Evaluating Plantation Forest vs. Natural Forest Regeneration for Biodiversity Enhancement in Hong Kong

Global trends predict a continuous increase in the proportion of forest occupied by plantations up to the end of the 21st century, while a dramatic loss of biodiversity is foreseen as a result of anthropogenic exploitation and climate change. This study compares the role and performance of plantation policies in Hong Kong, with natural regeneration of secondary forest, using detailed spatio-temporal data extracted from a previous study. The study extends over a 70-year period from 1945 to 2014 using aerial photographs and satellite images of five time periods to document spatio-temporal trends in plantation forestry and natural forest succession. Field data on species richness and woody biomass at different stages of forest succession are compared with available data from plantations in the same study area. Results indicate that plantation forests support relatively few native species in the understory, with much lower species richness than naturally regenerated forest, even after 6 to 7 decades. Time-sequential maps of habitat change show that natural forest succession from barren grassy hillsides, progressed at an annual rate of 7.8%, from only 0.2% of the landscape post WWII, to over 37% today. Plantation forestry on the other hand has been less successful, and has even acted as a barrier to natural forest regeneration, as mono-cultural plantations from the late 1960s to 1980s are still plantations today, whereas other similar areas have succeeded naturally to forest. The theory of plantations acting as a nurse crop for a woody native understory is not supported, as Pinus massoniana plantations, destroyed by two deadly nematodes during the 1970s, apparently had no woody understory, as they were seen to have reverted to grassland in 1989 and are still mainly grassland today.

Ecological Impact of Plantation Forestry on Blanket Bog on a Low Order Stream

<p>Blanket peat directly underlies between 11% and 13% of Ireland, with catchments containing more than 10% blanket bog coverage hosting the majority of Water Framework Directive High Status sites. Since 1998 approximately 40% of these sites have experienced a decline in status, with catchments having peat coverage greater than 40% experiencing disproportionate impacts. Declines in status have typically been accompanied by anthropogenic activities that have affected bog hydrology; these include planting / maturing of plantation forestry on deep peat (> 1 metre thick). Although our understanding of mechanisms driving aquatic ecosystem degradation in these areas immediately after planting and following felling has improved considerably in recent years, the impact of mature closed canopy forestry on runoff remains less well defined. Moreover, where research has been carried out, it has focused on sampling conditions during high (quick) flow, while base flow conditions have received less attention.</p><p>Comparison of runoff quality, in a stream draining a relatively intact blanket bog-covered catchment, with conditions further downstream, after it had flowed through a mature Sitka Spruce (P.sitchesnsis) plantation on deep peat, aimed to better characterise the impact of the forestry on the stream’s ecology. The study area selected for investigation receives approximately 1600 mm/yr of precipitation, occurring throughout the year (259 days with >0.2mm precipitation). Pairwise comparisons of runoff quality between areas draining open bog land and afforested areas further downstream failed to detect significant differences during high flow events. By contrast samples collected under drier conditions proved significantly more mineralised downstream, with water containing significantly higher levels of Calcium and Magnesium at the afforested area sampling point. Similarly, visual observations in forest drains feeding the stream revealed the presence of tufa mounds, which had developed following planting, and zones of focused iron oxyhydroxide-bearing groundwater upwelling; these features proved absent upstream of the forestry.</p><p>Screening for biotic status at the outlets of blanket bog and forested catchments, using the Irish biological quality rating system (Q-scores), suggested that the upstream sampling point was indicative of Good status (Q4), whilst the findings at the downstream forested site were more indicative of High status (Q4-5).   However, more detailed analysis of the species sampled suggested that although the sampling point in the forested area (downstream monitoring point) had higher biodiversity and as such allowed for the improvement in Q-score, it had slightly lower species density through lower counts of certain species. This is consistent with findings elsewhere which have highlighted the capacity of aqueous iron oxyhydroxides to detrimentally impact sensitive species, such as freshwater pearl mussel (M. margaritifera). Study results provide further evidence of the capacity of plantation forestry to impact on the aquatic ecology of low order streams, while further highlighting the need for alternative ecological metrics when investigating the impacts from human activity on lower order streams draining blanket bog.</p>

Use of a novel camera trapping approach to measure small mammal responses to peatland restoration

Small mammals, such as small rodents (Rodentia: Muroidea) and shrews (Insectivora: Soricidae), present particular challenges in camera trap surveys. Their size is often insufficient to trigger infra-red sensors, whilst resultant images may be of inadequate quality for species identification. The conventional survey method for small mammals, live-trapping, can be both labour-intensive and detrimental to animal welfare. Here, we describe a method for using camera traps for monitoring small mammals. We show that by attaching the camera trap to a baited tunnel, fixing a close-focus lens over the camera trap lens, and reducing the flash intensity, pictures or videos can be obtained of sufficient quality for identifying species. We demonstrate the use of the method by comparing occurrences of small mammals in a peatland landscape containing (i) plantation forestry (planted on drained former blanket bog), (ii) ex-forestry areas undergoing bog restoration, and (iii) unmodified blanket bog habitat. Rodents were detected only in forestry and restoration areas, whilst shrews were detected across all habitat. The odds of detecting small mammals were 7.6 times higher on camera traps set in plantation forestry than in unmodified bog, and 3.7 times higher on camera traps in restoration areas than in bog. When absolute abundance estimates are not required, and camera traps are available, this technique provides a low-cost survey method that is labour-efficient and has minimal animal welfare implications.

Plantation forestry in Malaysia: an evaluation of its successes and failures since the 1970

With reducing supply of logs from the sustainably managed natural forest to meet the processing demand of the large wood products industry in Malaysia, plantation forestry has been gaining importance since the early 1970s. Despite the government’s efforts through the provision of financial support and incentives, investments in plantation forestry has been slow. The promising start of the large-scale forest plantation programs in the early 1970s, followed by the 1980s and then the latest program in early 2000, appear to have been a mixed bag of failures and limited success. The rather below-par performance of the forest plantations has been attributed to several factors, such as insufficient good planting stock, poor species-site matching, poor soil quality, pest and diseases and the overall poor silvicultural and management regime laid out for forest plantations. Further, plantation forestry appears to be dominated by larger companies, while small and medium companies, have limited financial resources to overcome the prevailing challenges faced. Despite the poor performance until to date, the adoption of intensive research based silvicultural and management regime for the plantation forests, which are maturing in the next years, will hopefully produce better results and serve as the sunrise for plantation forestry in Malaysia.