Recent Drought-Induced Vitality Decline of Black Pine (Pinus nigra Arn.) in South-West Hungary—Is This Drought-Resistant Species under Threat by Climate Change?

Abstract

This paper analyses the recent recurring dieback and growth decline of Black pine (P. nigra Arn. var austriaca) in the Keszthely mountains of south-west Hungary, and their relations to water deficits due to droughts. These relations were studied in five stands with low soil water storage capacity for the period 1981-2016. The vitality was assessed using 60 tree-ring samples and changes in remotely sensed vegetation activity indices, i.e., the normalized difference vegetation index (NDVI) and the normalized difference infrared index (NDII). Water deficit was estimated by using meteorological drought indices such the standardized precipitation-evapotranspiration index (SPEI) and the forestry aridity index (FAI), as well as the relative extractable water (REW), calculated by the Brook90 hydrological model. Results revealed a strong dependency of annual tree ring width on the amount of water deficit as measured by all the above estimators, with the highest correlation shown by the summer REW. Droughts also showed a long-term superimposed effect on tree growth. NDII seemed to be more sensitive to drought conditions than NDVI. The robust dependency of tree growth on the summer water availability combined with the projected increasing aridity might lead to decreasing growth of Black pine in Hungary towards the end of the century. We thus argue that the suggestion by several papers that Black pine can be a possible substitute species in the Alpine and Mediterranean region in the future should be revisited.

Quantifying Growth Responses of Trees to Drought—a Critique of Commonly Used Resilience Indices and Recommendations for Future Studies

“…The majority of cases averaged growth of successive dry years [13,23,[57][58][59][60][61]. However, a few studies used the value of the last year of the drought event [62,63], and some studies did not explain how they dealt with this issue [64][65][66]. Since these two approaches (average vs. last year of drought period) are likely to yield different results, we recommend that the results obtained are at least compared for the different approaches when dealing with successive dry years.…”

Sustainability of Forest Cover under Climate Change on the Temperate-Continental Xeric Limits

“…Compared to annual allowable cut, in the peak year of salvation felling, a three times higher volume was removed and second-order trees and shrubs took over [88]. Móricz et al [107] recently published further details on Austrian (black) pine mortality. introduction of better adapted non-native species to future climatic conditions, have especially raised public controversy.…”

Freezing and Heating Tolerance of Pinus nigra Seedlings from Three South to North Balkan Provenances

“…This stress was confirmed in this study for P. nigra seedlings. P. nigra is a drought sensitive species, showing a negative tree growth trend highly correlated with increased temperature and drought in summer (in the Eastern Mediterranean [36], but in Hungary as well [37]). The results of this study showed that the exposure to moderate heat (45 • C) and short drought did increase damage to seedlings for both contrasting provenances (Grevena and Šargan), but without significant difference between them.…”