Increased Litter Greatly Enhancing Soil Respiration in Betula platyphylla Forests of Permafrost Region, Northeast China

Abstract

The change of litter input can affect soil respiration (Rs) by influencing the availability of soil organic carbon and nutrients, regulating soil microenvironments, thus resulting in a profound influence on soil carbon cycle of the forest ecosystem. We conducted an aboveground litterfall manipulation experiment in different-aged Betula platyphylla forests (25-, 40- and 61-year-old) of the permafrost region, located in the northeast of China, during May to October in 2018, with each stand treated with doubling litter (litter addition, DL), litter exclusion (no-litter, NL) and control litter (CK). Our results indicated that Rs decreased under NL treatment compared with CK treatment. The effect size lessened with the increase in the stand age; the greatest reduction was found for young Betula platyphylla forest (24.46% for 25-year-old stand) and tended to stabilize with the growth of forest with the reduction of 15.65% and 15.23% for 40-and 61- year-old stands, respectively. Meanwhile, under DL treatment, Rs increased by 27.38%, 23.83% and 23.58% on 25-, 40- and 61-year-old stands, respectively. Our results also showed that the increase caused by DL treatment was larger than the reduction caused by NL treatment, leading to a priming effect, especially on 40- and 61-year-old stands. The change in litter input was the principal factor affecting the change of Rs under litter manipulation. The soil temperature was also a main factor affecting the contribution rate of litter to Rs of different-aged stands, which had a significant positive exponential correlation with Rs. This suggests that there is a significant relationship between litter and Rs, which consequently influences the soil carbon cycle in Betula platyphylla forests of the permafrost region, Northeast China. Our finding indicated the increased litter enhanced the Rs in Betula platyphylla forest, which may consequently increase the carbon emission in a warming climate in the future. It is of great importance for future forest management in the permafrost region, Northeast China.

Strong Responses of Soil Greenhouse Gas Fluxes to Litter Manipulation in a Boreal Larch Forest, Northeastern China

“…On the contrary, increased plant litter inputs could increase litter decomposition because the priming effects resulting from the litter increase could accelerate the decomposition of organic matter and enhance soil respiration [13,50]. This priming effect was also reported in our study area [51], which is another reason explaining the high CO 2 fluxes in the LD treatment. Meanwhile, soil CO 2 fluxes were also positively related to soil temperature (Figure 5a), the main factor affecting seasonal variations in soil GHG fluxes (Tables 2 and 3).…”

Soil Microbial Community in Relation to Soil Organic Carbon and Labile Soil Organic Carbon Fractions under Detritus Treatments in a Subtropical Karst Region during the Rainy and Dry Seasons

“…Although research exploring how different two-factor or single-factor treatments affect the soil microbial community is comparably adequate, it is still largely unknown whether a variation in the amount of detritus removed or added impacts soil microbial communities in various climates differently. Previous work suggests that the sizes of detritus inputs will shift with climate change [19]. Via their alteration of soil carbon and nutrient content, climate change and detritus disturbance have the potential to influence the compositions of microbial communities [20].…”

Spatial Variation of Microbial Community Structure and Its Driving Environmental Factors in Two Forest Types in Permafrost Region of Greater Xing′an Mountains

“…The cold and humid environment sustains the growth of L. gmelinii forests and the occurrence of permafrost [13]. Betula platyphylla is the widely distributed secondary forest as a pioneer species in this region, which accounts for 41.59% and 41.15% of the total forest stock and the total forest area, respectively [14]. In recent years, the southern boundary of permafrost in the region has shifted northward by approximately 50-120 km with the superposition of climate warming and human activities, resulting in a dramatic reduction in the native forest zone dominated by L. gmelinii and the replacement of the primeval L. gmelinii forests by secondary B. platyphylla forests.…”