Assessment of tree vitality as an indicator of monitoring the health condition of community forest in agroforestry patterns

Management of forest health in a forest population incorporates the health of individual trees (Cavers 2015). Therefore, it is important to pay attention to the death of each tree because it can lead to a decrease in the population level. One of the important indicators that function as a notification system to maintain forest sustainability is the damage experienced by trees (Fuller and Quine 2016).

Based on the observations, 13 tree species were found in all cluster plots. The trees found were damaged in individual cases. Damage to trees is measured based on damage location, type of tree damage and serious illness. The species and number of trees that were damaged are presented in Table 3.

The types of damage that occurred were quite varied. Based on the observations that the tree damage was found in the roots, stems, branches, shoots and leaves. The characteristics of the appearance of attacks on a tree, as seen from the colour, size, shape and texture, can be a sign to identify a type of tree damage (Safe’i et al. 2020). The most common types of damage that occur are presented in Figure 2.

Figure 2

With the application of the FHM method, there were 259 trees in the entire FHM plot cluster, which were measured for the vitality condition of the trees. As seen from Figure 2, 14 types of damage are found on trees in community forest land with agroforestry patterns. The type of tree damage that is most likely to occur, ranging from leaf damage to broken branches to open wounds, is followed by the type of tree damage, as shown in Figure 3. Tree damage is the result of disturbance to trees caused by pathogens, insects, air pollution, natural conditions and human activities (Coulston et al. 2005). Insect pests and pathogens have a major role in causing tree damage (Bałazy 2020).

Figure 3

Damage to leaves became the type of damage with the highest percentage, at 25.29%. The damage found on the teak (Tectona grandis) tree occurs due to pest or disease attacks. Damage to the leaves is found in the form of hollow leaves and discoloured leaves. Symptoms of this type of damage are marked by the condition of the leaves, which are no longer green, turn yellow, fall off and also have holes due to pests (Safe’i et al. 2021).

The type of damage that occupies the second category is damage to branches in the form of broken branches. Damage was found on the jengkol tree (Achidendron pauciflorum) with an incidence percentage of 24.41%. This type of disease is characterised by symptoms of loss of twigs and leaves, and it seems as if there is weathering of dead branches. The condition of broken branches can occur due to the condition of weak or rotten branches. Destroying fungi and pathogens that attack can cause branches to become weak and rotten (Abimanyu et al. 2019). This will cause the tree's health to decline.

Open wounds were the third worst damage found on petai trees (Parkia speciosa) with an incidence of 23.24%. Open wounds can be caused by the activity of the tree itself or by human intervention. Open wounds are characterised by peeling tree bark (Safe’i et al. 2020). Owing to the peeling of the tree trunk, the damage becomes the starting point for the entry of pathogens into the interior of the trunk, causing further damage to the tree and decreasing tree health.

Overall, the tree damage assessment is seen in the tree damage index that occurred. The tree damage index calculation accumulates the three tree damage assessment parameters, consisting of damage location, type of tree damage and serious illness. In more detail, the damage index value that occurs in each FHM plot cluster is shown in Table 4. Table 4 shows the CLI value for each cluster plot FHM.

At the cluster plot level, a cluster that has a higher level of tree decay is indicated by a higher CLI value (Safe’i et al. 2019). The results presented in Table 4 show that the damage to trees in the high category is found in cluster plots 2 and 3. Moderate damage is found in cluster plots 1, 5 and 6. Meanwhile, in cluster plots 4 and 7, the damage is in a low category. Therefore, the average level of tree damage in a community forest with agroforestry patterns can be in the moderate category. The level of tree damage is influenced by three parameters measuring that damage location was found, type of tree damage and the serious illness. The type and part of the tree that cause worse impacts will also cause a higher level of damage (Widodo et al. 2022). Various tree damages have also occurred due to several environmental factors that influence it (Safe’i qand Upe 2022). Tree damage can be identified as the cause to provide valuable information so that it is possible to prevent or overcome the occurrence of further damage (Randolph et al. 2021).

The level of damage according to the different CLI values for each cluster results in different health values, meaning that tree damage plays an important role in improving forest health (Safe’i et al. 2021). If there is a lot of damage with a value above the serious illness threshold, it will ultimately affect forest health conditions (Safe’i et al. 2022). It is necessary to take maintenance action to overcome tree damage, such as pruning or eradicating pests and diseases that have attacked trees. To be more effective, the causes of the damage need to be adjusted. Therefore, to maintain good forest health conditions, good management needs to be carried out with proper and good maintenance activities (Safe’i et al. 2021).

In monitoring forest health, an assessment of the condition of the crown is important to determine the state of its vitality (Safe’i et al. 2022). Paying attention to canopy condition is important because vitality is expressed in a tree's ability to regenerate damaged crowns as a tree's growth potential (Czapski et al. 2015). The crown is the location for gathering leaves that play an important role in the photosynthesis process to support tree growth. The results of the assessment of the crown condition obtained the value of the crown appearance rating (VCR), which is the accumulated calculation of the five measurement parameters of the crown condition assessment. The VCR value for each cluster plot is presented in more detail in Table 5.

The more the VCR rating value shows, the better the crown condition. The results shown in Table 5 show that forest stands with good crown conditions based on the high VCR category value are in clusters 4, 5 and 6. Clusters 2 and 7 are in the moderate category, while crown conditions with low categories are in clusters 1 and 3. The five parameters for assessing the condition of the tree crown will determine the value of the VCR obtained.

This issue is consistent with the findings of Puspita et al. (2021) research, which found that conditions have a strong and significant relationship with forest health conditions. VCR high value indicates a normal crown condition. A normal crown condition is characterised by a good physical condition of the crown (Zarnoch et al. 2004). For example, a high VCR value is due to the large diameter crown, which makes the crown wide and dense so that the density is high. This shows that trees have a large number of leaves available for photosynthesis. The high density of the tree crown indicates a dense crown cover. This supports the photosynthesis process to help provide the needed nutrients. Meanwhile, bad crown condition shows that the crown has high transparency due to poor foliage caused by damage from pests, diseases or environmental factors such as drought and poor competition between plants.

The high crown conditions make the forest much healthier. This issue is consistent with the findings of Puspita et al. (2021) research, which found that conditions have a strong and significant relationship with forest health conditions. Good crown conditions make the tree able to carry out its functions optimally, which means the physiological tree is in a healthy condition so that tree growth will also be optimal. Farmers need to increase their attention to the condition of forest vitality to improve the process of tree growth in community forest lands for more optimal benefits. This is following the desired sustainable forest management because the goal is to efficiently utilise the typological capacity of the forest and its formation into highly productive and biologically sustainable stands (Yuriy et al. 2021).