growth, and their presence may thus be associated with a canopy openness of as little as 20% (Bässler et al., 2010; Müller et al., 2010). This is, of course, not a steadfast rule, and many open wood pastures may support a great abundance of saproxylic beetles (Harding & Rose, 1986).

It is also important to recognise that many species of saproxylic beetle are reliant upon particular stages of the wood decay process. For instance, species that require fresh phloem tissue will only be able to colonise briefly in the first few summers following on from the death of the phloem tissue (Falk, 2014). Other species require significantly-decayed wood in a particular micro-climate, and even of a particular tree species (Harding & Rose, 1986). There also exist intricate associations between species of fungi and saproxylic insects. Inonotus hispidus, which is usually found upon ash, is the habitat for Triplax russica and Orchesia micans, whilst the coal fungus (Daldinia concentrica), also oft found upon the deadwood of ash (Fraxinus excelsior), is the main provider of habitat for Platyrhinus resinosus (Falk, 2014). The birch polypore (Fomitopsis betulina) is also host to numerous species of Coleoptera (Harding & Rose, 1986); as is the polypore Fomitopsis pinicola (Jonsson & Nordlander, 2006; Komonen, 2003; Komonen et al., 2000). This means that these species may be found where there is a suitable population of the fungus’ host species, where sporophores are present and will likely fruit again in the future, across numerous trees, and for many years. Most beetle species rely on oak more so than other tree species however, as oak generally lives for much longer and thus provides a wider array of different micro-habitats, and possesses increased compositional complexity as a result (Harding & Rose, 1986; Siitonen & Ranius, 2015).

A fruiting body of Inonotus hispidus on apple (Malus sp.). This fungus not only creates habitat in the wood that it degrades but also is a direct habitat through its sporophore.

Therefore, the loss of suitable habitat through active management programmes (including logging, and felling trees for safety reasons in urban areas) will have a very adverse impact upon saproxylic beetles, though also certain species of moth, and even species associated with saproxylic insects, including parasitic wasps, solitary wasps (which use beetle bore holes for habitat), and predatory Coleoptera (Harding & Rose, 1986; Komonen et al., 2000). Curiously, research by Carpaneto et al. (2010) concluded that trees that were ranked as the most evidently ‘hazardous’ were host to the most saproxylic beetle species, and their removal would therefore have a drastic impact upon local populations. Similarly, fragmentation of woodland patches suitable for saproxylic populations has led to a decline in the meta-populations (Grove, 2002; Komonen et al., 2000), as has deadwood removal in a managed site itself (Gibb et al., 2006). Interestingly, though not surprisingly, ‘deadwood fragmentation’ also has an adverse impact upon saproxylic insect populations (Schiegg, 2000).

Both ants and termites also benefit from the presence of deadwood. With regards to both, nests will usually form at the base of a tree or at an area where there is at least moderate decay – enough to support a viable population (Jones et al., 2003; Shigo, 1986; Stokland et al., 2012). Ants and termites both follow CODIT (compartmentalisation of damage in trees) patterns in relation to how their nests progress, and thus their territory will increase as fungal decay propagates further into the host. Ants will not feed on the decaying wood of the host however, and will simply use the decaying site as a nesting area. Conversely, termites will feast upon decayed wood and essentially control (perhaps by slowing down) the spread of fungal decay in a manner that provides as much longevity of the host as possible for a viable nesting site (Shigo, 1986). In tropical rainforests, termites are in fact considered to be one of the principal means of wood decomposition (Mori et al., 2014), and thus the provisioning of deadwood habitat is absolutely critical. Without decaying wood within trees therefore, ants and particularly termites will lack a potential habitat, and thus where a stand is actively managed populations may be markedly reduced (Donovan et al., 2007; Eggleton et al., 1995). Of course, termites are not necessarily to be desired when they are invading the wood structure of a property, and therefore deadwood is not universally beneficial (Esenther & Beal, 1979; Morales-Ramos & Rojas, 2001) – at least, when human properties are involved.

Ecologically beneficial? Yes. Economically beneficial? No. Termites can – and do – damage timber-frames buildings, as is the case here. Source: Pestec.

The presence of deadwood may also be beneficial for ground-nesting and leaf-litter dwelling spiders, which can utilise downed woody debris (particularly pieces with only slight decay) for both nesting and foraging (Varady-Szabo & Buddle, 2006). In fact, research by Buddle (2001) suggested that such spiders may more routinely utilise downed woody material when compared to elevated woody material (dead branches and telephone poles) because of the greater array of associated micro-habitats, and particularly at certain life stages – such as during egg-laying, for females (Koch et al., 2010). Furthermore, as fallen woody debris can help to retain leaf litter (or even facilitate in the build-up leaf litter), spider populations are more abundant and more diverse in sites where such woody debris is present (Castro & Wise, 2010). Therefore, where woodlands are managed and areas are clear-cut, spider populations may be markedly reduced in terms of the diversity of species. However, generalist species may benefit from the amount of cut stumps (Pearce et al., 2004). Curiously, Koch et al. (2010) suggest that spiders may perhaps benefit from woodland clearance, because the vigorous re-growth of trees and the higher light availability to the woodland floor (promoting herbaceous plant growth) increases the abundance of potential prey. Despite this, old-growth species will suffer (Buddle & Shorthouse, 2008), and thus the population structure of spider populations may dramatically change.

Soil mites are a further group that benefit from coarse woody debris, though also from hollows and holes throughout the basal region of a tree (including water-filled cavities), and from fungal sporophores and hyphae associated with wood decay (Fashing, 1998; Johnston & Crossley, 1993). Typically, termites will use fungi and insects found within the wood as a food source, and the wood structure itself will provide for an array of niche micro-habitats that are critical at different life stages of a mite. Certain mite species are obligates that associate with coarse woody debris exclusively, and may in fact only be associated with certain species’ woody debris. Additionally, mites may utilise woody debris and hollows within trees to parasitise upon other species using the ‘resource’, with both lizards and snakes being parasitised by mites following their frequenting of such resources. Beetles may also be parasitised, though the mite in such an instance may use the beetle as a means of entry into woody debris (Norton, 1980).

It is not just deadwood that arthropods will utilise, however. Foliage, both alive and abscised, is also of use (Falk, 2014). For example, the ermine moth (Yponomeutidae) will rely upon the living foliage of a host tree as a food source, and the bird cherry ermine moth (Yponomeuta evonymella) is one example of this. During late spring, larvae will fully defoliate their host Prunus padus, before pupating, emerging, and then laying eggs upon the shoots ready for the following year (Leather & Bland, 1999). Many other moth species will, during their larval stage, also behave in such a manner and thus defoliate their host – either entirely, or in part (Herrick & Gansner, 1987). Other species may alternatively have larvae mine into the leaf and feed upon the tissues within (Thalmann et al., 2003), such as horse chestnut leaf miner (Cameraria ohridella). Flies, including the holly leaf-miner (Phytomyza ilicis), will also mine leaves in a similar fashion (Owen, 1978). Ultimately however, the same purpose is served – the insect uses the living tissues of a leaf to complete its life cycle, and fuel further generations.

Bird cherry ermine moth having defoliated an entire tree. Source: Wikimedia.

Fallen leaf litter, as briefly touched upon earlier when discussing spiders, may also be of marked benefit to many arthropods. Ants, beetles, and spiders are but three examples of groups that will utilise leaf litter as a means of habitat (Apigian et al., 2006). Beetles will, for instance, rely upon leaf litter to attract potential prey, though also to provide niche micro-climates that remain relatively stable in terms of humidity, light availability, and temperature (Haila & Niemelä, 1999). Their abundance may, according to Molnár et al., (2001) be greatest at forest edges, perhaps because prey is most abundant at these edge sites (Magura, 2002). Of course, this does not mean that edges created through artificial means will necessarily improve beetle populations, as research has shown that there are few ‘edge specialists’ and therefore populations usually will go into decline where there has been significant disturbance. Unless management mimics natural mortality events of forest trees, then constituent beetle populations may thus suffer adversely (Niemelä et al., 2007).

With regards to ants, Belshaw & Bolton (1993) suggest that management practices may not necessarily impact upon ant populations, though if there is a decline in leaf litter cover then ants associated with leaf litter presence may go into – perhaps only temporary (until leaf litter accumulations once again reach desirable levels) – decline (Woodcock et al., 2011). For example, logging within a stand may reduce leaf litter abundance for some years (Vasconcelos et al., 2000), as may (to a much lesser extent) controlled burning (Apigian et al., 2006; Vasconcelos et al., 2009), though in time (up to 10 years) leaf litter may once again reach a depth suitable to support a wide variety of ant species. However, the conversion of forest stands into plantations may be one driver behind more permanently falling ant populations (Fayle et al., 2010), as may habitat fragmentation (Carvalho & Vasconcelos, 1999) – particularly when forest patches are fragmented by vast monoculture plantations of tree or crop (Brühl et al., 2003). The conversion of Iberian wood pastures to eucalyptus plantations is one real world example of such a practice (Bergmeier & Roellig, 2014).

Also of benefit to many arthropods are nectar and pollen. Bees, beetles, butterflies, and hoverflies will, for instance, use nectar from flowers as a food source (Dick et al., 2003; Kay et al., 1984), and generally (but not always) a nectar source will lack significant specificity in terms of the insect species attracted (Karban, 2015). Despite this, different chemicals secreted by different flowers, and the toxicity of certain nectar sources to particular insects, means certain tree species may only be visited by certain insect species (Adler, 2000; Rasmont et al., 2005). Tree diversity may therefore be key to sustaining healthy insect populations (Holl, 1995), and where species may prefer to frequent herbaceous plant species the presence of a diverse woodland canopy above may still be very influential (Kitahara et al., 2008). This may be because a diverse array of woody plant species increases the diversity of herbaceous species. At times, pollen may also be a reward, as may (more rarely) a flower’s scent. Karban (2015) remarks that all are collectively dubbed as ‘floral rewards’.

References

Adler, L. (2000) The ecological significance of toxic nectar. Oikos. 91 (3). p409-420.

Apigian, K., Dahlsten, D., & Stephens, S. (2006) Fire and fire surrogate treatment effects on leaf litter arthropods in a western Sierra Nevada mixed-conifer forest. Forest Ecology and Management. 221 (1). p110-122.

Bässler, C., Müller, J., Dziock, F., & Brandl, R. (2010) Effects of resource availability and climate on the diversity of wood‐decaying fungi. Journal of Ecology. 98 (4). p822-832.

Belshaw, R. & Bolton, B. (1993) The effect of forest disturbance on the leaf litter ant fauna in Ghana. Biodiversity & Conservation. 2 (6). p656-666.

Bergmeier, E. & Roellig, M. (2014) Diversity, threats, and conservation of European wood-pastures. In Hartel, T. & Plieninger, T. (eds.) European wood-pastures in transition: A social-ecological approach. UK: Earthscan.

Brühl, C., Eltz, T., & Linsenmair, K. (2003) Size does matter–effects of tropical rainforest fragmentation on the leaf litter ant community in Sabah, Malaysia. Biodiversity & Conservation. 12 (7). p1371-1389.

Buddle, C. (2001) Spiders (Araneae) associated with downed woody material in a deciduous forest in central Alberta, Canada. Agricultural and Forest Entomology. 3 (4). p241-251.

Buddle, C. & Shorthouse, D. (2008) Effects of experimental harvesting on spider (Araneae) assemblages in boreal deciduous forests. The Canadian Entomologist. 140 (4). p437-452.

Carpaneto, G., Mazziotta, A., Coletti, G., Luiselli, L., & Audisio, P. (2010) Conflict between insect conservation and public safety: the case study of a saproxylic beetle (Osmoderma eremita) in urban parks. Journal of Insect Conservation. 14 (5). p555-565.

Carvalho, K. & Vasconcelos, H. (1999) Forest fragmentation in central Amazonia and its effects on litter-dwelling ants. Biological Conservation. 91 (2). p151-157.

Castro, A. & Wise, D. (2010) Influence of fallen coarse woody debris on the diversity and community structure of forest-floor spiders (Arachnida: Araneae). Forest Ecology and Management. 260 (12). p2088-2101.

Dick, C., Etchelecu, G., & Austerlitz, F. (2003) Pollen dispersal of tropical trees (Dinizia excelsa: Fabaceae) by native insects and African honeybees in pristine and fragmented Amazonian rainforest. Molecular Ecology. 12 (3). p753-764.

Donovan, S., Griffiths, G., Homathevi, R., & Winder, L. (2007) The spatial pattern of soil‐dwelling termites in primary and logged forest in Sabah, Malaysia. Ecological Entomology. 32 (1). p1-10.

Eggleton, P., Bignell, D., Sands, W., Waite, B., Wood, T., & Lawton, J. (1995) The species richness of termites (Isoptera) under differing levels of forest disturbance in the Mbalmayo Forest Reserve, southern Cameroon. Journal of Tropical Ecology. 11 (1). p85-98.

Esenther, G. & Beal, R. (1979) Termite control: decayed wood bait. Sociobiology. 4 (2). p215-222.

Falk, S. (2014) Wood-pastures as reservoirs for invertebrates. In Hartel, T. & Plieninger, T. (eds.) European wood-pastures in transition: A social-ecological approach. UK:     Earthscan.

Fashing, N. (1998) Functional morphology as an aid in determining trophic behaviour: the placement of astigmatic mites in food webs of water-filled tree-hole communities. Experimental & Applied Acarology. 22 (8). p435-453.

Fayle, T., Turner, E., Snaddon, J., Chey, V., Chung, A., Eggleton, P., & Foster, W. (2010) Oil palm expansion into rain forest greatly reduces ant biodiversity in canopy, epiphytes and leaf-litter. Basic and Applied Ecology. 11 (4). p337-345.

Gibb, H., Pettersson, R., Hjältén, J., Hilszczański, J., Ball, J., Johansson, T., Atlegrim, O., & Danell, K. (2006) Conservation-oriented forestry and early successional saproxylic beetles: responses of functional groups to manipulated dead wood substrates. Biological Conservation. 129 (4). p437-450.

Grove, S. (2002) Saproxylic insect ecology and the sustainable management of forests. Annual Review of Ecology and Systematics. 33 (1). p1-23.

Haila, Y. & Niemelä, J. (1999) Leaf litter and the small‐scale distribution of carabid beetles (Coleoptera, Carabidae) in the boreal forest. Ecography. 22 (4). p424-435.

Harding, P. & Rose, F. (1986) Pasture-Woodlands in Lowland Britain: A review of their importance for wildlife conservation. UK: NERC.

Herrick, O. & Gansner, D. (1987) Gypsy moth on a new frontier: forest tree defoliation and mortality. Northern Journal of Applied Forestry. 4 (3). p128-133.

Holl, K. (1995) Nectar resources and their influence on butterfly communities on reclaimed coal surface mines. Restoration Ecology. 3 (2). p76-85.

Jones, D., Susilo, F., Bignell, D., Hardiwinoto, S., Gillison, A., & Eggleton, P. (2003) Termite assemblage collapse along a land‐use intensification gradient in lowland central Sumatra, Indonesia. Journal of Applied Ecology. 40 (2). p380-391.

Jonsell, M. (2012) Old park trees as habitat for saproxylic beetle species. Biodiversity and Conservation. 21 (3). p619-642.

Jonsell, M. & Nordlander, G. (2004) Host selection patterns in insects breeding in bracket fungi. Ecological Entomology. 29 (6), p697-705.

Johnston, J. & Crossley, D. (1993) The significance of coarse woody debris for the diversity of soil mites. In McMinn, J. & Crossley, D. (eds.) Proceedings of the Workshop on Coarse Woody Debris in Southern Forests: Effects on Biodiversity. General Technical Report SE-94.

Jørgensen, D. & Quelch, P. (2014) The origins and history of medieval wood-pastures. In Hartel, T. & Plieninger, T. (eds.) European wood-pastures in transition: A social-ecological approach. UK: Earthscan.

Karban, R. (2015) Plant Sensing & Communication. USA: University of Chicago Press.

Kay, Q., Lack, A., Bamber, F., & Davies, C. (1984) Differences between sexes in floral morphology, nectar production and insect visits in a dioecious species, Silene dioica. New Phytologist. 98 (3). p515-529.

Kitahara, M., Yumoto, M., & Kobayashi, T. (2008) Relationship of butterfly diversity with nectar plant species richness in and around the Aokigahara primary woodland of Mount Fuji, central Japan. Biodiversity and Conservation. 17 (11). p2713-2734.

Koch, J., Grigg, A., Gordon, R., & Majer, J. (2010) Arthropods in coarse woody debris in jarrah forest and rehabilitated bauxite mines in Western Australia. Annals of Forest Science. 67 (1). p106-115.

Komonen, A. (2003) Distribution and abundance of insect fungivores in the fruiting bodies of Fomitopsis pinicola. Annales Zoologici Fennici. 40 (6). p495-504.

Komonen, A., Penttilä, R., Lindgren, M., & Hanski, I. (2000) Forest fragmentation truncates a food chain based on an old-growth forest bracket fungus. Oikos. 90 (1). p119-126.

Leather, S. & Bland, K. (1999) Naturalists’ Handbook 27: Insects on cherry trees. UK: The Richmond Publishing Co. Ltd.

Magura, T. (2002) Carabids and forest edge: spatial pattern and edge effect. Forest Ecology and Management. 157 (1). p23-37.

Molnár, T., Magura, T., Tóthmérész, B., & Elek, Z. (2001) Ground beetles (Carabidae) and edge effect in oak-hornbeam forest and grassland transects. European Journal of Soil Biology. 37 (4). p297-300.

Morales-Ramos, J. & Rojas, M. (2001) Nutritional Ecology of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae) – Feeding Response to Commercial Wood Species. Journal of Economic Entomology. 94 (2). p516-523.

Mori, S., Itoh, A., Nanami, S., Tan, S., Chong, L., & Yamakura, T. (2014) Effect of wood density and water permeability on wood decomposition rates of 32 Bornean rainforest trees. Journal of Plant Ecology. 7 (4). p356-363.

Müller, J., Noss, R., Bussler, H., & Brandl, R. (2010) Learning from a “benign neglect strategy” in a national park: Response of saproxylic beetles to dead wood accumulation. Biological Conservation. 143 (11). p2559-2569.

Norton, R. (1980) Observations on phoresy by oribatid mites (Acari: Oribatei). International Journal of Acarology. 6 (2). p121-130.

Niemelä, J., Koivula, M., & Kotze, D. (2007) The effects of forestry on carabid beetles (Coleoptera: Carabidae) in boreal forests. Journal of Insect Conservation. 11 (1). p5-18.

Owen, D. (1978) The effect of a consumer, Phytomyza ilicis, on seasonal leaf-fall in the holly, Ilex aquifolium. Oikos. 31 (2). p268-271.

Pearce, J., Venier, L., Eccles, G., Pedlar, J., & McKenney, D. (2004) Influence of habitat and microhabitat on epigeal spider (Araneae) assemblages in four stand types. Biodiversity & Conservation. 13 (7). p1305-1334.

Ramírez-Hernández, A., Micó, E., de los Ángeles Marcos-García, M., Brustel, H., & Galante, E. (2014) The “dehesa”, a key ecosystem in maintaining the diversity of Mediterranean saproxylic insects (Coleoptera and Diptera: Syrphidae). Biodiversity and Conservation. 23 (8). p2069-2086.

Rasmont, P., Regali, A., Ings, T., Lognay, G., Baudart, E., Marlier, M., Delcarte, E., Viville, P., Marot, C., Falmagne, P., & Verhaeghe, J. (2005) Analysis of pollen and nectar of Arbutus unedo as a food source for Bombus terrestris (Hymenoptera: Apidae). Journal of Economic Entomology. 98 (3). p656-663.

Schiegg, K. (2000) Are there saproxylic beetle species characteristic of high dead wood connectivity?. Ecography. 23 (5). p579-587.

Shigo, A. (1986) A New Tree Biology. USA: Shigo and Trees Associates.

Siitonen, J. & Ranius, T. (2015) The Importance of Veteran Trees for Saproxylic Insects. In Kirby, K. & Watkins, C. (eds.) Europe’s Changing Woods and Forests: From Wildwood to Managed Landscapes. UK: CABI.

Stokland, J., Siitonen, J., & Jonsson, B. (2012) Biodiversity in Dead Wood. UK: Cambridge University Press.

Thalmann, C., Freise, J., Heitland, W., & Bacher, S. (2003) Effects of defoliation by horse chestnut leafminer (Cameraria ohridella) on reproduction in Aesculus hippocastanum. Trees. 17 (5). p383-388.

Varady-Szabo, H. & Buddle, C. (2006) On the relationships between ground-dwelling spider (Araneae) assemblages and dead wood in a northern sugar maple forest. Biodiversity & Conservation. 15 (13). p4119-4141.

Vasconcelos, H., Pacheco, R., Silva, R., Vasconcelos, P., Lopes, C., Costa, A., & Bruna, E. (2009) Dynamics of the leaf-litter arthropod fauna following fire in a neotropical woodland savanna. PLoS One. 4 (11). p1-9.

Vasconcelos, H., Vilhena, J., & Caliri, G. (2000) Responses of ants to selective logging of a central Amazonian forest. Journal of Applied Ecology. 37 (3). p508-514.

Woodcock, P., Edwards, D., Fayle, T., Newton, R., Khen, C., Bottrell, S., & Hamer, K. (2011) The conservation value of South East Asia’s highly degraded forests: evidence from leaf-litter ants. Philosophical Transactions of the Royal Society of London B: Biological Sciences. 366 (1582). p3256-3264.

A wintry visit to Greenwich Park, London

Yesterday, as part of our monthly aim of visiting sites across the south east of England, a half-dozen strong group of arboriculturalists made the journey to London’s Greenwich Park – myself included. Indeed, as much of the park consists of deciduous specimens (principally, avenues of Castanea sativa and Aesculus hippocastanum), the park was rather bare in the foliage sense, though such barren canopies did allow us to appreciate the true magnitude of – most notably – some of the veteran sweet chestnuts. The frost-clad ground and crystalline sky provided a similar beauty, and thus we shall begin with one of the most iconic vistas from Greenwich Park – the city skyline.

As we stood adjacent to the observatory, we could admire – amongst the furor of tourists and scout groups – the sightly perverse beauty of a city. I say perverse, as such artificial and polluted landscapes don’t tend to suit those who don’t consider themselves urbanites, which includes myself.

Of course, we didn’t go there for the view, so let’s get into the main bulk of this account – trees and fungi. There’s no real order to how the below series of images rank, so don’t consider this post a chronological reflection of our trip!

Perhaps the best place in which to start the core section of this post are the huge sweet chestnuts, though we must begin on a rather sombre note. With a species of Phytophthora suspected on site and some of the older individuals exhibiting stunted and chlorotic leaf growth, there is a valid concern for the future of these veterans which is – without doubt – highly concerning. During the winter months, fully appreciating this contemporary issue is difficult, though we did spot some foliage on the floor that was certainly smaller in size than would be typically expected. Alas, this situation should not impact adversely on our admiration of these trees, and should in fact raise attention and draw intrigue to those within the industry and beyond, with an eye to ensuring we continue to care for the current and future populations of veterans. Therefore, promoting the Ancient Tree Forum and their most recent publication on ancient and veteran tree management is critical. And now, for some fine shots of various veterans!

This veteran sweet chestnut was the first one to greet us as we entered the park from the southern end. Not a bad induction!

As the city blocks paint the skyline to the right, we get a brilliant juxtaposition between the historic and the contemporary. In such a dynamic and ever-changing landscape such as London, this veteran sweet chestnut acts as a vestige of the old.

From another angle, the same sweet chestnut as above’s form can be more greatly appreciated. The helical patterns of the wood fibres and bark are as if they have been wound like rope.

This veteran has seen better days, though still stands proudly by the cafeteria. The ground beneath is woefully compacted, which must be having an impact upn the tree’s ability to function as a living being. Unlike the two shown above, it also doesn’t have a layer of mulch applied around its rooting environment.

Some of the veteran sweet chestnut we came across were also home to two annual common wood-decay fungi – Fistulina hepatica and Laetiporus sulphureus. Without doubt, the state of the fruiting bodies was not good, though when ravaged by time, wind, rain, frost and sun, to still even have a form is respectable! Certainly, a summer visit would have yielded a much greater haul of these two fungi on the sweet chestnuts, so a summer visit is probably on the cards.

One of Greenwich Park’s many veteran sweet chestnuts with an added extra – a small and rather weathered…

…you can see it…

…Fistulina hepatica! Picked off by parasitism before it reached a respectable stature, it still nonetheless produced a hymenium and thus likely produced spore.

A second sweet chestnut, this time slightly smaller, but again with Fistulina hepatica.

The state of it is, however, diabolical!

A smaller and thus younger sweet chestnut, in this instance.

It sports a fungal fruiting body, nonetheless!

A chicken of the woods, which is beaten and bruised.

Another smaller sweet chestnut, and another Laetiporus sulphureus.

Note how it emerges from behind a bark-covered area.

Again this sporophore is long beyond its best, though retains a little more dignity in the face of its impending crumble.

Away from the sweet chestnut, there was a variety of other large trees. Below, I share the ones that were home to fungi, through the identification of fruiting bodies. Absolutely, all trees on site are host to many species of fungi, though fruiting is not necessary in many instances, and it certainly costs the fungus energy to create and sustain. To begin, we’ll take a look at the ever-accomodating mature Robinia pseudoacacia in the park, which didn’t disappoint. In all, the population supported three species of wood-decay polypore, as we will see in the below images.

A very mature false acacia, with a very mature Laetiporus sulphureus fan on the main stem.

Well, sort of a fan – the remains of!

I imagine someone yanked this off, as it looks like a rather clean break.

Very close by, a second false acacia cradles another Laetiporus sulphureus.

Here, we can see how it’s at the base of the main stem, in place of higher up the structure.

This second one is far worse for wear!

A double-stemmed Robinia pseudoacacia, which was once at least triple-stemmed.

At the base, a senescent Perenniporia fraxinea and a cluster of broken active sporophores can be seen.

For good measure,here’s a better look at the entire bunch.

It’s a little disappointing that the fruiting bodies have been damaged, though that doesn’t stop them being Perenniporia fraxinea!

And a second example of Perenniporia fraxinea on this false acacia, too.

Right at the base, to the left.

This one appears slightly different to how it’d usually look (it’s not photogenic!).

Regardless, a showing of the trama reveals it as Perenniporia fraxinea.

It looks like the park managers are aware of the decay on this Robinia, as it has already been pruned!

If you look between the buttresses and into the basal cavity, you can spot a single Ganoderma australe. More were on the other side of the tree, though were old and worn.

With the sun behind the camera, this southern bracket looks rather pretty.

Steering attention away from false acacias, I now turn towards a focus on the brown-rotting polypore Rigidoporus ulmarius. With both horse chestnut (Aesculus hippocastanum) and beech (Fagus sylvatica) on the site, the chances are that there would have been a few examples of this fungus. Indeed, there were, as we will observe.

This first example, on horse chestnut, is an interesting one.

It’s the return of the cavity-dwelling Rigidoporus!

Away from the wrath of the elements, this sporophore doesn’t have the algal green stain atop and bathes in its own substrate.

A cutting identifies this specimen as Rigidoporus ulmarius, with the cinnamon tube layer and brilliantly white flesh.

The second horse chestnut sits in line for the toilets, patiently waiting for soneone to give it the 20p needed to get beyond the toll gate.

If you want, you can even sit down to inspect this tree!

This might well be this sporophore’s first season. I wonder how many more years it will see before it gets knocked-off or is aborted.

Half way up this steep hill, a beech stands seemingly without significant issue.

Oh, wait – here’s the issue!

Is that a shade of green?

From this shot, it looks most probably like Rigidoporus ulmarius. If so, we have two examples in one site of its cavity-dwelling abilities!

Greenwich Park also has a good number of large plane trees (Platanus x hispanica). The most abundant fungus on these trees was massaria (Splanchnonema platani), and there probably wasn’t a plane in the park that didn’t show at least some signs of its presence. However, it was the large plane with Inonotus hispidus that gained much of my eager attention, given I am not often around mature planes with extensive fungal decay.

A rather lofty plane tree.

As the crown breaks, we can spot a single Inonotus hispidus sporophore.

Whether there is an old wound at or around this site is hard to say, though for this fungus to be able to colonise one would expect so.

Perhaps an old branch stub above the fruiting body?

To round this post off, which has admittedly taken a long time to write, I’ll share some lovely images of a not-so-lovely bird – the parakeet (Psittacula krameri). Plaguing many of London’s parks and beyond, these things produce an utter cacophony and are certainly invasive, though one must admit that they are incredibly photogenic. Below, I share a few examples of where the parakeets were using cavities for shelter.

A horse chestnut monolith, seemingly vacant.

Wrong! Enter the parakeet(s).

This one stands proudly atop a pruning cut.

Along a plane tree branch, this parakeet appears to be guarding its abode.

“Oi m8, w0t u lookin’ @???”

A history of state forestry in Java, Indonesia

See part III of this series on state forestry in France here.

This phenomenon of the environmental and social misunderstandings of the peasantry and their forests can be further observed in Indonesia, and specifically upon the island of Java. This is because Indonesian state forestry practices began in Java with the State Forestry Corporation of Java in the 1870s, initiated by the Dutch colonial government, and emanated outward from the island into Indonesia more broadly.

The natural forests of Java have historically been a mix of a variety of tree species, including Altingia excelsa, Elaeocarpus macrocerus, Pinus merkusii, Tectona grandis, and Toona sureni. These forests have been the home of many millions of villagers, with their livelihoods being critically dependant upon the longevity and thus careful management of the forests and surrounding areas. Activities undertaken were rather similar to those undertaken in Uttarakhand, and in relation to construction teak (Tectona grandis) was the most favoured tree. Owned – pre-colonially – by Javanese kings and other elite individuals, villagers were permitted to use these forests under their decree, and often would there be a fair but entirely manageable (financial and free-labour) levy imposed on the villagers to maintain the functioning of the Javanese domains. However, because of the nature of forest communities, which were generally-speaking somewhat isolated from the king or other sovereign, villagers had a certain amount of freedom to ignore particular rules and regulations associated with their contract with the forest owner, though this of course varied with the extent of isolation – not that there were many limitations on how villagers could utilise the forest anyway, with only sparing and well-guarded royal forests and sacred groves being protected.

As far back at 1596, the Dutch, who would go on to rule Java from 1796, placed as important value on Javanese timber – notably teak. Javanese villagers, initially employed by the king or regional sultan under contract from the Dutch, though after 1743 generally directly employed by the Dutch, would harvest this timber, and sell it for purposes including ship building. Similar trade relations were also established with the Chinese. Subsequently, an informal ‘state’ forestry practice had actually begun centuries prior to the creation of the true state forestry department in 1865 (and the associated forest laws written between 1860-1934). However, the pre-colonial rule of Java was, as has been detailed, a relatively passive one, with villagers having a good degree of autonomy over their lives and forests. It was only when state forestry came into being, primarily for the cultivation of teak, that this began to drastically change, as the Dutch government sought to control and limit the relationship villagers had with their forests for the purposes of financial profit.

Notably, the tactics employed by the Dutch went about to usurp the villager and their relationship with the forest. In this sense, villagers had very little influence into the creation of teak plantations and felling operations, despite such operations having a sometimes quite drastic impact upon their livelihoods. One notable impact upon villagers, beyond the loss of forest cover, was their rapidly declining population of buffalo, for the buffalo were drafted by the Dutch to transport felled timber from the site of felling to the river or coast. Some of the largest teak trees, for example, required 80 buffalo to transport, and en route it was not uncommon for 10 of these buffalo to die. Because buffalo were used by villagers for cultivating land for agriculture, their population reduction had very real consequences for local food production.

An image, of unknown date, depicting two Indonesian workers felling a tree for its timber. Source: FAO.

By the same token, the environmental destruction associated with cleared forest areas, or even sparsely-forested areas after select trees were felled, had adverse impacts upon the lives of the villagers, and this occurred both before and after the onset of state forestry. The forest laws passed, notably those from 1860-1875, also saw large portions of land come under state ownership, which directly opposed cultural norms associated with villagers, in essence, owning the land surrounding their villages. These now state-owned areas were also policed, with quite harsh punishments for seemingly meagre ‘crimes’, which only became crimes – having once been customary villager rights – after the state itself detailed them as so under forest law. For instance, 45,000 people were arrested in 1905 for forest crimes, with most being for stealing wood – wood that was some decades earlier free to take.

Such changing of land ownership also limited the ability for villagers to farm in the surrounding landscape (by 1940, 3,057,200 hectares of land were state-owned), as did it hinder their ability to migrate to flee oppression and other undesirable circumstances, including excessive population growth and poor financial standing. However, with regards to farming, recently felled areas could be temporarily farmed (known as tumpang sari) by villagers with the permission of the state, for a period of between 1-3 years on average – the palette of crops was however limited to ones that would not have adverse impacts upon the trees regenerating within the area (usually teak or pine), either naturally or far more routinely artificially (from planted seed). Of course, this did mean that some villagers had to constantly follow the path of the forestry operations, in order to sustain their way of life; as did it sometimes require villagers to adhere to the demand of corrupt forest officials, who oversaw the allocation of tumpang sari land. Ultimately, the increasing levels of bureaucracy were alien to villagers, who were unaccustomed to such a myriad of regulations surrounding the use of forests.

A photo of a forester in central Java, taken between 1900-1940. Source: Wikimedia.

Such a situation was unfortunately only further exacerbated in World War II, when the Japanese took control of Java in 1942-1945 (Peluso, 1992). In this period state forestry operations, spearheaded by the Japanese Forest Service of Java, doubled in timber output compared to under the Dutch, and a ‘scorched earth’ policy by Dutch foresters and ransacking by Javanese villagers led to the forests deteriorating in quality quite massively in only three years – the effects are still observable today, in the landscape. Then, following Indonesian independence in 1949 (after four years of sometimes violent revolution), the new state only served to continue with state forestry operations (under the banner of the State Forestry Corporation), all whilst using the old Dutch laws (mostly almost verbatim – notably forest boundaries) and some of their foresters, albeit with recalibrated intentions that ‘better’ (a potentially malleable term, in this situation) served the nation’s populace.

In light of this, protest was certainly common from the late 1800s onward, and specifically from 1942-1966. The form a given protest took would however vary, with particular protests being non-violent (migration and ignoring the forest laws) and others certainly more violent (acts of crime, arson, and – more broadly – rebellion). Within the umbrella of protest, there are certain movements that deserve notable attention, however. One pertinent example is what was known as the Samin Movement, which was a social movement borne in 1890 but gained most notable momentum by 1907 when over 3,000 village families had adopted the ethos of the movement. This form of protest, founded by the peasant Surontiko Samin, was non-violent in approach and involved protesters purposely ignoring the instruction of state forest officials, for the purpose of safeguarding traditional customs of the Javanese villagers. However, because of the state’s pursuance of dissenting villagers, certain villager leaders did not support the movement, for fear of retribution if they did indeed show support. Therefore, some Saminists were exiled from their villagers, or excluded from communal practices.

A large teak (Tectona grandis) that the Samin Movement encouraged native Javans to utilise for their own needs, in place of supporting the Dutch forestry efforts. Source: Wikimedia.

Some decades later, during the second half of the 1940s (after the demise of the Japanese colonial government and at the inception of revolution, which itself ended in 1949), protests began to significantly rise in frequency and became far more organised, due to the adoption of a stance on forest politics by many political organisations. For example, in 1948, the Indonesian Communist Party and People’s Democratic Front attacked buildings and structures owned by the Forest Service, after it failed to amend forest policy in a manner that would more extensively benefit local people. These attacks caused rather extensive damage, and some main routes to transport timber were rendered impassable after bridges were destroyed. Two years prior, approximately 220,000 hectares of state-owned forest in Java was damaged (or destroyed) by protesting groups and individuals, and a further 110,000 hectares occupied by villagers and taken over or stripped for timber and firewood.

Alongside such protests, the Indonesian Forest Workers’ Union and Indonesian Peasants’ Front would support the villagers, in hope of returning Java’s forests to the people. In the few years following 1962, the Indonesian Forest Workers’ Union was most effective is achieving this aim of returning the state-owned forests to villagers; perhaps because nearly 25% (or 5,654,974 individuals) of the adult Indonesian peasantry were members. Granted, organisations did exist that were distinctly anti-communist, such as the Islamic Workers’ Union, who in fact battled with the Indonesian Communist Party over issues relating to state forestry. In the years immediately after 1964, the Islamic Workers’ Union was known to lead communist supporters into the forests of Java, shoot them, and then bury them in mass graves within the forest.

Following on from law changes in 1967, such protests generally begun to adopt a more clandestine approach. Because of the increasing militarisation of the forest service, notably with regards to its four different police forces, villagers were more fearful of reprisal if caught disobeying forest law. Stands comprised largely – or exclusively – of teak were most ferociously guarded. Granted, villagers did sometimes attack the armed police forces, and notably when the police forces were caught undertaking clandestine operations themselves, and also burned the state-owned forests of teak and pine (principally Pinus merkusii). At this time, the forest service also became more centralised, which further alienated a forest service from the villagers that, despite its now Indonesian-run state, reflected distinctly its Dutch ancestral roots, and diametrically opposed the traditional Javanese agrarian lifestyle. As a consequence of villager exclusion, the quality of the Javanese forests progressively declined over the decades because villagers had to resort to ‘theft’ to obtain what they could once gain on a subsistence basis (or to support black market demands for teak, in order to supplement the limited wages they would gain by working for the State Forestry Corporation on an ad hoc basis), which has contributed to sometimes quite severe environmental degradation. Such issues are still pertinent today.

Principal source

Peluso, N. (1992) Rich Forests, Poor People: Resource Control and Resistance in Java. USA: University of California Press.

Additional sources

Benda, H. & Castles, L. (1969) The Samin Movement. Bijdragen tot de Taal-, Land-en Volkenkunde. 125 (2). p207-240.

Boomgaard, P. (1992) Forest management and exploitation in colonial Java, 1677-1897. Forest & Conservation History. 36 (1). p4-14.

Colchester, M. (2006) Justice in the forest: rural livelihoods and forest law enforcement. Indonesia: CIFOR.

Galudra, G. & Sirait, M. (2009) A discourse on Dutch colonial forest policy and science in Indonesia at the beginning of the 20th century. International Forestry Review. 11 (4). p524-533.

Honna, J. (2010) The legacy of the New Order military in local politics: West, Central and East Java. In Aspinall, E. & Fealy, G. (eds.) Soeharto’s New Order and its Legacy. Australia: The Australian National University.

Korver, A. (1976) The Samin movement and millenarism. Bijdragen tot de Taal-, Land-en Volkenkunde. 132 (2-3). p249-266.

Lindayati, R. (2002) Ideas and institutions in social forestry policy. In COlfer, C. & Resosudarmo, I. (eds.) Which Way Forward?: People, Forests, and Policymaking in Indonesia. USA: Resources for the Future.

Lounela, A. (2012) Contesting State Forests in Post-Suharto Indonesia: Authority Formation, State Forest Land Dispute, and Power in Upland Central Java, Indonesia. Austrian Journal of South-East Asian Studies. 5 (2). p208-228.

Maring, P., (2015) Culture of control versus the culture of resistance in the case of control of forest. Makara Hubs-Asia. 19 (1). p27-38.

Peluso, N. (1991) The history of state forest management in colonial Java. Forest & Conservation History. 35 (2). p65-75.

Peluso, N. (1993) ‘Traditions’ of forest control in Java: Implications for social forestry and sustainability. Global Ecology and Biogeography Letters. 3 (4-6). p138-157.

Smiet, A. (1990) Forest ecology on Java: conversion and usage in a historical perspective. Journal of Tropical Forest Science. 2 (4). p286-302.

Vandergeest, P. & Peluso, N. (2006) Empires of forestry: Professional forestry and state power in Southeast Asia, Part 1. Environment and History. 12 (1). p31-64.

Trees and religion – Ancient Mesopotamia

See Part III of this series on trees and religions here.

As elucidated to previously (in the section on Christianity) in brief with regards to the goddess Asherah and the Canaanites, other cultures of the geographical region (encompassing the Levant, and the surrounding areas) that spawned the more contemporary religions that are Judaism, Christianity, and Islam, also had their associations with trees – associations that were much more direct, in terms of reverence.

For example, in the polytheistic Mesopotamian religions that spanned the Akkadian, Assyrian, and Babylonian empires, the goddess Ishtar, who was the goddess of fertility, was sometimes depicted alongside a sacred tree (Stuckey, 2002; Weinfeld, 1996). Inanna, the goddess of fertility in the earlier Sumerian empire, was also sometimes depicted alongside a sacred tree (Orrelle & Horwitz, 2016). This sacred tree was, in certain instances, palm-like (Stuckey, 2002; Orrelle & Horwitz, 2016). Perhaps, though by no means conclusively, like in the later monotheistic religions, Giovino (2007) writes, on the back of previous research, that this was the date palm (Phoenix dactylifera). This is supported by Altman (2000), with regards to the Assyrian cosmic tree being the date palm. The sacred tree of the Mesopotamian religions would also, in some instances, bear the fruit of the pomegranate (Punica granatum) (Parpola, 1993), as would it sometimes be used, by the Assyrians, to depict the generational family tree of their Gods (ranging from the upper tier of Aššur and Anu, to the middle and lower tiers of gods including Ishtar, Marduk, and Nergal). For the Babylonians, the Tree of Truth (synonymous with the Tree of Knowledge) and Tree of Life were also said to guard the eastern gate of the heavens (Altman, 2000).

The Assyrian Tree of Life. Source: Samizdat.

With reference to the cosmic tree (axis mundi) of the region’s religions, one can identify the outskirts of the city of Eridu, near to the delta of the Euphrates River, being host to the sacred tree of the Babylonians. As will be detailed later for other religions and their sacred trees, the river plays an important role in the location of the sacred tree, as the abyssal waters here were host to Ea (the god of life), and from this water did the earth become fertilised with life (Altman, 2000). In this sense, not only is the cosmic tree imbued with divine life, but from the roots of the this tree does all life obtain its support.

This cosmic tree also was the residence of the Babylonian’s primal mother goddess. For the earlier Sumerians, the cosmic tree, known as the huluppu (according to some sources this was a weeping willow – perhaps Salix babylonica), connected the underworld (Ereshkigal), the mortal realm (Enlil), and the heavenly realm (An), and was subsequently a symbol of life and renewal amongst the priest class (Altman, 2000; Kramer, 1972). Similarly, the tree was found on the banks of the Euphrates River, until being taken by Inanna to the city of Erech and planted in her garden. Here, Inanna hoped that it would grow tall so she could construct a throne from it, but it did not yield any new growth and it thus stood dead up until its demise at the hands of Gilgamesh and other inhabitants of the city (Kramer, 2010). After being felled, its timber was used to create an array of material goods.

Small statues of Asherah, the goddess of fertility in other ancient Semitic religions (as previously ascertained), have also been found in relative abundance, within the region. These statues, complete with upper body features including breasts and a head, are adjoined to a lower body that resembles a tree trunk (von Feldt, 2014). In the Ugaritic religion, there are similar depictions of deities and trees, with some artefacts showing trees emanating from the pubic region (or region between the navel and pubic area) of goddesses (including Athirat – known as Asherah, in later times), signifying again a divine association or similarity (in the conceptual sense) between trees and the mother goddess (Hadley, 2000; Sugimoto, 2012; Stuckey, 2002; Orrelle & Horwitz, 2016; Vidal, 2004; von Feldt, 2014).

The Epic of Gilgamesh, which was a prominent and lengthy poem of the cultures and religions of the Ancient Mesopotamian world, provides further reference to trees within the Mesopotamian region and its respective religions. In this poem, which does vary somewhat between the different Mesopotamian cultures (notably with regards to how Gilgamesh intends to establish his name in history and achieve immortality, after reaching the sacred forest), Gilgamesh and Enkidu task themselves with slaying Humbaba, the guardian of the near boundless primeval sacred cedar (Cedrus libani) forest as divinely appointed by Enlil (and where the gods and goddesses did reside – notably the goddess Ishtar), after Humbaba became enraged at the pair when Gilgamesh and Enkidu attempted to fell the sacred cedar that Humbaba embodied – in addition to other cedars within the forest (Cusack, 2011; Heidel, 1949; Lechler, 1937; Tigay, 1982). Humbaba exclaimed, in particular, that the sacred cedars were being desecrated and murdered by the pair (Kovacs, 1985; Shaffer, 1983).

Throughout the pair’s travel to the forest, and within it, the solar deity Shamash (Utu) aids them – albeit not initially – by appearing to Gilgamesh in his dreams (which Enkidu interprets), after Gilgamesh prays to Shamash every day for safe travels (which are granted) (Bilić, 2007; George, 2003; Harrison, 1992). Following the successful slaying of Humbaba (again made possible by Shamash), Gilgamesh and Enkidu proceeded to fell the cedars en masse, and use the timber for construction purposes within the largely treeless Mesopotamian region, including for the main door for the Temple of Enlil in Nippur (Harrison, 1992; Kovacs, 1985). Enlil was reportedly enraged by this act of killing Humbaba and felling the cedars, at least in the Sumerian version, and thus condemned Enkidu for the remainder of his life (Tigay, 1982).

The pair take battle with Humbaba. Source: Black Gate.

Whether or not the cedars themselves are any sort of main aspect of the Epic of Gilgamesh is questionable, though at the very least one can ascertain that the cedar forest was associated strongly with the gods, both because that was their home, and the fact that Enlil appointed a guardian to protect the cedar forest from the haunts of man. This guardian, according to Shaffer (1983), may have even potentially obtained its power from the cedars. Furthermore, the Old Babylonian Akkadian stone fragment of the tale cites the felling of the cedars as equating to that of murder, which suggests that the cedars were held in high regard. Such a high value of the cedar of Lebanon certainly extended to other religions of the world, as noted in earlier sections of this series.

References

Altman, N. (2000) Sacred Trees: Spirituality, Wisdom & Well-Being. USA: Sterling Publishing.

Bilić, T. (2007) A Note on the Celestial Orientation: Was Gilgamesh Guided to the Cedar Forest by the Pleiades?. The Journal of the Archaeological Museum in Zagreb. 40 (1). p11-14.

Cusack, C. (2011) The Sacred Tree: Ancient and Medieval Manifestations. UK: Cambridge Scholars Publishing.

George, A. (2003) The Babylonian Gilgamesh Epic: Introduction, Critical Edition and Cuneiform Texts – Volume II. USA: Oxford University Press.

Giovino, M. (2007) The Assyrian Sacred Tree: A History of Interpretations. Switzerland: Academic Press.

Hadley, J. (2000) The Cult of Asherah in Ancient Israel and Judah: Evidence for a Hebrew Goddess. UK: Cambridge University Press.

Harrison, R. (1992) Forests: The Shadow of Civilization. USA: The University of Chicago Press.

Heidel, A. (1949) The Gilgamesh Epic and Old Testament Parallels. 2nd ed. USA: The University of Chicago Press.

Kovacs, M. (1985) The Epic of Gilgamesh. USA: Stanford University Press.

Kramer, S. (1972) Sumerian Mythology: A Study of Spiritual and Literary Achievement in the Third Millennium B.C.. USA: University of Pennsylvania Press.

Kramer, S. (2010) The Sumerians: Their History, Culture, and Character. USA: The University of Chicago Press.

Lechler, G. (1937) The tree of life in Indo-European and Islamic cultures. Ars Islamica. 4 (1). p369-419.

Orrelle, E. & Horwitz, L. (2016) The pre-iconography, iconography and iconology of a sixth to fifth millennium BC Near Eastern incised bone. Time and Mind. 9 (1). p3-42.

Parpola, S. (1993) The Assyrian Tree of Life: Tracing the Origins of Jewish Monotheism and Greek Philosophy. Journal of Near Eastern Studies. 52 (3). p161-208.

Shaffer, A. (1983) Gilgamesh, the Cedar Forest and Mesopotamian History. Journal of the American Oriental Society. 103 (1). p307-313.

Stuckey, J. (2002) The great goddesses of the Levant. Bulletin of the Canadian Society for Mesopotamian Studies. 37 (1). p27-48.

Sugimoto, D. (2012) “Tree of Life” Decoration on Iron Age Pottery from the Southern Levant. Orient. 47 (1). p125-146.

Tigay, J. (1982) The Evolution of the Gilgamesh Epic. USA: University of Pennsylvania Press.

Vidal, J. (2004) The Sacred Landscape of the Kingdom Of Ugarit. Journal of Ancient Near Eastern Religions. 4 (1). p143-153.

von Feldt, A. (2014) Does God Have a Wife?. The FARMS Review. 19 (1). p81-118.

Weinfeld, M. (1996) Feminine features in the imagery of God in Israel: the sacred marriage and the sacred tree. Vetus Testamentum. 46 (1). p515-529.