L20: Baselines and Resilience I

Question 1

Where are baselines (or ‘reference’ conditions) frequently derived from?

Answer 1

From historical literature or from palaeoecological studies based on biological proxy, fossil or sub-fossil evidence (Willis et al 2010, Gillson et al, 2011).

Question 2

Recent work within restoration ecology has highlighted that ecological history is important for what?

Answer 2

Not only to determine the degree of change that has occurred from baseline reference conditions, but also the level of intervention required to restore an ecosystem that has been modified by human impacts to a more naturally functioning state.

Question 3

Conservation practitioners and policy makers highlight the need to develop ‘biodiversity baselines’ to measure what?

Answer 3

Changes in biodiversity over time and the effectiveness or otherwise of conservation strategies.

Question 4

The palaeoecological record can help to distinguish between what?

Answer 4

‘Normal’ ecosystem fluctuations and unprecedented degradation and thereby enable recognition of potential thresholds for concern.

Question 5

Understanding how ecosystems responded to past climate change and disturbance can help in predicting what?

Answer 5

How ecosystems might change in response to present-day global warming, and in evaluating the outputs of climate–vegetation models through the reconstruction of known past climate events.

Question 6

Many ecologists argue that the concept of baselines is problematic, because of what?

Answer 6

Most ecosystems are spatially and temporally variable!

Question 7

The complexity of managing ecosystems (specially islands) varies depending on what baseline is used:

Answer 7

1) a functioning and biodiverse ecosystem
2) a particular cultural landscape
3) a pre-human ecosystem when it was uninhabited (relevant for islands)

Question 8

Where in conservation management the concept of baseline is important?

Answer 8

1) Design of protected areas
2) Fragmentation (Lecture 19)
3) Restoration
4) Translocation
5) Rewilding

Question 9

Information needed in order to restore to the (pre-human?) baseline

Answer 9

1) Determination of the reference’ conditions baseline.
2) Determining the degree of change from reference
conditions.
3) Identification of main factors of change (e.g. climate and/or humans)
4) Is it feasible to restore?

Question 10

Case study -Wildfires in La Gomera, 2012

Answer 10

The fires burnt 18% of the 4000 ha of Garajonay National Park.
Widely reported as an ‘ecological disaster’ and a ‘severe threat to a UNESCO World Heritage area’.

2012, the summer season was one of the driest registered.
6 heat waves (temperatures above 30 oC and relative air moisture below 20%) from the Sahara.
Low rainfall rate along the previous winter and spring.

Question 11

Past Climate change in Garajanoy National Park

Answer 11

HUMID
Rapid respond to moisture-balance variability
Laurel forest taxa along with Phoenix canariensis and Salix canariensis EXPANSION

DRY
increase of the Macaronesian heath community together with a gradual loss of laurel taxa may be expected.
Increasing fire events and the opening of the forest

Question 12

Conclusions form La Gomera

Answer 12

• Low frequency of fires for the past 10000 years
• Fire events suggest a climatic shift as regional fires reached their maximum at 4800 cal.yr BP
• Local fires increase at 3000 cal. yr BP. Human arrival?

Question 13

Example 1: Laurel forest in La Gomera

“Palaeo results and baselines”:

Despite the presence of people for several thousand years…

Answer 13

…there was little impact on the Laurel forest.
No evidences of selective forest clearance, intensive grazing, and plantations.
The immediate challenge to the management it might not be the approach of climate change, but the environmental pressure by growing population and fire management (+23% since 2000).

The current management strategy: controlling leisure activities in the park -probably the correct strategy-

Question 14

Example 2: Easter Island- Pre-human arrival diversity

Answer 14

Easter Island, primarily covered by grasslands, but palaeoecological studies have shown the former presence of Dianella- native to Easter Island! Dianella cf. intermedia/adenanthera
(Xanthorrhoeaceae): grew and disappeared at the Raraku site long before human arrival.

Much of its original biota has been removed during the last two millennia, most likely by human activities, and little is known about the native flora!
Macrofossil and pollen analyses of a sediment core from the Raraku crater lake have revealed the occurrence of a Dianella cf. intermedia/adenanthera

Question 15

Example 2: Easter Island- Current distribution of Dianella

Answer 15

Dianella is currently extinct from the island!
The occurrence of Dianella within the Raraku sedimentary sequence (between 9.4 and 5.4 cal. kyr B.P.) could have been linked to the existence of favorable palaeoenvironmental conditions (peatland rather than the present-day lacustrine environment) during the early to mid Holocene

Question 16

Example 2: Easter Island- Conclusions from the island

Answer 16

This finding contributes new knowledge about indigenous plant diversity on Easter Island and reinforces the usefulness of further macrofossil and pollen analyses to identify native species on Easter Island and elsewhere.

The risk of applying inappropriate management to what are in fact native species is highlighted by these results. Paleoecology also has wider implications for the classification of invasive species throughout the Pacific Islands.

It is probable that these species are native to other regions in the Pacific where they may have been classified as non-native and also that there may be other presumed invasives that have been incorrectly designated.

Question 17

Appropriate fire management, restoration, eradication, and/or monitoring programmes in island ecosystems require:

Answer 17

1) to consider the impacts of multiple human arrivals (and colonization) through time. Multiple baselines.
2) the accurate determination of species’ provenance e.g. is a species native or introduced, and therefore identified for potential eradication or conservation?
3) providing a temporal framework for the examination ecological changes, with a special focus on island biodiversity conservation.