09 de mayo de 2020

Some notes on negative impacts of "ecological restoration" observed and experienced

Restoration and conservation are the most delightful undertakings imaginable. It gives the utmost joy to pass the hours in a place of great beauty or great potential, using one's wits and body to work towards an increase in the good things one sees or has seen, and to reduce the bad things.

The outcome, however, is not always what we envisaged. It takes several years, sometimes twenty, to assess the full impact of people coming into a natural area, and the flow-on effects of increased numan activity, however well-intentioned or appreciative of the surroundings.

My experience and observation suggest weed control will result in loss of native species and habitat unless it is slow, careful and based on:

a) thorough plant identification and assessment of actual and future impact of weeds both positive and negative

b) careful staging of weed reduction

c) knowledge of manual techniques necessary to avoid chemical contamination of soil, plants, fauna incl. freshwater life and land invertebrates

(Google the effects of the breakdown products of poisons, not just the poisons themselves, some of which reportedly break down quickly in soil. water etc. The breakdown products of some popular herbicides are mobile in soil and water, and have been reported to be taken up by other plants and organisms over far greater area; in fact the extent of uptake appears to be unknown).

Any proposals to make or "upgrade" public access, paths etc, or to address weed invasion, must be met with vigorous scrutiny and undertakings to

a) provide a non-destructive surface (ie no loose metal or plastic)

b) clearly and actively prohibit channelling of water off the land into waterways or reticulation, (eg by rutting of trodden clay without organic swale above it, or by piping of runoff into the stream or reticulation to elsewhere)

c) avoid increased runoff due to removal of weeds without replacement ground cover, rearranging forest floor debris or other vegetation; instead, ensure retention of even small amounts of debris, by placing sticks, fallen fern fronds etc transversely across slopes, directing the path of droplets across the slope instead of downhill, allowing time for more water to be absorbed before running off.

Publicado el mayo 9, 2020 03:05 MAÑANA por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario

18 de junio de 2019

27 de febrero de 2019

21 de noviembre de 2018

Taurepo - guaranteed to die out?

I have seen Rhabdothamnus solandri every time I walked the Native Plant Trail at Kaipatiki Creek. Not a lot of it about, so always enjoyed as a treat - something "different".

I don't even know what the whole plant looks like, only the leaves.

So I knew it was uncommon but I didn't know what I learned today through following this observation https://inaturalist.nz/observations/18514135

then looking up the "About" for the species, (I looked it up only because I had an erroneous idea it went by a different common-name).

What I learned was the concept of extinction debt, with a handy link in the article to this Wikipedia entry:

Extinction debt
From Wikipedia, the free encyclopedia

"In ecology, extinction debt is the future extinction of species due to events in the past. The phrases dead clade walking and survival without recovery express the same idea.[1]

Extinction debt occurs because of time delays between impacts on a species, such as destruction of habitat, and the species' ultimate disappearance. For instance, long-lived trees may survive for many years even after reproduction of new trees has become impossible, and thus they may be committed to extinction. Technically, extinction debt generally refers to the number of species in an area likely to become extinct, rather than the prospects of any one species, but colloquially it refers to any occurrence of delayed extinction.

Extinction debt may be local or global, but most examples are local as these are easier to observe and model. It is most likely to be found in long-lived species and species with very specific habitat requirements (specialists).[2] Extinction debt has important implications for conservation, as it implies that species may become extinct due to past habitat destruction, even if continued impacts cease, and that current reserves may not be sufficient to maintain the species that occupy them. Interventions such as habitat restoration may reverse extinction debt.

Immigration credit is the corollary to extinction debt. It refers to the number of species likely to immigrate to an area after an event such as the restoration of an ecosystem."

What can I say, except that it gives even more joyful purpose to hand-weeding, and dictates even more observation and care.

Publicado el noviembre 21, 2018 01:25 MAÑANA por kaipatiki_naturewatch kaipatiki_naturewatch | 0 comentarios | Deja un comentario

23 de agosto de 2018

Queen palms...are they a Plant Pest?

Having observed the large number of immense fruiting palms in the neighbourhood ...Queen, Phoenix, Bangalore, Chusan, Fan....we are keeping a sharp eye out for all kinds of exotic palm seedlings, and studying observations of exotic palm seedlings growing wild, ie from seed fallen or spread by birds.

Our observations of several very large Queen palms in the neighbourhood of Eskdale Forest and Kaipatiki Creek led us to Jon Sullivan's historic observation of the 2002 discovery of 71 Queen palm seedlings under a taraire in Vaughan's Nature Walk, Long Bay Regional Park, during a weed survey by its Council managers.


Elsewhere, someone commented that exotic palms are not considered a pest plant because they now occur in any neglected garden, or anywhere lawns are unmown.

Which is a good starting point to understanding what a pest plant, or weed, is, and why ecological restoration in NZ means, primarily, weeding.

If the lawn is mown, or the neglected garden-bed weeded, or the unwanted tree cut down while young, the plant is not a pest.

North Shore forest remnants and margins, streamsides, beach and estuarine plantings, public walkways, schools, roadside berms and residential properties, are mostly now essentially "neglected gardens", reecieving at best an annual once-over with chemical treatment of the largest invasions of the fastest spreading weeds.

The budget doesn't cover removing seedlings and young trees and shrubs, some of which reproduce themselves in a few years, creating thousands more invasions.

Only highly publicly visible amenity plantings and a few residences (those with long-term tenants with the necessary resources and plant knowledge to maintain a garden) receive regular survey and weed control, and even these contain largely exotic plants, many of them invasive and contributing to the problem in natural areas.

The results of weed control at home or in reserves reflect the awareness of the gardener or contractor of the invasion of wild exotics, their plant identification skills, and their understanding of the site as a whole.

Exotic palms, like wattles, pine and tree privet, grow to maturity much more rapidly than the natives they replace. Once exotic trees are mature it is rarely possible to control them, due to the expense of arborism, compounded by the resource consent required for any tree over 4m high.

North Shore Auckland now has thousands of exotic invasive trees in native habitat, and a tiny budget with which the managers of public land must choose which bits of natural heritage to attempt to protect, through the necessary but expensive regular survey and maintenance.

So exotic palms are a pest indeed.

Publicado el agosto 23, 2018 08:42 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 2 comentarios | Deja un comentario

31 de julio de 2018

"Weeds can protect habitat"...

  • observed @jon_sullivan in a recent Observation on Horseshoe Lake Reserve, Burwood, Christchurch.

Our experience in public reserves in the Kaipatiki area of North Shore Auckland leads us to agree wholeheartedly. It's one more reason to think carefully when planning intervention.

The most diverse habitat we've seen in the Birkdale/Glenfield neighbourhood was for decades used as an illegal dumping ground, with the most diverse remnant vegetation and natural regeneration hidden, protected from trampling and from most weeds by the rubbish and weeds on the outside.

Sadly, weeding the outer, visible margins of the area, along with construction of a walkway through the forest interior, made the public Reserve attractive and thus popular.

It became for a while a popular place to walk. Most people caused no damage, but cycling and jogging in winter rutted the path, making it boggy when wet, and then people began to walk on the revegetating path edges to avoid the mud.

The increased popularity of the site attracted Council budget allowing the felling of a mature pine on the roadside margin. The resulting loss of shade, without resources to monitor and weed that previously shaded streambank, allowed kikuyu invasion, followed by Japanese honeysuckle, ginger and Moth plant, inaccessible down a steep bank.

Freeing a large area of streamside from Pink Jasmine along the road edge allowed directly access into the bush from about 40m of roadside footpath. For reasons as yet unknown, little revegetation has occurred in this area in the 20 years since jasmine removal.

Hopefully we can learn to avoid the potential negative impacts of weeding by strategizing weed control, through thorough planning of pedestrian-only, low-impact, minimal-width sustainable paths, maintained by users adding dead ponga fronds and fallen wood that are usually within easy reach and break up easily.

Awareness of the damage caused by jogging and cycling on wet clay paths could be achieved through public education including pictorial signage, and the frequent presence of Site Curators/Kaitiaki/visitor guides in each natural heritage reserve.

Publicado el julio 31, 2018 11:25 TARDE por kaipatiki_naturewatch kaipatiki_naturewatch | 5 comentarios | Deja un comentario