We now have data up to July 2014, this will be available soon

Volunteers from the Woodland Trust and HNHS have set up a Heartwood Monitoring Group to record the changes in habitat and wildlife as Heartwood Forest develops.
This page has all the results of the work to monitor survival and growth of the newly planted trees.
Information on the studies to monitor the changing flora and fauna can be found on the Heartwood Project pages. 

Sapling Survival and Growth

Survey Methods

At the start it was essential to devise a strategy to select a random sample of saplings for survey. After preliminary investigations we decided to measure all saplings within 5m radius circles from randomly selected sample points. At each point all saplings within 5m were located, identified to species, scored as alive, dead or missing, their height measured to the nearest 5cm and the evidence of top browsing assessed. The pre and post planting treatments of individual saplings were recorded as follows; no treatment, weed killed patch, spread straw, straw bales, protective tube and natural regeneration.

In the first year (September 2010) it was important to ascertain whether the methods selected for ground preparation, planting and post planting treatment would achieve the required level of sapling survival. So 51 sampling points were selected spaced on a 100m grid over the whole area planted in the winter 2009/10 and surveyed by Ken and Linda Smith. The grid points were centred on the 100m intersections of the Ordnance Survey grid and were located using a handheld high sensitivity GPS receiver. For the natural regeneration area we distributed points throughout with the aim of including a wide range of distances from the existing wood which was thought to be the most likely seed source.

This density of sampling points was not necessary or sustainable, so in the second and subsequent years the monitoring regime was adapted. Eighteen of the sample points in the 2009/10 planting area were retained together with two in the natural regeneration area and 18 sample points were selected in the areas planted in 2010/11. All were marked with wooden posts, see the map below. The monitoring method remained the same and Ken and Linda were joined by Brian Legg, Tim Wright and Chris Shortall. Sampling will be extended into new planting each year.

Results

Numbers of dead stems in the planted areas

In August 2010 a total of 962 saplings were checked at 51 points in the areas planted at that time: Verulam, Guinness (World Record Attempt), Witchels, Daily Mail Wood, Sunday Times Wood and Magical Wood (part), see Map3. Of these, 230 (23.9%) were dead or missing; giving an overall survival rate of 76%. The percentage dead varied greatly between species with Salix sp (53.8%), Hazel (24.3%), Oak (23.4%) and Hornbeam (21.1%) the highest and Crab Apple (4.3%), Rowan (6.3%) and Ash (8.3%) the lowest. It was often impossible to determine the species of dead stems so these were recorded as unknown species.

As well as the variation between species there were big differences in the survival of saplings between zones. Saplings had survival rates of 94% or better in three zones (the fenced exclosure and the ‘tubed’ area in Verulam, to the southwest of Langley Wood and the Sunday Times Wood); but survival was 70% or worse in the four other zones (the Guinness 'world record attempt' area to the west of Langley Wood, the ‘tubed’ area adjacent to the railway line, the Daily Mail Wood, and the Magical Wood). The low sapling survival in these four zones did not seem to be related to the species mix. For the most numerous species, Oak, the pattern of low survival matched well with the overall pattern. It seemed more likely that the low survival was related to the nature of the ground and its preparation and the quality of the planting.

The effects of different planting treatments

In the Guinness, World Record Attempt area a variety of planting treatments were employed; part straw bales, spread straw plus herbicide, herbicide alone and no apparent treatment. We examined the data to look for differences in browsing level and survival of saplings with these different treatments (Table 3). There is no evidence to support the idea that, in this zone at least, there was any effect of planting treatment on survival or browsing levels.

Table 3. Sapling survival and browsing levels under different planting treatments in the Guinness zone at August 2010.

Treatment

Total No of saplings

Dead or missing

Live saplings browsed

 
 
No.
%
No.
%
Straw bales
156
42
26.9
36
31.6
Straw + herbicide
16
5
31.2
1
9.1
Herbicide
99
32
32.3
17
25.4
None
21
8
38.1
6
46.2

Evidence of browsing

There was considerable evidence of browsing of unprotected stems but usually of low side branches. We recorded the number of saplings showing evidence of browsing of the tops which would be expected to have a negative impact on the stature of the plant and the speed with which it can grow through the period of susceptibility. For living stems there was considerable evidence of browsing except where the saplings were protected by tubes. Overall, a higher fraction of dead stems were top browsed than live ones; 68.3% for dead stems compared with 20.0% for live ones.

Natural regeneration zone

Fourteen sample points were placed in the natural regeneration zone (to the southeast of Well and Pudler's Woods and now called 'The Thicket') and the numbers of stems counted within a 5m radius of the point in exactly the same way as the points in the planted areas. This area appears to have been tilled in 2008 and been seeded naturally from the adjacent woods. Ash was by far the most common species (215 stems) but there were also significant numbers of Hornbeam (67), Oak (18) and Birch (11). Bramble, Crab Apple, Field Maple, Blackthorn were also found in the sampled areas. The stem density was much higher than in any of the planted areas at over 3200 per Ha. Although the numbers of saplings at individual points was variable, there was a significant decline in the numbers of saplings with distance from the existing woodland (regression of log10(numbers of saplings) against distance, F1,12=4.97, p=0.046, Figure 1) such that numbers halved at about 50m from the wood.

Sapling monitoring - second and subsequent years

The Woodland Trust used the experience of the first winter planting and sapling survival results to modify the planting regime in the second and third years. Planting direct into stubble or tilled land was favoured and straw mulching discontinued. To combat the high losses due to browsing by hares, deer and rabbits some areas were enclosed by rabbit proof fences, plastic protective tubes were used in key areas and the specimen fruit trees in the orchard area were protected by deer proof wire cages.

The results of the monitoring at the 38 permanently marked points is summarised below.

Survival of saplings by year in the areas planted in 2009/10 and 2010/11 and number of saplings in the sample plots in the seeded and regeneration areas.

Year planted
Date measured

Number of plots

% survival (n=18)

No. stems per plot (average)

Trees/ha
Saplings 2009-10
Aug 2010
18
77%
14.3
1,820
Sept 2011
18
82%
14.4
1,830
Saplings 2010-11
Sept 2011
18
68%
14.3
1,820
Seeded plots 2010-11
May 2011
1
 
98
12,500
Natural regeneration
Aug 2010
2
 
61
7,800
May 2011
2
 
100
12,700

In both years the survival rate was highly variable. For the 2009-2010 plantings the variation was probably caused by poor planting in some areas and losses due to browsing. For the 2010-2011 plantings the low survival was almost certainly caused by dry conditions in spring affecting the later plantings.