Woodland Conservation Management

With only a couple of weeks left of my Ecology, Conservation and Habitat Management course, it is the latter, Habitat Management that I have been reading up on recently and more specifically, it is Woodland Conservation Management that I have been particularly interested in.

Woodland is extremely rich in species, but unfortunately every single one cannot be individually managed.  Certain groups of plants and animals however have become the main focal points for woodland conservation management, as they ultimately benefit many other species.  Some of the main species may use a range of habitats for example, or may even be very rare and specialised, which are equally as important.

So what are these groups and management plans?

Tree communities

There are around 54 types of tree community today in ancient woodland, and most are genetically the direct descendants of the original trees that grew.  Trees of the same type can be found in all areas of Britain, but no one individual tree will harbour all of the insect/lichen/bird/fauna species that are known to be associated with that type, or even the woodland it is in.  This is due to climatic and geographical variations in different areas of Britain.

To maintain the variety of trees and therefore species that benefit from them, it is important that semi-natural tree communities are managed through natural regeneration (the growth of trees that develop from seeds that fall and germinate on site) and/or by planting new trees of local provenance.

Ground flora

Like the tree communities, ground flora varies greatly from one woodland to another due to location variations and actually tends to be more abundant and concentrated in ancient woodland than in newer woodland.  However, the isolation of ancient woods, could in fact lead to the extinction of some plant and invertebrate species (particularly those with poor mobility), so it is important that such species are encouraged to colonise or re-colonise to avoid extinction from habitiat deterioration.  Open spaces and development of young growth are both vital for certain species.

Epiphytic flora and fungi

Plants that grow harmlessly upon another plant and derive moisture and nutrients from the air, rain, and sometimes from debris are called epiphytes, and many mature trees in relatively unpolluted parts of Britain carry an interesting and huge array of epiphytic flora and fungi (including more than 70 species of lichens alone).  Particularly in the west of the country, these epiphytes are very rich and resemble those that lived in the original forests.

Epiphytes need to be conserved with methods such as partial-cutting to ensure that the mature tree communities they grow on remain in particular woodland sites and continue to naturally regenerate.

Small mammals

There are several small mammals in British woodlands that are rare and thankfully protected, and one of these is the Dormouse.  The Dormouse is an elusive nocturnal mammal which can be found mainly in woodlands in the southern counties of the UK. Over the last 100 years its distribution has declined and it is now extinct in 7 counties where it previously existed. This is mainly due to changes in woodland management and habitat fragmentation.  They feed on a combination of plant materials including flowers, fruits and nuts as well as insects, so it is important to manage sites specifically for them or any other rare species.  Good management will help increase numbers and make the site more ‘valuable’.

Management for small mammals must include the provision of nest-boxes, tracking and surveying, coppicing and the encouragement of mixed species in the woodland to ensure good food supplies.

Birds

Although birds are different to most other woodland groups in terms of being very mobile, woodlands still have to be managed to ensure a range of birds benefit.  Some species prefer mature, native trees or depend on dense close-canopy scrub, whereas others are associated with replanted areas.

Woodland management for birds is therefore concentrated on maintaining a mixture of age classes, by reducing the amount of old habitat deterioration and creating new suitable habitats.

Butterflies and moths

Many woodland butterflies and moths inhabit areas of young growth where nectar sources and food-plants for their larvae can be found.  There has been declines in several species for many years however, and this is due to many things including woods becoming isolated which in turn weakens the ability for colonisation, as well as a reduction in coppicing which would produce new growth.

Understanding the complex life cycles of butterflies and moths provides an insight into what they need from woodland habitats and could provide the answer to effective conservation.  Each stage may require a different habitat, from sheltered, warm places to areas that are plentiful in food sources, so management must concentrate on providing nectar-rich areas and suitable habitat for egg-laying and larval development.

Saproxylic invertebrates

These animals depend on dead, decaying or living wood and fungi to survive, so it is important that areas of mature trees, or even individuals are maintained and protected, to avoid dead wood being removed which would ultimately reduce or destroy the specialised habitats of many saproxylic invertebrates, including beetles and flies.  Populations of such species rely on old wood being in a specific condition, so it is vital at these sites that the continuity of prime wood and trees is considered.

 

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Mutualism and Parasitism

Over the last three weeks, I have been introduced to the world of Abiotic and Biotic interactions.  I have an interest in the different behaviours and relationships of organisms so found these particular topics highly fascinating.

Mutualism

Association between individuals of two species for mutual benefit.

Now, I have seen many examples of mutualism documented on television, but up until now have never really researched this relationship.  There are countless mammals, birds, insects, plants, fungi, bacteria etc which interact with one another symbiotically.  One of the most obvious mutualistic relationships is the interaction between pollinators and flowering plants.  The plants gain by having their pollen transferred from one flower to another and the pollinators gain a reward of nectar.

An example of mutualism that I found through my research is between the Oxpecker bird and Rhino or Zebra.  The Oxpecker will land and sit on the Rhino or Zebra, where it will eat ticks and parasites off their skin.  The bird gains food and the mammal gains a personal ‘pest-controller’.  Another interesting point is that the Oxpecker will also fly upwards and call a warning sound if in danger, which of course also benefits the Rhino or Zebra.

Mutualism is a +/+ relationship and Ecologists describe Biotic relationships in terms of who benefits and who loses…

+ signifies that one party benefits

– signifies that one party loses

0 signifies that one party is unaffected

Parasitism 

A relationship between two organisms where a parasite gains from a relationship with its host.

Whereas mutualism is a +/+ relationship, parasitism tends to be +/- or +/0 relationship.  Initially the host may not be affected, however as a parasite continues it’s aim of gaining nutrients, a favourable environment or even the use of biochemical processes, the host inevitably suffers and dies once the parasite has reproduced.

One particular +/0/- interactions that I find to be the perfect mix of both amazing and disturbing is the Green-banded Broodsac, Snail and Bird cycle!  The ultimate goal of a Green-banded Broodsac parasite is to live inside the warm interior of a bird and feed off it. The larvae of this parasite live in bird droppings, which is eaten by snails. Once inside, the parasite grows and moves through the snail, protrudes out through the eyes, develops green bands like a caterpillar and pulsates in a similar way to a caterpillar. The parasite even manages to control the brain, making the snail move to somewhere noticeable.

Birds are consequently fooled into seeing two caterpillars and thinking they are getting a double snack, eat the snails’ eyestalks and therefore the parasite. The larva moves into the birds interior, lives and breeds… the bird then passes out the eggs in it’s droppings and the cycle continues.

Green-banded Broodsacs benefit – they achieve the goal of a warm interior and food for reproduction.  Birds gain a small meal but nothing much else (they apparently do not mind the parasite’s presence).  Snails infected with this parasite often live longer than snails that do not have it, but other than gaining a meal, the snails lose as they are ultimately turned into ‘zombies’.

Parasitic plants

As defined earlier, parasitism is a relationship between two organisms, and this of course includes plants.  There are over 4,000 species of parasitic flowering plants in the world – the most famous probably being Mistletoe, but after some interesting reading, I discovered the ‘Corpse flower’.  It is the largest individual flower in the world and is found in the forests of Malaysia and Indonesia.  It is nearly 1 meter in diameter and weighs up to 11 kg. As the name suggests, the corpse flower smells like rotting flesh in order to attract carrion-feeding flies as pollinators, whilst it’s sticky fruit is spread by rodents.  It cannot photosynthesize on its own, so being a parasite, steals it’s nutrients from the roots of neighbouring vines!

Do you know of any other interesting parasites or mutualistic relationships?