2 pp. / Other Forest Health Publications / Cypress bark beetles are native insects that often impact ornamental Arizona cypress and Leyland cypress trees. Healthy, vigorous cypress trees can usually withstand substantial beetle pressure. However, significant mortality of host tree species often occurs during periods of extended drought. Tree vigor can easily be maintained through deep, infrequent irrigation during drought periods.

Revised; Originally Published: 2003 / 2 pp.

Thesis (Doctor of Phil.) - University of KwaZulu-Natal, Pietermaritzburg, 2008. / Full text also available online. Scroll down for electronic link.

Tsuga canadensis (L.) Carr. (eastern hemlock), a long lived and shade tolerant coniferous tree species native to eastern North America, is currently threatened by the hemlock woolly adelgid (Adelges tsugae Annand, HWA). This exotic, invasive insect poses a serious threat to T. canadensis stands throughout their native range. The loss of this unique tree species is often coupled with numerous ecological consequences. HWA-induced mortality has exceeded 95% in some forest types, and will likely continue to decimate T. canadensis populations in the coming years. Shortly after HWA was found in Great Smoky Mountains National Park (GSMNP), long-term monitoring plots were established across a gradient of T. canadensis associated forest communities to monitor HWA impacts and stand decline. Our objectives were to (1) determine how T. canadensis populations have changed in conjunction with HWA infestation, and (2) document how HWA has affected vegetative community dynamics following five to six years of infestation in GSMNP. We assessed T. canadensis associated overstory communities and determined that crown density, top dieback, and T. canadensis stem density has significantly declined over the observational period. Furthermore, we found that midstory T. canadensis trees were experiencing greater rates of decline than those of the overstory. Even with these losses, overstory and midstory community composition did not significantly change from 2003 to 2008/09. Many studies have documented rapid pulses of understory vegetative productivity in conjunction with T. canadensis defoliation, which often allows increased amounts of solar radiation to reach the forest floor. Although we observed significant T. canadensis mortality at most plots sampled, understory species composition did not significantly change following HWA infestation. We attribute this lack of species response to the overwhelming abundance of Rhododendron maximum in the mid/understory, which restricts increased light from reaching the forest floor despite the formation of small overstory gaps. However, we found that understory composition significantly varied among ecological groupings, and differences were largely associated with soil properties and elevation. Overall, results of this project suggest that T. canadensis may largely disappear from southern Appalachian forests resulting from infestations of HWA. Although community composition of T. canadensis associated stands has not yet been altered, changes are likely to occur as duration of infestation progresses.

Eastern hemlock (Tsuga canadensis [L.] Carr.) is a foundation species that occupies a unique niche in forest ecosystems and which often forms pure stands throughout the eastern United States. Throughout the last half of a century, widespread mortality of T. canadensis had been occurring with the introduction of the invasive pest, hemlock woolly adelgid (Adelges tsugae Annand) (HWA). HWA now threatens to destroy millions of hectares of hemlock dominated forests and to disrupt its associated ecosystems. In order to determine how HWA impacts hemlock physiology, three sites with various degrees of infestation were chosen and half of the trees at each site were treated with imidacloprid (Merit® 2 F, Bayer, Kansas City, MO) while the rest were left untreated. Needle gas exchange was assessed monthly using a LI-COR 6400 portable open path gas exchange system (LI-COR Inc, Lincoln NE). Chlorophyll fluorescence and bud break were also characterized for all trees at two of the three sites. After one complete growing season, we found a slight increase in photosynthetic rates (4.98 %), increased bud break at Fishburn (562 %) and Mountain Lake (25.6 %) sites, and no change in chlorophyll fluorescence for imidacloprid treated trees. These results suggest that HWA is causing tree mortality largely through a reduction of leaf area and not a reduction in leaf level photosynthetic capacity. By quantifying the physiological response of T. canadensis to HWA, better insights can be made into understanding tree decline as it relates to HWA. / Master of Science

Northeastern forests are being impacted by unprecedented environmental stressors, including acid deposition, invasive pests, and climate change. Forest health monitoring at a landscape scale is necessary to evaluate the changing condition of forest resources and to inform management of forest stressors. Traditional forest health monitoring is often limited to specific sites experiencing catastrophic decline or widespread mortality. Satellite remote sensing can complement these efforts by providing comprehensive forest health assessments over broad regions. Subtle changes in canopy health can be monitored over time by applying spectral vegetation indices to multitemporal satellite imagery. This project used historical archives of Landsat-5 TM imagery and geographic information systems to examine forest health trends in the northern Green Mountains of Vermont from 1984 to 2009. Results indicate that canopy health has remained relatively stable across most of the landscape, although decline was present in localized areas. Significant but weak relationships were discovered between declining forest health and spruce-fir-paper birch forests at high elevations. Possible causes of decline include the interacting effects of acid deposition, windthrow, and stressful growing environments typical of montane forests.

The global climate is changing; there are many predictions about the ecological impacts, and even more uncertainty. Predicted ecological impacts include northward shifting biomes, invasive species, decoupling of biotic interactions, all of which are threats to the ecological integrity (EI) of Canada’s National Parks System. To maintain EI, parks must be managed for resilience with climate change in mind. Lack of human and financial resources are restrictions to managing for climate change, challenges exacerbated by government cutbacks in 2012. To overcome these restrictions a tool for informing management in a climate was designed using an existing research program and management based scenario building at the case study location of Bruce Peninsula National Park (BPNP). The tool designed for informing management is called Scenario Building, which accounts for uncertainty and focuses on the essential drivers of the local ecological community. Diversity and health in the forest community are essential drivers in the BPNP ecosystem with interactions at many tropic levels so the forest health research program was selected as the basis for scenarios. Results show a range of tree species that require a variety of soil and moisture regimes. Understanding the ecology of the keystone forest species allows for understanding of how they may reacted to predicted climate changes. Regional climate predictions based on the A2 and B1 primary climate scenarios of the IPCC were integrated with the forest health data, and two levels management option- passive and active to develop 4 scenarios that can inform management of the park. Passive and active management were defined by the number of dollars spent on active management. The 4 scenarios developed were: Scenario 1 B1 Passive Management - Status Quo, Scenario 2 B1 Active Management - Regional Resilience, Scenario 3 A2 Passive Management - Evolving Forests, Scenario 4 A2 Active Management- Anticipatory Restoration. A set of scenarios allows managers to set a management trajectory balances resilience and EI with economic viability in the face of climate change. Analysis of the BPNP scenario suite tell us that BPNP is one park that is in a good position to be able to adapt to a changing climate without major risk to EI, however significant steps can be taken to minimize losses or even improve EI by anticipating needs and investing in active management.

Bendrą šalies miškų sanitarinę būklę ženkliai veikia paprastosios pušies ir paprastosios eglės formuojamų grynų arba mišrių medynų sveikatingumas, kadangi šios dvi spygliuočių rūšys užima daugiau nei pusę (56,1 %) šalies medynų ploto. Nors per paskutinį dešimtmetį pušynų plotas padidėjo 9,7 tūkst. ha, tačiau šalies eglynų plotas per tą patį laikotarpį sumažėjo 16,2 tūkst. ha. Kaip viena iš galimų paprastosios eglės formuojamų medynų mažėjimą sukeliančių priežasčių gali būti įvardytas gamtinių veiksnių sukeliamų pažeidimų eglynuose skaičiaus didėjimas. Šių veiksnių įtaka Lietuvos spygliuočių būklei bei kaitos tendencijos įgyja nemažai svarbos besikeičiančio klimato sąlygomis. Šio baigiamojo magistro darbo tikslas – pagal miškų monitoringo duomenis nustatyti biotinių ir abiotinių medžių pažeidimų kaitos pokyčių tendencijas šalies eglynuose ir pušynuose bei įvertinti galimą klimato kaitos įtaką spygliuočių pažeidžiamumui. Pagal miškų monitoringo duomenis nustatytas gamtinių veiksnių pažeidimų skaičius paprastosios eglės ir paprastosios pušies formuojamuose medynuose leido įvertinti šių medžių rūšių pažeidžiamumo kaitą 1989-2013 metų laikotarpiu. Pažeidimų gausos kitimo vertinimui naudota koreliacinė analizė, o vizualiai identifikuojamų pažeidimų poveikis medžio būklei įvertintas paskaičiavus skirtumus tarp pažeidimo požymius turinčių ir jų neturinčių medžių vidutinės lajos defoliacijos. Taip pat analizuotas ir medžių pažeidimų pasiskirstymas pagal tam tikras klimato sąlygas... [toliau žr. visą tekstą] / The condition of coniferous tree species is the main cause of all country forest health because of high proportion of coniferous stands in a country forests. These species cover more than half (56,1 %) of forest land. The area of Scots pine stands expanded by 9700 ha over the last ten years while the area of Norway spruce reduced by 16200 ha during the same period. Damages of biotic and abiotic factors may be called as the one of main cause of this reduction in spruce stands. Moreover the influence of the state of coniferous tree species by these factors increases under the climate change. The aim of this Master thesis is to establish the extent of biotic and abiotic damages and its changes in coniferous stands in Lithuania according to the forest monitoring data and to evaluate the possible influence of climate change to vulnerability of these tree species. According to forest monitoring data the number of biotic and abiotic damages in Norway spruce and Scots pine stands helped to evaluate the tendency of vulnerability of these tree species during the 1989-2013. Moreover, the correlation analysis revealed the changes in the extent of trees’ damages and the influence of visually identifiable damages on the condition of tree has been determined by subtracting the average overgrowth’s defoliation of undamaged trees from damaged trees. Also the distribution of tree damages in different climatic regions in a country was analysed to evaluate the impact of climate change in... [to full text]

Thesis (Ph. D.)--Carleton University, 2001. / Includes bibliographical references (p. 221-249). Also available in electronic format on the Internet.

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